National Library of Energy BETA

Sample records for neutron scattering techniques

  1. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    SciTech Connect (OSTI)

    Overbury, Steven {Steve} H; Coates, Leighton; Herwig, Kenneth W; Kidder, Michelle

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  2. Dynamic neutron scattering on incoherent systems using efficient resonance spin flip techniques

    SciTech Connect (OSTI)

    Hussler, Wolfgang [Heinz Maier-Leibnitz Zentrum, Technische Universitt Mnchen, D-85748 Garching, Germany and Physik-Department E21, Technische Universitt Mnchen, D-85748 Garching (Germany); Kredler, Lukas [Physik-Department E21, Technische Universitt Mnchen, D-85748 Garching (Germany)

    2014-05-15

    We have performed numerical ray-tracing Monte-Carlo-simulations of incoherent dynamic neutron scattering experiments. We intend to optimize the efficiency of incoherent measurements depending on the fraction of neutrons scattered without and with spin flip at the sample. In addition to conventional spin echo, we have numerically and experimentally studied oscillating intensity techniques. The results point out the advantages of these different spin echo variants and are an important prerequisite for neutron resonance spin echo instruments like RESEDA (FRM II, Munich), to choose the most efficient technique depending on the scattering vector range and the properties of the sample system under study.

  3. Improved Technique of Hydrogen Content Analysis by Slow Neutron Scattering

    DOE R&D Accomplishments [OSTI]

    Rainwater, L. J.; Havens, W. W. Jr.

    1945-02-28

    A slow-neutron-transmission method fro determining the H content of fluorcarbons is described (G.Y.)

  4. MAGNETIC NEUTRON SCATTERING

    SciTech Connect (OSTI)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science

  5. Lujan Neutron Scattering Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    responds to radiological incident August 27, 2012 The Laboratory is investigating the inadvertent spread of Technetium 99 by employees and contractors at the Lujan Neutron Scattering Center August 27, 2012-The Laboratory is investigating the inadvertent spread of Technetium 99 by employees and contractors at the Lujan Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE), a multidisciplinary accelerator facility used for both civilian and national security research. The

  6. Characterization of porous materials using combined small-angle X-ray and neutron scattering techniques

    SciTech Connect (OSTI)

    Hu, Naiping; Borkar, Neha; Kohls, Doug; Schaefer, Dale W. (UCIN)

    2014-09-24

    A combination of ultra small angle X-ray scattering (USAXS) and ultra small angle neutron scattering (USANS) is used to characterize porous materials. The analysis methods yield quantitative information, including the mean skeletal chord length, mean pore chord length, skeletal density, and composition. A mixed cellulose ester (MCE) membrane with a manufacturer-labeled pore size of 0.1 {mu}m was used as a model to elucidate the specifics of the method. Four approaches describing four specific scenarios (different known parameters and form of the scattering data) are compared. Pore chords determined using all four approaches are in good agreement with the scanning electron microscopy estimates but are larger than the manufacturer's nominal pore size. Our approach also gives the average chord of the skeletal solid (struts) of the membrane, which is also consistent for all four approaches. Combined data from USAXS and USANS gives the skeletal density and the strut composition.

  7. Neutron scatter camera

    DOE Patents [OSTI]

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  8. SciTech Connect: "neutron scattering"

    Office of Scientific and Technical Information (OSTI)

    neutron scattering" Find + Advanced Search Term Search Semantic Search Advanced Search All Fields: "neutron scattering" Semantic Semantic Term Title: Full Text: Bibliographic...

  9. Phase Concentration Determination of Fe16N2 Using State of the Art Neutron Scattering Techniques

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bennett, S. P.; Feygenson, M.; Jiang, Y.; Zande, B. J.; Zhang, X.; Sankar, S. G.; Wang, J. P.; Lauter, V.

    2016-03-25

    Limitation on the availability of rare earth elements have made it imperative that new high energy product rare earth free permanent magnet materials are developed for the next generation of energy systems. One promising low cost permanent magnet candidate for a high energy magnet is -Fe16N2, whose giant magnetic moment has been predicted to be well above any other from conventional first principles calculations. Despite its great promise, the phase is metastable; making synthesis of the pure phase difficult, resulting in less than ideal magnetic characteristics. This instability gives way to a slew of possible secondary phases (i.e. -Fe, Fe2O3,more » Fe8N, Fe4N ) whose concentrations are difficult to detect by conventional x-ray diffraction. Moreover, we show how high resolution neutron diffraction and polarized neutron reflectometry can be used to extract the phase concentration ratio of the giant magnetic phase from ultra-small powder sample sizes (~0.1g) and thin films. These studies have led to the discovery of promising fabrication methods for both homogeneous thin films, and nanopowders containing the highest reported to date (>95%) phase concentrations of room temperature stable -Fe16N2.« less

  10. Call issued for Lujan Neutron Scattering Center proposals

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    (polarized and unpolarized) Inelastic neutron scattering spectroscopy Small angle neutron scattering Neutron radiographytomography The Lujan instruments webpage...

  11. Neutron scattering and absorption properties

    SciTech Connect (OSTI)

    Holden, N.E.

    1993-12-01

    The Table in this report presents an evaluated set of values for the experimental quantities, which characterize the properties for scattering and absorption of neutrons. The neutron cross section is given for room temperature neutrons, 20.43{degree}C, corresponds to a thermal neutron energy of 0.0253 electron volts (eV) or a neutron velocity of 2200 meters/second. The neutron resonance integral is defined over the energy range from 0.5 eV to 0.1 {times} 10{sup 6} eV, or 0.1 MeV. A list of the major references used is given below. The literature cutoff data is October 1993. Uncertainties are given in parentheses. Parentheses with two or more numbers indicate values to the excited states(s) and to the ground state of the product nucleus.

  12. 10th LANSCE School on Neutron Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    10th LANSCE School on Neutron Scattering LANSCE 10th LANSCE School on Neutron Scattering Home Abstract Lecturers Hands-On Experiments Free Day About the School Sponsors FAQ's...

  13. Neutron inelastic scattering in natural Pb as a background in...

    Office of Scientific and Technical Information (OSTI)

    SCATTERING; ISOTOPES; LEAD; LEAD 206; LEAD 207; LEVELS; NEUTRONS; SCATTERING Inelastic neutron scattering on Pb isotopes can result in gamma rays near the signature endpoint...

  14. Adsorption of Supercritical CO2 in Aeroglass Studied by Small--Angle Neutron Scattering and Neutron Transmission Techniques

    SciTech Connect (OSTI)

    Melnichenko, Yuri B [ORNL; Wignall, George D [ORNL; Cole, David R [ORNL; Frielinghaus, H. [Forschungszentrum Julich, Julich, Germany

    2006-01-01

    Small-angle neutron scattering (SANS) has been used to study the adsorption behavior of supercritical carbon dioxide (CO{sub 2}) in porous Vycor glass and silica aerogels. Measurements were performed along two isotherms (T = 35 and 80 C) as a function of pressure (P) ranging from atmospheric up to 25 MPa, which corresponds to the bulk fluid densities ranging from {rho}CO{sub 2} - 0 to 0.9 g/cm{sup 3}. The intensity of scattering from CO{sub 2}-saturated Vycor porous glass can be described by a two-phase model which suggests that CO{sub 2} does not adsorb on the pore walls and fills the pore space uniformly. In CO{sub 2}-saturated aerogels an adsorbed phase is formed with a density substantially higher that of the bulk fluid, and neutron transmission data were used to monitor the excess adsorption at different pressures. The results indicate that adsorption of CO{sub 2} is significantly stronger in aerogels than in activated carbons, zeolites, and xerogels due to the extremely high porosity and optimum pore size of these materials. SANS data revealed the existence of a compressed adsorbed phase with the average density - 1.07 g/cm{sup 3}, close to the density corresponding to closely packed van der Waals volume of CO{sub 2}. A three-phase model [W. L. Wu, Polymer 23, 1907 (1982)] was used to estimate the volume fraction {phi}{sub 3} of the adsorbed phase as a function of the fluid density, and gave {phi}{sub 3} - 0.78 in the maximum adsorption regime around {rho}CO{sub 2} - 0.374 g/cm{sup 3}. The results presented in this work demonstrate the utility of SANS combined with the transmission measurements to study the adsorption of supercritical fluids in porous materials.

  15. Neutron and X-ray Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutron and X-ray Scattering Neutron and X-ray Scattering When used together, neutrons and high-energy x-rays provide a supremely powerful scientific tool for mining details about the structure of materials. Combining neutrons and high-energy x-rays to explore the frontiers of materials in extreme environments. Illuminating previously inaccessible time and spatial scales. Enabling in situ research to design, discover, and control materials. Get Expertise Donald Brown Email Pushing the limits of

  16. Evaluation of Neutron Elastic Scatter (NES) technique for detection of graphitic corrosion in gas cast iron pipe. Final report, March 1996-April 1997

    SciTech Connect (OSTI)

    Charatis, G.; Hugg, E.; McEllistrem, M.

    1997-04-01

    PENETRON, Inc., in two phases, demonstrated the effectiveness of its Neutron elastic Scatter (NES) techniques in detecting the change in the carbon weight percentage (CWt%) as a measure of corrosion in gray cast iron pipe. In Phase I, experiments were performed with synthetic standards supplied by IIT Research Institute (IITRI) to test the applicability of the NES techniques. Irradiation experiments performed at the University of Kentucky showed that CWt% could be detected, ranging from 1.6% to 13%, within an uncertainty of around 4%. In Phase II, experiments were performed on seven (7) corroded pipe sections supplied by MichCon. Tests were made on pipe sliced lengthwise into quarter sections, and in re-assembled whole pipe sections. X-ray films of the quarter sections indicated probable areas of corrosion for each quarter section.

  17. Neutron scattering studies of premartensitic phenomena

    SciTech Connect (OSTI)

    Shapiro, S.M.

    1989-01-01

    Elastic neutron diffraction and inelastic neutron scattering are ideal techniques for studying premartensitic behavior in metallic alloys. By necessity, real, bulk samples are probed replete with their intrinsic defects. Also, because of the properties of the neutron it is straightforward to probe the behavior of the phonon modes away from the zone center which is probed in the normal ultrasonic techniques. A wide variety of alloys exhibiting martensitic transformations have been studied. It will be shown that most systems undergoing diffusionless transformations exhibit premartensitic behavior in that precursor effects are seen at temperatures well above the martensitic transformation temperature, T{sub M}. This behavior manifests itself in an anomalous temperature dependence of the energy of a particular phonon mode as the temperature approaches T{sub M}. The wavevector of this mode is frequently away from the zone center (i.e., q {ne} O). This softening is nearly always accompanied by elastic diffuse scattering at the same wavevector. Particular examples to be discussed are the alkali metals, {omega}-phase materials and Ni-based alloys. 34 refs., 9 figs.

  18. Scattering Techniques and Geometries

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    grains - Thin films - Texture (crystallite orientation) - Real time experiments (electrochemistry, stress-strain) Get to know your beamlines incident scattered Detector Q...

  19. American Conference on Neutron Scattering 2014

    SciTech Connect (OSTI)

    Dillen, J. Ardie

    2014-12-31

    Scientists from the around the world converged in Knoxville, TN to have share ideas, present technical information and contribute to the advancement of neutron scattering. Featuring over 400 oral/poster presentations, ACNS 2014 offered a strong program of plenary, invited and contributed talks and poster sessions covering topics in soft condensed matter, hard condensed matter, biology, chemistry, energy and engineering applications in neutron physics – confirming the great diversity of science that is enabled by neutron scattering.

  20. 2012 LANSCE Neutron Scattering School | Los Alamos National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2 LANSCE Neutron Scattering School LANSCE 2012 LANSCE Neutron Scattering School Home About the School Hands-On Experiments Quick Links Application - Closed Schedule Poster...

  1. 2012 LANSCE Neutron Scattering School | Los Alamos National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1 LANSCE Neutron Scattering School LANSCE 2011 LANSCE Neutron Scattering School Home NSS 2011 About the School Lecturers Hands-On Experiments Quick Links Application Schedule...

  2. Application of Neutron Imaging and Scattering to Fluid Flow and...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS ...

  3. Neutron scattering of iron-based superconductors (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Neutron scattering of iron-based superconductors Citation Details In-Document Search Title: Neutron scattering of iron-based superconductors Low-energy spin excitations have been...

  4. Quasielastic Neutron Scattering Study of Water Confined in Carbon...

    Office of Scientific and Technical Information (OSTI)

    Quasielastic Neutron Scattering Study of Water Confined in Carbon Nanopores Citation Details In-Document Search Title: Quasielastic Neutron Scattering Study of Water Confined in...

  5. Electroweak bremsstrahlung from neutron-neutron scattering

    SciTech Connect (OSTI)

    Li Yi; Liou, M. K.; Schreiber, W. M.

    2009-09-15

    Background: Nucleon-nucleon (NN) bremsstrahlung processes NN{gamma} (nn{gamma}, np{gamma}, and pp{gamma}) have been extensively investigated. Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering NN{nu}{nu} (nn{nu}{nu}, np{nu}{nu}, and pp{nu}{nu}) have recently attracted attention in studies of neutrino emission in neutron stars. The calculated NN{nu}{nu} cross sections (or emissivities) are found to be sensitive to the two-nucleon dynamical model used in the calculations. Purpose and Method: A realistic one-boson-exchange (ROBE) model for NN interactions is used to construct the electroweak bremsstrahlung amplitudes using the well-known nucleon electromagnetic and weak interaction vertices. The constructed nn{gamma} and nn{nu}{nu} amplitudes are investigated by applying them to calculate nn{gamma} and nn{nu}{nu} cross sections, respectively. Results: (i) The 190-MeV ROBE nn{gamma} cross sections agree well with those calculated using the TuTts amplitude, but they are in disagreement with those calculated using the Low amplitude. (ii) The calculated nn{nu}{nu} cross sections using the ROBE amplitude at the neutrino-pair energy {omega} = 1 MeV are in quantitative agreement with those calculated by Timmermans et al.[Phys. Rev. C 65, 064007 (2002)], who used the leading-order term of the soft neutrino-pair bremsstrahlung amplitude. Conclusions: The nn{gamma} amplitude in the ROBE approach, which obeys the soft-photon theorem, has a predictive power similar to that of the TuTts amplitude. The nn{nu}{nu} amplitude in the ROBE approach, which is consistent with the soft neutrino-pair bremsstrahlung theorem, has a predictive power similar to that of the soft neutrino-pair bremsstrahlung amplitude of Timmermans et al. in the low neutrino-pair energy region.

  6. Solutions for implementing time-of-flight techniques in low-angle neutron scattering, as realized on the Low-Q Diffractometer at Los Alamos

    SciTech Connect (OSTI)

    Hjelm, R.P. Jr.; Seeger, P.A.

    1992-12-01

    The implementation of small-angle (Low-momentum transfer) neutron scattering at pulsed spallation sources, using time of flight methods, has meant the introduction of some new ideas in instrument design, data acquisition, data reduction and computer management of the experiment and the data. Here we recount some of the salient aspects of solutions for implementing time of fight small-angle neutron scattering instruments at pulsed sources, as realized on the Low-Q Diffractometer, LQD, at Los Alamos. We consider, fortlier, some of the problems that are yet to be solved, and take a short excursion into the future of SANS instrumentation at pulsed sources.

  7. A New Polyethylene Scattering Law Determined Using Inelastic Neutron Scattering

    SciTech Connect (OSTI)

    Lavelle, Christopher M [ORNL; Liu, C [Oak Ridge National Laboratory (ORNL); Stone, Matthew B [ORNL

    2013-01-01

    Monte Carlo neutron transport codes such as MCNP rely on accurate data for nuclear physics cross-sections to produce accurate results. At low energy, this takes the form of scattering laws based on the dynamic structure factor, S (Q, E). High density polyethylene (HDPE) is frequently employed as a neutron moderator at both high and low temperatures, however the only cross-sections available are for T =300 K, and the evaluation has not been updated in quite some time. In this paper we describe inelastic neutron scattering measurements on HDPE at 5 and 300 K which are used to improve the scattering law for HDPE. We describe the experimental methods, review some of the past HDPE scattering laws, and compare computations using these models to the measured S (Q, E). The total cross-section is compared to available data, and the treatment of the carbon secondary scatterer as a free gas is assessed. We also discuss the use of the measurement itself as a scattering law via the 1 phonon approximation. We show that a scattering law computed using a more detailed model for the Generalized Density of States (GDOS) compares more favorably to this experiment, suggesting that inelastic neutron scattering can play an important role in both the development and validation of new scattering laws for Monte Carlo work.

  8. 11th LANSCE School on Neutron Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    11th LANSCE School on Neutron Scattering LANSCE » 11th LANSCE School on Neutron Scattering Home Abstract Lecturers Lecturer Abstracts Hands-On Experiments Free Day About the School Sponsors FAQ's Quick Links Application - Closed Reference Form - closed Schedule- tentative Poster Contacts School: neutronschool@lanl.gov School Co-Directors: A. Llobet allobet@lanl.gov H. Nakotte hnakotte@nmsu.edu Local Organizing Committee: Edwin Fohtung (Co-Chair) efohtung@nmsu.edu Ph:575.646.5631 Graham King

  9. 11th LANSCE School on Neutron Scattering | About the School

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    students calculate results About the LANSCE School on Neutron Scattering The annual Los Alamos Neutron Science Center (LANSCE) School on Neutron Scattering is 9- to 10-day school focusing on specific science topics to which neutron scattering makes a critical impact. The focus-driven agenda makes it distinct from other neutron schools in the nation. The LANSCE Neutron Scattering School began in 2004 and it has had a continuous and successful run to this day. General School Format The first day

  10. Event-Based Processing of Neutron Scattering Data

    SciTech Connect (OSTI)

    Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; Taylor, Russell J.; Zikovsky, Janik L.

    2015-09-16

    Many of the world's time-of-flight spallation neutrons sources are migrating to the recording of individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode that preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final errors, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniques will be shown for comparison.

  11. A short note on physical properties to irradiated nuclear fuel by means of X-ray diffraction and neutron scattering techniques

    SciTech Connect (OSTI)

    Abdullah, Yusof Husain, Hishamuddin; Hak, Cik Rohaida Che; Alias, Nor Hayati; Yusof, Mohd Reusmaazran; Kasim, Norasiah Ab; Zali, Nurazila Mat; Mohamed, Abdul Aziz

    2015-04-29

    For nuclear reactor applications, understanding the evolution of the fuel materials microstructure during irradiation are of great importance. This paper reviews the physical properties of irradiated nuclear fuel analysis which are considered to be of most importance in determining the performance behavior of fuel. X-rays diffraction was recognize as important tool to investigate the phase identification while neutron scattering analyses the interaction between uranium and other materials and also investigation of the defect structure.

  12. Room-return scattering in fission neutron outputs (Conference...

    Office of Scientific and Technical Information (OSTI)

    Room-return scattering in fission neutron outputs Citation Details In-Document Search Title: Room-return scattering in fission neutron outputs You are accessing a document from...

  13. Optimizing Moderator Dimensions for Neutron Scattering at the Spallation Neutron Source

    SciTech Connect (OSTI)

    Zhao, Jinkui [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL; Gallmeier, Franz X [ORNL; Riemer, Bernie [ORNL

    2013-01-01

    In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source. In a recent study of the planned second target station at the Spallation Neutron Source (SNS) facility [1,2], we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter for a smaller viewing area [4]. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories, those with natural collimation and those that use neutron guide systems. We found that the cross-sections of the sample and the neutron guide, respectively, are the deciding factors for choosing the moderator. Beam divergence plays no role as long as it is within the reach of practical constraints. Namely, the required divergence is not too large for the guide or sample to be located close enough to the moderator on an actual spallation source.

  14. Crystals for neutron scattering studies of quantum magnetism

    SciTech Connect (OSTI)

    Yankova, Tantiana; Hüvonen, Dan; Mühlbauer, Sebastian; Schmidiger, David; Wulf, Erik; Hong, Tao; Garlea, Vasile O; Custelcean, Radu; Ehlers, Georg

    2012-01-01

    We review a strategy for targeted synthesis of large single crystal samples of prototype quantum magnets for inelastic neutron scattering experiments. Four case studies of organic copper halogenide S = 1/2 systems are presented. They are meant to illustrate that exciting experimental results pertaining to the forefront of many-body quantum physics can be obtained on samples grown using very simple techniques, standard laboratory equipment, and almost no experience in advanced crystal growth techniques.

  15. Contraband detection via neutron elastic scattering

    SciTech Connect (OSTI)

    Gomberg, H.J.; Charatis, G.; Brundage, J.

    1993-04-01

    Reliable detection of explosives and narcotics depends on generating signatures of compounds which characterize them. Major explosives and also alkaloid narcotics contain unique concentrations of Carbon (C), Nitrogen (N), and Oxygen (O). The kinematic energy shifts of neutrons scattered through angles larger than 140{degrees} allows separate determinations of C, N, and O; ratios of N/C and O/C together give clear signatures of the presence of plastic explosives or narcotics. The ability to detect these signatures under conditions similar to those that would obtain for airport screening has been demonstrated for neutrons for energies less {le} 3 MeV. Strong N resonances and a deep window for scattering from O enhance the confidence of element quantification. Detection of contraband in large cargo containers presents a much more difficult problem. Use of higher energy neutrons is now being tested for shielding penetration, so narcotic signatures could be identified behind the shielding of cargo containers. Scattered neutron spectra, or {open_quotes}signatures{close_quotes} of different organic compounds will be presented.

  16. Optimizing moderator dimensions for neutron scattering at the spallation neutron source

    SciTech Connect (OSTI)

    Zhao, J. K.; Robertson, J. L.; Herwig, Kenneth W.; Gallmeier, Franz X.; Riemer, Bernard W. [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2013-12-15

    In this work, we investigate the effect of neutron moderator dimensions on the performance of neutron scattering instruments at the Spallation Neutron Source (SNS). In a recent study of the planned second target station at the SNS facility, we have found that the dimensions of a moderator play a significant role in determining its surface brightness. A smaller moderator may be significantly brighter over a smaller viewing area. One of the immediate implications of this finding is that for modern neutron scattering instrument designs, moderator dimensions and brightness have to be incorporated as an integrated optimization parameter. Here, we establish a strategy of matching neutron scattering instruments with moderators using analytical and Monte Carlo techniques. In order to simplify our treatment, we group the instruments into two broad categories: those with natural collimation and those that use neutron guide systems. For instruments using natural collimation, the optimal moderator selection depends on the size of the moderator, the sample, and the moderator brightness. The desired beam divergence only plays a role in determining the distance between sample and moderator. For instruments using neutron optical systems, the smallest moderator available that is larger than the entrance dimension of the closest optical element will perform the best (assuming, as is the case here that smaller moderators are brighter)

  17. Neutron scattering effects on fusion ion temperature measurements.

    SciTech Connect (OSTI)

    Ziegler, Lee; Starner, Jason R.; Cooper, Gary Wayne; Ruiz, Carlos L.; Franklin, James Kenneth; Casey, Daniel T.

    2006-06-01

    To support the nuclear fusion program at Sandia National Laboratories (SNL), a consistent and verifiable method to determine fusion ion temperatures needs to be developed. Since the fusion temperature directly affects the width in the spread of neutron energies produced, a measurement of the neutron energy width can yield the fusion temperature. Traditionally, the spread in neutron energies is measured by using time-of-flight to convert a spread in neutron energies at the source to a spread in time at detector. One potential obstacle to using this technique at the Z facility at SNL is the need to shield the neutron detectors from the intense bremsstrahlung produced. The shielding consists of eight inches of lead and the concern is that neutrons will scatter in the lead, artificially broaden the neutron pulse width and lead to an erroneous measurement. To address this issue, experiments were performed at the University of Rochester's Laboratory for Laser Energetics, which demonstrated that a reliable ion temperature measurement can be achieved behind eight inches of lead shielding. To further expand upon this finding, Monte Carlo N-Particle eXtended (MCNPX) was used to simulate the experimental geometric conditions and perform the neutron transport. MCNPX was able to confidently estimate results observed at the University of Rochester.

  18. Scattered Neutron Tomography Based on A Neutron Transport Inverse Problem

    SciTech Connect (OSTI)

    William Charlton

    2007-07-01

    Neutron radiography and computed tomography are commonly used techniques to non-destructively examine materials. Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions.

  19. Event-Based Processing of Neutron Scattering Data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; Taylor, Russell J.; Zikovsky, Janik L.

    2015-09-16

    Many of the world's time-of-flight spallation neutrons sources are migrating to the recording of individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode that preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final errors, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniquesmore » will be shown for comparison.« less

  20. 11th LANSCE School on Neutron Scattering | FAQ's

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Frequently Asked Questions Who can apply? The LANSCE School on Neutron Scattering is intended primarily for graduate students & post-docs in the topical area of that year's school. Undergraduate students applying to the school, who plan on pursuing an advanced degree after graduation, will be taken into consideration. What are the main objectives of the school? to attract new users to the neutron-scattering community, to increase diversity among expert neutron scatterers, to broaden the

  1. International Conference on Neutron Scattering (ICNS2009) May...

    Office of Scientific and Technical Information (OSTI)

    Title: International Conference on Neutron Scattering (ICNS2009) May 3-7, 2009, Knoxville, TN, USA No abstract prepared. Authors: Smith, Gregory Scott 1 ; Ekkebus, Allen E 1 + ...

  2. OSTIblog Articles in the neutron scattering Topic | OSTI, US...

    Office of Scientific and Technical Information (OSTI)

    X-ray scattering has been used to gather clues about materials' atomic structures for about a century. Once reactors were built that could provide intense neutron beams, ...

  3. BUILDING A NETWORK FOR NEUTRON SCATTERING EDUCATION (Technical...

    Office of Scientific and Technical Information (OSTI)

    to define and design a roadmap for a comprehensive neutron scattering education program in the United States. Successful implementation of the roadmap will maximize the national ...

  4. Temperature effects of resonance scattering for epithermal neutrons...

    Office of Scientific and Technical Information (OSTI)

    Title: Temperature effects of resonance scattering for epithermal neutrons in MCNP Authors: Brown, Forrest B 1 ; Kiedrowski, Brian C 1 ; Sunny, Eva E 2 ; Martin, William R ...

  5. Enhanced reaction rates in NDP analysis with neutron scattering

    SciTech Connect (OSTI)

    Downing, R. Gregory

    2014-04-15

    Neutron depth profiling (NDP) makes accessible quantitative information on a few isotopic concentration profiles ranging from the surface into the sample a few micrometers. Because the candidate analytes for NDP are few, there is little interference encountered. Furthermore, neutrons have no charge so mixed chemical states in the sample are of no direct concern. There are a few nuclides that exhibit large probabilities for neutron scattering. The effect of neutron scattering on NDP measurements has not previously been evaluated as a basis for either enhancing the reaction rates or as a source of measurement error. Hydrogen is a common element exhibiting large neutron scattering probability found in or around sample volumes being analyzed by NDP. A systematic study was conducted to determine the degree of signal change when neutron scattering occurs during analysis. The relative signal perturbation was evaluated for materials of varied neutron scattering probability, concentration, total mass, and geometry. Signal enhancements up to 50% are observed when the hydrogen density is high and in close proximity to the region of analysis with neutron beams of sub thermal energies. Greater signal enhancements for the same neutron number density are reported for thermal neutron beams. Even adhesive tape used to position the sample produces a measureable signal enhancement. Because of the shallow volume, negligible distortion of the NDP measured profile shape is encountered from neutron scattering.

  6. 11th LANSCE School on Neutron Scattering | Hands-On Experiments

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    sample picture Hands-on Experiments Students will have an opportunity to participate in experimental set-up and data-analysis of various exemplary neutron experiments in the areas of materials at the mesoscale. They will use several instruments utlizing different neutron scattering and complementary techniques. Featured Instruments (tentative) HIPPO: Texture Studies SPEAR: Study of nanoparticle assemblies with neutron reflectometry LQD: Self-Assembled Structures NPDF: Study of nanostructured

  7. Experimental methods in the study of neutron scattering at small angles

    SciTech Connect (OSTI)

    Dragolici, Cristian A.

    2014-11-24

    Small angle scattering (SAS) is the collective name given to the techniques of small angle neutron (SANS) and X-ray (SAXS) scattering. They offer the possibility to analyze particles without disturbing their natural environment. In each of these techniques radiation is elastically scattered by a sample and the resulting scattering pattern is analyzed to provide information about the size, shape and orientation of some component of the sample. Accordingly, a large number of methods and experimental patterns have been developed to ease the investigation of condensed matter by use of these techniques. Some of them are the discussed in this paper.

  8. A neutron imaging device for sample alignment in a pulsed neutron scattering instrument

    SciTech Connect (OSTI)

    Grazzi, F.; Scherillo, A.; Zoppi, M.

    2009-09-15

    A neutron-imaging device for alignment purposes has been tested on the INES beamline at ISIS, the pulsed neutron source of Rutherford Appleton Laboratory (U.K.). Its use, in conjunction with a set of movable jaws, turns out extremely useful for scattering application to complex samples where a precise and well-defined determination of the scattering volume is needed.

  9. Majewski named Fellow of the Neutron Scattering Society of America

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Majewski named Fellow of the Neutron Scattering Society of America Majewski named Fellow of the Neutron Scattering Society of America The Society recognized Majewski for "contributions to our understanding of weakly organized two-dimensional systems, including surfactant molecules found in biological systems." May 9, 2016 Jaroslaw (Jarek) Majewski Jaroslaw (Jarek) Majewski Communications Office (505) 667-7000 The American Physical Society named him as Fellow for his contributions to

  10. Elastic Neutron Scattering at 96 MeV

    SciTech Connect (OSTI)

    Hildebrand, A.; Blomgren, J.; Atac, A.; Bergenwall, B.; Johansson, C.; Klug, J.; Mermod, P.; Nilsson, L.; Pomp, S.; Esterlund, M.; Dangtip, S.; Tippawan, U.; Phansuke, P.; Jonsson, O.; Renberg, P.-U.; Prokofiev, A.; Nadel-Turonski, P.; Elmgren, K.; Olsson, N.; Blideanu, V.

    2005-05-24

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20 - 180-MeV neutron beam line of The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C, 16O, 56Fe, 89Y, and 208Pb has been studied at 96 MeV in the 10-70 deg. interval. The results from 12C and 208Pb have recently been published,6 while the data from 16O, 56Fe, and 89Y are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic theory. Applications for these measurements are nuclear-waste incineration, single-event upsets in electronics, and fast-neutron therapy.

  11. 2010 American Conference on Neutron Scattering (ACNS 2010)

    SciTech Connect (OSTI)

    Billinge, Simon

    2011-06-17

    The ACNS provides a focal point for the national neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as “would-be” neutron users. The American Conference on Neutron Scattering thus serves a dual role as a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. As a “super-user” meeting, the ACNS fulfills the main objectives of users' meetings previously held periodically at individual national neutron facilities, with the advantage of a larger and more diverse audience. To this end, each of the major national neutron facilities (NIST, LANSCE, HFIR and SNS) have an opportunity to exchange information and update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities. For many of the national facilities, this super-user meeting should obviate the need for separate user meetings that tax the time, energy and budgets of facility staff and the users alike, at least in years when the ACNS is held. We rely upon strong participation from the national facilities. The NSSA intends that the American Conference on Neutron Scattering (ACNS) will occur approximately every two years, but not in years that coincide with the International or European Conferences on Neutron Scattering. The ACNS is to be held in association with one of the national neutron centers in a rotating sequence, with the host facility providing local organization

  12. Small-Angle Neutron Scattering Studies of a-Si:H and a-Si:D

    SciTech Connect (OSTI)

    Williamson, D. L.; Marr, D. W. M.; Nelson, B. P.; Iwaniczko, E.; Yang, J.; Yan, B.; Guha, S.

    2000-01-01

    The heterogeneity of hydrogen and deuterium on the nanometer scale has been probed by samll-angle neutron scattering (SANS) from a-Si:H and a-Si:D films. Films were depsoited by two techniques, plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) using conditions that yield high quality films and devices.

  13. At Los Alamos's Lujan Neutron Scattering Center, crystallographer Olivier Gourdon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    crystallographer keen on showing off the revealing properties of neutrons February 27, 2014 At Los Alamos's Lujan Neutron Scattering Center, crystallographer Olivier Gourdon shows visiting researchers some of the latest tricks that can be performed using this 100-year old multidisciplinary science, which has a spectacular record of demystifying materials as varied as DNA and Martian rocks."Crystallography has the image of an old science. I'm trying to refresh that," said Gourdon, an

  14. Neutron Scattering Data Vickie Lynch, Jose Borreguero-Calvo,

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Discovery in Neutron Scattering Data Vickie Lynch, Jose Borreguero-Calvo, Mark Hagen & Thomas Proffen Neutron Data Analysis & Visualization Division Galen Shipman & Bobby Sumpter Computational Science & Mathematics Division Center for Nanophase Materials Science Olivier Delaire Materials Science and Technology Division Oak Ridge National Laboratory NERSC 40 th Anniversary User's Meeting February 5, 2014 Analysis - "data on disk is useless" * Data on disk is

  15. A brief History of Neutron Scattering at the Oak Ridge High Flux...

    Office of Scientific and Technical Information (OSTI)

    A brief History of Neutron Scattering at the Oak Ridge High Flux Isotope Reactor Citation Details In-Document Search Title: A brief History of Neutron Scattering at the Oak Ridge ...

  16. A workshop on enhanced national capability for neutron scattering

    SciTech Connect (OSTI)

    Hurd, Alan J; Rhyne, James J; Lewis, Paul S

    2009-01-01

    This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.

  17. Neutron scattering of CeNi at the SNS-ORNL: A preliminary report

    SciTech Connect (OSTI)

    Mirmelstein, A. [Russian Federal Nuclear Center VNIITF, Snezhinsk, Russia; Podlesnyak, Andrey A [ORNL; Kolesnikov, Alexander I [ORNL; Saporov, B. [Oak Ridge National Laboratory (ORNL); Sefat, A.S. [Oak Ridge National Laboratory (ORNL); Tobin, J. G. [Lawrence Livermore National Laboratory (LLNL)

    2014-01-01

    This is a preliminary report of a neutron scattering experiment used to investigate 4f electron behavior in Ce.

  18. Anisotropic Elastic Resonance Scattering model for the Neutron Transport equation

    SciTech Connect (OSTI)

    Mohamed Ouisloumen; Abderrafi M. Ougouag; Shadi Z. Ghrayeb

    2014-11-24

    The resonance scattering transfer cross-section has been reformulated to account for anisotropic scattering in the center-of-mass of the neutron-nucleus system. The main innovation over previous implementations is the relaxation of the ubiquitous assumption of isotropic scattering in the center-of-mass and the actual effective use of scattering angle distributions from evaluated nuclear data files in the computation of the angular moments of the resonant scattering kernels. The formulas for the high order anisotropic moments in the laboratory system are also derived. A multi-group numerical formulation is derived and implemented into a module incorporated within the NJOY nuclear data processing code. An ultra-fine energy mesh cross section library was generated using these new theoretical models and then was used for fuel assembly calculations with the PARAGON lattice physics code. The results obtained indicate a strong effect of this new model on reactivity, multi-group fluxes and isotopic inventory during depletion.

  19. Pores in Marcellus Shale: A Neutron Scattering and FIB-SEM Study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gu, Xin; Cole, David R.; Rother, Gernot; Mildner, David F. R.; Brantley, Susan L.

    2015-01-26

    The production of natural gas has become more and more important in the United States because of the development of hydraulic fracturing techniques, which significantly increase the permeability and fracture network of black shales. The pore structure of shale is a controlling factor for hydrocarbon storage and gas migration. In this work, we investigated the porosity of the Union Springs (Shamokin) Member of the Marcellus Formation from a core drilled in Centre County, PA, USA, using ultrasmall-angle neutron scattering (USANS), small-angle neutron scattering (SANS), focused ion beam scanning electron microscopy (FIB-SEM), and nitrogen gas adsorption. The scattering of neutrons bymore » Marcellus shale depends on the sample orientation: for thin sections cut in the plane of bedding, the scattering pattern is isotropic, while for thin sections cut perpendicular to the bedding, the scattering pattern is anisotropic. The FIB-SEM observations allow attribution of the anisotropic scattering patterns to elongated pores predominantly associated with clay. The apparent porosities calculated from scattering data from the bedding plane sections are lower than those calculated from sections cut perpendicular to the bedding. A preliminary method for estimating the total porosity from the measurements made on the two orientations is presented. This method is in good agreement with nitrogen adsorption for both porosity and specific surface area measurements. Neutron scattering combined with FIB-SEM reveals that the dominant nanosized pores in organic-poor, clay-rich shale samples are water-accessible sheetlike pores within clay aggregates. In contrast, bubble-like organophilic pores in kerogen dominate organic-rich samples. Lastly, developing a better understanding of the distribution of the water-accessible pores will promote more accurate models of water–mineral interactions during hydrofracturing.« less

  20. Pores in Marcellus Shale: A Neutron Scattering and FIB-SEM Study

    SciTech Connect (OSTI)

    Gu, Xin; Cole, David R.; Rother, Gernot; Mildner, David F. R.; Brantley, Susan L.

    2015-01-26

    The production of natural gas has become more and more important in the United States because of the development of hydraulic fracturing techniques, which significantly increase the permeability and fracture network of black shales. The pore structure of shale is a controlling factor for hydrocarbon storage and gas migration. In this work, we investigated the porosity of the Union Springs (Shamokin) Member of the Marcellus Formation from a core drilled in Centre County, PA, USA, using ultrasmall-angle neutron scattering (USANS), small-angle neutron scattering (SANS), focused ion beam scanning electron microscopy (FIB-SEM), and nitrogen gas adsorption. The scattering of neutrons by Marcellus shale depends on the sample orientation: for thin sections cut in the plane of bedding, the scattering pattern is isotropic, while for thin sections cut perpendicular to the bedding, the scattering pattern is anisotropic. The FIB-SEM observations allow attribution of the anisotropic scattering patterns to elongated pores predominantly associated with clay. The apparent porosities calculated from scattering data from the bedding plane sections are lower than those calculated from sections cut perpendicular to the bedding. A preliminary method for estimating the total porosity from the measurements made on the two orientations is presented. This method is in good agreement with nitrogen adsorption for both porosity and specific surface area measurements. Neutron scattering combined with FIB-SEM reveals that the dominant nanosized pores in organic-poor, clay-rich shale samples are water-accessible sheetlike pores within clay aggregates. In contrast, bubble-like organophilic pores in kerogen dominate organic-rich samples. Lastly, developing a better understanding of the distribution of the water-accessible pores will promote more accurate models of water–mineral interactions during hydrofracturing.

  1. 2009 International Conference on Neutron Scattering (ICNS 2009)

    SciTech Connect (OSTI)

    Gopal Rao, PhD; Gillespie, Donna

    2010-08-05

    The ICNS provides a focal point for the worldwide neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as would-be neutron users. The International Conference on Neutron Scattering thus serves a dual role as an international user meeting and a scientific meeting. As a venue for scientific exchange, the ICNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. Each of the major national neutron facilities (NIST, LANSCE, ANL, HFIR and SNS), along with their international counterparts, has an opportunity to exchange information with each other and to update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities.

  2. Complete Monte Carlo Simulation of Neutron Scattering Experiments

    SciTech Connect (OSTI)

    Drosg, M.

    2011-12-13

    In the far past, it was not possible to accurately correct for the finite geometry and the finite sample size of a neutron scattering set-up. The limited calculation power of the ancient computers as well as the lack of powerful Monte Carlo codes and the limitation in the data base available then prevented a complete simulation of the actual experiment. Using e.g. the Monte Carlo neutron transport code MCNPX [1], neutron scattering experiments can be simulated almost completely with a high degree of precision using a modern PC, which has a computing power that is ten thousand times that of a super computer of the early 1970s. Thus, (better) corrections can also be obtained easily for previous published data provided that these experiments are sufficiently well documented. Better knowledge of reference data (e.g. atomic mass, relativistic correction, and monitor cross sections) further contributes to data improvement. Elastic neutron scattering experiments from liquid samples of the helium isotopes performed around 1970 at LANL happen to be very well documented. Considering that the cryogenic targets are expensive and complicated, it is certainly worthwhile to improve these data by correcting them using this comparatively straightforward method. As two thirds of all differential scattering cross section data of {sup 3}He(n,n){sup 3}He are connected to the LANL data, it became necessary to correct the dependent data measured in Karlsruhe, Germany, as well. A thorough simulation of both the LANL experiments and the Karlsruhe experiment is presented, starting from the neutron production, followed by the interaction in the air, the interaction with the cryostat structure, and finally the scattering medium itself. In addition, scattering from the hydrogen reference sample was simulated. For the LANL data, the multiple scattering corrections are smaller by a factor of five at least, making this work relevant. Even more important are the corrections to the Karlsruhe data

  3. Solid phases of spatially nanoconfined oxygen: A neutron scattering study

    SciTech Connect (OSTI)

    Kojda, Danny [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany) [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany); Freie Universitt Berlin, 14195 Berlin (Germany); Wallacher, Dirk; Hofmann, Tommy, E-mail: tommy.hofmann@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany)] [Helmholtz-Zentrum Berlin fr Materialien und Energie GmbH, 14109 Berlin (Germany); Baudoin, Simon; Hansen, Thomas [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)] [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Huber, Patrick [Technische Universitt Hamburg-Harburg, 21073 Hamburg (Germany)] [Technische Universitt Hamburg-Harburg, 21073 Hamburg (Germany)

    2014-01-14

    We present a comprehensive neutron scattering study on solid oxygen spatially confined in 12 nm wide alumina nanochannels. Elastic scattering experiments reveal a structural phase sequence known from bulk oxygen. With decreasing temperature cubic ?-, orthorhombic ?- and monoclinic ?-phases are unambiguously identified in confinement. Weak antiferromagnetic ordering is observed in the confined monoclinic ?-phase. Rocking scans reveal that oxygen nanocrystals inside the tubular channels do not form an isotropic powder. Rather, they exhibit preferred orientations depending on thermal history and the very mechanisms, which guide the structural transitions.

  4. Accurate Development of Thermal Neutron Scattering Cross Section Libraries

    SciTech Connect (OSTI)

    Hawari, Ayman; Dunn, Michael

    2014-06-10

    The objective of this project is to develop a holistic (fundamental and accurate) approach for generating thermal neutron scattering cross section libraries for a collection of important enutron moderators and reflectors. The primary components of this approach are the physcial accuracy and completeness of the generated data libraries. Consequently, for the first time, thermal neutron scattering cross section data libraries will be generated that are based on accurate theoretical models, that are carefully benchmarked against experimental and computational data, and that contain complete covariance information that can be used in propagating the data uncertainties through the various components of the nuclear design and execution process. To achieve this objective, computational and experimental investigations will be performed on a carefully selected subset of materials that play a key role in all stages of the nuclear fuel cycle.

  5. Neutron Scattering Facilities | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Facilities Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Spallation Neutron Source (SNS) High Flux Isotope Reactor (HFIR) Nanoscale Science Research Centers (NSRCs) Projects Accelerator & Detector Research Science Highlights Principal Investigators' Meetings BES Home User Facilities Neutron Scattering Facilities Print Text Size: A A A FeedbackShare Page This activity supports the operation of two neutron scattering

  6. Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    EGS Environments | Department of Energy Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments presentation at the April 2013 peer review meeting held in Denver, Colorado. neutrons_peer2013.pdf (1.51 MB) More Documents & Publications Development of a Geological and

  7. 11th LANSCE School on Neutron Scattering | School Abstract

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Materials at the Mesoscale The 11th LANSCE School on Neutron Scattering will focus on science of Materials at the Mesoscale: the influence of surfaces, interfaces, and micro-structure in properties of materials and functionalities. The goal of the 11th School is to convey characterization of the hierarchical structure of materials from the nano- to the meso-scale, and the tailored control of their properties that have impact on the society (e.g. fracking, engineering materials, geological

  8. Bragg optics computer codes for neutron scattering instrument design

    SciTech Connect (OSTI)

    Popovici, M.; Yelon, W.B.; Berliner, R.R.; Stoica, A.D.

    1997-09-01

    Computer codes for neutron crystal spectrometer design, optimization and experiment planning are described. Phase space distributions, linewidths and absolute intensities are calculated by matrix methods in an extension of the Cooper-Nathans resolution function formalism. For modeling the Bragg reflection on bent crystals the lamellar approximation is used. Optimization is done by satisfying conditions of focusing in scattering and in real space, and by numerically maximizing figures of merit. Examples for three-axis and two-axis spectrometers are given.

  9. Applying nonlinear diffusion acceleration to the neutron transport k-Eigenvalue problem with anisotropic scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Willert, Jeffrey; Park, H.; Taitano, William

    2015-10-12

    High-order/low-order (or moment-based acceleration) algorithms have been used to significantly accelerate the solution to the neutron transport k-eigenvalue problem over the past several years. Recently, the nonlinear diffusion acceleration algorithm has been extended to solve fixed-source problems with anisotropic scattering sources. In this paper, we demonstrate that we can extend this algorithm to k-eigenvalue problems in which the scattering source is anisotropic and a significant acceleration can be achieved. Lastly, we demonstrate that the low-order, diffusion-like eigenvalue problem can be solved efficiently using a technique known as nonlinear elimination.

  10. Inelastic magnetic neutron scattering in CePd{sub 3}.

    SciTech Connect (OSTI)

    Lawrence, J. M.; Fanelli, V. R.; Goremychkin, E. A.; Osborn, R.; Bauer, E. D.; McClellan, K. J.; Christianson, A. D.; Univ. of California at Irvine; LANL; ORNL

    2008-01-01

    We have performed time-of-flight neutron scattering measurements on a single crystal of the intermediate valence compound CePd{sub 3}. At 10 K, a Kondo-esque inelastic magnetic scattering peak occurs near {Delta}E = 60 meV with maximum intensity for momentum transfer Q near the (1/2, 1/2, 0) zone boundary. Spectral weight is transferred to lower energy as Q varies until at zone center the intensity at 60 meV is considerably weaker. These results are in qualitative accord with predictions of the Anderson lattice. The Q-dependence may resolve an older controversy concerning the low-temperature scattering. We discuss the relationship of these results to our recent results in YbAl{sub 3}.

  11. Monte Carlo Code System for Calculation of Multiple Scattering of Neutrons in the Resonance Region.

    Energy Science and Technology Software Center (OSTI)

    1983-01-25

    Version 00 MCRTOF systematically calculates capture and scattering probabilities for neutrons incident on a material disk, with neutron cross sections calculated from the resonance parameters. Capture, front and rear face scattering, transmission, etc., probabilities are obtained from the average destinations of the incident neutrons.

  12. Dynamics of water in prussian blue analogues: Neutron scattering study

    SciTech Connect (OSTI)

    Sharma, V. K.; Mitra, S.; Thakur, N.; Yusuf, S. M.; Mukhopadhyay, R.; Juranyi, Fanni

    2014-07-21

    Dynamics of crystal water in Prussian blue (PB), Fe(III){sub 4}[Fe(II)(CN){sub 6}]{sub 3}.14H{sub 2}O and its analogue Prussian green (PG), ferriferricynaide, Fe(III){sub 4}[Fe(III)(CN){sub 6}]{sub 4}.16H{sub 2}O have been investigated using Quasielastic Neutron Scattering (QENS) technique. PB and its analogue compounds are important materials for their various interesting multifunctional properties. It is known that crystal water plays a crucial role towards the multifunctional properties of Prussian blue analogue compounds. Three structurally distinguishable water molecules: (i) coordinated water molecules at empty nitrogen sites, (ii) non-coordinated water molecules in the spherical cavities, and (iii) at interstitial sites exist in PB. Here spherical cavities are created due to the vacant sites of Fe(CN){sub 6} units. However, PG does not have any such vacant N or Fe(CN){sub 6} units, and only one kind of water molecules, exists only at interstitial sites. QENS experiments have been carried out on both the compounds in the temperature range of 260360?K to elucidate the dynamical behavior of different kinds of water molecules. Dynamics is found to be much more pronounced in case of PB, compared to PG. A detailed data analysis showed that localized translational diffusion model could describe the observed data for both PB and PG systems. The average diffusion coefficient is found to be much larger in the PB than PG. The obtained domain of dynamics is found to be consistent with the geometry of the structure of the two systems. Combining the data of the two systems, a quantitative estimate of the dynamics, corresponding to the water molecules at different locations is made.

  13. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    SciTech Connect (OSTI)

    Grammer, K. B.; Alarcon, R.; Barrn-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velzquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttil, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section d?/d? from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.

  14. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; et al

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component)more » using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.« less

  15. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    SciTech Connect (OSTI)

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velázquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttilä, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.

  16. Method for improving the angular resolution of a neutron scatter camera

    DOE Patents [OSTI]

    Mascarenhas, Nicholas; Marleau, Peter; Gerling, Mark; Cooper, Robert Lee; Mrowka, Stanley; Brennan, James S.

    2012-12-25

    An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of neutron detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned either much closer together or further apart. However, by doubling the separation distance between the 2 planes from 20 cm to a distance of 40 cm we improved the angular resolution of the detector from about 12.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. without adding additional detectors or ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration, therefore, is increased at the expanse of detection sensitivity. However, the diminished sensitivity may be acceptable for those applications where the detector is able to interrogate a particular site for an extended period.

  17. (Neutron scattering studies of the high-temperature superconducting materials)

    SciTech Connect (OSTI)

    Mook, H.A. Jr.

    1991-01-04

    The traveler was given beam time at the ILL to continue neutron scattering work on high-temperature superconductivity. The unique facilities at the ILL for both high-energy and low-energy neutron instrumentation made the experiments possible. The measurements consisted of two basic types. The first of these is the study of the nature of spin fluctuations in high-{Tc} materials. This work is fundamental to the mechanism that is responsible for the high-transition temperatures. The second consisted of experiments on the flux lattice in high-temperature superconductors. The flux lattice has interesting physics in its own right and is important in understanding the current-carrying capability of superconductors.

  18. Neutron inelastic scattering in natural Pb as a background in neutrinoless

    Office of Scientific and Technical Information (OSTI)

    double-beta decay experiments (Journal Article) | SciTech Connect Neutron inelastic scattering in natural Pb as a background in neutrinoless double-beta decay experiments Citation Details In-Document Search Title: Neutron inelastic scattering in natural Pb as a background in neutrinoless double-beta decay experiments Inelastic neutron scattering on Pb isotopes can result in {gamma} rays near the signature endpoint energy in a number of {beta}{beta} isotopes. In particular, there are

  19. Neutron Scattering Studies of Vortex Matter in Type-II Superconductors

    SciTech Connect (OSTI)

    Xinsheng Ling

    2012-02-02

    and phase transitions in condensed matter systems with random pinning. The broader impact of the program includes the training of future generation of neutron scientists, and further development of neutron scattering and complementary techniques for studies of superconducting materials. The graduate and undergraduate students participating in this project will learn the state-of-the-art neutron scattering techniques, acquire a wide range of materials research experiences, and participate in the frontier research of superconductivity. This should best prepare the students for future careers in academia, industry, or government.

  20. Neutron scattering at the high flux isotope reactor at Oak Ridge National Laboratory

    SciTech Connect (OSTI)

    Yethiraj, M.; Fernandez-Baca, J.A.

    1995-03-01

    Since its beginnings in Oak Ridge and Argonne in the late 1940`s, neutron scattering has been established as the premier tool to study matter in its various states. Since the thermal neutron wavelength is of the same order of magnitude as typical atomic spacings and because they have comparable energies to those of atomic excitations in solids, both structure and dynamics of matter can be studied via neutron scattering. The High Flux Isotope Reactor (HFIR) provides an intense source of neutrons with which to carry out these measurements. This paper summarizes the available neutron scattering facilities at the HFIR.

  1. X-ray and neutron scattering from nano-mgantic clusters | The...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    X-ray and neutron scattering from nano-mgantic clusters The student will participate in hands on X-ray scattering experiments on bio-inspired inorganic materials (i.e., magnetic...

  2. Compact turnkey focussing neutron guide system for inelastic scattering investigations

    SciTech Connect (OSTI)

    Brandl, G.; Georgii, R.; Dunsiger, S. R.; Tsurkan, V.; Loidl, A.; Adams, T.; Pfleiderer, C.; Böni, P.

    2015-12-21

    We demonstrate the performance of a compact neutron guide module which boosts the intensity in inelastic neutron scattering experiments by approximately a factor of 40. The module consists of two housings containing truly curved elliptic focussing guide elements, positioned before and after the sample. The advantage of the module lies in the ease with which it may be reproducibly mounted on a spectrometer within a few hours, on the same timescale as conventional sample environments. It is particularly well suited for samples with a volume of a few mm{sup 3}, thus enabling the investigation of materials which to date would have been considered prohibitively small or samples exposed to extreme environments, where there are space constraints. We benchmark the excellent performance of the module by measurements of the structural and magnetic excitations in single crystals of model systems. In particular, we report the phonon dispersion in the simple element lead. We also determine the magnon dispersion in the spinel ZnCr{sub 2}Se{sub 4} (V = 12.5 mm{sup 3}), where strong magnetic diffuse scattering at low temperatures evolves into distinct helical order.

  3. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; Katsaras, John

    2015-09-21

    In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach producesmore » robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).« less

  4. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    SciTech Connect (OSTI)

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; Katsaras, John

    2015-09-21

    In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).

  5. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    SciTech Connect (OSTI)

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization to 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.

  6. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization tomore » 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.« less

  7. Application of electrically invisible antennas to the Modulated Scatterer Technique

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve themore » MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. Our paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).« less

  8. Application of electrically invisible antennas to the modulated scatterer technique

    SciTech Connect (OSTI)

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. This paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).

  9. Application of electrically invisible antennas to the Modulated Scatterer Technique

    SciTech Connect (OSTI)

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. Our paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).

  10. Application of electrically invisible antennas to the modulated scatterer technique

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Crocker, Dylan A.; Donnell, Kristen M.

    2015-09-16

    The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve themore » MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. This paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).« less

  11. Single-Volume Neutron Scatter Camera for High-Efficiency Neutron Imaging and Source Characterization. Year 2 of 3 Summary

    SciTech Connect (OSTI)

    Brubaker, Erik

    2015-10-01

    The neutron scatter camera (NSC), an imaging spectrometer for fission energy neutrons, is an established and proven detector for nuclear security applications such as weak source detection of special nuclear material (SNM), arms control treaty verification, and emergency response. Relative to competing technologies such as coded aperture imaging, time-encoded imaging, neutron time projection chamber, and various thermal neutron imagers, the NSC provides excellent event-by-event directional information for signal/background discrimination, reasonable imaging resolution, and good energy resolution. Its primary drawback is very low detection efficiency due to the requirement for neutron elastic scatters in two detector cells. We will develop a singlevolume double-scatter neutron imager, in which both neutron scatters can occur in the same large active volume. If successful, the efficiency will be dramatically increased over the current NSC cell-based geometry. If the detection efficiency approaches that of e.g. coded aperture imaging, the other inherent advantages of double-scatter imaging would make it the most attractive fast neutron detector for a wide range of security applications.

  12. Synthesis and characterization of nanophase zirconia : reverse micelle method and neutron scattering study.

    SciTech Connect (OSTI)

    Li, X.

    1998-11-23

    Zirconia is an important transition-metal oxide for catalytic applications. It has been widely used in automotive exhaust treatment, methanol synthesis, isomerization, alkylation, etc. [1]. Nanophase materials have unique physiochemical properties such as quantum size effects, high surface area, uniform morphology, narrow size distribution, and improvement of sintering rates[2]. Microemulsion method provides the means for controlling the microenvironment under which specific chemical reactions may occur in favoring the formation of homogeneous, nanometer-size particles. In this paper, we report the synthesis of nanophase zirconia and the characterization of the microemulsions as well as the powders by small- and wide-angle neutron scattering techniques.

  13. The use of neutron scattering in nuclear weapons research

    SciTech Connect (OSTI)

    Juzaitis, R.J.

    1995-10-01

    We had a weapons science breakout session last week. Although it would have been better to hold it closer in time to this workshop, I think that it was very valuable. it may have been less of a {open_quotes}short-sleeve{close_quotes} workshop environment than we would have liked, but as the first time two communities-the weapons community and the neutron scattering community- got together, it was a wonderful opportunity to transfer information during the 24 presentations that were made. This report contains discussions on the fundamental analysis of documentation of the enduring stockpile; LANSCE`s contribution to weapons; spallation is critical to understanding; weapons safety assessments; applied nuclear physics requires cross section information; fission models need refinement; and establishing teams on collaborative projects.

  14. SXST 2014 - 7th SSRL School on Synchrotron X-Ray Scattering Techniques

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    important techniques including small angle scattering, thin-film scattering, powder diffraction, structure refinement and surface x-ray scattering. The school will address topics...

  15. A novel compact three-dimensional laser-sintered collimator for neutron scattering

    SciTech Connect (OSTI)

    Ridley, Christopher J.; Manuel, Pascal; Khalyavin, Dmitry; Kirichek, Oleg; Kamenev, Konstantin V.

    2015-09-15

    Improvements in the available flux at neutron sources are making it increasingly feasible to obtain refineable neutron diffraction data from samples smaller than 1 mm{sup 3}. The signal is typically too weak to introduce any further sample environment in the 30–50 mm diameter surrounding the sample (such as the walls of a pressure cell) due to the high ratio of background to sample signal, such that even longer count times fail to reveal reflections from the sample. Many neutron instruments incorporate collimators to reduce parasitic scattering from the instrument and from any surrounding material and larger pieces of sample environment, such as cryostats. However, conventional collimation is limited in the volume it can focus on due to difficulties in producing tightly spaced neutron-absorbing foils close to the sample and in integrating this into neutron instruments. Here we present the design of a novel compact 3D rapid-prototyped (or “printed”) collimator which reduces these limitations and is shown to improve the ratio of signal to background, opening up the feasibility of using additional sample environment for neutron diffraction from small sample volumes. The compactness and ease of customisation of the design allows this concept to be integrated with existing sample environment and with designs that can be tailored to individual detector geometries without the need to alter the setup of the instrument. Results from online testing of a prototype collimator are presented. The proof of concept shows that there are many additional collimator designs which may be manufactured relatively inexpensively, with a broad range of customisation, and geometries otherwise impossible to manufacture by conventional techniques.

  16. Coherent neutron scattering and collective dynamics on mesoscale

    SciTech Connect (OSTI)

    Novikov, Vladimir; Schweizer, Kenneth S; Sokolov, Alexei P

    2013-01-01

    By combining, and modestly extending, a variety of theoretical concepts for the dynamics of liquids in the supercooled regime, we formulate a simple analytic model for the temperature and wavevector dependent collective density fluctuation relaxation time that is measurable using coherent dynamic neutron scattering. Comparison with experiments on the ionic glass-forming liquid Ca K NO3 in the lightly supercooled regime suggests the model captures the key physics in both the local cage and mesoscopic regimes, including the unusual wavevector dependence of the collective structural relaxation time. The model is consistent with the idea that the decoupling between diffusion and viscosity is reflected in a different temperature dependence of the collective relaxation time at intermediate wavevectors and near the main (cage) peak of the static structure factor. More generally, our analysis provides support for the ideas that decoupling information and growing dynamic length scales can be at least qualitatively deduced by analyzing the collective relaxation time as a function of temperature and wavevector, and that there is a strong link between dynamic heterogeneity phenomena at the single and many particle level. Though very simple, the model can be applied to other systems, such as molecular liquids.

  17. An X-ray and Neutron Scattering Study of the Formation of Core...

    Office of Scientific and Technical Information (OSTI)

    of the Formation of Core-Shell Type Polyoxometalates Citation Details In-Document Search Title: An X-ray and Neutron Scattering Study of the Formation of Core-Shell Type ...

  18. Neutron Scattering Facilities | U.S. DOE Office of Science (SC)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutron Scattering Facilities User Facilities User Facilities Home User Facilities at a Glance All User Facilities ASCR User Facilities BES User Facilities X-Ray Light Sources Neutron Scattering Facilities Nanoscale Science Research Centers (NSRCs) BER User Facilities FES User Facilities HEP User Facilities NP User Facilities User Resources User Statistics Policies and Processes Frequently Asked Questions User Facility Science Highlights User Facility News Contact Information Office of Science

  19. The Manuel Lujan, Jr. Neutron Scattering Center LANSCE experiment reports 1989 run cycle

    SciTech Connect (OSTI)

    Hyer, D.K.; DiStravolo, M.A.

    1990-10-01

    This report contains a listing and description of experiments carried on at the LANSCE neutron scattering facility in the following areas: High Density Powder Diffraction; Neutron Powder Diffractometer, (NPD); Single Crystal Diffractometer, (SCD); Low-Q Diffractometer, (LQD); Surface Profile Analysis Reflectometer, (SPEAR); Filter Difference Spectrometer, (FDS); and Constant-Q Spectrometer.

  20. 16th National School on Neutron and X-ray Scattering

    SciTech Connect (OSTI)

    Chakoumakos, Bryan; Achilles, Cherie; Cybulskis, Viktor; Gilbert, Ian

    2014-07-02

    Students talk about their experience at the 16th National School on Neutron and X-ray Scattering, or NXS 2014. Jointly conducted by Oak Ridge and Argonne national laboratories, NXS immerses graduate students in national user facilities to learn in a hands-on environment how to use neutrons and X-rays in their research.

  1. 16th National School on Neutron and X-ray Scattering

    ScienceCinema (OSTI)

    Chakoumakos, Bryan; Achilles, Cherie; Cybulskis, Viktor; Gilbert, Ian

    2014-07-23

    Students talk about their experience at the 16th National School on Neutron and X-ray Scattering, or NXS 2014. Jointly conducted by Oak Ridge and Argonne national laboratories, NXS immerses graduate students in national user facilities to learn in a hands-on environment how to use neutrons and X-rays in their research.

  2. Structural and magnetic properties of transition metal substituted BaFe{sub 2}As{sub 2} compounds studied by x-ray and neutron scattering

    SciTech Connect (OSTI)

    Kim, Min Gyu

    2012-08-28

    The purpose of my dissertation is to understand the structural and magnetic properties of the newly discovered FeAs-based superconductors and the interconnection between superconductivity, antiferromagnetism, and structure. X-ray and neutron scattering techniques are powerful tools to directly observe the structure and magnetism in this system. I used both xray and neutron scattering techniques on di#11;erent transition substituted BaFe2As2 compounds in order to investigate the substitution dependence of structural and magnetic transitions and try to understand the connections between them.

  3. Development of neutron tomography and phase contrast imaging technique

    SciTech Connect (OSTI)

    Kashyap, Y. S.; Agrawal, Ashish; Sarkar, P. S.; Shukla, Mayank; Sinha, Amar

    2013-02-05

    This paper presents design and development of a state of art neutron imaging technique at CIRUS reactor with special reference for techniques adopted for tomography and phase contrast imaging applications. Different components of the beamline such as collimator, shielding, sample manipulator, digital imaging system were designed keeping in mind the requirements of data acquisition time and resolution. The collimator was designed in such a way that conventional and phase contrast imaging can be done using same collimator housing. We have done characterization of fuel pins, study of hydride blisters in pressure tubes hydrogen based cells, two phase flow visualization, and online study of locomotive parts etc. using neutron tomography and radiography technique. We have also done some studies using neutron phase contrast imaging technique on this beamline.

  4. Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

    SciTech Connect (OSTI)

    Sakuma, Takashi Makhsun,; Sakai, Ryutaro; Xianglian; Takahashi, Haruyuki; Basar, Khairul; Igawa, Naoki; Danilkin, Sergey A.

    2015-04-16

    Diffuse neutron scattering measurement on BaF{sub 2} crystals was performed at 10?K and 295?K. Oscillatory form in the diffuse scattering intensity of BaF{sub 2} was observed at 295?K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. The force constants among neighboring atoms in BaF{sub 2} were determined and compared to those in ionic crystals and semiconductors.

  5. Elastic and inelastic neutron scattering cross sections for fission reactor applications

    SciTech Connect (OSTI)

    Hicks, S. F.; Combs, B.; Downes, L.; Girgis, J.; Kersting, L. J.; Lueck, C. J.; McDonough, P. J.; Schniederjan, J.; Sidwell, L.; Sigillito, A. J.; Chakraborty, A.; Crider, B. P.; Kumar, A.; McEllistrem, M. T.; Peters, E. E.; Prados-Estevz, F. M.; Vanhoy, J. R.; Watts, D.; Yates, S. W.

    2013-04-19

    Nuclear data important for the design and development of the next generation of light-water reactors and future fast reactors include neutron elastic and inelastic scattering cross sections on important structural materials, such as Fe, and on coolant materials, such as Na. These reaction probabilities are needed since neutron reactions impact fuel performance during irradiations and the overall efficiency of reactors. While neutron scattering cross sections from these materials are available for certain incident neutron energies, the fast neutron region, particularly above 2 MeV, has large gaps for which no measurements exist, or the existing uncertainties are large. Measurements have been made at the University of Kentucky Accelerator Laboratory to measure neutron scattering cross sections on both Fe and Na in the region where these gaps occur and to reduce the uncertainties on scattering from the ground state and first excited state of these nuclei. Results from measurements on Fe at incident neutron energies between 2 and 4 MeV will be presented and comparisons will be made to model calculations available from data evaluators.

  6. Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abrahamyan, Sergey; Albataineh, Hisham; Aniol, Konrad; Armstrong, David; Armstrong, Whitney; Averett, Todd; Babineau, Benjamin; Barbieri, A.; Bellini, Vincenzo; Beminiwattha, Rakitha; et al

    2012-03-15

    We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV = 0.656 ± 0.060 (stat) ± 0.013 (syst) corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp = 0.33-0.18+0.16 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

  7. STUDY MAGNETIC EXCITATIONS IN DOPED TRANSITION METAL OXIDES USING INELASTIC NEUTRON SCATTERING

    SciTech Connect (OSTI)

    Dai, Pengcheng

    2014-02-18

    Understanding the interplay between magnetism and superconductivity continues to be a hot topic in modern condensed matter physics. The discovery of high-temperature superconductivity in iron-based materials in 2008 provided an unique opportunity to compare and contrast these materials with traditional high-Tc copper oxide superconductors. Neutron scattering plays an important role in determining the dynamical spin properties in these materials. This proposal is a continuation of previous DOE supported proposal. This report summarizes the final progress we have made over from May 2005 till Aug. 2013. Overall, we continue to carry out extensive neutron scattering experiments on Fe-based materials, focusing on understanding their magnetic properties. In addition, we have established a materials laboratory at UT that has allowed us to grow these superconductors. Because neutron scattering typically demands a large amount of samples, by growing these materials in our own laboratory, we can now pursuit neutron scattering experiments over the entire electronic phase diagram, focusing on regions of interests. The material synthesis laboratory at UT was established entirely with the support of DOE funding. This not only allowed us to carry out neutron scattering experiments, but also permit us to provide samples to other US/International collaborators for studying these materials.

  8. 11th LANSCE School on Neutron Scattering | Lecturers

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lecturers (Tentative) Lectures are primarily given by outside experts relevant to this year's topic. John Ankner | Oak Ridge National Laboratory John Ankner, Oak Ridge National Laboratory John Ankner is a Senior Research Scientist at the Spallation Neutron Source at Oak Ridge National Laboratory. His research centers on the design, optimization, and application of neutron reflectometers to the study of condensed-matter interfaces. Materials of interest include synthetic polymers, biological and

  9. Quantification of Organic Porosity and Water Accessibility in Marcellus Shale Using Neutron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gu, Xin; Mildner, David F. R.; Cole, David R.; Rother, Gernot; Slingerland, Rudy; Brantley, Susan L.

    2016-04-28

    Pores within organic matter (OM) are a significant contributor to the total pore system in gas shales. These pores contribute most of the storage capacity in gas shales. Here we present a novel approach to characterize the OM pore structure (including the porosity, specific surface area, pore size distribution, and water accessibility) in Marcellus shale. By using ultrasmall and small-angle neutron scattering, and by exploiting the contrast matching of the shale matrix with suitable mixtures of deuterated and protonated water, both total and water-accessible porosity were measured on centimeter-sized samples from two boreholes from the nanometer to micrometer scale withmore » good statistical coverage. Samples were also measured after combustion at 450 °C. Analysis of scattering data from these procedures allowed quantification of OM porosity and water accessibility. OM hosts 24–47% of the total porosity for both organic-rich and -poor samples. This porosity occupies as much as 29% of the OM volume. In contrast to the current paradigm in the literature that OM porosity is organophilic and therefore not likely to contain water, our results demonstrate that OM pores with widths >20 nm exhibit the characteristics of water accessibility. In conclusion, our approach reveals the complex structure and wetting behavior of the OM porosity at scales that are hard to interrogate using other techniques.« less

  10. Neutron Scattering and the 30 S Ribosomal Subunit of E. Coli

    DOE R&D Accomplishments [OSTI]

    Moore, P. B.; Engelman, D. M.; Langer, J. A.; Ramakrishnan, V. R.; Schindler, D. G.; Schoenborn, B. P.; Sillers, I. Y.; Yabuki, S.

    1982-06-01

    This paper reviews the progress made in the study of the internal organization of the 30 S ribosomal subunit of E. coli by neutron scattering since 1975. A map of that particle showing the position of 14 of the subunit's 21 proteins is presented, and the methods currently used for collecting and analyzing such data are discussed. Also discussed is the possibility of extending the interpretation of neutron mapping data beyond the limits practical today.

  11. Updated flux information for neutron scattering and irradiation facilities at the BNL High Flux Beam Reactor

    SciTech Connect (OSTI)

    Holden, N.E.; Hu, J.P.; Reciniello, R.N.; Sengupta, S.; Greenwood, L.R.; Farrell, K.

    1997-08-01

    The HFBR is a heavy water, D{sub 2}O, cooled and moderated reactor with twenty-eight fuel elements containing a maximum of 9.8 kilograms of {sup 235}U. While most reactors attempt to minimize the escape of neutrons from the core, the HFBR`s D{sub 2}O design allows the thermal neutron flux to peak in the reflector region and maximizes the number of thermal neutrons available to nine horizontal external beams, H-1 to H-9, used for neutron scattering and capture reactions, supporting physics, chemistry and biology experiments. All horizontal beam tubes were built tangential to the direction of the emerging neutrons, except for the H-2 beam tube, which looks directly at the core and has been used for neutron cross section measurements utilizing fast neutrons and for the TRISTAN fission product studies. In recent years, there have been some beam modifications and new instrumentation introduced at the HFBR. A high resolution neutron powder diffractometer instrument is now operating with a resolution of 5 {times} 10{sup {minus}4} at horizontal beam line H-1. To study scattering from liquid surfaces, a neutron reflection spectrometer was introduced on the CNF beam line at H-9. In the past year, a fourth beam line has been added to the CNF line at H-9. The existing beam plug at the H-6 beam line has recently been removed and a new plug, which will feature super mirrored surfaces, is now being installed. Last year, the vertical beam thimble, V-13, a fixed port filled with thirty year old samples used for HFBR material surveillance studies was replaced by a new thimble and charging station at the core edge creating an irradiation facility to substitute for the original V-13. A neutron dosimetry program has begun to measure and calculate the energy dependent neutron and gamma ray flux densities and/or dose rates at horizontal beam lines and vertical irradiation thimbles.

  12. OSTIblog Articles in the National School on Neutron and X-ray Scattering

    Office of Scientific and Technical Information (OSTI)

    (NXS) Topic | OSTI, US Dept of Energy Office of Scientific and Technical Information School on Neutron and X-ray Scattering (NXS) Topic The NXS Class of 2014 by Kathy Chambers 19 Nov, 2014 in Every summer for the past 16 years, the Department of Energy has invited the best and brightest graduates from across the country to attend the National School on Neutron and X-ray Scattering (NXS). This year, 65 graduate students attending North American universities, and studying physics, chemistry,

  13. Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy .28.2011]: Neutron Scattering and Full-Spectrum Solar Cells Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells January 28, 2011 - 5:11pm Addthis Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Niketa Kumar Niketa Kumar Public Affairs Specialist,

  14. Note: Versatile sample stick for neutron scattering experiments in high electric fields

    SciTech Connect (OSTI)

    Bartkowiak, M., E-mail: marek.bartkowiak@psi.ch [Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); White, J. S. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland) [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Rnnow, H. M.; Pra, K. [Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)] [Laboratory for Quantum Magnetism, Ecole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2014-02-15

    We present a versatile high voltage sample stick that fits into all cryomagnets and standard cryostats at the Swiss Spallation Neutron Source, Paul Scherrer Institut, and which provides a low effort route to neutron scattering experiments that combine electric field with low temperature and magnetic field. The stick allows for voltages up to 5 kV and can be easily adapted for different scattering geometries. We discuss the design consideration and thermal behavior of the stick, and give one example to showcase the abilities of the device.

  15. Elastic neutron scattering at 96 MeV from {sup 12}C and {sup 208}Pb

    SciTech Connect (OSTI)

    Klug, J.; Blomgren, J.; Atac, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Pomp, S.; Tippawan, U.; Nilsson, L.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A.V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Oesterlund, M.; Le Brun, C.

    2003-12-01

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL, has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from {sup 12}C and {sup 208}Pb has been studied at 96 MeV in the 10 deg. -70 deg. interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions based on phenomenology or microscopic nuclear theory.

  16. Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper

    SciTech Connect (OSTI)

    Akimov, D. Moscow Engineering Physics Institute , Russia; Bernstein, A. Lawrence Livermore National Laboratory; BarbeauP.,; Barton, P. J. Lawrence Berkeley National Laboratory; Bolozdynya, A. Moscow Engineering Physics Institute , Russia; Cabrera-Palmer, B. Sandia National Laboratories; Cavanna, F. Yale University; Cianciolo, Vince ORNL; Collar, J. University of Chicago, Enrico Fermi Institute; Cooper, R. J. Indiana University; Dean, D. J. Oak Ridge National Laboratory; Efremenko, Yuri University of Tennessee and Oak Ridge National Laboratory; Etenko, A. Moscow Engineering Physics Institute , Russia; Fields, N. University of Chicago, Enrico Fermi Institute; Foxe, M. Pennsylvania State University, University Park, PA; Figueroa-Feliciano, E. Massachusetts Institute of Technology; Fomin, N. University of Tennessee, Knoxville; Gallmeier, F. Oak Ridge National Laboratory; Garishvili, I. University of Tennessee, Knoxville; Gerling, M. Sandia National Laboratories; Green, M. University of North Carolina, Chapel Hill; Greene, Geoffrey University of Tennessee, Knoxville; Hatzikoutelis, A. University of Tennessee, Knoxville; Henning, Reyco University of North Carolina, Chapel Hill; Hix, R. University of Tennessee and Oak Ridge National Laboratory; Hogan, D. University of California-Berkeley; Hornback, D. University of Tennessee and Oak Ridge National Laboratory; Jovanovic, I. Pennsylvania State University, University Park, PA; Hossbach, T. Pacific Northwest National Laboratory; Iverson, Erik B ORNL; Klein, S. R. Lawrence Berkeley National Laboratory; Khromov, A. Moscow Engineering Physics Institute , Russia; Link, J. Virginia Polytechnic Institute and State University; Louis, W. Los Alamos National Laboratory; Lu, W. Oak Ridge National Laboratory; Mauger, C. Los Alamos National Laboratory; Marleau, P. Sandia National Laboratories; Markoff, D. North Carolina Central University, Durham; Martin, R. D. University of South Dakota; Mueller, Paul Edward ORNL; Newby, J. Oak Ridge National Laboratory; Orrell, John L. Pacific Northwest National Laboratory; O'Shaughnessy, C. University of North Carolina, Chapel Hill; Penttila, Seppo Oak Ridge National Laboratory; Patton, K. North Carolina State University, Raleigh; Poon, A. W. Lawrence Berkeley National Laboratory; Radford, David C ORNL; Reyna, D. Sandia National Laboratories; Ray, H. University of Florida, Gainesville; Scholberg, K. Duke University, North Carolina; Sosnovtsev, V. Moscow Engineering Physics Institute , Russia; Tayloe, R. Indiana University; Vetter, K. Lawrence Berkeley National Laboratory; Virtue, C. Laurentian University, Canada; Wilkerson, J. University of North Carolina, Chapel Hill; Yoo, J. Fermi National Accelerator Laboratory; Yu, Chang-Hong ORNL

    2013-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).

  17. Active helium target: Neutron scalar polarizability extraction via Compton scattering

    SciTech Connect (OSTI)

    Morris, Meg Hornidge, David; Annand, John; Strandberg, Bruno

    2015-12-31

    Precise measurement of the neutron scalar polarizabilities has been a lasting challenge because of the lack of a free-neutron target. Led by the University of Glasgow and the Mount Allison University groups of the A2 collaboration in Mainz, Germany, preparations have begun to test a recent theoretical model with an active helium target with the hope of determining these elusive quantities with small statistical, systematic, and model-dependent errors. Apparatus testing and background-event simulations have been carried out, with the full experiment projected to run in 2015. Once determined, these values can be applied to help understand quantum chromodynamics in the nonperturbative region.

  18. New opportunities for quasielastic and inelastic neutron scattering at steady-state sources using mechanical selection of the incident and final neutron energy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mamantov, Eugene

    2015-06-12

    We propose a modification of the neutron wide-angle velocity selector (WAVES) device that enables inelastic (in particular, quasielastic) scattering measurements not relying on the neutron time-of-flight. The proposed device is highly suitable for a steady-state neutron source, somewhat similar to a triple-axis spectrometer, but with simultaneous selection of the incident and final neutron energy over a broad range of scattering momentum transfer. Both the incident and final neutron velocities are defined by the WAVES geometry and rotation frequency. The variable energy transfer is achieved through the natural variation of the velocity of the transmitted neutrons as a function of themore » scattering angle component out of the equatorial plane.« less

  19. SSRL School 2007 on Hard X-ray Scattering Techniques in MES

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    May 15-17, 2007 SSRL School on Hard X-ray Scattering Techniques in Materials and Environmental Sciences Group photo taken at the SSRL School on Hard X-ray Scattering Techniques in...

  20. Manufacturing techniques studies of ceramics by neutron and ?-ray radiography

    SciTech Connect (OSTI)

    Latini, R. M.; Bellido, A. V. B.; Souza, M. I. S.; Almeida, G. L.

    2014-11-11

    In this study, the aim was to evaluate capabilities and constraints of radiographic imagery using thermal neutrons and gamma-rays as tools to identify the type of technique employed in ceramics manufacturing especially that used in prehistoric Brazilian pottery from Acre state. For this purpose, radiographic images of test objects made with clay of this region using both techniques - palette and rollers - have been acquired with a system comprised of a source of gamma-rays or thermal neutrons and a corresponding X-ray or neutron-sensitive Imaging Plate as detector. For the neutrongraphy samples were exposed to a thermal neutron flux of order of 10{sup 5}n.cm{sup ?2}.s{sup ?1} for 3 minutes at main port of Argonauta research reactor of the Instituto de Engenharia Nuclear - IEN/CNEN. The radiographic images using ?-rays from {sup 165}Dy (95 keV) and {sup 198}Au (412 keV) both produced at this reactor, have been acquired under an exposure time of a couple of hours. After acquisition, images have undergone a treatment to improve their quality through enhancement of their contrast, a procedure involving corrections of the beam divergence, sample shape and averaging of the attenuation map profile. Preliminary results show that difference between manufacturing techniques is better identified by radiography using low energy ?-rays from {sup 165}Dy rather than neutrongraphy or ?-rays from {sup 198}Au. Nevertheless, disregarding the kind of employed radiation, it should be stressed that feasibility to apply the technique is tightly tied to homogeneity of the clay itself and tempers due to their different attenuation.

  1. SANS (small angle neutron scattering) measurement of deuterium-dislocation correlation in palladium

    SciTech Connect (OSTI)

    Heuser, B.J.; Summerfield, G.C.; King, J.S. ); Epperson, J.E. )

    1989-11-01

    Small angle neutron scattering (SANS) measurements have been made on deformed polycrystal palladium samples with and without deuterium dissolved in the solution phase ({alpha}) at room temperature. Concentrations were held constant during SANS experiments by an equilibrium gas pressure cell. The difference scattering cross section for the same sample with and without deuterium loading has a 1/Q behavior (Q=4{pi}/{lambda} sin{theta}/2) at intermediate values of Q. At very low values of Q the dependence is much stronger than 1/Q. The 1/Q behavior is attributed to deuterium trapping close to long dislocation cores forming rod-like scattering structures.

  2. The role of CP violating scatterings in baryogenesiscase study of the neutron portal

    SciTech Connect (OSTI)

    Baldes, Iason; Bell, Nicole F.; Millar, Alexander; Volkas, Raymond R.; Petraki, Kalliopi E-mail: n.bell@unimelb.edu.au E-mail: kpetraki@nikhef.nl

    2014-11-01

    Many baryogenesis scenarios invoke the charge parity (CP) violating out-of-equilibrium decay of a heavy particle in order to explain the baryon asymmetry. Such scenarios will in general also allow CP violating scatterings. We study the effect of these CP violating scatterings on the final asymmetry in a neutron portal scenario. We solve the Boltzmann equations governing the evolution of the baryon number numerically and show that the CP violating scatterings play a dominant role in a significant portion of the parameter space.

  3. Nanoscale structure in AgSbTe2 determined by diffuse elastic neutron scattering

    SciTech Connect (OSTI)

    Specht, Eliot D [ORNL; Ma, Jie [ORNL; Delaire, Olivier A [ORNL; Budai, John D [ORNL; May, Andrew F [ORNL; Karapetrova, Evguenia A. [Argonne National Laboratory (ANL)

    2015-01-01

    Diffuse elastic neutron scattering measurements confirm that AgSbTe2 has a hierarchical structure, with defects on length scales from nanometers to microns. While scattering from mesoscale structure is consistent with previously-proposed structures in which Ag and Sb order on a NaCl lattice, more diffuse scattering from nanoscale structure suggests a structural rearrangement in which hexagonal layers form a combination of (ABC), (ABA), and (AAB) stacking sequences. The AgCrSe2 structure is the best-fitting model for the local atomic arrangements.

  4. A novel approach to neutron scattering instrumentation for probing multiscale dynamics in soft and biological matter

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mamontov, Eugene

    2016-06-29

    We present a concept and ray-tracing simulation results of a mechanical device that will enable inelastic neutron scattering measurements where the data at energy transfers from a few eV to several hundred meV can be collected in a single, gapless spectrum. Besides covering 5 orders of magnitude on the energy (time) scale, the device provides data over 2 orders of magnitude on the scattering momentum (length) scale in a single measurement. Such capabilities are geared primarily toward soft and biological matter, where the broad dynamical features of relaxation origin largely overlap with vibration features, thus necessitating gapless spectral coverage overmore » several orders of magnitude in time and space. Furthermore, neutron scattering experiments with such a device are performed with a fixed neutron final energy, which enables measurements, with neutron energy loss in the sample, at arbitrarily low temperatures over the same broad spectral range. Lastly, this capability is also invaluable in biological and soft matter research, as the variable temperature dependence of different relaxation components allows their separation in the scattering spectra as a function of temperature.« less

  5. FINAL REPORT: DOE CONTRACT NUMBER FG0205ER64026 Biological Neutron Scattering: A Collaboration with the Oak Ridge Center for Structural Molecular Biology

    SciTech Connect (OSTI)

    Jill Trewhella

    2011-01-12

    The overarching goal of this project was to promote applications of small-angle scattering in structural molecular biology by providing model examples of cutting edge applications that demonstrate the unique capabilities and potential of the DOE national user facilities at Oak Ridge, especially the newly commissioned BioSANS. The approach taken was three-fold: (1) to engage in high impact collaborative research projects that would benefit from small-angle neutron scattering to both demonstrate the power of the technique while expanding the potential user community; (2) to provide access to scattering facilities established at the University of Utah to as broad a set of researchers as possible to increase the expertise in small-angle scattering generally; and (3) to develop new methods and tools for small-angle scattering. To these ends, three major research collaborations were pursued that resulted in a significant body of published work where neutron scattering and contrast variation played a major role. These major collaborations involved studies of protein complexes involved in (1) bacterial transcription regulation and adaptive response (a DOE/BER priority area); (2) regulation of cardiac muscle; and (3) neuronal disorders. In addition, to broaden the impact of the project, smaller collaborative efforts were supported that used either small-angle X-ray or neutron scattering. Finally, the DOE supported facilities at the University of Utah were made available to researchers on a service basis and a number of independent groups took advantage of this opportunity. In all of this work, there was an emphasis on the training of students and post docs in scattering techniques, and a set of publications (a book chapter, a review, and an encyclopedia article) were produced to guide the non-specialist potential user of scattering techniques in successful applications of the techniques. We also developed a suite of user friendly web-based computational tools currently

  6. Neutron Scattering Investigation of Phonon Scattering Rates in Ag1-xSb1+xTe2+x (x = 0, 0.1, and 0.2)

    SciTech Connect (OSTI)

    Abernathy, Douglas L [ORNL; Budai, John D [ORNL; Delaire, Olivier A [ORNL; Ehlers, Georg [ORNL; Hong, Tao [ORNL; Karapetrova, Evguenia A. [Argonne National Laboratory (ANL); Ma, Jie [ORNL; May, Andrew F [ORNL; McGuire, Michael A [ORNL; Specht, Eliot D [ORNL

    2014-01-01

    The phonon dispersions and scattering rates of the thermoelectric material AgSbTe$_{2}$ were measured as a function of temperature with inelastic neutron scattering. The results show that phonon scattering rates are large and weakly dependent on temperature. The lattice thermal conductivity was calculated from the measured phonon lifetimes and group velocities, providing good agreement with bulk transport measurements. The measured phonon scattering rates and their temperature dependence are compared with models of phonon scattering by anharmonicity and point defect. We find that these processes cannot account for the large total phonon scattering rates observed, and their lack of temperature dependence. Neutron and synchrotron diffraction measurements on single crystals revealed an extensive nanostructure from cation ordering, which is likely responsible for the strong phonon scattering.

  7. Dopant effects on 2-ethyl-1-hexanol: A dual-channel impedance spectroscopy and neutron scattering study

    SciTech Connect (OSTI)

    Singh, Lokendra P.; Richert, Ranko; Raihane, Ahmed; Alba-Simionesco, Christiane

    2015-01-07

    A two-channel impedance technique has been used to study the relaxation behavior of 2-ethyl-1-hexanol with polar and non-polar dopants at the few percent concentration level over a wide temperature and frequency range. The non-polar dopants shift both the Debye and the primary structural relaxation time in the same direction, to shorter times for 3-methylpentane and to longer times for squalane, consistent with the relative glass transition temperatures (T{sub g}) of the components. By contrast, polar dopants such as water or methanol modify the ?-process towards slower dynamics and increased amplitude, while the Debye process is accelerated and with a decreased amplitude. This effect of adding water to alcohol is explained by water promoting more compact structures with reduced Kirkwood correlation factors. This picture is consistent with a shift in the neutron scattering pre-peak to lower scattering vectors and with simulation work on alcohol-water systems.

  8. Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors. Final Report

    SciTech Connect (OSTI)

    Hawari, Ayman; Ougouag, Abderrafi

    2014-07-08

    This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermalization is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.

  9. Molecular dynamics force-field refinement against quasi-elastic neutron scattering data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Borreguero Calvo, Jose M.; Lynch, Vickie E.

    2015-11-23

    Quasi-elastic neutron scattering (QENS) is one of the experimental techniques of choice for probing the dynamics at length and time scales that are also in the realm of full-atom molecular dynamics (MD) simulations. This overlap enables extension of current fitting methods that use time-independent equilibrium measurements to new methods fitting against dynamics data. We present an algorithm that fits simulation-derived incoherent dynamical structure factors against QENS data probing the diffusive dynamics of the system. We showcase the difficulties inherent to this type of fitting problem, namely, the disparity between simulation and experiment environment, as well as limitations in the simulationmore » due to incomplete sampling of phase space. We discuss a methodology to overcome these difficulties and apply it to a set of full-atom MD simulations for the purpose of refining the force-field parameter governing the activation energy of methyl rotation in the octa-methyl polyhedral oligomeric silsesquioxane molecule. Our optimal simulated activation energy agrees with the experimentally derived value up to a 5% difference, well within experimental error. We believe the method will find applicability to other types of diffusive motions and other representation of the systems such as coarse-grain models where empirical fitting is essential. In addition, the refinement method can be extended to the coherent dynamic structure factor with no additional effort.« less

  10. Review of the Lujan neutron scattering center: basic energy sciences prereport February 2009

    SciTech Connect (OSTI)

    Hurd, Alan J; Rhyne, James J; Lewis, Paul S

    2009-01-01

    The Lujan Neutron Scattering Center (Lujan Center) at LANSCE is a designated National User Facility for neutron scattering and nuclear physics studies with pulsed beams of moderated neutrons (cold, thermal, and epithermal). As one of five experimental areas at the Los Alamos Neutron Science Center (LANSCE), the Lujan Center hosts engineers, scientists, and students from around the world. The Lujan Center consists of Experimental Room (ER) 1 (ERl) built by the Laboratory in 1977, ER2 built by the Office of Basic Energy Sciences (BES) in 1989, and the Office Building (622) also built by BES in 1989, along with a chem-bio lab, a shop, and other out-buildings. According to a 1996 Memorandum of Agreement (MOA) between the Defense Programs (DP) Office of the National Nuclear Security Agency (NNSA) and the Office of Science (SC, then the Office of Energy Research), the Lujan Center flight paths were transferred from DP to SC, including those in ERI. That MOA was updated in 2001. Under the MOA, NNSA-DP delivers neutron beam to the windows of the target crypt, outside of which BES becomes the 'landlord.' The leveraging nature of the Lujan Center on the LANSCE accelerator is a substantial annual leverage to the $11 M BES operating fund worth approximately $56 M operating cost of the linear accelerator (LINAC)-in beam delivery.

  11. Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\\mu SR$ Experiments

    SciTech Connect (OSTI)

    Arnold, Owen; Bilheux, Jean-Christophe; Borreguero Calvo, Jose M; Buts, Alex; Campbell, Stuart I; Doucet, Mathieu; Draper, Nicholas J; Ferraz Leal, Ricardo F; Gigg, Martyn; Lynch, Vickie E; Mikkelson, Dennis J; Mikkelson, Ruth L; Miller, Ross G; Perring, Toby G; Peterson, Peter F; Ren, Shelly; Reuter, Michael A; Savici, Andrei T; Taylor, Jonathan W; Taylor, Russell J; Zhou, Wenduo; Zikovsky, Janik L

    2014-11-01

    The Mantid framework is a software solution developed for the analysis and visualization of neutron scattering and muon spin measurements. The framework is jointly developed by a large team of software engineers and scientists at the ISIS Neutron and Muon Facility and the Oak Ridge National Laboratory. The objective of the development is to improve software quality, both in terms of performance and ease of use, for the the user community of large scale facilities. The functionality and novel design aspects of the framework are described.

  12. Passive and Active Neutron Matrix Correction for Heterogeneous Distributions Utilizing the Neutron Imaging Technique

    SciTech Connect (OSTI)

    Villani, M.F.; Croft, St.; Alvarez, E.; Wilkins, C.G.; Stamp, D.; Fisher, J.; Ambrifi, A.; Simone, G.; Bourva, L.C.

    2008-07-01

    Classical Non-Destructive Assay (NDA) Passive Neutron Coincidence Counting (PNCC) and Differential Die-Away (DDA) active neutron interrogation techniques [1, 2] are well suited for determining the gross matrix correction factors for homogenous mass distributions of Special Nuclear Material (SNM) within an interfering waste drum matrix. These measured passive and active matrix correction factors are crucial in quantifying the SNM mass, associated Total Measurement Uncertainty (TMU), and Minimum Detectable Activity (MDA) within the drum. When heterogeneous SNM mass distributions are encountered, the measured SNM mass, TMU and MDA biases introduced may be 100%, or greater, especially for dense hydrogenous matrices. The standard matrix correction factors can be adjusted if a coarse spatial image of the SNM mass, relative to the matrix, is available. The image can then be analyzed to determine the spatially-adjusted, matrix correction factors case by case. This image analysis approach was accomplished by modifying the standard Passive-Active Neutron (PAN) counter design [3] to accommodate a unique data acquisition architecture that supports a newly developed image acquisition and analysis application called the Neutron Imaging Technique (NIT). The NIT functionality supports both PNCC and DDA acquisition and analysis modes and exploits the symmetry between a stored set of factory acquired NIT images with those from the unknown PAN assay. The NIT result is then an adjustment to the classical correction factor reducing, if not removing, the SNM mass bias and revealing the true TMU and MDA values. In this paper we describe the NIT for the PAN design from the software and algorithmic perspectives and how this technique accommodates waste matrix drums that are difficult, from the classical standpoint, if not impossible, to extract meaningful SNM mass, TMU and MDA results. (authors)

  13. Neutron capture strategy and technique developments for GNEP

    SciTech Connect (OSTI)

    Couture, Aaron Joseph

    2008-01-01

    The initial three years of neutron capture measurements have been very successful in providing data for the Advanced Fuel Cycle Initiative/Global Nuclear Energy Partnership (AFCI/GNEP) program. Now that the most straightforward measurements have been completed, additional technical challenges face future measurements. In particular, techniques are needed to perform measurements that exhibit at least one of three major problems -- large fission:capture ratios, large capture:capture ratios, and high intrinsic activity samples. This paper will set forward a plan for attacking these technical challenges and moving forward with future measurements.

  14. Neutron Scatter Camera for Radiaton Detection - Energy Innovation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular ...

  15. Characteristic Features of Water Dynamics in Restricted Geometries Investigated with Quasi-Elastic Neutron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Osti, Naresh C.; Mamontov, Eugene; Ramirez-cuesta, A.; Wesolowski, David J.; Diallo, S. O.

    2015-12-10

    Understanding the molecular behavior of water in spatially restricted environments is important to better understanding its role in many biological, chemical and geological processes. Here we examine the translational diffusion of water confined to a variety of substrates, from flat surfaces to nanoporous media, in the context of a recently proposed universal scaling law (Chiavazzo 2014) [1]. Using over a dozen previous neutron scattering results, we test the validity of this law, evaluating separately the influence of the hydration amount, and the effects of the size and morphology of the confining medium. Additionally, we investigate the effects of changing instrumentmore » resolutions and fitting models on the applicability of this law. Finally, we perform quasi-elastic neutron scattering measurements on water confined inside nanoporous silica to further evaluate this predictive law, in the temperature range 250≤T≤290 K.« less

  16. Characteristic Features of Water Dynamics in Restricted Geometries Investigated with Quasi-Elastic Neutron Scattering

    SciTech Connect (OSTI)

    Osti, Naresh C.; Mamontov, Eugene; Ramirez-cuesta, A.; Wesolowski, David J.; Diallo, S. O.

    2015-12-10

    Understanding the molecular behavior of water in spatially restricted environments is important to better understanding its role in many biological, chemical and geological processes. Here we examine the translational diffusion of water confined to a variety of substrates, from flat surfaces to nanoporous media, in the context of a recently proposed universal scaling law (Chiavazzo 2014) [1]. Using over a dozen previous neutron scattering results, we test the validity of this law, evaluating separately the influence of the hydration amount, and the effects of the size and morphology of the confining medium. Additionally, we investigate the effects of changing instrument resolutions and fitting models on the applicability of this law. Finally, we perform quasi-elastic neutron scattering measurements on water confined inside nanoporous silica to further evaluate this predictive law, in the temperature range 250≤T≤290 K.

  17. X-ray and neutron scattering studies of the complex compounds | Stanford

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Synchrotron Radiation Lightsource X-ray and neutron scattering studies of the complex compounds Wednesday, September 25, 2013 - 1:00pm SLAC, Conference Room 137-322 Presented by Dr. Hoyoung Jang, Max Planck Institute for Solid State Research in Stuttgart, Germany In condensed matter physics, in particular a field of complex oxide materials, most of the research-activity is focusing on finding a new functionality in materials as well as its understanding. In this fashion, during past few

  18. Structure and dynamics of cadmium telluride studied by x-ray and inelastic neutron scattering

    SciTech Connect (OSTI)

    Niedziela, J. L., E-mail: niedzielajl@ornl.gov [Instrument and Source Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Stone, M. B., E-mail: stonemb@ornl.gov [Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-09-08

    We present a combined study of density functional theory, x-ray diffraction, and inelastic neutron scattering examining the temperature dependent structure and lattice dynamics of commercially available cadmium telluride. A subtle change in the structure is evinced near 80?K, which manifests also in the measured phonon density of states. There is no change to the long-range ordered structure. The implications of the change in relation to structural defects are discussed.

  19. Structure and dynamics of cadmium telluride studied by x-ray and inelastic neutron scattering

    SciTech Connect (OSTI)

    Niedziela, Jennifer L [ORNL; Stone, Matthew B [ORNL

    2014-01-01

    We present a combined study of density functional theory, x-ray diffraction, and inelastic neutron scattering examining the temperature dependent structure and lattice dynamics of commercially available cadmium telluride. A subtle change in the structure is evinced near 80~K, which manifests also in the measured phonon density of states. There is no change to the long-range ordered structure. The implications of the change in relation to structural defects are discussed.

  20. Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments Yarom Polsky Oak Ridge National Laboratory Track Name Project Officer: Greg Stillman Total Project Funding: $300K April 23, 2013 This presentation does not contain any proprietary confidential, or otherwise restricted information. 2 | US DOE Geothermal Office eere.energy.gov Relevance/Impact of Research Goals: 1) Develop an experimental capability to image/characterize fluid flow through fractures 2)

  1. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; Mastalerz, Maria; Schimmelmann, Arndt

    2014-12-17

    We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of themore » polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.« less

  2. X-ray and Neutron Scattering Study of the Formation of Core–Shell-Type Polyoxometalates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yin, Panchao; Wu, Bin; Mamontov, Eugene; Daemen, Luke L.; Cheng, Yongqiang; Li, Tao; Seifert, Soenke; Hong, Kunlun; Bonnesen, Peter V.; Keum, Jong Kahk; et al

    2016-02-05

    A typical type of core-shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo72Fe30}. Small angle X-ray scattering is used to study the structural features and stability of the core-shell structures in aqueous solutions. Time-resolved small angle X-ray scattering is applied to monitor the synthetic reactions and a three-stage formation mechanism is proposed to describe the synthesis of the core-shell polyoxometalates based on the monitoring results. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core-shell structures and two different types of water molecules,more » the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures. A typical type of core shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo72Fe30}. Small-angle X-ray scattering is used to study the structural features and stability of the core shell structures in aqueous solutions. Time-resolved small-angle X-ray scattering is applied to monitor the synthetic reactions, and a three-stage formation mechanism is proposed to describe the synthesis of the core shell polyoxometalates based on the monitoring results. New protocols have been developed by fitting the X-ray data with custom physical models, which provide more convincing, objective, and completed data interpretation. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core shell structures, and two different types of water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.« less

  3. X-ray and Neutron Scattering Study of the Formation of Core-Shell Type Polyoxometalates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yin, Panchao; Wu, Bin; Mamontov, Eugene; Daemen, Luke L; Cheng, Yongqiang; Hong, Kunlun; Bonnesen, Peter V; Keum, Jong Kahk; Ramirez-Cuesta, Anibal J

    2016-01-01

    A typical type of core-shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo72Fe30}. Small angle X-ray scattering is used to study the structural features and stability of the core-shell structures in aqueous solutions. Time-resolved small angle X-ray scattering is applied to monitor the synthetic reactions and a three-stage formation mechanism is proposed to describe the synthesis of the core-shell polyoxometalates based on the monitoring results. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core-shell structures and two different types of water molecules,morethe confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.A typical type of core shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo72Fe30}. Small-angle X-ray scattering is used to study the structural features and stability of the core shell structures in aqueous solutions. Time-resolved small-angle X-ray scattering is applied to monitor the synthetic reactions, and a three-stage formation mechanism is proposed to describe the synthesis of the core shell polyoxometalates based on the monitoring results. New protocols have been developed by fitting the X-ray data with custom physical models, which provide more convincing, objective, and completed data interpretation. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core shell structures, and two different types of water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.less

  4. SSRL School 2007 on Hard X-ray Scattering: Techniques in MES

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    peak intensities, A. Vailionis SAXS, J. Pople Tuesday Afternoon, Bulk-Structure Techniques Structure characterization, A. Mehta In-situ scattering, S. Webb Amorphous...

  5. Structure of spontaneously formed solid-electrolyte interphase on lithiated graphite determined using small-angle neutron scattering

    SciTech Connect (OSTI)

    Sacci, Robert L [ORNL; Banuelos, Jose Leo [ORNL; Veith, Gabriel M [ORNL; Littrell, Ken [ORNL; Cheng, Yongqiang [ORNL; Wildgruber, Christoph U [ORNL; Jones, Lacy L [ORNL; Ramirez-Cuesta, Anibal J [ORNL; Rother, Gernot [ORNL; Dudney, Nancy J [ORNL

    2015-01-01

    We report the first small-angle neutron scattering of a chemically formed solid-electrolyte interphase from LixC6 reacting with ethylene carbonate/dimethyl carbon solvent. This provides a different and perhaps simpler view of SEI formation than the usual electrochemically-driven reaction. We show that an organic layer coats the graphite particles filling in micro-pores and is polymeric in nature being 1-3 nm thick. We used inelastic neutron scattering to probe the chemistry, and we found that the SEI showed similar inelastic scattering to polyethylene oxide.

  6. Structure of spontaneously formed solid-electrolyte interphase on lithiated graphite determined using small-angle neutron scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sacci, Robert L.; Banuelos, Jose Leobardo; Veith, Gabriel M.; Littrell, Ken C.; Cheng, Yongqiang Q.; Wildgruber, Christoph U.; Jones, Lacy L.; Ramirez-Cuesta, Anibal J.; Rother, Gernot; Dudney, Nancy J.

    2015-03-25

    We report the first small-angle neutron scattering of a chemically formed solid-electrolyte interphase from LixC6 reacting with ethylene carbonate/dimethyl carbon solvent. This provides a different and perhaps simpler view of SEI formation than the usual electrochemically-driven reaction. We show that an organic layer coats the graphite particles filling in micro-pores and is polymeric in nature being 1-3 nm thick. We used inelastic neutron scattering to probe the chemistry, and we found that the SEI showed similar inelastic scattering to polyethylene oxide.

  7. Laterally patterned spin-valve superlattice: Magnetometry and polarized neutron scattering study

    SciTech Connect (OSTI)

    Brüssing, F.; Devishvili, A.; Zabel, H.; Toperverg, B. P.; Badini Confalonieri, G. A.; Theis-Bröhl, K.

    2015-04-07

    The magnetization reversal of magnetic multilayers with spin-valve like characteristics, patterned into an array of parallel stripes, was structurally and magnetically analyzed, in detail, via x-ray scattering, magnetometry, and polarized neutron reflectivity. Each stripe contains a multiple repetition of the layer sequence [Fe/Cr/Co/Cr]. X-ray and neutron scattering maps of the patterned multilayer show rich details resulting from the superposition of Bragg peaks representing the lateral in-plane periodicity and the out-of-plane multilayer period. Detailed analysis of specular and off-specular polarized neutron intensity was used to ascertain the antiparallel alignment of the Co and Fe magnetization within the kink region of their combined hysteresis loop between the coercive fields of Fe and Co layers. This includes also an examination of domain formation and inter- as well as intra-stripe correlation effects upon magnetization reversal. Our combined study shows that the shape induced anisotropy via patterning is capable of overriding the four-fold crystal anisotropy but is unable to eliminate the ripple domain state of the Co layers, already present in the continuous multilayer.

  8. Low Resolution Structure and Dynamics of a Colicin-Receptor Complex Determined by Neutron Scattering

    SciTech Connect (OSTI)

    Clifton, Luke A; Johnson, Christopher L; Solovyova, Alexandra; Callow, Phil; Weiss, Kevin L; Ridley, Helen; Le Brun, Anton P; Kinane, Christian; Webster, John; Holt, Stephen A; Lakey, Jeremy H

    2012-01-01

    Proteins that translocate across cell membranes need to overcome a significant hydrophobic barrier. This is usually accomplished via specialized protein complexes, which provide a polar transmembrane pore. Exceptions to this include bacterial toxins, which insert into and cross the lipid bilayer itself. We are studying the mechanism by which large antibacterial proteins enter Escherichia coli via specific outer membrane proteins. Here we describe the use of neutron scattering to investigate the interaction of colicin N with its outer membrane receptor protein OmpF. The positions of lipids, colicin N, and OmpF were separately resolved within complex structures by the use of selective deuteration. Neutron reflectivity showed, in real time, that OmpF mediates the insertion of colicin N into lipid monolayers. This data were complemented by Brewster Angle Microscopy images, which showed a lateral association of OmpF in the presence of colicin N. Small angle neutron scattering experiments then defined the three-dimensional structure of the colicin N-OmpF complex. This revealed that colicin N unfolds and binds to the OmpF-lipid interface. The implications of this unfolding step for colicin translocation across membranes are discussed.

  9. High-energy magnetic excitations in overdoped La 2 - x Sr x CuO 4 studied by neutron and resonant inelastic x-ray scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wakimoto, S.; Ishii, K.; Kimura, H.; Fujita, M.; Dellea, G.; Kummer, K.; Braicovich, L.; Ghiringhelli, G.; Debeer-Schmitt, L. M.; Granroth, G. E.

    2015-05-21

    We have performed neutron inelastic scattering and resonant inelastic x-ray scattering (RIXS) at the Cu-L₃ edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La2-xSrxCuO₄ with x=0.25 (Tc=15 K) and x=0.30 (nonsuperconducting) using identical single-crystal samples for the two techniques. From constant-energy slices of neutron-scattering cross sections, we have identified magnetic excitations up to ~250 meV for x=0.25. Although the width in the momentum direction is large, the peak positions along the (π,π) direction agree with the dispersion relation of the spin wave in the nondoped La₂CuO₄ (LCO), which is consistent with themore » previous RIXS results of cuprate superconductors. Using RIXS at the Cu-L₃ edge, we have measured the dispersion relations of the so-called paramagnon mode along both (π,π) and (π,0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (π,0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (π,π) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin wave of LCO near (π/2,π/2). Thus, our results indicate consistency between neutron inelastic scattering and RIXS, and elucidate the entire magnetic excitation in the (π,π) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. A possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (π,π) direction as detected by the x-ray scattering.« less

  10. Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.

    SciTech Connect (OSTI)

    McCray, John; Navarre-Sitchler, Alexis; Mouzakis, Katherine; Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot

    2010-11-01

    Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of

  11. XRS 2016 - 8th SSRL School on Synchrotron X-Ray Scattering Techniques

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    XRS 2016 - 8th SSRL School on Synchrotron X-Ray Scattering Techniques Home Registration Location Visitor Information Transportation About XRS 2016 - 8th SSRL School on Synchrotron X-Ray Scattering Techniques Materials and Environmental Sciences: Theory and Application June 21-23 2016 BL2-1 Feedback Form Agenda 2016 Agenda Maps & Directions Visiting SLAC This school will provide a practical users' guide to planning and conducting scattering measurements at SSRL beam lines, and will cover

  12. Exploration of deeply virtual Compton scattering on the neutron in the Hall A of Jefferson Laboratory

    SciTech Connect (OSTI)

    Malek Mazouz

    2006-12-08

    Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive process involving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysis methods and the experiment results, leading to preliminary constraints on the GPD E, are presented.

  13. Inelastic neutron scattering and molecular simulation of the dynamics of interlayer water in smectite clay minerals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cygan, Randall T.; Daemen, Luke L.; Ilgen, Anastasia G.; Krumhansl, James L.; Nenoff, Tina M.

    2015-11-16

    The study of mineral–water interfaces is of great importance to a variety of applications including oil and gas extraction, gas subsurface storage, environmental contaminant treatment, and nuclear waste repositories. Understanding the fundamentals of that interface is key to the success of those applications. Confinement of water in the interlayer of smectite clay minerals provides a unique environment to examine the interactions among water molecules, interlayer cations, and clay mineral surfaces. Smectite minerals are characterized by a relatively low layer charge that allows the clay to swell with increasing water content. Montmorillonite and beidellite varieties of smectite were investigated to comparemore » the impact of the location of layer charge on the interlayer structure and dynamics. Inelastic neutron scattering of hydrated and dehydrated cation-exchanged smectites was used to probe the dynamics of the interlayer water (200–900 cm–1 spectral region) and identify the shift in the librational edge as a function of the interlayer cation. Molecular dynamics simulations of equivalent phases and power spectra, derived from the resulting molecular trajectories, indicate a general shift in the librational behavior with interlayer cation that is generally consistent with the neutron scattering results for the monolayer hydrates. Both neutron scattering and power spectra exhibit librational structures affected by the location of layer charge and by the charge of the interlayer cation. Furthermore, divalent cations (Ba2+ and Mg2+) characterized by large hydration enthalpies typically exhibit multiple broad librational peaks compared to monovalent cations (Cs+ and Na+), which have relatively small hydration enthalpies.« less

  14. Inelastic neutron scattering and molecular simulation of the dynamics of interlayer water in smectite clay minerals

    SciTech Connect (OSTI)

    Cygan, Randall T.; Daemen, Luke L.; Ilgen, Anastasia G.; Krumhansl, James L.; Nenoff, Tina M.

    2015-11-16

    The study of mineral–water interfaces is of great importance to a variety of applications including oil and gas extraction, gas subsurface storage, environmental contaminant treatment, and nuclear waste repositories. Understanding the fundamentals of that interface is key to the success of those applications. Confinement of water in the interlayer of smectite clay minerals provides a unique environment to examine the interactions among water molecules, interlayer cations, and clay mineral surfaces. Smectite minerals are characterized by a relatively low layer charge that allows the clay to swell with increasing water content. Montmorillonite and beidellite varieties of smectite were investigated to compare the impact of the location of layer charge on the interlayer structure and dynamics. Inelastic neutron scattering of hydrated and dehydrated cation-exchanged smectites was used to probe the dynamics of the interlayer water (200–900 cm–1 spectral region) and identify the shift in the librational edge as a function of the interlayer cation. Molecular dynamics simulations of equivalent phases and power spectra, derived from the resulting molecular trajectories, indicate a general shift in the librational behavior with interlayer cation that is generally consistent with the neutron scattering results for the monolayer hydrates. Both neutron scattering and power spectra exhibit librational structures affected by the location of layer charge and by the charge of the interlayer cation. Furthermore, divalent cations (Ba2+ and Mg2+) characterized by large hydration enthalpies typically exhibit multiple broad librational peaks compared to monovalent cations (Cs+ and Na+), which have relatively small hydration enthalpies.

  15. Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

    SciTech Connect (OSTI)

    Ono, K. Inami, N.; Saito, K.; Takeichi, Y.; Kawana, D.; Yokoo, T.; Itoh, S.; Yano, M.; Shoji, T.; Manabe, A.; Kato, A.; Kaneko, Y.

    2014-05-07

    The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant D{sub sw} (100.0??4.9?meV.{sup 2}) and the exchange stiffness constant A (6.6 0.3 pJ/m)

  16. SU-E-I-07: An Improved Technique for Scatter Correction in PET

    SciTech Connect (OSTI)

    Lin, S; Wang, Y; Lue, K; Lin, H; Chuang, K

    2014-06-01

    Purpose: In positron emission tomography (PET), the single scatter simulation (SSS) algorithm is widely used for scatter estimation in clinical scans. However, bias usually occurs at the essential steps of scaling the computed SSS distribution to real scatter amounts by employing the scatter-only projection tail. The bias can be amplified when the scatter-only projection tail is too small, resulting in incorrect scatter correction. To this end, we propose a novel scatter calibration technique to accurately estimate the amount of scatter using pre-determined scatter fraction (SF) function instead of the employment of scatter-only tail information. Methods: As the SF depends on the radioactivity distribution and the attenuating material of the patient, an accurate theoretical relation cannot be devised. Instead, we constructed an empirical transformation function between SFs and average attenuation coefficients based on a serious of phantom studies with different sizes and materials. From the average attenuation coefficient, the predicted SFs were calculated using empirical transformation function. Hence, real scatter amount can be obtained by scaling the SSS distribution with the predicted SFs. The simulation was conducted using the SimSET. The Siemens Biograph 6 PET scanner was modeled in this study. The Software for Tomographic Image Reconstruction (STIR) was employed to estimate the scatter and reconstruct images. The EEC phantom was adopted to evaluate the performance of our proposed technique. Results: The scatter-corrected image of our method demonstrated improved image contrast over that of SSS. For our technique and SSS of the reconstructed images, the normalized standard deviation were 0.053 and 0.182, respectively; the root mean squared errors were 11.852 and 13.767, respectively. Conclusion: We have proposed an alternative method to calibrate SSS (C-SSS) to the absolute scatter amounts using SF. This method can avoid the bias caused by the insufficient

  17. Small-angle neutron scattering measurement of deuterium trapping at dislocations and grain boundaries in palladium

    SciTech Connect (OSTI)

    Heuser, B.J.

    1991-01-01

    Small angle neutron scattering measurements have been performed on deformed single and polycrystalline palladium with and without deuterium dissolved in the solution phase at room temperature. The purpose of these experiments was to directly measure the spatial distribution of trapped deuterium at dislocations in the deformed metal. The net scattering cross section for the same smaple with and without deuterium shows a behavior expected from deuterium correlation with dislocations froming rod-like scattering structures. The measured cross sections indicate the trapped deuterium is within 2 to 3 Burgers vectors of the dislocation core. On average 1 to 3 deuterons per {angstrom} are trapped at the dislocations in the deformed samples. The measurements also indicate the straight, rod-like correlation geometry extends on average 50 to 100 {angstrom} along the dislocations. Dislocation densities on the order of 5 {times} 10{sup 11} cm/cm{sup 3} were found for all samples investigated. Net scattering from a well annealed polycrystalline palladium sample exhibiting a behavior expected from spherical shells has been observed. This net scattering is attributed to deuterium trapping at grain boundaries in the polycrystalline sample. net scattering in excess of that expected from deuterium correlated at dislocations was also observed in a deformed polycrystalline measurement. This too is attributed to deuterium trapping at grain boundaries. The dislocation substructure of the deformed palladium samples was characterized by transmission electron microscopy (TEM). This analysis illustrated the cellular arrangement that evolved in palladium during cold working. The presence of MnO particles also was confirmed by TEM analysis.

  18. In-situ Neutron Scattering Determination of 3D Phase-Morphology Correlations in Fullerene Block Copolymer Systems

    SciTech Connect (OSTI)

    Karim, Alamgir; Bucknall, David; Raghavan, Dharmaraj

    2015-02-23

    a fundamental study that does not set out to evaluate new materials or produce devices, but rather we wish to understand from first principles how the molecular structure of polymer-fullerene mixtures determined using neutron scattering (small angle neutron scattering and neutron reflection) affects device characteristics and consequently performance. While this seems a very obvious question to ask, this critical understanding is far from being realized despite the wealth of studies into OPV’s and is severely limiting organic PV devices from achieving their theoretical potential. Despite the fundamental nature of proposed work, it is essential to remain technologically relevant and therefore to ensure we address these issues we have developed relationships on the fundamental nature of structure-processing-property paradigm as applied to future need for large area, flexible OPV devices. Nanoscale heterojunction systems consisting of fullerenes dispersed in conjugated polymers are promising materials candidates for achieving high performance organic photovoltaic (OPV) devices. In order to understand the phase behavior in these devices, neutron reflection is used to determine the behavior of model conjugated polymer-fullerene mixtures. Neutron reflection is particularly useful for these types of thin film studies since the fullerene generally have a high scattering contrast with respect to most polymers. We are studying model bulk heterojunction (BHJ) films based on mixtures of poly(3-hexyl thiophene)s (P3HT), a widely used photoconductive polymer, and different fullerenes (C60, PCBM and bis-PCBM). The characterization technique of neutron reflectivity measurements have been used to determine film morphology in a direction normal to the film surfaces. The novelty of the approach over previous studies is that the BHJ layer is sandwiched between a PEDOT/PSS and Al layers in real device configuration. Using this model system, the effect of typical thermal annealing

  19. Investigation of the tripoli porous structure by small-angle neutron scattering

    SciTech Connect (OSTI)

    Avdeev, M. V.; Blagoveshchenskii, N. M.; Garamus, V. M.; Novikov, A. G. Puchkov, A. V.

    2011-12-15

    The characteristics of the tripoli porous structure have been investigated by small-angle neutron scattering (SANS). Tripoli is a finely porous sedimentary rock formed by small spherical opal particles. Its main component is aqueous silica SiO{sub 2} {center_dot} nH{sub 2}O (80-90%). Tripoli is widely used in practice as a working medium for sorption filters and in some other commercial and construction technologies. The shape of the experimental SANS curves indicates the presence of small and large pores in tripoli. The small-pore size was estimated to be {approx}100 Angstrom-Sign . The size of large pores turned out to be beyond the range of neutron wave vector transfers Q that are available for the instrument used; however, their size was indirectly estimated to be {approx}(2000-2500) Angstrom-Sign . The pores of both groups behave as surfacetype fractal scatterers with the fractal dimension D {approx} 2.2-2.6. The densities of pores of these two groups differ by approximately three orders of magnitude ({approx}10{sup 16} and {approx}10{sup 13} cm{sup -3} for small and large pores, respectively); the fraction of large pores amounts to 70-80% of the total pore volume. The found pore characteristics (their densities, sizes, and relative volumes) are in satisfactory agreement (when a comparison is possible) with the absorption data.

  20. Equilibrium Structure of a Triblock Copolymer System Revealed by Mesoscale Simulation and Neutron Scattering

    SciTech Connect (OSTI)

    Do, Changwoo [ORNL] [ORNL; Chen, Wei-Ren [ORNL] [ORNL; Hong, Kunlun [ORNL] [ORNL; Smith, Gregory Scott [ORNL] [ORNL

    2013-01-01

    We have performed both mesoscale simulations and neutron scattering experiments on Pluronic L62, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer system in aqueous solution. The influence of simulation variables such PEO/PPO block ratio, interaction parameters, and coarse-graining methods is extensively investigated by covering all permutations of parameters found in the literatures. Upon increasing the polymer weight fraction from 50 wt% to 90 wt%, the equilibrium structure of the isotropic, reverse micellar, bicontinuous, worm-like micelle network, and lamellar phases are respectively predicted from the simulation depending on the choices of simulation parameters. Small angle neutron scattering (SANS) measurements show that the same polymer systems exhibit the spherical micellar, lamellar, and reverse micellar phases with the increase of the copolymer concentration at room temperature. Detailed structural analysis and comparison with simulations suggest that one of the simulation parameter sets can provide reasonable agreement with the experimentally observed structures.

  1. The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report

    SciTech Connect (OSTI)

    Farrer, R.; Longshore, A.

    1995-06-01

    This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation.

  2. Diffuse magnetic neutron scattering in the highly frustrated double perovskite Ba2YRuO6

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nilsen, Gøran. J.; Thompson, Corey M.; Ehlers, Georg; Marjerrison, Casey A.; Greedan, John E.

    2015-02-23

    Here we investigated diffuse magnetic scattering in the highly frustrated double perovskite Ba2YRuO6 using polarized neutrons. Consistent with previous reports, the material shows two apparent transitions at 47 and 36 K to an eventual type I face-centered-cubic magnetic ground state. The (100) magnetic reflection shows different behavior from the five other observed reflections upon heating from 1.8 K, with the former broadening well beyond the resolution limit near 36 K. Closer examination of the latter group reveals a small, but clear, increase in peak widths between 36 and 47 K, indicating that this regime is dominated by short-range spin correlations.more » Diffuse magnetic scattering persists above 47 K near the position of (100) to at least 200 K, consistent with strong frustration. Reverse Monte Carlo (RMC) modeling of the diffuse scattering from 45 to 200 K finds that the spin-spin correlations between nearest and next-nearest neighbors are antiferromagnetic and ferromagnetic, respectively, at temperatures near the upper ordering temperature, but both become antiferromagnetic and of similar magnitude above 100 K. The significance of this unusual crossover is discussed in light of the super-superexchange interactions between nearest and next-nearest neighbors in this material and the demands of type I order. The dimensionality of the correlations is addressed by reconstructing the scattering in the (hk0) plane using the RMC spin configurations. This indicates that one-dimensional spin correlations dominate at temperatures close to the first transition. In addition, a comparison between mean-field calculations and (hk0) scattering implies that further neighbor couplings play a significant role in the selection of the ground state. Finally, the results and interpretation are compared with those recently published for monoclinic Sr2YRuO6, and similarities and differences are emphasized.« less

  3. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    SciTech Connect (OSTI)

    Meyer, Matthew W.

    2013-03-14

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  4. Neutron total and scattering cross sections of /sup 6/Li in the few MeV region

    SciTech Connect (OSTI)

    Smith, A.; Guenther, P.; Whalen, J.

    1980-02-01

    Neutron total cross sections of /sup 6/Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of approx.< 10 keV. Neutron differential elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at approx.> 10 scattering angles and at incident-neutron intervals of approx.< 100 keV. Neutron differential inelastic-scattering cross sections are measured in the incident-energy range 3.5 to 4.0 MeV. The experimental results are extended to lower energies using measured neutron total cross sections recently reported elsewhere by the authors. The composite experimental data (total cross sections from 0.1 to 4.8 MeV and scattering cross sections from 0.22 to 4.0 MeV) are interpreted in terms of a simple two-level R-matrix model which describes the observed cross sections and implies the reaction cross section in unobserved channels; notably the (n;..cap alpha..)t reaction (Q = 4.783 MeV). The experimental and calculational results are compared with previously reported results as summarized in the ENDF/B-V evaluated nuclear data file.

  5. Development and Validation of Temperature Dependent Thermal Neutron Scattering Laws for Applications and Safety Implications in Generation IV Reactor Designs

    SciTech Connect (OSTI)

    Ayman Hawari

    2008-06-20

    The overall obljectives of this project are to critically review the currently used thermal neutron scattering laws for various moderators as a function of temperature, select as well documented and representative set of experimental data sensitive to the neutron spectra to generate a data base of benchmarks, update models and models parameters by introducing new developments in thermalization theory and condensed matter physics into various computational approaches in establishing the scattering laws, benchmark the results against the experimentatl set. In the case of graphite, a validation experiment is performed by observing nutron slowing down as a function of temperatures equal to or greater than room temperature.

  6. Measurement of the Neutron Radius of 208Pb Through Parity Violation in Electron Scattering

    SciTech Connect (OSTI)

    Saenboonruang, Kiadtisak

    2013-05-01

    In contrast to the nuclear charge densities, which have been accurately measured with electron scattering, the knowledge of neutron densities still lack precision. Previous model-dependent hadron experiments suggest the difference between the neutron radius, Rn, of a heavy nucleus and the proton radius, Rp, to be in the order of several percent. To accurately obtain the difference, Rn-Rp, which is essentially a neutron skin, the Jefferson Lab Lead (208Pb) Radius Experiment (PREX) measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 208Pb at an energy of 1.06 GeV and a scattering angle of 5° . Since Z0 boson couples mainly to neutrons, this asymmetry provides a clean measurement of Rn with respect to Rp. PREX was conducted at the Jefferson lab experimental Hall A, from March to June 2010. The experiment collected a final data sample of 2x 107 helicity-window quadruplets. The measured parity-violating electroweak asymmetry APV = 0.656 ± 0.060 (stat) ± 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions, Rn-Rp = 0.33+0.16-0.18 fm and provides the first electroweak observation of the neutron skin as expected in a heavy, neutron-rich nucleus. The value of the neutron radius of 208Pb has important implications for models of nuclear structure and their application in atomic physics and astrophysics such as atomic parity non-conservation (PNC) and neutron stars.

  7. Monte Carlo and analytical model predictions of leakage neutron exposures from passively scattered proton therapy

    SciTech Connect (OSTI)

    Prez-Andjar, Anglica [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)] [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Zhang, Rui; Newhauser, Wayne [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner Avenue, Houston, Texas 77030 (United States)] [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner Avenue, Houston, Texas 77030 (United States)

    2013-12-15

    Purpose: Stray neutron radiation is of concern after radiation therapy, especially in children, because of the high risk it might carry for secondary cancers. Several previous studies predicted the stray neutron exposure from proton therapy, mostly using Monte Carlo simulations. Promising attempts to develop analytical models have also been reported, but these were limited to only a few proton beam energies. The purpose of this study was to develop an analytical model to predict leakage neutron equivalent dose from passively scattered proton beams in the 100-250-MeV interval.Methods: To develop and validate the analytical model, the authors used values of equivalent dose per therapeutic absorbed dose (H/D) predicted with Monte Carlo simulations. The authors also characterized the behavior of the mean neutron radiation-weighting factor, w{sub R}, as a function of depth in a water phantom and distance from the beam central axis.Results: The simulated and analytical predictions agreed well. On average, the percentage difference between the analytical model and the Monte Carlo simulations was 10% for the energies and positions studied. The authors found that w{sub R} was highest at the shallowest depth and decreased with depth until around 10 cm, where it started to increase slowly with depth. This was consistent among all energies.Conclusion: Simple analytical methods are promising alternatives to complex and slow Monte Carlo simulations to predict H/D values. The authors' results also provide improved understanding of the behavior of w{sub R} which strongly depends on depth, but is nearly independent of lateral distance from the beam central axis.

  8. Estimation and modeling of coal pore accessibility using small angle neutron scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; Elsworth, Derek; Melnichenko, Yuri; He, Lilin; Wang, Yi

    2015-09-04

    Gas diffusion in coal is controlled by nano-structure of the pores. The interconnectivity of pores not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify pore accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical pore accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas pressure using deuterated methane (CD4) at low Qmore » values for both coals. Pores smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the pore radius is larger than 40 nm, the pore accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of pores are accessible to CD4 for anthracite and 37% for sub-bituminous coal, where the pore radius is 16 nm. For these two coals, pore accessibility and pore radius follows a power-law relationship.« less

  9. Final Report Gentile, Thomas R. 36 MATERIALS SCIENCE neutron...

    Office of Scientific and Technical Information (OSTI)

    spin filter; polarization; helium-3 We propose to extend the technique of polarized neutron scattering into new domains by continued development and application of polarized...

  10. Investigation of Three-Body Force Effects in Neutron-Deuteron Scattering at 95 MeV

    SciTech Connect (OSTI)

    Mermod, P.; Blomgren, J.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Klug, J.; Oesterlund, M.; Pomp, S.; Nilsson, L.; Olsson, N.; Tippawan, U.; Jonsson, O.; Prokofiev, A.; Renberg, P.-U.; Nadel-Turonski, P.; Maeda, Y.; Sakai, H.; Tamii, A.

    2005-05-24

    We have measured the neutron-deuteron (nd) elastic-scattering differential cross section at 95 MeV incident neutron energy, using both the Medley and the SCANDAL setups at TSL in Uppsala. The full angular distribution was covered by detecting recoil deuterons from thin CD2 targets, and the result was normalized to the neutron-proton (np) cross section. Recent theories predict that three-nucleon (3N) force effects, if present, would affect the cross section in the minimum region by about 30%. The results are compared with theoretical calculations and are well described if 3N forces are included.

  11. 5th Annual SSRL School on Synchrotron X-ray Scattering Techniques...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Web | People Search SSRL Go 5th Annual SSRL School on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences: Theory and Application June 1-3, 2010...

  12. Response to 'Comment on 'Elastic incoherent neutron scattering operating by varying instrumental energy resolution: Principle, simulations, and experiments of the resolution elastic neutron scattering (RENS)'' [Rev. Sci. Instrum. 83, 107101 (2012)

    SciTech Connect (OSTI)

    Magazu, Salvatore; Migliardo, Federica; Benedetto, Antonio [Dipartimento di Fisica, Universita di Messina, C.da Papardo n Degree-Sign 31, P.O. Box 55, Vill. S. Agata 98166 Messina (Italy)

    2012-10-15

    Recently [S. Magazu et al., Rev. Sci. Instrum. 82, 105115 (2011)] we have proposed a new method for characterizing, by neutron scattering, the dynamical properties of complex material systems, such as, the ones of interest in the biophysical field. This approach called Resolution Elastic Neutron Scattering, in short RENS, is based on the detection of the elastically scattered neutron intensity as a function of the instrumental energy resolution. By experimental, theoretical, and numerical findings, we have pointed out that an inflection point occurs in the elastic intensity when the system relaxation time approaches the instrumental energy resolution time. This approach, differently from quasi-elastic neutron scattering (QENS), gives the chance to evaluate the system relaxation times without using pre-defined models that can be wrong and/or misleading. Here, we reply to a Comment on the above-mentioned main paper in which Wuttke proposes a different approach to evaluate the above-mentioned inflection point; on this regard, it should be noticed that the existence of the inflection point, which is the main topic of our work, is not questioned and that the approach proposed by Wuttke in the Comment, although valid for a class of dynamical processes, is not applicable when different and distinct processes occur simultaneously at different time scale.

  13. Measurement of cross sections for inelastic cold-neutron scattering in metals and polymers by the method of (n, {gamma}) analysis

    SciTech Connect (OSTI)

    Arzumanov, S. S.; Bondarenko, L. N.; Geltenbort, P.; Morozov, V. I.; Panin, Yu. N.; Chernyavsky, S. M.

    2008-11-15

    The results obtained by measuring the cross sections for the inelastic scattering of very cold neutrons for a number of metals and polymers by the method of a neutron-irradiation analysis are presented. The method is based on simultaneously measuring events of inelastic scattering and neutron capture in the sample under investigation via recording gamma radiation with a semiconductor germanium detector. Neutron capture by a nucleus of the sample is accompanied by the prompt radiation of gamma rays having a known spectrum. Upon inelastic scattering, a neutron acquires thermal energy. Upon leaving the sample, this neutron is absorbed in a special converter that contains the isotope {sup 10}B. The capture of the neutron by a {sup 10}B nucleus is followed by the emission of a 477-keV gamma ray. The probabilities of capture and inelastic scattering are proportional to the respective neutron-interaction cross sections, and the ratio of the recorded detector counts corresponding to events of the two types does not depend on the spectrum of the incident flux of very cold neutrons or on the trajectory of neutron motion in the sample. The sought inelastic-scattering cross section at a fixed sample temperature is calculated by using this ratio and the known cross section for neutron capture by the sample isotope having a known gamma-radiation spectrum.

  14. Small angle neutron scattering as fingerprinting of ancient potteries from Sicily (Southern Italy)

    SciTech Connect (OSTI)

    Barone, G.; Mazzoleni, P.; Crupi, V.; Majolino, D.; Venuti, V.; Teixeira, J.

    2009-09-01

    Small angle neutron scattering measurements have been carried out in order to investigate, in microdestructive way, the mesoscopic structure of a variety of potteries of relevance to cultural heritage coming from different Sicilian (Southern Italy) archeological sites belonging to the 'Strait of Messina' area and dated back to 7th-3rd century B.C. Data have been compared with the mesoscopic parameters extracted for two series of clayey sediments typical of the Strait of Messina area and fired under controlled conditions. The observed agreement between the features of reference and archeological samples allowed us to estimate the maximum firing temperature of the latter. Information on the pore sizes was obtained by the use of the concept of fractal surface, and compared with porosimetry results.

  15. A New On-the-Fly Sampling Method for Incoherent Inelastic Thermal Neutron Scattering Data in MCNP6

    SciTech Connect (OSTI)

    Pavlou, Andrew Theodore; Brown, Forrest B.; Ji, Wei

    2014-09-02

    At thermal energies, the scattering of neutrons in a system is complicated by the comparable velocities of the neutron and target, resulting in competing upscattering and downscattering events. The neutron wavelength is also similar in size to the target's interatomic spacing making the scattering process a quantum mechanical problem. Because of the complicated nature of scattering at low energies, the thermal data files in ACE format used in continuous-energy Monte Carlo codes are quite large { on the order of megabytes for a single temperature and material. In this paper, a new storage and sampling method is introduced that is orders of magnitude less in size and is used to sample scattering parameters at any temperature on-the-fly. In addition to the reduction in storage, the need to pre-generate thermal scattering data tables at fine temperatures has been eliminated. This is advantageous for multiphysics simulations which may involve temperatures not known in advance. A new module was written for MCNP6 that bypasses the current S(?,?) table lookup in favor of the new format. The new on-the-fly sampling method was tested for graphite for two benchmark problems at ten temperatures: 1) an eigenvalue test with a fuel compact of uranium oxycarbide fuel homogenized into a graphite matrix, 2) a surface current test with a \\broomstick" problem with a monoenergetic point source. The largest eigenvalue difference was 152pcm for T= 1200K. For the temperatures and incident energies chosen for the broomstick problem, the secondary neutron spectrum showed good agreement with the traditional S(?,?) sampling method. These preliminary results show that sampling thermal scattering data on-the-fly is a viable option to eliminate both the storage burden of keeping thermal data at discrete temperatures and the need to know temperatures before simulation runtime.

  16. High-energy magnetic excitations in overdoped La2-xSrxCuO4 studied by neutron and resonant inelastic X-ray scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wakimoto, S.; Ishii, K.; Kimura, H.; Fujita, M.; Dellea, G.; Kummer, K.; Braicovich, L.; Ghiringhelli, G.; Debeer-Schmitt, Lisa M.; Granroth, Garrett E.

    2015-05-21

    We have performed neutron inelastic scattering and resonant inelastic x-ray scattering (RIXS) at the Cu-L3 edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La2₋xSrxCuO4 with x=0.25 (Tc=15 K) and x=0.30 (nonsuperconducting) using identical single-crystal samples for the two techniques. From constant-energy slices of neutron-scattering cross sections, we have identified magnetic excitations up to ~250 meV for x=0.25. Although the width in the momentum direction is large, the peak positions along the (π,π) direction agree with the dispersion relation of the spin wave in the nondoped La2CuO4 (LCO), which is consistent with themore » previous RIXS results of cuprate superconductors. Using RIXS at the Cu-L3 edge, we have measured the dispersion relations of the so-called paramagnon mode along both (π,π) and (π,0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (π,0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (π,π) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin wave of LCO near (π/2,π/2). Thus, our results indicate consistency between neutron inelastic scattering and RIXS, and elucidate the entire magnetic excitation in the (π,π) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. Lastly, we find a possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (π,π) direction as detected by the x-ray scattering.« less

  17. Forward-angle neutron-proton scattering at 96 MeV

    SciTech Connect (OSTI)

    Johansson, C.; Blomgren, J.; Atac, A.; Bergenwall, B.; Hildebrand, A.; Klug, J.; Mermod, P.; Pomp, S.; Oesterlund, M.; Dangtip, S.; Tippawan, U.; Elmgren, K.; Jonsson, O.; Prokofiev, A.V.; Renberg, P.-U.; Nadel-Turonski, P.; Nilsson, L.; Olsson, N.

    2005-02-01

    The differential np scattering cross section has been measured at 96 MeV in the angular range {theta}{sub c.m.}=20 deg. -76 deg. Together with an earlier data set at the same energy, covering the angles {theta}{sub c.m.}=74 deg. -180 deg., a new data set has been formed in the angular range {theta}{sub c.m.}=20 deg. - 180 deg. This extended data set has been normalized to the experimental total np cross section, resulting in a renormalization of the earlier data of 0.7%, which is well within the reported normalization uncertainty for that experiment. A novel normalization technique has been investigated. The results on forward np scattering are in reasonable agreement with theory models and partial wave analyses and have been compared with data from the literature.

  18. Characterization of a Thermo Scientific D711 D-T Neutron Generator Located in a Low-Scatter Facility

    SciTech Connect (OSTI)

    Hayes, John W.; Finn, Erin C.; Greenwood, Lawrence R.; Wittman, Richard S.

    2014-03-21

    A dosimetry experiment used to measure the neutron flux and spectrum of a D-T neutron generator is presented. The D-T generator at Pacific Northwest National Laboratory is installed in the middle of a large room to minimize scatter of neutrons back to the sample. The efficacy of maintaining a pure fast neutron field for the sample is investigated. Twenty-one positions within 13 cm of the neutron source contained foils or wires of Fe, Ni, Al with additional Au, and In monitors at some locations. Spectral adjustment of the neutron flux at each position based on measured reaction rates and theoretical Monte Carlo calculations show that at least 99.1% of the spectrum lies above 110 keV for all measured positions, and neutrons above 14 MeV can account for as much as 91% at locations along the axis of the generator and close to the source. The 14 MeV component drops to 77% in radial positions far from the source. The largest total flux observed was 8.29E+08 n/cm2-s (1.4%) in the center of the cooling cap, although additional experiments have shown this value could be as high as 1.20E+09 n/cm2-s.

  19. Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yan, Y.; Qian, S.; Littrell, K.; Parish, C. M.; Plummer, L. K.

    2015-02-13

    A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distributionmore » of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. This study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor will be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.« less

  20. Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

    SciTech Connect (OSTI)

    Yan, Y.; Qian, S.; Littrell, K.; Parish, C. M.; Plummer, L. K.

    2015-02-13

    A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distribution of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. This study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor will be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.

  1. Fast, Quantitative, and Nondestructive Evaluation on Hydrided LWR Fuel Cladding by Small Angle Incoherent Neutron Scattering of Hydrogen

    SciTech Connect (OSTI)

    Yan, Yong; Qian, Shuo; Littrell, Ken; Parish, Chad M; Plummer, Lee K

    2015-01-01

    A non-destructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentration were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distribution of circumferential hydrides across the wall. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Our study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount ( 20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor can be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for absolute hydrogen concentration determination.

  2. An Analysis Technique for Active Neutron Multiplicity Measurements Based on First Principles

    SciTech Connect (OSTI)

    Evans, Louise G; Goddard, Braden; Charlton, William S; Peerani, Paolo

    2012-08-13

    Passive neutron multiplicity counting is commonly used to quantify the total mass of plutonium in a sample, without prior knowledge of the sample geometry. However, passive neutron counting is less applicable to uranium measurements due to the low spontaneous fission rates of uranium. Active neutron multiplicity measurements are therefore used to determine the {sup 235}U mass in a sample. Unfortunately, there are still additional challenges to overcome for uranium measurements, such as the coupling of the active source and the uranium sample. Techniques, such as the coupling method, have been developed to help reduce the dependence of calibration curves for active measurements on uranium samples; although, they still require similar geometry known standards. An advanced active neutron multiplicity measurement method is being developed by Texas A&M University, in collaboration with Los Alamos National Laboratory (LANL) in an attempt to overcome the calibration curve requirements. This method can be used to quantify the {sup 235}U mass in a sample containing uranium without using calibration curves. Furthermore, this method is based on existing detectors and nondestructive assay (NDA) systems, such as the LANL Epithermal Neutron Multiplicity Counter (ENMC). This method uses an inexpensive boron carbide liner to shield the uranium sample from thermal and epithermal neutrons while allowing fast neutrons to reach the sample. Due to the relatively low and constant fission and absorption energy dependent cross-sections at high neutron energies for uranium isotopes, fast neutrons can penetrate the sample without significant attenuation. Fast neutron interrogation therefore creates a homogeneous fission rate in the sample, allowing for first principle methods to be used to determine the {sup 235}U mass in the sample. This paper discusses the measurement method concept and development, including measurements and simulations performed to date, as well as the potential

  3. Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies

    SciTech Connect (OSTI)

    Singh, Saurabh; Junghans, Ann; Watkins, Erik; Kapoor, Yash; Toomey, Ryan; Majewski, Jaroslaw

    2015-02-17

    The structure of layer-by-layer (LbL) deposited nanofilm coatings consists of alternating polyethylenimine (PEI) and polystyrenesulfonate (PSS) films deposited on a single crystal quartz substrate. LbL-deposited nanofilms were investigated by neutron reflectomery (NR) in contact with water in the static and fluid shear stress conditions. The fluid shear stress was applied through a laminar flow of the liquid parallel to the quartz/polymer interface in a custom-built solid–liquid interface cell. The scattering length density profiles obtained from NR results of these polyelectrolyte multilayers (PEM), measured under different shear conditions, showed proportional decrease of volume fraction of water hydrating the polymers. For the highest shear rate applied (ca. 6800 s–1) the water volume fraction decreased by approximately 7%. The decrease of the volume fraction of water was homogeneous through the thickness of the film. Since there were not any significant changes in the total polymer thickness, it resulted in negative osmotic pressures in the film. The PEM films were compared with the behavior of thin films of thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) deposited via spin-coating. The PEM and pNIPAM differ in their interactions with water molecules, and they showed opposite behaviors under the fluid shear stress. In both cases the polymer hydration was reversible upon the restoration of static conditions. Furthermore, a theoretical explanation is given to explain this difference in the effect of shear on hydration of polymeric thin films.

  4. Multi-component modeling of quasielastic neutron scattering from phospholipid membranes

    SciTech Connect (OSTI)

    Wanderlingh, U. DAngelo, G.; Branca, C.; Trimarchi, A.; Rifici, S.; Finocchiaro, D.; Conti Nibali, V.; Crupi, C.; Ollivier, J.; Middendorf, H. D.

    2014-05-07

    We investigated molecular motions in the 0.3350 ps time range of D{sub 2}O-hydrated bilayers of 1-palmitoyl-oleoyl-sn-glycero-phosphocholine and 1,2-dimyristoyl-sn-glycero-phosphocholine in the liquid phase by quasielastic neutron scattering. Model analysis of sets of spectra covering scale lengths from 4.8 to 30 revealed the presence of three types of motion taking place on well-separated time scales: (i) slow diffusion of the whole phospholipid molecules in a confined cylindrical region; (ii) conformational motion of the phospholipid chains; and (iii) fast uniaxial rotation of the hydrogen atoms around their carbon atoms. Based on theoretical models for the hydrogen dynamics in phospholipids, the spatial extent of these motions was analysed in detail and the results were compared with existing literature data. The complex dynamics of protons was described in terms of elemental dynamical processes involving different parts of the phospholipid chain on whose motions the hydrogen atoms ride.

  5. Small Angle Neutron Scattering (SANS) Studies on the Structural Evolution of Pyromellitamide Self-assembled Gels

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Scott, Jamieson; Tong, Katie; William, Hamilton; He, Lilin; James, Michael; Thordarson, Pall; Boukhalfa, Sofiane

    2014-10-31

    The kinetics of aggregation of two pyromellitamide gelators; tetrabutyl- (C4) and tetrahexylpyromellitamide (C6), in deuterated cyclohexane has been investigated by small angle neutron scattering (SANS) for up to six days. The purpose of this study was to improve our understanding of how self-assembled gels are formed. Short-term (< 3 hour) time scales revealed multiple phases with the data for the tetrabutylpyromellitamide C4 indicating one dimensional stacking and aggregation corresponding to a multi-fiber braided cluster arrangement that is about 35 Å in diameter. The corresponding tetrahexylpyromellitamide C6 data suggests that the C6 also forms one-dimensional stacks but that these aggregate tomore » a thicker multi-fiber braided cluster that have a diameter of 61.8 Å. Over a longer period of time, the radius, persistence length and contour length all continue to increase in 6 days after cooling. This data suggests that structural changes in self-assembled gels occur over a period exceeding several days and that fairly subtle changes in the structure (e.g. tail-length) can influence the packing of molecules in self-assembled gels on the single-to-few fiber bundle stage.« less

  6. Inelastic neutron scattering study on boson peaks of imidazolium-based ionic liquids

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kofu, Maiko; Inamura, Yasuhiro; Podlesnyak, Andrey A.; Ehlers, Georg; Yamamuro, Osamu; Moriya, Yosuke

    2015-07-26

    Low energy excitations of 1-alkyl-3-methylimidazolium ionic liquids (ILs) have been investigated by means of neutron spectroscopy. In the spectra of inelastic scattering, a broad excitation peak referred to as a “boson peak” appeared at 1–3 meV in all of the ILs measured. The intensity of the boson peak was enhanced at the Q positions corresponding to the diffraction peaks, reflecting the in-phase vibrational nature of the boson peak. Furthermore the boson peak energy (EBP) was insensitive to the length of the alkyl-chain but changed depending on the radius of the anion. From the correlation among EBP, the anion radius, andmore » the glass transition temperature Tg, we conclude that both EBP and Tg in ILs are predominantly governed by the inter-ionic Coulomb interaction which is less influenced by the alkyl-chain length. Furthermore, we also found that the EBP is proportional to the inverse square root of the molecular weight as observed in molecular glasses.« less

  7. Measurement Of Neutron Radius In Lead By Parity Violating Scattering Flash ADC DAQ

    SciTech Connect (OSTI)

    Ahmed, Zafar

    2012-06-01

    This dissertation reports the experiment PREx, a parity violation experiment which is designed to measure the neutron radius in {sup 208}Pb. PREx is performed in hall A of Thomas Jefferson National Accelerator Facility from March 19th to June 21st. Longitudionally polarized electrons at energy 1 GeV scattered at and angle of {theta}{sub lab} = 5.8 {degrees} from the Lead target. Beam corrected pairty violaing counting rate asymmetry is (A{sub corr} = 594 ± 50(stat) ± 9(syst))ppb at Q{sup 2} = 0.009068GeV {sup 2}. This dissertation also presents the details of Flash ADC Data Acquisition(FADC DAQ) system for Moller polarimetry in Hall A of Thomas Jefferson National Accelerator Facility. The Moller polarimeter measures the beam polarization to high precision to meet the specification of the PREx(Lead radius experiment). The FADC DAQ is part of the upgrade of Moller polarimetery to reduce the systematic error for PREx. The hardware setup and the results of the FADC DAQ analysis are presented

  8. Characterization of the Neutron Fields in the Lawrence Livermore National Laboratory (LLNL) Radiation Calibration Laboratory Low Scatter Calibration Facility

    SciTech Connect (OSTI)

    Radev, R

    2009-09-04

    In June 2007, the Department of Energy (DOE) revised its rule on Occupational Radiation Protection, Part 10 CFR 835. A significant aspect of the revision was the adoption of the recommendations outlined in International Commission on Radiological Protection (ICRP) Report 60 (ICRP-60), including new radiation weighting factors for neutrons, updated internal dosimetric models, and dose terms consistent with the newer ICRP recommendations. ICRP-60 uses the quantities defined by the International Commission on Radiation Units and Measurements (ICRU) for personnel and area monitoring including the ambient dose equivalent H*(d). A Joint Task Group of ICRU and ICRP has developed various fluence-to-dose conversion coefficients which are published in ICRP-74 for both protection and operational quantities. In February 2008, Lawrence Livermore National Laboratory (LLNL) replaced its old pneumatic transport neutron irradiation system in the Radiation Calibration Laboratory (RCL) Low Scatter Calibration Facility (B255, Room 183A) with a Hopewell Designs irradiator model N40. The exposure tube for the Hopewell system is located close to, but not in exactly the same position as the exposure tube for the pneumatic system. Additionally, the sources for the Hopewell system are stored in Room 183A where, prior to the change, they were stored in a separate room (Room 183C). The new source configuration and revision of the 10 CFR 835 radiation weighting factors necessitate a re-evaluation of the neutron dose rates in B255 Room 183A. This report deals only with the changes in the operational quantities ambient dose equivalent and ambient dose rate equivalent for neutrons as a result of the implementation of the revised 10 CFR 835. In the report, the terms 'neutron dose' and 'neutron dose rate' will be used for convenience for ambient neutron dose equivalent and ambient neutron dose rate equivalent unless otherwise stated.

  9. Neutron Scattering Facilities | U.S. DOE Office of Science (SC...

    Office of Science (SC) Website

    High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory The HFIR facility is the United States' highest flux reactor-based neutron source, and is a major neutron ...

  10. (A neutron scattering experiment to study the high-energy spin dynamics of the itinerant antiferromagnet Mn sub 90 Cu sub 10 )

    SciTech Connect (OSTI)

    Fernandez-Baca, J.A.

    1990-10-26

    The traveler performed a neutron scattering experiment to study the high-energy spin dynamics of the itinerant antiferromagnet. This experiment was conducted at a unique instrument located at the hot-neutron source at the ILL. The traveler also held various scientific discussions with ILL research staff members and visiting scientists.

  11. Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chen, Sow-Hsin; Lagi, Marco; Chu, Xiang-qiang; Zhang, Yang; Kim, Chansoo; Faraone, Antonio; Fratini, Emiliano; Baglioni, Piero

    2010-01-01

    This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling between them. We found that the key to this strong coupling is the existence of a fragile-to-strong dynamic crossover (FSC) phenomenon occurring at around T L = 225±5 K in the hydration water. On lowering of the temperature toward FSC, the structure of hydration water makes a transition from predominantly the high density form (HDL), a more fluid state, to predominantly the low density formmore » (LDL), a less fluid state, derived from the existence of a liquid–liquid critical point at an elevated pressure. We show experimentally that this sudden switch in the mobility of hydration water on Lysozyme, B-DNA and RNA triggers the dynamic transition, at a temperature T D = 220 K, for these biopolymers. In the glassy state, below T D , the biopolymers lose their vital conformational flexibility resulting in a substantial diminishing of their biological functions. We also performed molecular dynamics (MD) simulations on a realistic model of hydrated lysozyme powder, which confirms the existence of the FSC and the hydration level dependence of the FSC temperature. Furthermore, we show a striking feature in the short time relaxation ( β -relaxation) of protein dynamics, which is the logarithmic decay spanning 3 decades (from ps to ns). The long time α -relaxation shows instead a diffusive behavior, which supports the liquid-like motions of protein constituents. We then discuss our recent high-resolution X-ray inelastic scattering studies of globular proteins, Lysozyme and Bovine Serum Albumin. We were able to measure the dispersion relations of collective, intra-protein phonon-like excitations in these proteins for the first time. We found that the phonon energies show a marked softening and at the same time their population increases

  12. A versatile setup using femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering

    SciTech Connect (OSTI)

    Shen, Yujie; Voronine, Dmitri V.; Sokolov, Alexei V.; Scully, Marlan O.

    2015-08-15

    We report a versatile setup based on the femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering. The setup uses a femtosecond Ti:Sapphire oscillator source and a folded 4f pulse shaper, in which the pulse shaping is carried out through conventional optical elements and does not require a spatial light modulator. Our setup is simple in alignment, and can be easily switched between the collinear single-beam and the noncollinear two-beam configurations. We demonstrate the capability for investigating both transparent and highly scattering samples by detecting transmitted and reflected signals, respectively.

  13. Effects of fluid shear stress on polyelectrolyte multilayers by neutron scattering studies

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Singh, Saurabh; Junghans, Ann; Watkins, Erik; Kapoor, Yash; Toomey, Ryan; Majewski, Jaroslaw

    2015-02-17

    The structure of layer-by-layer (LbL) deposited nanofilm coatings consists of alternating polyethylenimine (PEI) and polystyrenesulfonate (PSS) films deposited on a single crystal quartz substrate. LbL-deposited nanofilms were investigated by neutron reflectomery (NR) in contact with water in the static and fluid shear stress conditions. The fluid shear stress was applied through a laminar flow of the liquid parallel to the quartz/polymer interface in a custom-built solid–liquid interface cell. The scattering length density profiles obtained from NR results of these polyelectrolyte multilayers (PEM), measured under different shear conditions, showed proportional decrease of volume fraction of water hydrating the polymers. For themore » highest shear rate applied (ca. 6800 s–1) the water volume fraction decreased by approximately 7%. The decrease of the volume fraction of water was homogeneous through the thickness of the film. Since there were not any significant changes in the total polymer thickness, it resulted in negative osmotic pressures in the film. The PEM films were compared with the behavior of thin films of thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) deposited via spin-coating. The PEM and pNIPAM differ in their interactions with water molecules, and they showed opposite behaviors under the fluid shear stress. In both cases the polymer hydration was reversible upon the restoration of static conditions. Furthermore, a theoretical explanation is given to explain this difference in the effect of shear on hydration of polymeric thin films.« less

  14. Neutron Scattering of Residual Hydrogen in 1,4-Dioxane-D8 Liquid. Understanding Measurements with Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    de Almeida, Valmor F.; Liu, Hongjun; Herwig, Kenneth W.; Kidder, Michelle

    2016-01-01

    That incoherent scattering from protiated molecular liquids adds a constant background to the measured scattering intensity is well known, but less appreciated is the fact that coherent scattering is also induced by the presence of hydrogen in a deuterated liquid. In fact, the scattering intensity can be very sensitive, in the small-q region, with respect to the amounts and distribution of residual H in the system. We used 1,4-dioxane liquid to demonstrate that the partial structure factors of the HD and DD atom pairs contribute significantly to inter-molecular scattering and that uncertainty in the extent of deuteration account for discrepancies between simulations and measurements. Both contributions to uncertainty have similar magnitudes: scattering interference of the hydrogen-deuterium pair, and complementary interference from the deuterium-deuterium pair by virtue of chemical inhomogeneity. This situation arises in practice since deuteration of liquids is often 99% or less. A combined experimental and extensive computational study of static thermal neutron scattering of 1,4-dioxane demonstrates the foregoing. We show, through simulations, that the reason for the differences is the content of protiated dioxane (vendors quote 1%). We estimate that up to 5% (at 298K and at 343K) protiated mole fraction may be involved in generating the scattering differences. Finally, we find that the particular distribution of hydrogen in the protiated molecules affects the results significantly; here we considered molecules to be either fully protiated or fully deuterated. This scenario best reconciles the computational and experimental results, and leads us to speculate that the deuteration synthesis process tends to leave a molecule either fully deuterated or fully protiated. Although we have used 1,4-dioxane as a model liquid, the effects described in this study extend to similar liquids and similar systematic experimental/computational studies can be performed to either

  15. Neutron scattering of residual hydrogen in 1,4-dioxane d8 liquid: Understanding measurements with molecular dynamics simulations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Hongjun; Herwig, Kenneth W.; Kidder, Michelle K.; de Almeida, Valmor F.

    2016-06-08

    That incoherent scattering from protiated molecular liquids adds a constant background to the measured scattering intensity is well-known, but less appreciated is the fact that coherent scattering is also induced by the presence of hydrogen in a deuterated liquid. In fact, the scattering intensity can be very sensitive, in the small-q region, with respect to the amounts and distribution of residual H in the system. We used 1,4-dioxane liquid to demonstrate that the partial structure factors of the HD and DD atom pairs contribute significantly to intermolecular scattering and that uncertainty in the extent of deuteration account for discrepancies betweenmore » simulations and measurements. Both contributions to uncertainty have similar magnitudes: scattering interference of the hydrogen–deuterium pair, and complementary interference from the deuterium–deuterium pair by virtue of chemical inhomogeneity. This situation arises in practice since deuteration of liquids is often 99% or less. A combined experimental and extensive computational study of static thermal neutron scattering of 1,4-dioxane demonstrates the foregoing. We show, through simulations, that the reason for the differences is the content of protiated dioxane (vendors quote 1%). We estimate that up to 5% (at 298 K and at 343 K) protiated molar fraction may be involved in generating the scattering differences. Finally, we find that the particular distribution of hydrogen in the protiated molecules affects the results significantly; here, we considered molecules to be either fully protiated or fully deuterated. This scenario best reconciles the computational and experimental results, and leads us to speculate that the deuteration synthesis process tends to leave a molecule either fully deuterated or fully protiated. As a result, we have used 1,4-dioxane as a model liquid, the effects described in this study extend to similar liquids, and similar systematic experimental/computational studies can be

  16. Level crossings and zero-field splitting in the {Cr8}-cubane spin-cluster studied using inelastic neutron scattering and magnetization

    SciTech Connect (OSTI)

    Vaknin, D.; Garlea, Vasile O; Demmel, F.; Mamontov, Eugene; Nojiri, H; Martin, Catalin; Chiorescu, Irinel; Qiu, Y.; Luban, M.; Kogerler, P.; Fielden, J.; Engelhardt, L; Rainey, C

    2010-01-01

    Inelastic neutron scattering (INS) in variable magnetic field and high-field magnetization measurements in the millikelvin temperature range were performed to gain insight into the low-energy magnetic excitation spectrum and the field-induced level crossings in the molecular spin cluster {Cr8}-cubane. These complementary techniques provide consistent estimates of the lowest level-crossing field. The overall features of the experimental data are explained using an isotropic Heisenberg model, based on three distinct exchange interactions linking the eight CrIII paramagnetic centers (spins s = 3/2), that is supplemented with a relatively large molecular magnetic anisotropy term for the lowest S = 1 multiplet. It is noted that the existence of the anisotropy is clearly evident from the magnetic field dependence of the excitations in the INS measurements, while the magnetization measurements are not sensitive to its effects.

  17. Calibrating and training of neutron based NSA techniques with less SNM standards

    SciTech Connect (OSTI)

    Geist, William H; Swinhoe, Martyn T; Bracken, David S; Freeman, Corey R; Newell, Matthew R

    2010-01-01

    Accessing special nuclear material (SNM) standards for the calibration of and training on nondestructive assay (NDA) instruments has become increasingly difficult in light of enhanced safeguards and security regulations. Limited or nonexistent access to SNM has affected neutron based NDA techniques more than gamma ray techniques because the effects of multiplication require a range of masses to accurately measure the detector response. Neutron based NDA techniques can also be greatly affected by the matrix and impurity characteristics of the item. The safeguards community has been developing techniques for calibrating instrumentation and training personnel with dwindling numbers of SNM standards. Monte Carlo methods have become increasingly important for design and calibration of instrumentation. Monte Carlo techniques have the ability to accurately predict the detector response for passive techniques. The Monte Carlo results are usually benchmarked to neutron source measurements such as californium. For active techniques, the modeling becomes more difficult because of the interaction of the interrogation source with the detector and nuclear material; and the results cannot be simply benchmarked with neutron sources. A Monte Carlo calculated calibration curve for a training course in Indonesia of material test reactor (MTR) fuel elements assayed with an active well coincidence counter (AWCC) will be presented as an example. Performing training activities with reduced amounts of nuclear material makes it difficult to demonstrate how the multiplication and matrix properties of the item affects the detector response and limits the knowledge that can be obtained with hands-on training. A neutron pulse simulator (NPS) has been developed that can produce a pulse stream representative of a real pulse stream output from a detector measuring SNM. The NPS has been used by the International Atomic Energy Agency (IAEA) for detector testing and training applications at the

  18. Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scattering Print When a crystalline sample is illuminated with x-rays, the x-rays are scattered (diffracted) into very specific directions with various intensities. Detectors are used to measure this "diffraction pattern," which is then processed by computers to deduce the arrangement of atoms within the crystal. Hard x-rays have wavelengths comparable to the distance between atoms. Essentially everything we know about the atomic structure of materials is based on results from x-ray

  19. Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scattering Print When a crystalline sample is illuminated with x-rays, the x-rays are scattered (diffracted) into very specific directions with various intensities. Detectors are used to measure this "diffraction pattern," which is then processed by computers to deduce the arrangement of atoms within the crystal. Hard x-rays have wavelengths comparable to the distance between atoms. Essentially everything we know about the atomic structure of materials is based on results from x-ray

  20. Characterization of a Thermo Scientific D711 D-T Neutron Generator Located in a Low-Scatter Facility

    SciTech Connect (OSTI)

    Hayes, John W.; Finn, Erin C.; Greenwood, Lawrence R.; Wittman, Richard S.

    2014-03-21

    Pacific Northwest National Laboratory (PNNL) purchased and installed a D711 D-T neutron generator (D-T) from Thermo Scientific in August 2011. The D-T nominally produces 14 MeV neutrons which are important for research in matters of national security. Fast neutrons provide the capability of harnessing threshold reactions for the production of rare isotopes, which are of interest to radiochemistry groups at PNNL concerned with validating radioanalytical techniques for the separation of these isotopes. Rare fission product isotopes from fast fission of 235U, 238U, and 239Pu are also desired to further develop these techniques. Experiments with 14 MeV neutrons are also of interest because nuclear data for fast fission has not been researched as extensively as it has been for thermal fission. Analyses of these applications require first that the source spectrum be well characterized. Neutron fluences in Fe, Ni, Al, In, and Au were measured in 21 locations near the generator head. STAYSL PNNL and MCNP codes were used to produce flux spectra based on experimental fluences.

  1. The HD molecule in small and medium cages of clathrate hydrates: Quantum dynamics studied by neutron scattering measurements and computation

    SciTech Connect (OSTI)

    Colognesi, Daniele; Celli, Milva; Ulivi, Lorenzo; Powers, Anna; Xu, Minzhong; Bačić, Zlatko

    2014-10-07

    We report inelastic neutron scattering (INS) measurements on molecular hydrogen deuteride (HD) trapped in binary cubic (sII) and hexagonal (sH) clathrate hydrates, performed at low temperature using two different neutron spectrometers in order to probe both energy and momentum transfer. The INS spectra of binary clathrate samples exhibit a rich structure containing sharp bands arising from both the rotational transitions and the rattling modes of the guest molecule. For the clathrates with sII structure, there is a very good agreement with the rigorous fully quantum simulations which account for the subtle effects of the anisotropy, angular and radial, of the host cage on the HD microscopic dynamics. The sH clathrate sample presents a much greater challenge, due to the uncertainties regarding the crystal structure, which is known only for similar crystals with different promoter, but nor for HD (or H{sub 2}) plus methyl tert-butyl ether (MTBE-d12)

  2. Neutron diffraction and scattering study on M/sub x/WO/sub 3/ (M=Rb and K)

    SciTech Connect (OSTI)

    Sato, M.; Fujishita, H.; Moodenbaugh, A.R.; Hoshino, S.; Grier, B.H.

    1982-01-01

    To study the relationship between the lattice instability and the superconductivity of nonstoichiometric hexagonal tungsten bronze, M/sub x/WO/sub 3/, neutron diffraction and scattering studies were made. Two types of the structural phase transitions were observed. One is associated with the distortion of the corner linked WO/sub 6/ octahedra. The other is associated with the ordering of the M atoms which partially fill the sites in the WO/sub 3/ cage. A long period modulation of the structure appears for some values of x at low temperature. The discussion on the x dependence of the superconducting transition temperature is presented.

  3. Investigation of coercivity mechanism in hot deformed Nd-Fe-B permanent magnets by small-angle neutron scattering

    SciTech Connect (OSTI)

    Yano, M., E-mail: masao-yano-aa@mail.toyota.co.jp; Manabe, A.; Shoji, T.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Ono, K. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Harada, M. [Toyota Central R and D Labs, Inc., Aichi 480-1192 (Japan); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

    2014-05-07

    The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd{sub 2}Fe{sub 14}B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the TeubnerStray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains.

  4. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

    SciTech Connect (OSTI)

    Li, Chen [ORNL] [ORNL; Ma, Jie [ORNL] [ORNL; May, Andrew F [ORNL] [ORNL; Cao, Huibo [ORNL] [ORNL; Christianson, Andrew D [ORNL] [ORNL; Ehlers, Georg [ORNL] [ORNL; Singh, David J [ORNL] [ORNL; Sales, Brian C [ORNL] [ORNL; Delaire, Olivier A [ORNL] [ORNL

    2014-01-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

  5. A Survey of Students from the National School on Neutron and X-ray Scattering: Communication Habits and Preferences

    SciTech Connect (OSTI)

    Bryant, Rebecca

    2010-12-01

    Oak Ridge National Laboratory (ORNL) offers the scientific community unique access to two types of world-class neutron sources at a single site - the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR). The 85-MW HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world. And the SNS is one of the world's most intense pulse neutron beams. Management of these resources is the responsibility of the Neutron Sciences Directorate (NScD). NScD started conducting the National School on Neutron and X-ray Scattering (NXS) in conjunction with the Advanced Photon Source (APS) at Argonne National Laboratory in 2007. This survey was conducted to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites and social media, for communicating with students about neutron science The survey was conducted in two phases using a classic qualitative investigation to confirm language and content followed by a survey designed to quantify issues, assumptions, and working hypotheses. Phase I consisted of a focus group in late June 2010 with students attending NXS. The primary intent of the group was to inform development of an online survey. Phase two consisted of an online survey that was developed and pre-tested in July 2010 and launched on August 9, 2010 and remained in the field until September 9, 2010. The survey achieved an overall response rate of 48% for a total of 157 completions. The objective of this study is to determine the most effective ways to reach students with information about what SNS and HFIR offer the scientific community, including content and communication vehicles. The emphasis is on gaining insights into compelling messages and the most effective channels, e.g., Web sites, social media

  6. Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory

    SciTech Connect (OSTI)

    Zimbal, Andreas; Reginatto, Marcel; Schuhmacher, Helmut; Wiegel, Burkhard; Degering, Detlev; Zuber, Kai

    2013-08-08

    We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a {sup 228}Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed {sup 228}Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10{sup −6}. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of {sup 3}He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operated by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.

  7. Anharmonic lattice dynamics of Ag2O studied by inelastic neutron scattering and first-principles molecular dynamics simulations

    SciTech Connect (OSTI)

    Lan, Tian; Li, Chen; Niedziela, Jennifer L; Smith, Hillary; Abernathy, Douglas L; Rossman, George; Fultz, B.

    2014-01-01

    Inelastic neutron scattering measurements on silver oxide (Ag2O) with the cuprite structure were performed at temperatures from 40 to 400 K, and Fourier transform far-infrared spectra were measured from 100 to 300 K. The measured phonon densities of states and the infrared spectra showed unusually large energy shifts with temperature, and large linewidth broadenings. First principles molecular dynamics (MD) calculations were performed at various temperatures, successfully accounting for the negative thermal expansion (NTE) and local dynamics. Using the Fourier-transformed velocity autocorrelation method, the MD calculations reproduced the large anharmonic effects of Ag2O, and were in excellent agreement with the neutron scattering data. The quasiharmonic approximation (QHA) was less successful in accounting for much of the phonon behavior. The QHA could account for some of the NTE below 250 K, although not at higher temperatures. Strong anharmonic effects were found for both phonons and for the NTE. The lifetime broadenings of Ag2O were explained by anharmonic perturbation theory, which showed rich interactions between the Ag-dominated modes and the O-dominated modes in both up- and down-conversion processes.

  8. Secondary neutron spectrum from 250-MeV passively scattered proton therapy: Measurement with an extended-range Bonner sphere system

    SciTech Connect (OSTI)

    Howell, Rebecca M.; Burgett, E. A.

    2014-09-15

    Purpose: Secondary neutrons are an unavoidable consequence of proton therapy. While the neutron dose is low compared to the primary proton dose, its presence and contribution to the patient dose is nonetheless important. The most detailed information on neutrons includes an evaluation of the neutron spectrum. However, the vast majority of the literature that has reported secondary neutron spectra in proton therapy is based on computational methods rather than measurements. This is largely due to the inherent limitations in the majority of neutron detectors, which are either not suitable for spectral measurements or have limited response at energies greater than 20 MeV. Therefore, the primary objective of the present study was to measure a secondary neutron spectrum from a proton therapy beam using a spectrometer that is sensitive to neutron energies over the entire neutron energy spectrum. Methods: The authors measured the secondary neutron spectrum from a 250-MeV passively scattered proton beam in air at a distance of 100 cm laterally from isocenter using an extended-range Bonner sphere (ERBS) measurement system. Ambient dose equivalent H*(10) was calculated using measured fluence and fluence-to-ambient dose equivalent conversion coefficients. Results: The neutron fluence spectrum had a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate energy continuum between the thermal and evaporation peaks. The H*(10) was dominated by the neutrons in the evaporation peak because of both their high abundance and the large quality conversion coefficients in that energy interval. The H*(10) 100 cm laterally from isocenter was 1.6 mSv per proton Gy (to isocenter). Approximately 35% of the dose equivalent was from neutrons with energies ≥20 MeV. Conclusions: The authors measured a neutron spectrum for external neutrons generated by a 250-MeV proton beam using an ERBS measurement system that was sensitive to neutrons over the entire

  9. Structural homologies of component C5 of human complement with components C3 and C4 by neutron scattering

    SciTech Connect (OSTI)

    Perkins, S.J.; Smith, K.F.; Nealis, A.S.; Lachmann, P.J.; Harrison, R.A. )

    1990-02-06

    The complement component C5 is one of a family of structurally related plasma proteins that includes components C3 and C4. Activation of C5 is the initial step in the formation of the membrane attack complex of complement. Analysis of the solution structure of C5 and comparisons with similar analyses of the structures of C3 and C4 are reported here. Neutron solution scattering gave an Mr for C5 of 201,000, which demonstrates that C5 is monomeric in solution. The radius of gyration RG of C5 at infinite contrast is 4.87 nm and corresponds to an elongated structure. The longest length of C5 was determined to be at least 15-16 nm from three calculations on the basis of the RG, the scattering intensity at zero angle I(0), and the indirect transformation of the scattering curve into real space. Comparison of the RG and contrast variation data and indirect transformations of the scattering curves for C3, C4, and C5 show that these have very similar structures. Comparisons of the C5 scattering curve with Debye small-sphere models previously employed for C4 and C3 show that good curve fits could be obtained. Unlike previous studies that have suggested significant differences, these experiments indicate that, while C5 differs from C3 and C4 in its activation and inactivation pathways, significant structural homology exists between the native proteins, as might be predicted from their high (and similar) sequence homology.

  10. Neutron scattering study on cathode LiMn{sub 2}O{sub 4} and solid electrolyte 5(Li{sub 2}O)(P{sub 2}O{sub 5})

    SciTech Connect (OSTI)

    Kartini, E. Putra, Teguh P. Jahya, A. K. Insani, A.; Adams, S.

    2014-09-30

    Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO{sub 2}, LiMn{sub 2}O{sub 4} and LiFePO{sub 4}, and solid electrolyte Li{sub 3}PO{sub 4}. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn{sub 2}O{sub 4} and 5(Li{sub 2}O)(P{sub 2}O{sub 5}), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

  11. A Second Look at Neutron Resonance Transmission Analysis as a Spent Fuel NDA Technique

    SciTech Connect (OSTI)

    James W .Sterbentz; David L. Chichester

    2011-07-01

    Many different nondestructive analysis techniques are currently being investigated as a part of the United States Department of Energy's Next Generation Safeguards Initiative (NGSI) seeking methods to quantify plutonium in spent fuel. Neutron Resonance Transmission Analysis (NRTA) is one of these techniques. Having first been explored in the mid-1970s for the analysis of individual spent-fuel pins a second look, using advanced simulation and modeling methods, is now underway to investigate the suitability of the NRTA technique for assaying complete spent nuclear fuel assemblies. The technique is similar to neutron time-of-flight methods used for cross-section determinations but operates over only the narrow 0.1-20 eV range where strong, distinguishable resonances exist for both the plutonium (239, 240, 241,242Pu) and uranium (235,236,238U) isotopes of interest in spent fuel. Additionally, in this energy range resonances exists for six important fission products (99Tc, 103Rh, 131Xe, 133Cs, 145Nd, and 152Sm) which provide additional information to support spent fuel plutonium assay determinations. Initial modeling shows excellent agreement with previously published experimental data for measurements of individual spent-fuel pins where plutonium assays were demonstrated to have a precision of 2-4%. Within the simulation and modeling analyses of this project scoping studies have explored fourteen different aspects of the technique including the neutron source, drift tube configurations, and gross neutron transmission as well as the impacts of fuel burn up, cooling time, and fission-product interferences. These results show that NRTA may be a very capable experimental technique for spent-fuel assay measurements. The results suggest sufficient transmission strength and signal differentiability is possible for assays through up to 8 pins. For an 8-pin assay (looking at an assembly diagonally), 64% of the pins in a typical 17 ? 17 array of a pressurized water reactor fuel

  12. Structure of light neutron-rich nuclei and mechanism of elastic proton scattering

    SciTech Connect (OSTI)

    Ibraeva, E. T.; Zhusupov, M. A.; Imambekov, O.

    2011-11-15

    Differential cross sections for elastic p{sup 6}He, p{sup 8}Li, and p{sup 9}Li scattering at two energies of 70 and 700 MeV per nucleon were calculated within the Glauber theory of multiple diffractive scattering. Threeparticle wave functions ({alpha}-n-n for {sup 6}He, {alpha}-t-n for {sup 8}Li, and {sup 7}Li-n-n for {sup 9}Li) were used for realistic potentials of intercluster interactions. The sensitivity of elastic scattering to proton-nucleus interaction and to the structure of nuclei was explored. In particular, the dependence of the differential cross section on the contribution of higher order collisions, on scattering on the core and peripheral nucleons, and on the contribution of small wave-function components and their asymptotic behavior was determined. A comparison with available experimental data and with the results of calculations within different formalisms was performed.

  13. Key research issues in the pulsed fast-neutron analysis technique for cargo inspection

    SciTech Connect (OSTI)

    Micklich, B.J.; Fink, C.L.; Yule, T.J.

    1994-07-01

    Non-invasive inspection systems based on the use of fast neutrons are being studied for the inspection of large cargo containers. A key advantage of fast neutrons is their sensitivity to low-Z elements such as carbon, nitrogen, and oxygen, which are the primary constituents of explosives and narcotics. The high energy allows penetration of relatively large containers. The pulsed fast-neutron analysis (PFNA) technique is currently the baseline system. A workshop on the PFNA technique involving industrial, government, and university participants was held at Argonne National Lab. in January 1994. The purpose of this workshop was to review the status of research on the key technical issues involved in PFNA, and to develop a list of those areas where additional modeling and/or experimentation were needed. The workshop also focused on development of a near-term experimental assessment program using existing prototypes and on development of a long-term test program at the Tacoma Testbed, where a PFNA prototype will be installed in 1995. A summary of conclusions reached at this workshop is presented. Results from analytic and Monte Carlo modeling of simplified PFNA systems are also presented.

  14. Further Evaluation of the Neutron Resonance Transmission Analysis (NRTA) Technique for Assaying Plutonium in Spent Fuel

    SciTech Connect (OSTI)

    J. W. Sterbentz; D. L. Chichester

    2011-09-01

    This is an end-of-year report (Fiscal Year (FY) 2011) for the second year of effort on a project funded by the National Nuclear Security Administration's Office of Nuclear Safeguards (NA-241). The goal of this project is to investigate the feasibility of using Neutron Resonance Transmission Analysis (NRTA) to assay plutonium in commercial light-water-reactor spent fuel. This project is part of a larger research effort within the Next-Generation Safeguards Initiative (NGSI) to evaluate methods for assaying plutonium in spent fuel, the Plutonium Assay Challenge. The second-year goals for this project included: (1) assessing the neutron source strength needed for the NRTA technique, (2) estimating count times, (3) assessing the effect of temperature on the transmitted signal, (4) estimating plutonium content in a spent fuel assembly, (5) providing a preliminary assessment of the neutron detectors, and (6) documenting this work in an end of the year report (this report). Research teams at Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), Pacific Northwest National Laboratory (PNNL), and at several universities are also working to investigate plutonium assay methods for spent-fuel safeguards. While the NRTA technique is well proven in the scientific literature for assaying individual spent fuel pins, it is a newcomer to the current NGSI efforts studying Pu assay method techniques having just started in March 2010; several analytical techniques have been under investigation within this program for two to three years or more. This report summarizes work performed over a nine month period from January-September 2011 and is to be considered a follow-on or add-on report to our previous published summary report from December 2010 (INL/EXT-10-20620).

  15. Coupling of the hydration water dynamics and the internal dynamics of actin detected by quasielastic neutron scattering

    SciTech Connect (OSTI)

    Fujiwara, Satoru; Plazanet, Marie; Oda, Toshiro

    2013-02-15

    Highlights: ► Quasielastic neutron scattering spectra of F-actin and G-actin were measured. ► Analysis of the samples in D{sub 2}O and H{sub 2}O provided the spectra of hydration water. ► The first layer hydration water around F-actin is less mobile than around G-actin. ► This difference in hydration water is in concert with the internal dynamics of actin. ► Water outside the first layer behaves bulk-like but influenced by the first layer. -- Abstract: In order to characterize dynamics of water molecules around F-actin and G-actin, quasielastic neutron scattering experiments were performed on powder samples of F-actin and G-actin, hydrated either with D{sub 2}O or H{sub 2}O, at hydration ratios of 0.4 and 1.0. By combined analysis of the quasielastic neutron scattering spectra, the parameter values characterizing the dynamics of the water molecules in the first hydration layer and those of the water molecules outside of the first layer were obtained. The translational diffusion coefficients (D{sub T}) of the hydration water in the first layer were found to be 1.2 × 10{sup −5} cm{sup 2}/s and 1.7 × 10{sup −5} cm{sup 2}/s for F-actin and G-actin, respectively, while that for bulk water was 2.8 × 10{sup −5} cm{sup 2}/s. The residence times were 6.6 ps and 5.0 ps for F-actin and G-actin, respectively, while that for bulk water was 0.62 ps. These differences between F-actin and G-actin, indicating that the hydration water around G-actin is more mobile than that around F-actin, are in concert with the results of the internal dynamics of F-actin and G-actin, showing that G-actin fluctuates more rapidly than F-actin. This implies that the dynamics of the hydration water is coupled to the internal dynamics of the actin molecules. The D{sub T} values of the water molecules outside of the first hydration layer were found to be similar to that of bulk water though the residence times are strongly affected by the first hydration layer. This supports the

  16. Biomembranes research using thermal and cold neutrons

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Heberle, Frederick A.; Myles, Dean A. A.; Katsaras, John

    2015-08-01

    In 1932 James Chadwick discovered the neutron using a polonium source and a beryllium target (Chadwick, 1932). In a letter to Niels Bohr dated February 24, 1932, Chadwick wrote: “whatever the radiation from Be may be, it has most remarkable properties.” Where it concerns hydrogen-rich biological materials, the “most remarkable” property is the neutron’s differential sensitivity for hydrogen and its isotope deuterium. Such differential sensitivity is unique to neutron scattering, which unlike X-ray scattering, arises from nuclear forces. Consequently, the coherent neutron scattering length can experience a dramatic change in magnitude and phase as a result of resonance scattering, impartingmore » sensitivity to both light and heavy atoms, and in favorable cases to their isotopic variants. Furthermore, this article describes recent biomembranes research using a variety of neutron scattering techniques.« less

  17. Biomembranes research using thermal and cold neutrons

    SciTech Connect (OSTI)

    Heberle, Frederick A.; Myles, Dean A. A.; Katsaras, John

    2015-08-01

    In 1932 James Chadwick discovered the neutron using a polonium source and a beryllium target (Chadwick, 1932). In a letter to Niels Bohr dated February 24, 1932, Chadwick wrote: “whatever the radiation from Be may be, it has most remarkable properties.” Where it concerns hydrogen-rich biological materials, the “most remarkable” property is the neutron’s differential sensitivity for hydrogen and its isotope deuterium. Such differential sensitivity is unique to neutron scattering, which unlike X-ray scattering, arises from nuclear forces. Consequently, the coherent neutron scattering length can experience a dramatic change in magnitude and phase as a result of resonance scattering, imparting sensitivity to both light and heavy atoms, and in favorable cases to their isotopic variants. Furthermore, this article describes recent biomembranes research using a variety of neutron scattering techniques.

  18. Structure of neutron-rich Isotopes {sup 8}Li and {sup 9}Li and allowance for it in elastic scattering

    SciTech Connect (OSTI)

    Ibraeva, E. T.; Zhusupov, M. A.; Imambekov, O.; Sagindykov, Sh. Sh.

    2008-07-15

    The differential cross sections for elastic proton scattering on the unstable neutron-rich nuclei {sup 8}Li and {sup 9}Li at E = 700 and 60 MeV per nucleon were considered. The {sup 8}Li nucleus was treated on the basis of the three-body {alpha}-t-n model, while the {sup 9}Li nucleus was considered within the {alpha}-t-n and {sup 7}Li-n-n models. The cross sections in question were calculated within Glauber diffraction theory. A comparison of the results with available experimental data made it possible to draw conclusions on the quality of the wave functions and potential used in the calculations.

  19. Communication: The H{sub 2}@C{sub 60} inelastic neutron scattering selection rule: Expanded and explained

    SciTech Connect (OSTI)

    Poirier, Bill

    2015-09-14

    Recently [M. Xu et al., J. Chem. Phys. 139, 064309 (2013)], an unexpected selection rule was discovered for the title system, contradicting the previously held belief that inelastic neutron scattering (INS) is not subject to any selection rules. Moreover, the newly predicted forbidden transitions, which emerge only in the context of coupled H{sub 2} translation-rotation (TR) dynamics, have been confirmed experimentally. However, a simple physical understanding, e.g., based on group theory, has been heretofore lacking. This is provided in the present paper, in which we (1) derive the correct symmetry group for the H{sub 2}@C{sub 60} TR Hamiltonian and eigenstates; (2) complete the INS selection rule, and show that the set of forbidden transitions is actually much larger than previously believed; and (3) evaluate previous theoretical and experimental results, in light of the new findings.

  20. The quantum nature of the OH stretching mode in ice and water probed by neutron scattering experiments

    SciTech Connect (OSTI)

    Senesi, Roberto; Flammini, Davide; Kolesnikov, Alexander I; Murray, Eamonn D.; Galli, Giulia; Andreani, Carla

    2013-01-01

    The OH stretching vibrational spectrum of water was measured in a wide range of temperatures across the triple point, 269 K < T < 296 K, using Inelastic Neutron Scattering (INS). The hydrogen projected density of states and the proton mean kinetic energy, _OH, were determined for the first time within the framework of a harmonic description of the proton dynamics. We found that in the liquid the value of _OH is nearly constant as a function of T, indicating that quantum effects on the OH stretching frequency are weakly dependent on temperature. In the case of ice, ab initio electronic structure calculations, using non-local van der Waals functionals, provided _OH values in agreement with INS experiments. We also found that the ratio of the stretching (_OH) to the total (_exp) kinetic energy, obtained from the present measurements, increases in going from ice, where hydrogen bonding is the strongest, to the liquid at ambient conditions and then to the vapour phase, where hydrogen bonding is the weakest. The same ratio was also derived from the combination of previous deep inelastic neutron scattering data, which does not rely upon the harmonic approximation, and the present measurements. We found that the ratio of stretching to the total kinetic energy shows a minimum in the metastable liquid phase. This finding suggests that the strength of intermolecular interactions increases in the supercooled phase, with respect to that in ice, contrary to the accepted view that supercooled water exhibits weaker hydrogen bonding than ice.

  1. SU-E-T-591: Measurement and Monte Carlo Simulation of Stray Neutrons in Passive Scattering Proton Therapy: Needs and Challenges

    SciTech Connect (OSTI)

    Farah, J; Bonfrate, A; Donadille, L; Dubourg, N; Lacoste, V; Martinetti, F; Sayah, R; Trompier, F; Clairand, I [IRSN - Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-roses (France); Caresana, M [Politecnico di Milano, Milano (Italy); Delacroix, S; Nauraye, C [Institut Curie - Centre de Protontherapie d Orsay, Orsay (France); Herault, J [Centre Antoine Lacassagne, Nice (France); Piau, S; Vabre, I [Institut de Physique Nucleaire d Orsay, Orsay (France)

    2014-06-01

    Purpose: Measure stray radiation inside a passive scattering proton therapy facility, compare values to Monte Carlo (MC) simulations and identify the actual needs and challenges. Methods: Measurements and MC simulations were considered to acknowledge neutron exposure associated with 75 MeV ocular or 180 MeV intracranial passively scattered proton treatments. First, using a specifically-designed high sensitivity Bonner Sphere system, neutron spectra were measured at different positions inside the treatment rooms. Next, measurement-based mapping of neutron ambient dose equivalent was fulfilled using several TEPCs and rem-meters. Finally, photon and neutron organ doses were measured using TLDs, RPLs and PADCs set inside anthropomorphic phantoms (Rando, 1 and 5-years-old CIRS). All measurements were also simulated with MCNPX to investigate the efficiency of MC models in predicting stray neutrons considering different nuclear cross sections and models. Results: Knowledge of the neutron fluence and energy distribution inside a proton therapy room is critical for stray radiation dosimetry. However, as spectrometry unfolding is initiated using a MC guess spectrum and suffers from algorithmic limits a 20% spectrometry uncertainty is expected. H*(10) mapping with TEPCs and rem-meters showed a good agreement between the detectors. Differences within measurement uncertainty (1015%) were observed and are inherent to the energy, fluence and directional response of each detector. For a typical ocular and intracranial treatment respectively, neutron doses outside the clinical target volume of 0.4 and 11 mGy were measured inside the Rando phantom. Photon doses were 210 times lower depending on organs position. High uncertainties (40%) are inherent to TLDs and PADCs measurements due to the need for neutron spectra at detector position. Finally, stray neutrons prediction with MC simulations proved to be extremely dependent on proton beam energy and the used nuclear models and cross

  2. Format requirements of thermal neutron scattering data in a nuclear data format to succeed the ENDF format

    SciTech Connect (OSTI)

    Brown, D.

    2014-03-31

    In November 2012, the Working Party on Evaluation Cooperation Subgroup 38 (WPEC-SG38) began with the task of developing a nuclear data format and supporting infrastructure to replace the now nearly 50 year old ENDF format. The first step in this process is to develop requirements for the new format and infrastructure. In this talk, I will review the status of ENDF's Thermal Scattering Law (TSL) formats as well as support for this data in the GND format (from which the new format is expected to evolve). Finally, I hope to begin a dialog with members of the thermal neutron scattering community so that their data needs can be accurately and easily accommodated by the new format and tools, as captured by the requirements document. During this discussion, we must keep in mind that the new tools and format must; Support what is in existing data files; Support new things we want to put in data files; and Be flexible enough for us to adapt it to future unanticipated challenges.

  3. Mechanical properties of interacting lipopolysaccharide membranes from bacteria mutants studied by specular and off-specular neutron scattering

    SciTech Connect (OSTI)

    Schneck, Emanuel; Tanaka, Motomu; Oliveira, Rafael G.; Rehfeldt, Florian; Deme, Bruno; Brandenburg, Klaus; Seydel, Ulrich

    2009-10-15

    Specular and off-specular neutron scattering are used to study the influence of molecular chemistry (mutation) on the intermembrane interactions and mechanical properties of the outer membrane of Gram-negative bacteria consisting of lipopolysaccharides (LPSs). For this purpose, solid-supported multilayers of mutant LPS membranes are deposited on silicon wafers and hydrated either at defined humidity or in bulk buffers. The planar sample geometry allows to identify out-of-plane and in-plane scattering vector components. The measured two-dimensional reciprocal space maps are simulated with membrane displacement correlation functions determined by two mechanical parameters (vertical compression modulus and bending rigidity) and an effective cutoff radius for the membrane fluctuation wavelength. Experiments at controlled humidity enable one to examine the influence of the disjoining pressure on the saccharide-mediated intermembrane interactions, while experiments in bulk buffers (i.e., in the absence of an external osmotic stress) reveal the effect of divalent cations on LPS membranes, highlighting the role of divalent cations in the survival mechanism of bacteria in the presence of antimicrobial molecules.

  4. The Manuel Lujan, Jr. Neutron Scattering Center (LANSCE) experiment reports 1992 run cycle. Progress report

    SciTech Connect (OSTI)

    DiStravolo, M.A.

    1993-09-01

    This year was the fifth in which LANSCE ran a formal user program. A call for proposals was issued before the scheduled run cycles, and experiment proposals were submitted by scientists from universities, industry, and other research facilities around the world. An external program advisory committee, which LANSCE shares with the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory, examined the proposals and made recommendations. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and an associated Proton Storage Ring (PSR), which can alter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. One hundred sixty-seven proposals were submitted for unclassified research and twelve proposals for research of a programmatic interest to the Laboratory; six experiments in support of the LANSCE research program were accomplished during the discretionary periods. Oversubscription for instrument beam time by a factor of three was evident with 839 total days requested and only 371 available for allocation.

  5. The Manuel Lujan, Jr. Neutron Scattering Center, LANSCE experiment reports: 1990 Run Cycle

    SciTech Connect (OSTI)

    DiStravolo, M.A.

    1991-10-01

    This year was the third in which LANSCE ran a formal user program. A call for proposals was issued before the scheduled run cycles, and experiment proposals were submitted by scientists from universities, industry, and other research facilities around the world. An external program advisory committee, which LANSCE shares with the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory examined the proposals and made recommendations. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and an associated Proton Storage Ring (PSR), which can alter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each six-month LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. One hundred thirty-four proposals were submitted for unclassified research and twelve proposals for research of a programmatic nature to the Laboratory. Our definition of beam availability is when the proton current from the PSR exceeds 50% of the planned value. The PSR ran at 65{mu}A current (average) at 20 Hz for most of 1990. All of the scheduled experiments were performed and experiments in support of the LANSCE research program were accomplished during the discretionary periods.

  6. Neutron scattering from myelin revisited: bilayer asymmetry and water-exchange kinetics

    SciTech Connect (OSTI)

    Denninger, Andrew R. [Boston College, Chestnut Hill, MA 02467 (United States); Dem, Bruno; Cristiglio, Viviana [Institut LaueLangevin (ILL), CS 20156, F-38042 Grenoble CEDEX 9 (France); LeDuc, Graldine [European Synchrotron Radiation Facility (ESRF), CS 40220, F-38043 Grenoble CEDEX 9 (France); Feller, W. Bruce [NOVA Scientific Inc., Sturbridge, MA 01566 (United States); Kirschner, Daniel A., E-mail: kirschnd@bc.edu [Boston College, Chestnut Hill, MA 02467 (United States)

    2014-12-01

    The structure of internodal myelin in the rodent central and peripheral nervous systems has been determined using neutron diffraction. The kinetics of water exchange in these tissues is also described. Rapid nerve conduction in the central and peripheral nervous systems (CNS and PNS, respectively) of higher vertebrates is brought about by the ensheathment of axons with myelin, a lipid-rich, multilamellar assembly of membranes. The ability of myelin to electrically insulate depends on the regular stacking of these plasma membranes and on the presence of a number of specialized membrane-protein assemblies in the sheath, including the radial component, SchmidtLanterman incisures and the axoglial junctions of the paranodal loops. The disruption of this fine-structure is the basis for many demyelinating neuropathies in the CNS and PNS. Understanding the processes that govern myelin biogenesis, maintenance and destabilization requires knowledge of myelin structure; however, the tight packing of internodal myelin and the complexity of its junctional specializations make myelin a challenging target for comprehensive structural analysis. This paper describes an examination of myelin from the CNS and PNS using neutron diffraction. This investigation revealed the dimensions of the bilayers and aqueous spaces of myelin, asymmetry between the cytoplasmic and extracellular leaflets of the membrane, and the distribution of water and exchangeable hydrogen in internodal multilamellar myelin. It also uncovered differences between CNS and PNS myelin in their water-exchange kinetics.

  7. Polarized Neutron in Structural Biology Present and Future Outlook

    SciTech Connect (OSTI)

    Zhao, Jinkui [ORNL; Robertson, Lee [ORNL; Herwig, Kenneth W [ORNL; Crabb, Don [University of Virginia

    2013-01-01

    Hydrogen has a strong polarization-dependent neutron scattering cross section. This property has been exploited in the study of soft matters, especially biological macromolecules. When a polarized neutron beam is scattered off a polarized hydrogenous sample, the otherwise large hydrogen incoherent cross section is drastically reduced while the coherent signal is significantly increased. Past experiments have demonstrated the potentials and benefits of polarized neutron scattering from soft materials. The main technical challenge of polarized neutron scattering from biological matters lies at sample polarization. Dynamic nuclear polarization is a proven yet rather sophisticated technique. Its complexity is one of the main reasons for the technique's slow adoption. The future of polarized neutron scattering in biology may rest largely in neutron protein crystallography. Polarization of protein crystals is much easier to accomplish, since protein crystals are typically rather small (<<1 mm) and only require small and easy- to-operate polarization apparatuses. In addition, the high resolution nature of neutron protein crystallography means that we will be able to study individual atoms using the polarized neutron scattering technique.

  8. Neutron Scattering Studies of the Interplay of Amyloid β Peptide(1–40) and An Anionic Lipid 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rai, Durgesh K.; Sharma, Veerendra K.; Anunciado, Divina; O’Neill, Hugh; Mamontov, Eugene; Urban, Volker; Heller, William T.; Qian, Shuo

    2016-08-09

    The interaction between lipid bilayers and Amyloid β peptide (Aβ) plays a critical role in proliferation of Alzheimer’s disease (AD). AD is expected to affect one in every 85 humans by 2050, and therefore, deciphering the interplay of Aβ and lipid bilayers at the molecular level is of profound importance. In this work, we applied an array of neutron scattering methods to study the structure and dynamics of Aβ(1–40) interacting 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) bilayers. In the structural investigations of lipid bilayer’s response to Aβ binding, Small Angle Neutron Scattering and Neutron Membrane Diffraction revealed that the Aβ anchors firmly to themore » highly charged DMPG bilayers in the interfacial region between water and hydrocarbon chain, and it doesn’t penetrate deeply into the bilayer. This association mode is substantiated by the dynamics studies with high resolution Quasi-Elastic Neutron Scattering experiments, showing that the addition of Aβ mainly affects the slower lateral motion of lipid molecules, especially in the fluid phase, but not the faster internal motion. The results revealed that Aβ associates with the highly charged membrane in surface with limited impact on the structure, but the altered membrane dynamics could have more influence on other membrane processes.« less

  9. Neutron scattering study of spin ordering and stripe pinning in superconducting La1.93Sr0.07CuO4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jacobsen, H.; Zaliznyak, I. A.; Savici, A. T.; Winn, B. L.; Chang, S.; Hücker, M.; Gu, G. D.; Tranquada, J. M.

    2015-11-20

    Tmore » he relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La1.93Sr0.07CuO4 a superconductor with a transition temperature of c = 20 K. At << c, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below ~ 10 K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO6 octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO2 planes. Moreover, we observed a weak elastic (3 ⁻30) superlattice peak that implies a reduced lattice symmetry. he presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped La2-xSrxCuO4. he coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function.« less

  10. Characterization of nanostructured zirconia prepared by hydrolysis and reverse micelle synthesis by small-angle neutron and X-ray scattering

    SciTech Connect (OSTI)

    Thiyagarajan, P.; Li, X.; Littrell, K.; Seifert, S.; Csencsits, R.; Loong, C.

    1999-12-07

    Low temperature techniques such as hydrolysis and reverse micelle syntheses provide the opportunity to determine the relationship between the structural properties and preparation conditions of zirconia powders as well as to tailor their physicochemical properties. The authors have performed small-angle neutron and synchrotron X-ray scattering (SANS and SAXS) experiments to study the nucleation and organization of zirconia nanoparticles via different preparation routes. First, the formation of reverse micelles in individual and mixed solutions of (ZrOCl{sub 2}+D{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3}, and (NH{sub 4}OH+H{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3} systems at water/AOT molar ratio of 20 was characterized. Second, the aggregation of zirconia gels obtained from the reaction of the reverse micelle solutions after heat treatments was studied. Third, the nanostructure of zirconia powders prepared by the reverse micelle method is compared with the corresponding powders prepared by hydrolysis after different heat treatments.

  11. Transport of thermal neutrons in D/sub 2/O in the temperature Range 5 to 60/sup 0/C based on a new scattering kernel

    SciTech Connect (OSTI)

    Bansal, R.M.; Kothari, L.S.; Tewari, S.P.

    1980-10-01

    A new scattering kernel for heavy water has been proposed. The kernel takes into account the chemical binding energy effects and also includes the rotational and intramolecular vibrational modes. Using this scattering kernel, various neutron transport processes in the temperature range 5 to 60/sup 0/C have been studied and compared with the corresponding experimental results. The calculated results include total neutron scattering cross section at 20/sup 0/C; asymptotic decay of neutron pulses in the temperature range 5 to 60/sup 0/C and temperature variation of the diffusion coefficient and diffusion cooling coefficient; timedependent spectra inside finite-sized assemblies of heavy water at 20 and 43.3/sup 0/C thermalization time; and diffusion length and space-dependent study in pure and poisoned assemblies of heavy water. The calculated results are in good agreement with the experimental results. At some places notable differences are observed between the results obtained using our scattering kernel and those based on the Honeck kernel.

  12. New insights into water bonding during early tricalcium silicate hydration with quasielastic neutron scattering

    SciTech Connect (OSTI)

    Gutberlet, T.; Hilbig, H.; Beddoe, R.E.; Lohstroh, W.

    2013-09-15

    New information on the water bonding during the first 36 h of hydration of tricalcium silicate was obtained using the high neutron flux at the sample position of the time-of-flight spectrometer (TOFTOF), FRM II in Garching, Germany, together with {sup 29}Si NMR and X-ray diffraction measurements. A rapid increase in the amount of constrained water was observed at the beginning of the induction period. This is attributed to the formation of an early C-S-H with a large specific surface area (around 800 m{sup 2}/g). During subsequent hydration, the amount of constrained water, as given by the total surface area of the hydration products, is controlled by (a) the formation of new metastable early C-S-H which increases total surface area and (b) polymerisation processes which reduce total surface area. The relative contribution of these processes varies during hydration.

  13. Spectroscopy of the neutron-rich hypernucleus HeΛ7 from electron scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; et al

    2016-08-12

    Here, the missing mass spectroscopy of themore » $$^{7}_{\\Lambda}$$He hypernucleus was performed, using the $$^{7}$$Li$$(e,e^{\\prime}K^{+})^{7}_{\\Lambda}$$He reaction at the Thomas Jefferson National Accelerator Facility Hall C. The $$\\Lambda$$ binding energy of the ground state (1/2$$^{+}$$) was determined with a smaller error than that of the previous measurement, being $$B_{\\Lambda}$$ = 5.55 $$\\pm$$ 0.10(stat.) $$\\pm$$ 0.11(sys.) MeV. The experiment also provided new insight into charge symmetry breaking in p-shell hypernuclear systems. Finally, a peak at $$B_{\\Lambda}$$ = 3.65 $$\\pm$$ 0.20(stat.) $$\\pm$$ 0.11(sys.) MeV was observed and assigned as a mixture of 3/2$$^{+}$$ and 5/2$$^{+}$$ states, confirming the "gluelike" behavior of $$\\Lambda$$, which makes an unstable state in $$^{6}$$He stable against neutron emission.« less

  14. Magnetic Transitions in Iron Porphyrin Halides by Inelastic Neutron Scattering and Ab-initio Studies of Zero-Field Splittings

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stavretis, Shelby E.; Atanasov, Mihail; Podlesnyak, Andrey A.; Hunter, Seth C.; Neese, Frank; Xue, Zi-Ling

    2015-10-02

    Zero-field splitting (ZFS) parameters of nondeuterated metalloporphyrins [Fe(TPP)X] (X = F, Br, I; H2TPP = tetraphenylporphyrin) are determined by inelastic neutron scattering (INS). The ZFS values are D = 4.49(9) cm–1 for tetragonal polycrystalline [Fe(TPP)F], and D = 8.8(2) cm–1, E = 0.1(2) cm–1 and D = 13.4(6) cm–1, E = 0.3(6) cm–1 for monoclinic polycrystalline [Fe(TPP)Br] and [Fe(TPP)I], respectively. Along with our recent report of the ZFS value of D = 6.33(8) cm–1 for tetragonal polycrystalline [Fe(TPP)Cl], these data provide a rare, complete determination of ZFS parameters in a metalloporphyrin halide series. The electronic structure of [Fe(TPP)X] (X =more » F, Cl, Br, I) has been studied by multireference ab initio methods: the complete active space self-consistent field (CASSCF) and the N-electron valence perturbation theory (NEVPT2) with the aim of exploring the origin of the large and positive zero-field splitting D of the 6A1 ground state. D was calculated from wave functions of the electronic multiplets spanned by the d5 configuration of Fe(III) along with spin–orbit coupling accounted for by quasi degenerate perturbation theory. Results reproduce trends of D from inelastic neutron scattering data increasing in the order from F, Cl, Br, to I. A mapping of energy eigenvalues and eigenfunctions of the S = 3/2 excited states on ligand field theory was used to characterize the σ- and π-antibonding effects decreasing from F to I. This is in agreement with similar results deduced from ab initio calculations on CrX63- complexes and also with the spectrochemical series showing a decrease of the ligand field in the same directions. A correlation is found between the increase of D and decrease of the π- and σ-antibonding energies eλX (λ = σ, π) in the series from X = F to I. Analysis of this correlation using second-order perturbation theory expressions in terms of angular overlap parameters rationalizes the experimentally deduced trend

  15. Early stages of spinodal decomposition in Fe–Cr resolved by in-situ small-angle neutron scattering

    SciTech Connect (OSTI)

    Hörnqvist, M. Thuvander, M.; Steuwer, A.; King, S.; Odqvist, J.; Hedström, P.

    2015-02-09

    In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe–35Cr were performed at 773 and 798 K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a′{sup  }= 0.10–0.11 and a″ = 0.67–0.86). Furthermore, the method allows tracking of the high–Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773 K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a′{sup  }= 0.12–0.20 depending on the assumed mobility)

  16. A Measurement of the Neutron Electric Form Factor in Dvec (evec,e'n)p Quasielastic Scattering at Q2=0.5(GeV/c)2

    SciTech Connect (OSTI)

    Hongguo Zhu

    2000-08-01

    The form factors of the neutron give information on fundamental properties of the nucleons and provide a critical testing ground for models based on QCD. In late 1998, Jefferson Lab (JLAB) experiment E93-026 measured the spin-dependent part of the exclusive (e, e'n) scattering cross section from a polarized deuterated ammonia ({sup 15}ND{sub 3}) target at a four momentum transfer squared of Q{sup 2} = 0.5 (GeV/c){sub 2}. A longitudinally polarized electron beam was scattered from the polarized target and the quasi-elastically scattered electron was detected in coincidence with the knocked-out neutron. The data have been analyzed in terms of the spin-correlation parameter, or the electron-deuteron vector asymmetry (A{sub ed}{sup V}), of (e, e'n) to determine the neutron electric form factor G{sub E}{sup n}. The result is consistent with data from existing experiments and shows a good agreement with the Galster parameterization of G{sub E}{sup n} within experimental uncertainty.

  17. Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

    SciTech Connect (OSTI)

    Dahing, Lahasen Normanshah; Yahya, Redzuan; Yahya, Roslan; Hassan, Hearie

    2014-09-03

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm{sup 3} and 15×15×15 cm{sup 3} were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed.

  18. Neutron Scattering Studies of Liquid on or Confined in Nano- and Mesoporous Carbons, Including Carbide-Derived Carbons

    SciTech Connect (OSTI)

    Wesolowski, David J

    2014-07-01

    This project involved the synthesis of microporous graphitic-carbon powders with subnanometer average pore size, and very narrow pore size distributions, and the use of these materials in experimental studies of pore-fluid structure and dynamics. Samples of carbide-derived carbon powder, synthesized by extraction of the metal cations from TiC by a high temperature chlorination process, followed by high temperature vacuum annealing, were prepared by Ranjan Dash and his associates at CRADA partner Y-Carbon, Inc. The resulting material had average pore sizes ranging from 5 to 8 . These powders were used in two experiments conducted by researchers involved in the Energy Frontier Research Center Directed by David J. Wesolowski at ORNL, the Fluid Interface Reactions, Structures and Transport (FIRST) Center. FIRST-funded researchers at Drexel University collaborated with scientists at the Paul Scherrer Institute, Switzerland, to measure the expansion and contraction of the microporous carbon particles during charging and discharging of supercapactor electrodes composed of these particles (Hantell et al., 2011, Electrochemistry Communications, v. 13, pp. 1221-1224.) in an electrolyte composed of tetraethylammonium tetrafluoroborate dissolved in acetonitrile. In the second experiment, researchers at Oak Ridge National Laboratory and Drexel University conducted quasielastic neutron scattering studies of the diffusional dynamics of water imbibed into the micropores of the same material (Chathoth et al., 2011, EuroPhysics Journal, v. 95, pp. 56001/1-6). These studies helped to establish the role of pores approaching the size of the solvent and dissolved ions in altering diffusional dynamics, ion transport and physical response of conducting substrates to ion desolvation and entry into subnamometer pores.

  19. Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering

    SciTech Connect (OSTI)

    Swenson, Jan Elamin, Khalid; Chen, Guo; Lohstroh, Wiebke; Sakai, Victoria Garcia

    2014-12-07

    The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H{sub 2}O (or D{sub 2}O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0–90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the corresponding bulk system, showing the important role of hydrogen bonding for the dynamics. In this study we have elucidated how this non-monotonic concentration dependence is affected by the confined geometry. The results show that this behaviour is maintained in the confinement, but the slowest diffusive dynamics of 2PGME is now observed at a considerably higher water concentration; at 75 wt.% water in MCM-41 compared to 30 wt.% water in the corresponding bulk system. This difference can be explained by an improper mixing of the two confined liquids. The results suggest that water up to a concentration of about 20 wt.% is used to hydrate the hydrophilic hydroxyl surface groups of the silica pores, and that it is only at higher water contents the water becomes partly mixed with 2PGME. Hence, due to this partial micro-phase separation of the two liquids larger, and thereby slower relaxing, structural entities of hydrogen bonded water and 2PGME molecules can only be formed at higher water contents than in the bulk system. However, the Q-dependence is unchanged with confinement, showing that the nature of the molecular motions is preserved. Thus, there is no indication of localization of the dynamics at length scales of less than 20 Å. The dynamics of both water and 2PGME is strongly dominated by translational diffusion at a temperature of 280 K.

  20. Nondestructive determination of plutonium mass in spent fuel: prelliminary modeling results using the passive neutron Albedo reactivity technique

    SciTech Connect (OSTI)

    Evans, Louise G; Tobin, Stephen J; Schear, Melissa A; Menlove, Howard O; Lee, Sang Y; Swinhoe, Martyn T

    2009-01-01

    There are a variety of motivations for quantifying plutonium (Pu) in spent fuel assemblies by means of nondestructive assay (NDA) including the following: strengthening the capability of the International Atomic Energy Agency (LAEA) to safeguard nuclear facilities, quantifying shipper/receiver difference, determining the input accountability value at pyrochemical processing facilities, providing quantitative input to burnup credit and final safeguards measurements at a long-term repository. In order to determine Pu mass in spent fuel assemblies, thirteen NDA techniques were identified that provide information about the composition of an assembly. A key motivation of the present research is the realization that none of these techniques, in isolation, is capable of both (1) quantifying the Pu mass of an assembly and (2) detecting the diversion of a significant number of rods. It is therefore anticipated that a combination of techniques will be required. A 5 year effort funded by the Next Generation Safeguards Initiative (NGSI) of the U.S. DOE was recently started in pursuit of these goals. The first two years involves researching all thirteen techniques using Monte Carlo modeling while the final three years involves fabricating hardware and measuring spent fuel. Here, we present the work in two main parts: (1) an overview of this NGSI effort describing the motivations and approach being taken; (2) The preliminary results for one of the NDA techniques - Passive Neutron Albedo Reactivity (PNAR). The PNAR technique functions by using the intrinsic neutron emission of the fuel (primarily from the spontaneous fission of curium) to self-interrogate any fissile material present. Two separate measurements of the spent fuel are made, both with and without cadmium (Cd) present. The ratios of the Singles, Doubles and Triples count rates obtained in each case are analyzed; known as the Cd ratio. The primary differences between the two measurements are the neutron energy spectrum

  1. IPNS neutron scattering instrumentation: A -- Existing and planned; B -- Possibilities for IPNS upgrade, a 1-MW spallation source

    SciTech Connect (OSTI)

    Brown, B.; Crawford, K.

    1994-12-01

    The Intense Pulsed Neutron Source (IPNS) is a pulsed spallation neutron source located at Argonne National Laboratory near Chicago, Illinois in the US. This facility is the outgrowth of a long line of pioneering work on pulsed spallation neutron sources begun at Argonne in the early 1970s. IPNS uses protons accelerated in the Rapid Cycling Synchrotron to produce neutrons via the spallation process (effectively a nuclear evaporation in which 10--50 neutrons are released per incident proton) in a heavy-element target. These neutrons are then moderated to produce spectra peaked at thermal or subthermal energies, and directed into beams which serve a variety of instruments. This paper discusses the diffractometers, various spectrometers, and reflectometers in existence and those planned for the upgrade of the IPNS.

  2. Demonstration of a novel technique to measure two-photon exchange effects in elastic e±p scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moteabbed, Maryam; Niroula, Megh; Raue, Brian A.; Weinstein, Lawrence B.

    2013-08-30

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e±p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e±p comparisons, which has themore » potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e±p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference

  3. Demonstration of a novel technique to measure two-photon exchange effects in elastic ep scattering

    SciTech Connect (OSTI)

    Moteabbed, Maryam [Florida Institute of Technology; Niroula, Megh [Old Dominion University; Raue, Brian [Florida International University; Weinstein, Lawrence [Old Dominion University

    2013-08-01

    The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in ep scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct ep comparisons, which has the potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for ep with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the

  4. Neutron detector

    DOE Patents [OSTI]

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  5. Scattering Of Light Nuclei

    SciTech Connect (OSTI)

    Quaglioni, S; Navratil, P; Roth, R

    2009-12-15

    The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.

  6. Spallation Neutron Source | Neutron Science at ORNL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The recently commissioned 11 Tesla horizontal field magnet at GP-SANS will enable advanced neutron scattering research. Credit: Genevieve MartinORNL. 11 Tesla Magnet Commissioned ...

  7. Lujan Neutron Scattering Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    that can travel through several feet of air, but are generally stopped by clothing and skin. Beta emitters occur naturally in the environment, and this incident involved...

  8. Neutron-scattering evidence for a periodically modulated superconducting phase in the underdoped cuprate La1.905Ba0.095CuO4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xu, Zhijun; Stock, C.; Chi, Songxue; Kolesnikov, A. I.; Xu, Guangyong I.; Gu, Genda; Tranquada, J. M.

    2014-10-01

    The role of antiferromagnetic spin correlations in high-temperature superconductors remains a matter of debate. We present inelastic neutron-scattering evidence that gapless spin fluctuations coexist with superconductivity in La1.905Ba0.095CuO4. Furthermore, we observe that both the low-energy magnetic spectral weight and the spin incommensurability are enhanced with the onset of superconducting correlations. We propose that the coexistence occurs through intertwining of spatial modulations of the pair wave function and the antiferromagnetic correlations. This proposal is also directly relevant to sufficiently underdoped La2-xSrxCuO4 and YBa2Cu3O6+x.

  9. Influence of static Jahn-Teller distortion on the magnetic excitation spectrum of PrO{sub 2}: A synchrotron x-ray and neutron inelastic scattering study

    SciTech Connect (OSTI)

    Webster, C. H.; Helme, L. M.; Boothroyd, A. T.; McMorrow, D. F.; Wilkins, S. B.; Detlefs, C.; Detlefs, B.; Bewley, R. I.; McKelvy, M. J.

    2007-10-01

    A synchrotron x-ray diffraction study of the crystallographic structure of PrO{sub 2} in the Jahn-Teller distorted phase is reported. The distortion of the oxygen sublattice, which was previously ambiguous, is shown to be a chiral structure in which neighboring oxygen chains have opposite chiralities. A temperature dependent study of the magnetic excitation spectrum, probed by neutron inelastic scattering, is also reported. Changes in the energies and relative intensities of the crystal field transitions provide an insight into the interplay between the static and dynamic Jahn-Teller effects.

  10. Collective relaxation, single particle motion and short range order in. cap alpha. '-NbD/sub x/: A quasielastic neutron scattering study

    SciTech Connect (OSTI)

    Hempelmann, R.; Richter, D.; Faux, D.A.; Ross, D.K.

    1988-01-01

    Applying both incoherent and coherent quasielastic neutron scattering we have studied simultaneously single particle motion, collective relaxation and short range order of deuterium in ..cap alpha..'-NbD/sub x/. A comparison with recent Monte Carlo simulations lead to a consistent description of all results in terms of strongly repulsive deuterium-deuterium interactions. Relating the independently determined tracer and chemical diffusion coefficients with the also measured structure factor we show experimentally that for lattice gases the de Gennes narrowing Ansatz needs to be modified by correlation factors. 18 refs., 3 figs., 1 tab.

  11. Neutron scattering studies of the H2a-H2b and (H3-H4)/sub 2/ histone complexes

    SciTech Connect (OSTI)

    Carlson, R.D.

    1982-01-01

    Neutron scattering experiments have shown that both the (H3-H4)/sub 2/ and H2a-H2b histone complexes are quite asymmetric in solution. The (H3-H4)/sub 2/ tetramer is an oblate or flattened structure, with a radius of gyration almost as large as that of the core octamer. If the tetramer is primarily globular, it must have an axial ratio of about 1:5. It is more likely, however, that this asymmetry results in part from N-terminal arms that extend outward approximately within the major plane of the particle. If this is the case, less asymmetric models for the globular part of the tetramer, including a dislocated disk, can be made consistent with the scattering data. The H2a-H2b dimer, on the other hand, is an elongated structure. 48 references, 12 figures, 1 table.

  12. A portable hydro-thermo-mechanical loading cell for in-situ small angle neutron scattering studies of proton exchange membranes

    SciTech Connect (OSTI)

    Yu, Dunji; An, Ke; Gao, Carrie Y; Heller, William T; Chen, Xu

    2013-01-01

    A portable hydro-thermo-mechanical loading cell has been designed to enable in-situ small angle neutron scattering (SANS) studies of proton exchange membranes (PEM) under immersed tensile loadings at different temperatures. The cell consists of three main parts as follows: a letter-paper-size motor-driven mechanical load frame, a SANS friendly reservoir that provides stable immersed and thermal sample conditions, and a data acquisition & control system. The ex-situ tensile tests of Nafion 212 membranes demonstrated a satisfactory thermo-mechanical testing performance of the cell for either dry or immersed conditions at elevated temperatures. The in-situ SANS tensile measurements on the Nafion 212 membranes immersed in D2O at 70oC proved the feasibility and capability of the cell for small angle scattering study on deformation behaviors of PEM and other polymer materials under hydro-thermo-mechanical loading.

  13. Influence of length and conformation of saccharide head groups on the mechanics of glycolipid membranes: Unraveled by off-specular neutron scattering

    SciTech Connect (OSTI)

    Yamamoto, Akihisa E-mail: tanaka@uni-heidelberg.de; Tanaka, Motomu E-mail: tanaka@uni-heidelberg.de; Abuillan, Wasim; Körner, Alexander; Burk, Alexandra S.; Ries, Annika; Werz, Daniel B.; Demé, Bruno

    2015-04-21

    The mechanical properties of multilayer stacks of Gb3 glycolipid that play key roles in metabolic disorders (Fabry disease) were determined quantitatively by using specular and off-specular neutron scattering. Because of the geometry of membrane stacks deposited on planar substrates, the scattered intensity profile was analyzed in a 2D reciprocal space map as a function of in-plane and out-of-plane scattering vector components. The two principal mechanical parameters of the membranes, namely, bending rigidity and compression modulus, can be quantified by full calculation of scattering functions with the aid of an effective cut-off radius that takes the finite sample size into consideration. The bulkier “bent” Gb3 trisaccharide group makes the membrane mechanics distinctly different from cylindrical disaccharide (lactose) head groups and shorter “bent” disaccharide (gentiobiose) head groups. The mechanical characterization of membranes enriched with complex glycolipids has high importance in understanding the mechanisms of diseases such as sphingolipidoses caused by the accumulation of non-degenerated glycosphingolipids in lysosomes or inhibition of protein synthesis triggered by the specific binding of Shiga toxin to Gb3.

  14. DOE Science Showcase - Neutron Science Research from DOE Databases...

    Office of Scientific and Technical Information (OSTI)

    Neutron Science Research from DOE Databases Additional neutron science research in DOE Databases Information Bridge Neutron scattering research was pioneered in 1946 by ORNL's ...

  15. Measurement of porosity in a composite high explosive as a function of pressing conditions by ultra-small-angle neutron scattering with contrast variation

    SciTech Connect (OSTI)

    Mang, Joseph Thomas; Hjelm, Rex P; Francois, Elizabeth G

    2009-01-01

    We have used ultra-small-angle neutron scattering (USANS) with contrast variation to measure the porosity (voids and binder-filled regions) in a composite high explosive, PBX 9501, formulated with a deuterated binder. Little is known about the microstructure of pressed PBX 9501 parts and thus how it is affected by processing. Here, we explore the effect of varying the pressing intensity on the PBX 9501 microstructure. Disk-shaped samples of PBX 9501 were die-pressed with applied pressures ranging between 10,000 and 29,000 psi at 90 C. Five samples were prepared at each pressure that differed in the fraction of deuterated binder, facilitating variation of the neutron scattering length density contrast ({Delta}{rho}) and thus, the resolution of microstructural details. The sample composition was determined by calculation of the Porod Invariant as a function of {Delta}{rho} and compared with compositional estimates obtained from the bulk sample density. Structural modeling of the USANS data, at different levels of contrast, assuming both spherical and cylindrical morphologies, allowed the mean size and size distribution of voids and binder-filled regions to be determined. A decrease in the mean diameter of binder-filled regions was found with increasing pressing intensity, while the mean void diameter showed no significant change.

  16. Test of the consistency of various linearized semiclassical initial value time correlation functions in application to inelastic neutron scattering from liquid para-hydrogen

    SciTech Connect (OSTI)

    Miller, William; Liu, Jian; Miller, William H.

    2008-03-15

    The linearized approximation to the semiclassical initial value representation (LSC-IVR) is used to calculate time correlation functions relevant to the incoherent dynamic structure factor for inelastic neutron scattering from liquid para-hydrogen at 14 K. Various time correlations functions were used which, if evaluated exactly, would give identical results, but they do not because the LSC-IVR is approximate. Some of the correlation functions involve only linear operators, and others involve non-linear operators. The consistency of the results obtained with the various time correlation functions thus provides a useful test of the accuracy of the LSC-IVR approximation and its ability to treat correlation functions involving both linear and nonlinear operators in realistic anharmonic systems. The good agreement of the results obtained from different correlation functions, their excellent behavior in the spectral moment tests based on the exact moment constraints, and their semi-quantitative agreement with the inelastic neutron scattering experimental data all suggest that the LSC-IVR is indeed a good short-time approximation for quantum mechanical correlation functions.

  17. Anomalous volume expansion in CaRu{sub 0.85}Fe{sub 0.15}O{sub 3}: Neutron powder diffraction and magnetic Compton scattering

    SciTech Connect (OSTI)

    Taniguchi, T.; Mizusaki, S.; Okada, N.; Nagata, Y.; Mori, K.; Wuernisha, T.; Kamiyama, T.; Hiraoka, N.; Itou, M.; Sakurai, Y.; Ozawa, T. C.; Noro, Y.; Samata, H.

    2007-01-01

    Neutron powder diffraction and magnetic Compton scattering measurements were conducted for ferromagnetic CaRu{sub 0.85}Fe{sub 0.15}O{sub 3} at temperatures between 10 and 300 K. Anomalous volume expansion was observed in the neutron diffraction measurement below the Curie temperature (85 K), and Invar-like behavior was observed below 40 K. However, no structural phase transition was observed down to 10 K. The strong correlation between the volume expansion, {delta}V, and the square magnetization, M{sup 2}, suggests that the anomalous volume expansion is due to the magnetovolume effect that is caused by the occurrence of ferromagnetism. The magnetic Compton scattering experiments revealed the existence of a magnetic moment on Ru and the antiferromagnetic configuration of Fe and Ru moments. The formation of a ferrimagnetic order through the induction of the magnetic moment on the Ru ion is a possible reason for the anomalous volume expansion observed for CaRu{sub 0.85}Fe{sub 0.15}O{sub 3}.

  18. Small-angle neutron scattering study of the short-range organization of dispersed CsNi[Cr(CN){sub 6}] nanoparticles

    SciTech Connect (OSTI)

    Ridier, Karl; Gillon, Béatrice; André, Gilles; Chaboussant, Grégory; Catala, Laure; Mazérat, Sandra; Mallah, Talal

    2015-09-21

    Prussian blue analogues magnetic nanoparticles (of radius R{sub 0} = 2.4–8.6 nm) embedded in PVP (polyvinylpyrrolidone) or CTA{sup +} (cetyltrimethylammonium) matrices have been studied using neutron diffraction and small angle neutron scattering (SANS) at several concentrations. For the most diluted particles in neutral PVP, the SANS signal is fully accounted for by a “single-particle” spherical form factor with no structural correlations between the nanoparticles and with radii comparable to those inferred from neutron diffraction. For higher concentration in PVP, structural correlations modify the SANS signal with the appearance of a structure factor peak, which is described using an effective “mean-field” model. A new length scale R{sup * }≈ 3R{sub 0}, corresponding to an effective repulsive interaction radius, is evidenced in PVP samples. In CTA{sup +}, electrostatic interactions play a crucial role and lead to a dense layer of CTA{sup +} around the nanoparticles, which considerably alter the SANS patterns as compared to PVP. The SANS data of nanoparticles in CTA{sup +} are best described by a core-shell model without visible inter-particle structure factor.

  19. In-situ neutron scattering studies of magnetic shape memory alloys under stress, temperature, and magnetic fields

    SciTech Connect (OSTI)

    Brown, Donald W; Sisneros, Thomas A; Kabra, Saurabh; Schlagel, Deborah

    2010-01-01

    We have utilized the SMARTS engineering neutron diffractometer to study the crystallographic orientation and phase transformations in the ferromagnetic shape memory alloy Ni 2MnGa under conditions of temperature (200-600K), stress (500MPa), and magnetic field (2T). Neutrons are uniquely suited to probe the crystallographic response of materials to external stimuli because of their high penetration, which allows them to sample the bulk of the material (as opposed to the surface) as well as pass through environmental chambers. A single crystal of Ni{sub 5}MnGa was repeatedly thermally cycled through the Austenitic-Martensitic phase transformation under varying conditions of applied stress, magnetic field or both. In-situ neutron diffraction was used to quantitatively monitor the population of the crystallographic variants in the martensitic phase as a function of the external stimuli during cooling. Neutron diffraction was used to monitor variant selection in the Ferromagnetic Shape Memory Alloy Ni{sub 2}Mn Ga during austenitic to martensitic transformation under varying conditions of externally applied stress and magnetic field. Qualitatively, the results were to be expected in this simple example. The shorter and magnetically soft c-axis of the tetragonal martensitic phase aligned with the compressive stress or magnetic field. However, neutron diffraction proved useful in directly quantifying the selection of the preferred variant by external influence. For instance, by quantifying the variant selection, the neutron diffraction results made apparent that the sample 'remembered' a loading cycle following a 'reset' cycle with no external applied stress. Moreover, the power of in-situ neutron diffraction will become more apparent when applied to more complex, less understood, samples such as polycrystalline samples or composite samples.

  20. SSRL School 2008 on Hard X-ray Scattering Techniques in MES

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    May 20-22, 2008 SSRL School on Synchrotron X-ray Absorption Spectroscopy Techniques in Environmental and Materials Sciences: Theory and Application Group photo from the 2008 SSRL...

  1. Observation of long-range ferromagnetic order in the heavy-fermion compuound URu/sub 1. 2/Re/sub 0. 8/Si/sub 2/ by neutron scattering

    SciTech Connect (OSTI)

    Torikachvili, M.S.; Rebelsky, L.; Motoya, K.; Shapiro, S.M.; Dalichaouch, Y.; Maple, M.B.

    1989-01-01

    We have performed a neutron scattering study of the heavy-fermion compound URu/sub 1.2/Re/sub 0.8/Si/sub 2/, in order to verify the occurrence of long-range ferromagnetic order. This study consisted of measurements of elastic, inelastic, and polarized neutron scattering, measurement of low-angle critical scattering, and the determination of the temperature dependence of the order parameter. We found a sharp peak in the critical scattering at /approx/ 30 K for the wavevector q = 0.08 /angstrom//sup /minus/1/; and an enhancement of the intensity at the position of the (101) nuclear Bragg reflection below the Curie temperature. These measurements suggest the occurrence of long-range magnetic order. The value of the ordered moment is estimated to be /approx/ 0.53 /mu//sub B/ at 10 K. 17 refs., 3 figs.

  2. Quantification of the sensitivity range in neutron dark-field imaging

    SciTech Connect (OSTI)

    Betz, B.; Harti, R. P.; Hovind, J.; Kaestner, A.; Lehmann, E.; Grünzweig, C.; Strobl, M.; Van Swygenhoven, H.

    2015-12-15

    In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons.

  3. Ferroelectric nanoscale domains and the 905 K phase transition in SrSnO{sub 3}: A neutron total-scattering study

    SciTech Connect (OSTI)

    Goodwin, Andrew L.; Redfern, Simon A. T.; Dove, Martin T.; Keen, David A.; Tucker, Matthew G.

    2007-11-01

    The 905 K Pnma-Imma phase transition in SrSnO{sub 3} is studied here using a combination of variable-temperature neutron total scattering together with the reverse Monte Carlo (RMC) refinement method. The real-space RMC configurations obtained are analyzed in terms of bond distance and bond-angle distributions, and a geometric algebra approach is used to quantify the associated octahedral-tilting distributions. What emerges from this analysis is that the transition is displacive in nature, in contrast to the results of a recent average-structure investigation in which an order-disorder model was proposed [E. H. Mountstevens et al., Phys. Rev. B 71, 220102(R) (2005)]. Three-dimensional diffuse scattering patterns calculated from the same RMC configurations reveal the existence of an additional disorder mechanism which persists across the Pnma-Imma transition. The ''reflection conditions'' of this diffuse scattering, together with displacement correlation calculations, point to the existence of ferroelectric nanoscale domains within the configurations, which are found to extend across planar regions of approximately 10-15 A ring in diameter.

  4. Progress in development of neutron energy spectrometer for deuterium plasma operation in KSTAR

    SciTech Connect (OSTI)

    Tomita, H. Yamashita, F.; Nakayama, Y.; Morishima, K.; Yamamoto, Y.; Sakai, Y.; Hayashi, S.; Kawarabayashi, J.; Iguchi, T.; Cheon, M. S.; Isobe, M.; Ogawa, K.

    2014-11-15

    Two types of DD neutron energy spectrometer (NES) are under development for deuterium plasma operation in KSTAR to understand behavior of beam ions in the plasma. One is based on the state-of-the-art nuclear emulsion technique. The other is based on a coincidence detection of a recoiled proton and a scattered neutron caused by an elastic scattering of an incident DD neutron, which is called an associated particle coincidence counting-NES. The prototype NES systems were installed at J-port in KSTAR in 2012. During the 2012 and 2013 experimental campaigns, multiple shots-integrated neutron spectra were preliminarily obtained by the nuclear emulsion-based NES system.

  5. The Synergy Between Total Scattering and Advanced Simulation Techniques: Quantifying Geopolymer Gel Evolution

    SciTech Connect (OSTI)

    White, Claire; Bloomer, Breaunnah E.; Provis, John L.; Henson, Neil J.; Page, Katharine L.

    2012-05-16

    With the ever increasing demands for technologically advanced structural materials, together with emerging environmental consciousness due to climate change, geopolymer cement is fast becoming a viable alternative to traditional cements due to proven mechanical engineering characteristics and the reduction in CO2 emitted (approximately 80% less CO2 emitted compared to ordinary Portland cement). Nevertheless, much remains unknown regarding the kinetics of the molecular changes responsible for nanostructural evolution during the geopolymerization process. Here, in-situ total scattering measurements in the form of X-ray pair distribution function (PDF) analysis are used to quantify the extent of reaction of metakaolin/slag alkali-activated geopolymer binders, including the effects of various activators (alkali hydroxide/silicate) on the kinetics of the geopolymerization reaction. Restricting quantification of the kinetics to the initial ten hours of reaction does not enable elucidation of the true extent of the reaction, but using X-ray PDF data obtained after 128 days of reaction enables more accurate determination of the initial extent of reaction. The synergies between the in-situ X-ray PDF data and simulations conducted by multiscale density functional theory-based coarse-grained Monte Carlo analysis are outlined, particularly with regard to the potential for the X-ray data to provide a time scale for kinetic analysis of the extent of reaction obtained from the multiscale simulation methodology.

  6. Theory of Neutron Chain Reactions: Extracts from Volume I, Diffusion and Slowing Down of Neutrons: Chapter I. Elementary Theory of Neutron Diffusion. Chapter II. Second Order Diffusion Theory. Chapter III. Slowing Down of Neutrons

    DOE R&D Accomplishments [OSTI]

    Weinberg, Alvin M.; Noderer, L. C.

    1951-05-15

    The large scale release of nuclear energy in a uranium fission chain reaction involves two essentially distinct physical phenomena. On the one hand there are the individual nuclear processes such as fission, neutron capture, and neutron scattering. These are essentially quantum mechanical in character, and their theory is non-classical. On the other hand, there is the process of diffusion -- in particular, diffusion of neutrons, which is of fundamental importance in a nuclear chain reaction. This process is classical; insofar as the theory of the nuclear chain reaction depends on the theory of neutron diffusion, the mathematical study of chain reactions is an application of classical, not quantum mechanical, techniques.

  7. Particle Imaging Velocimetry Technique Development for Laboratory Measurement of Fracture Flow Inside a Pressure Vessel Using Neutron Imaging

    SciTech Connect (OSTI)

    Polsky, Yarom; Bingham, Philip R; Bilheux, Hassina Z; Carmichael, Justin R

    2015-01-01

    This paper will describe recent progress made in developing neutron imaging based particle imaging velocimetry techniques for visualizing and quantifying flow structure through a high pressure flow cell with high temperature capability (up to 350 degrees C). This experimental capability has great potential for improving the understanding of flow through fractured systems in applications such as enhanced geothermal systems (EGS). For example, flow structure measurement can be used to develop and validate single phase flow models used for simulation, experimentally identify critical transition regions and their dependence on fracture features such as surface roughness, and study multiphase fluid behavior within fractured systems. The developed method involves the controlled injection of a high contrast fluid into a water flow stream to produce droplets that can be tracked using neutron radiography. A description of the experimental setup will be provided along with an overview of the algorithms used to automatically track droplets and relate them to the velocity gradient in the flow stream. Experimental results will be reported along with volume of fluids based simulation techniques used to model observed flow.

  8. Predicting fissile content of spent nuclear fuel assemblies with the passive neutron Albedo reactivity technique and Monte Carlo code emulation

    SciTech Connect (OSTI)

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-10-13

    There is a great need in the safeguards community to be able to nondestructively quantify the mass of plutonium of a spent nuclear fuel assembly. As part of the Next Generation of Safeguards Initiative, we are investigating several techniques, or detector systems, which, when integrated, will be capable of quantifying the plutonium mass of a spent fuel assembly without dismantling the assembly. This paper reports on the simulation of one of these techniques, the Passive Neutron Albedo Reactivity with Fission Chambers (PNAR-FC) system. The response of this system over a wide range of spent fuel assemblies with different burnup, initial enrichment, and cooling time characteristics is shown. A Monte Carlo method of using these modeled results to estimate the fissile content of a spent fuel assembly has been developed. A few numerical simulations of using this method are shown. Finally, additional developments still needed and being worked on are discussed.

  9. Small angle neutron scattering analyses and high temperature mechanical properties of nano-structured oxide dispersion strengthened steels produced via cryomilling

    SciTech Connect (OSTI)

    Kim, Jeoung Han; Byun, Thak Sang; Shin, Eunjoo; Seol, Jae-Bok; Young, Sung; Reddy, N. S.

    2015-08-17

    Three oxide dispersion-strengthened (ODS) steels are produced in order to investigate the effect of the mechanical alloying (MA) temperature on the microstructural evolution and high temperature mechanical properties. The microstructural evolution with different MA conditions is examined using small angle neutron scattering. As the MA temperature decreases, the density of the nanoclusters below 10 nm increases and their mean diameter decreases. A low temperature during MA leads to a high strength in the compression tests performed at 500 *C; however, this effect disappears in testing at 900 *C. The milling process at *70 *C exhibits excellent high fracture toughness, which is better than the benchmark material 14YWT-SM10. However, the *150 *C milling process results in significantly worse fracture toughness properties. The reasons for this strong temperature dependency are discussed.

  10. A high resolution neutron scattering study of Tb2Mo2O7: A geometrically frustrated and disorder-free spin glass

    SciTech Connect (OSTI)

    Ehlers, Georg; Gardner, Jason; Qiu, Y.; Rule, K; Greedan, John E; Stewart, John Ross; Fouquet, Peter; Cornelius, A. L.; Adriano, Cris; Pagliuso, P G

    2010-01-01

    Neutron scattering, muon spin relaxation, and de susceptibility studies have been carried out on polycrystalline Tb{sub 2}Ti{sub 2}O{sub 7}, a pyrochlore antiferromagnet in which the Tb{sup 3+} moments reside on a network of corner-sharing tetrahedra. Unlike other geometrically frustrated systems, Tb{sub 2}Ti{sub 2}O{sub 7} remains paramagnetic down to {approx}0.07 K, rather than ordering into a conventional Neel or spin-glass-like state, despite the fact that short-range antiferromagnetic correlations (AFC) develop at {approx}50 K. At the first AFC wave vector, its low-lying, relatively flat magnetic excitation spectrum softens partially below 30 K.

  11. Structural evolution across the insulator-metal transition in oxygen-deficient BaTiO3-δ studied using neutron total scattering and Rietveld analysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jeong, I.-K.; Lee, Seunghun; Jeong, Se-Young; Won, C. J.; Hur, N.; Llobet, A.

    2011-08-29

    Oxygen-deficient BaTiO3-δ exhibits an insulator-metal transition with increasing δ. We performed neutron total scattering measurements to study structural evolution across an insulator-metal transition in BaTiO3-δ. Despite its significant impact on resistivity, slight oxygen reduction (δ=0.09) caused only a small disturbance on the local doublet splitting of Ti-O bond. This finding implies that local polarization is well preserved under marginal electric conduction. In the highly oxygen-deficient metallic state (δ=0.25), however, doublet splitting of the Ti-O bond became smeared. The smearing of the local Ti-O doublet is complemented with long-range structural analysis and demonstrates that the metallic conduction in the highly oxygen-reducedmore » BaTiO3-δ is due to the appearance of nonferroelectric cubic lattice.« less

  12. Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

    SciTech Connect (OSTI)

    Saito, Kotaro Ono, Kanta; Ueno, Tetsuro; Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira; Harada, Masashi; Keiderling, Uwe

    2015-05-07

    The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd{sub 2}Fe{sub 14}B grains.

  13. Characterization of a Fe/Y{sub 2}O{sub 3} metal/oxide interface using neutron and x-ray scattering

    SciTech Connect (OSTI)

    Watkins, E. B.; Majewski, J. E-mail: jarek@lanl.gov; Kashinath, A.; Wang, P.; Baldwin, J. K.; Demkowicz, M. J. E-mail: jarek@lanl.gov

    2014-07-28

    The structure of metal/oxide interfaces is important to the radiation resistance of oxide dispersion-strengthened steels. We find evidence of gradual variations in stoichiometry and magnetization across a Fe/Y{sub 2}O{sub 3} metal/oxide heterophase interface using neutron and x-ray reflectometry. These findings suggest that the Fe/Y{sub 2}O{sub 3} interface is a transitional zone approximately ?64?-thick containing mixtures or compounds of Fe, Y, and O. Our results illustrate the complex chemical and magnetic nature of Fe/oxide interfaces and demonstrate the utility of combined neutron and x-ray techniques as tools for characterizing them.

  14. Detection of illicit HEU production in gaseous centrifuge enrichment plants using neutron counting techniques on product cylinders

    SciTech Connect (OSTI)

    Freeman, Corey R; Geist, William H

    2010-01-01

    Innovative and novel safeguards approaches are needed for nuclear energy to meet global energy needs without the threat of nuclear weapons proliferation. Part of these efforts will include creating verification techniques that can monitor uranium enrichment facilities for illicit production of highly-enriched uranium (HEU). Passive nondestructive assay (NDA) techniques will be critical in preventing illicit HEU production because NDA offers the possibility of continuous and unattended monitoring capabilities with limited impact on facility operations. Gaseous centrifuge enrichment plants (GCEP) are commonly used to produce low-enriched uranium (LEU) for reactor fuel. In a GCEP, gaseous UF{sub 6} spins at high velocities in centrifuges to separate the molecules containing {sup 238}U from those containing the lighter {sup 235}U. Unfortunately, the process for creating LEU is inherently the same as HEU, creating a proliferation concern. Insuring that GCEPs are producing declared enrichments poses many difficult challenges. In a GCEP, large cascade halls operating thousands of centrifuges work together to enrich the uranium which makes effective monitoring of the cascade hall economically prohibitive and invasive to plant operations. However, the enriched uranium exiting the cascade hall fills product cylinders where the UF{sub 6} gas sublimes and condenses for easier storage and transportation. These product cylinders hold large quantities of enriched uranium, offering a strong signal for NDA measurement. Neutrons have a large penetrability through materials making their use advantageous compared to gamma techniques where the signal is easily attenuated. One proposed technique for detecting HEU production in a GCEP is using neutron coincidence counting at the product cylinder take off stations. This paper discusses findings from Monte Carlo N-Particle eXtended (MCNPX) code simulations that examine the feasibility of such a detector.

  15. Effective atomic numbers of blue topaz at different gamma-rays energies obtained from Compton scattering technique

    SciTech Connect (OSTI)

    Tuschareon, S. Limkitjaroenporn, P. Kaewkhao, J.

    2014-03-24

    Topaz occurs in a wide range of colors, including yellow, orange, brown, pink-to-violet and blue. All of these color differences are due to color centers. In order to improve the color of natural colorless topaz, the most commonly used is irradiated with x- or gamma-rays, indicated that attenuation parameters is important to enhancements by irradiation. In this work, the mass attenuation coefficients of blue topaz were measured at the different energy of ?-rays using the Compton scattering technique. The results show that, the experimental values of mass attenuation coefficient are in good agreement with the theoretical values. The mass attenuation coefficients increase with the decrease in gamma rays energies. This may be attributed to the higher photon interaction probability of blue topaz at lower energy. This result is a first report of mass attenuation coefficient of blue topaz at different gamma rays energies.

  16. Neutron Resonance Transmission Analysis (NRTA): A Nondestructive Assay Technique for the Next Generation Safeguards Initiative’s Plutonium Assay Challenge

    SciTech Connect (OSTI)

    J. W. Sterbentz; D. L. Chichester

    2010-12-01

    This is an end-of-year report for a project funded by the National Nuclear Security Administration's Office of Nuclear Safeguards (NA-241). The goal of this project is to investigate the feasibility of using Neutron Resonance Transmission Analysis (NRTA) to assay plutonium in commercial light-water-reactor spent fuel. This project is part of a larger research effort within the Next-Generation Safeguards Initiative (NGSI) to evaluate methods for assaying plutonium in spent fuel, the Plutonium Assay Challenge. The first-year goals for this project were modest and included: 1) developing a zero-order MCNP model for the NRTA technique, simulating data results presented in the literature, 2) completing a preliminary set of studies investigating important design and performance characteristics for the NRTA measurement technique, and 3) documentation of this work in an end of the year report (this report). Research teams at Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), Pacific Northwest National Laboratory (PNNL), and at several universities are also working to investigate plutonium assay methods for spent-fuel safeguards. While the NRTA technique is well proven in the scientific literature for assaying individual spent fuel pins, it is a newcomer to the current NGSI efforts studying Pu assay method techniques having just started in March 2010; several analytical techniques have been under investigation within this program for two to three years or more. This report summarizes a nine month period of work.

  17. Determining fissile content in PWR spent fuel assemblies using a passive neutron Albedo reactivity with fission chambers technique

    SciTech Connect (OSTI)

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-01-01

    State regulatory bodies and organizations such as the IAEA that are concerned with preventing the proliferation of nuclear weapons are interested in a means of quantifying the amount of plutonium in a given spent fuel assembly. The complexity of spent nuclear fuel makes the measurement of plutonium content challenging. There are a variety of techniques that can measure various properties of spent nuclear fuel including burnup, and mass of fissile content. No single technique can provide all desired information, necessitating an approach using multiple detector systems and types. This paper presents our analysis of the Passive Neutron Albedo Reactivity Fission Chamber (PNAR-FC) detector system. PNAR-FC is a simplified version of the PNAR technique originally developed in 1997. This earlier research was performed with a high efficiency, {sup 3}He-based system (PNAR-3He) with which multiplicty analysis was performed. With the PNAR technique a portion of the spent fuel assembly is wrapped in a 1 mm thick cadmium liner. Neutron count rates are measured both with and without the cadmium liner present. The ratio of the count rate with the cadmium liner to the count rate without the cadmium liner is calculated and called the cadmium ratio. In the PNAR-3He technique, multiplicity measurements were made and the cadmium ratio was shown to scale with the fissile content of the material being measured. PNAR-FC simplifies the PNAR technique by using only a few fission chambers instead of many {sup 3}He tubes. Using a simplified PNAR-FC technique provides for a cheaper, lighter, and thus more portable detector system than was possible with the PNAR-3He system. The challenge with the PNAR-FC system are two-fold: (1) the change in the cadmium ratio is weaker as a afunction of the changing fissile content relative to multiplicity count rates, and (2) the efficiency for the fission chamber based system are poorer than for the {sup 3}He based detectors. In this paper, we present our

  18. Deep Inelastic Electron Scattering: Experimental

    DOE R&D Accomplishments [OSTI]

    Friedman, J. I.

    1971-10-01

    This report reviews and brings up to date the experimental information on high energy inelastic electron scattering from proton and neutron.

  19. The application of inelastic neutron scattering to explore the significance of a magnetic transition in an iron based Fischer-Tropsch catalyst that is active for the hydrogenation of CO

    SciTech Connect (OSTI)

    Warringham, Robbie; McFarlane, Andrew R.; Lennon, David; MacLaren, Donald A.; Webb, Paul B.; Tooze, Robert P.; Taylor, Jon; Ewings, Russell A.; Parker, Stewart F.

    2015-11-07

    An iron based Fischer-Tropsch synthesis catalyst is evaluated using CO hydrogenation at ambient pressure as a test reaction and is characterised by a combination of inelastic neutron scattering (INS), powder X-ray diffraction, temperature-programmed oxidation, Raman scattering, and transmission electron microscopy. The INS spectrum of the as-prepared bulk iron oxide pre-catalyst (hematite, α-Fe{sub 2}O{sub 3}) is distinguished by a relatively intense band at 810 cm{sup −1}, which has previously been tentatively assigned as a magnon (spinon) feature. An analysis of the neutron scattering intensity of this band as a function of momentum transfer unambiguously confirms this assignment. Post-reaction, the spinon feature disappears and the INS spectrum is characterised by the presence of a hydrocarbonaceous overlayer. A role for the application of INS in magnetic characterisation of iron based FTS catalysts is briefly considered.

  20. Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Han, Youngkyu; Ahn, Suk-kyun; Zhang, Zhe; Smith, Gregory S.; Do, Changwoo

    2016-06-01

    We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotubemore » particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. In conclusion, this method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.« less

  1. Neutron scattering studies of spin-phonon hybridization and superconducting spin gaps in the high temperature superconductor La2-x(Sr;Ba)xCuO4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wagman, J. J.; Carlo, Jeremy P.; Gaudet, J.; Van Gastel, G. J.; Abernathy, Douglas L.; Stone, Matthew B.; Granroth, Garrett E.; Kolesnikov, Alexander I.; Savici, Andrei T.; Kim, Young -June; et al

    2016-03-14

    We present time-of-flight neutron-scattering measurements on single crystals of La2-xBaxCuO4 (LBCO) with 0 ≤ x ≤ 0.095 and La2-xSrxCuO4 (LSCO) with x = 0.08 and 0.11. This range of dopings spans much of the phase diagram relevant to high temperature cuprate superconductivity, ranging from insulating, three dimensional commensurate long range antiferromagnetic order for x ≤ 0.02 to two dimensional (2D) incommensurate antiferromagnetism co-existing with superconductivity for x ≥ 0.05. Previous work on lightly doped LBCO with x = 0.035 showed a clear resonant enhancement of the inelastic scattering coincident with the low energy crossings of the highly dispersive spin excitationsmore » and quasi-2D optic phonons. The present work extends these measurements across the phase diagram and shows this enhancement to be a common feature to this family of layered quantum magnets. Furthermore we show that the low temperature, low energy magnetic spectral weight is substantially larger for samples with non-superconducting ground states relative to any of the samples with superconducting ground states. Lastly spin gaps, suppression of low energy magnetic spectral weight, are observed in both superconducting LBCO and LSCO samples, consistent with previous observations for superconducting LSCO« less

  2. Raw neutron scattering data for strain measurement of hydraulically loaded granite and marble samples in triaxial stress state

    SciTech Connect (OSTI)

    Polsky, Yarom

    2014-05-23

    This entry contains raw data files from experiments performed on the Vulcan beamline at the Spallation Neutron Source at Oak Ridge National Laboratory using a pressure cell. Cylindrical granite and marble samples were subjected to confining pressures of either 0 psi or approximately 2500 psi and internal pressures of either 0 psi, 1500 psi or 2500 psi through a blind axial hole at the center of one end of the sample. The sample diameters were 1.5" and the sample lengths were 6". The blind hole was 0.25" in diameter and 3" deep. One set of experiments measured strains at points located circumferentially around the center of the sample with identical radii to determine if there was strain variability (this would not be expected for a homogeneous material based on the symmetry of loading). Another set of experiments measured load variation across the radius of the sample at a fixed axial and circumferential location. Raw neutron diffraction intensity files and experimental parameter descriptions are included.

  3. Raw neutron scattering data for strain measurement of hydraulically loaded granite and marble samples in triaxial stress state

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Polsky, Yarom

    This entry contains raw data files from experiments performed on the Vulcan beamline at the Spallation Neutron Source at Oak Ridge National Laboratory using a pressure cell. Cylindrical granite and marble samples were subjected to confining pressures of either 0 psi or approximately 2500 psi and internal pressures of either 0 psi, 1500 psi or 2500 psi through a blind axial hole at the center of one end of the sample. The sample diameters were 1.5" and the sample lengths were 6". The blind hole was 0.25" in diameter and 3" deep. One set of experiments measured strains at points located circumferentially around the center of the sample with identical radii to determine if there was strain variability (this would not be expected for a homogeneous material based on the symmetry of loading). Another set of experiments measured load variation across the radius of the sample at a fixed axial and circumferential location. Raw neutron diffraction intensity files and experimental parameter descriptions are included.

  4. Plutonium Detection with Straw Neutron Detectors

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Guss, Paul

    2014-03-27

    A kilogram of weapons grade plutonium gives off about 56,000 neutrons per second of which 55,000 neutrons come from spontaneous fission of 240Pu (~6% by weight of the total plutonium). Actually, all even numbered isotopes (238Pu, 240Pu, and 242Pu) produce copious spontaneous fission neutrons. These neutrons induce fission in the surrounding fissile 239Pu with an approximate multiplication of a factor of ~1.9. This multiplication depends on the shape of the fissile materials and the surrounding material. These neutrons (typically of energy 2 MeV and air scattering mean free path >100 meters) can be detected 100 meters away from the source by vehicle-portable neutron detectors. [1] In our current studies on neutron detection techniques, without using 3He gas proportional counters, we designed and developed a portable high-efficiency neutron multiplicity counter using 10B-coated thin tubes called straws. The detector was designed to perform like commercially available fission meters (manufactured by Ortec Corp.) except instead of using 3He gas as a neutron conversion material, we used a thin coating of 10B.

  5. Pulsed-neutron monochromator

    DOE Patents [OSTI]

    Mook, Jr., Herbert A. (Oak Ridge, TN)

    1985-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  6. Pulsed-neutron monochromator

    DOE Patents [OSTI]

    Mook, H.A. Jr.

    1984-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  7. Neutron Instruments Added at Oak Ridge (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Neutron Instruments Added at Oak Ridge Citation Details In-Document Search Title: Neutron Instruments Added at Oak Ridge The neutron scattering facilities at Oak Ridge National ...

  8. Scattering Society of America

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Majewski named Fellow of the Neutron Scattering Society of America May 9, 2016 The Neutron Scattering Society of America (NSSA) has honored Jaroslaw (Jarek) Majewski of the Center for Integrated Nanotechnologies (MPA-CINT) with the title of Fellow. The Society recognized Majewski for "contributions to our understanding of weakly organized two-dimensional systems, including surfactant molecules found in biological systems. Majewski's achievements Majewski received a doctorate in Materials

  9. Protein Folding Dynamics Detected By Time-Resolved Synchrotron X-ray Small-Angle Scattering Technique

    SciTech Connect (OSTI)

    Fujisawa, Tetsuro; Takahashi, Satoshi [RIKEN Harima Institute, SPring-8 Center, Laboratory for Biometal Science, Hyogo 679-5148 (Japan); Institute for Protein Research, Osaka University Suita Osaka 565-0871/CREST, JST (Japan)

    2007-03-30

    The polypeptide collapse is an essential dynamics in protein folding. To understand the mechanism of the collapse, in situ observation of folding by various probes is necessary. The changes in secondary and tertiary structures in the folding process of globular proteins, whose chain lengths are less than 300 polypeptides, were observed by circular dichrosim and intrinsic fluorescence spectroscopies, respectively. On the other hand, those in protein compactness could be only detected by using time-resolved synchrotron x-ray small-angle scattering technique. The observed dynamics for several proteins with different topologies suggested a common folding mechanism termed 'collapse and search' dynamics, in which the polypeptide collapse precedes the formation of the native contact formation. In 'collapse and search' dynamics, the most outstanding feature lied in the compactness of the initial intermediates. The collapsed intermediates demonstrated the scaling relationship between radius of gyration (Rg) and chain length with a scaling exponent of 0.35 {+-} 0.11, which is close to the value (1/3) predicted by mechano-statistical theory for the collapsed globules of polymers in poor solvent. Thus, it was suggested that the initial collapse is caused by the coil-globule transition of polymers. Since the collapse is essential to the folding of larger proteins, further investigations on the collapse likely lead to an important insight into the protein folding phenomena.

  10. Small-angle neutron scattering study of magnetic ordering and inhomogeneity across the martensitic phase transformation in Ni50–xCoxMn₄₀Sn₁₀ alloys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bhatti, Kanwal Preet; El-Khatib, S.; Srivastava, Vijay; James, R. D.; Leighton, C.

    2012-04-27

    The Heusler-derived multiferroic alloy Ni50–xCoxMn₄₀Sn₁₀ has recently been shown to exhibit, at just above room temperature, a highly reversible martensitic phase transformation with an unusually large magnetization change. In this work the nature of the magnetic ordering above and below this transformation has been studied in detail in the critical composition range x = 6–8 via temperature-dependent (5–600 K) magnetometry and small-angle neutron scattering (SANS). We observe fairly typical paramagnetic to long-range-ordered ferromagnetic phase transitions on cooling to 420–430 K, with the expected critical spin fluctuations, followed by first-order martensitic phase transformations to a nonferromagnetic state below 360–390 K. Themore » static magnetization reveals complex magnetism in this low-temperature nonferromagnetic phase, including a Langevin-like field dependence, distinct spin freezing near 60 K, and significant exchange bias effects, consistent with superparamagnetic blocking of ferromagnetic clusters of nanoscopic dimensions. We demonstrate that these spin clusters, whose existence has been hypothesized in a variety of martensitic alloys exhibiting competition between ferromagnetic and antiferromagnetic exchange interactions, can be directly observed by SANS. The scattering data are consistent with a liquidlike spatial distribution of interacting magnetic clusters with a mean center-to-center spacing of 12 nm. Considering the behavior of the superparmagnetism, cooling-field and temperature-dependent exchange bias, and magnetic SANS, we discuss in detail the physical form and origin of these spin clusters, their intercluster interactions, the nature of the ground-state magnetic ordering in the martensitic phase, and the implications for our understanding of such alloy systems.« less

  11. Measurement/Evaluation Techniques and Nuclear Data Associated with Fission of 239Pu by Fission Spectrum Neutrons

    SciTech Connect (OSTI)

    Baisden, P; Bauge, E; Ferguson, J; Gilliam, D; Granier, T; Jeanloz, R; McMillan, C; Robertson, D; Thompson, P; Verdon, C; Wilkerson, C; Young, P

    2010-03-16

    This Panel was chartered to review and assess new evaluations of work on fission product data, as well as the evaluation process used by the two U.S. nuclear weapons physics laboratories. The work focuses on fission product yields resulting from fission spectrum neutrons incident on plutonium, and includes data from measurements that had not been previously published as well as new or revised fission product cumulative yield data, and related quantities such as Q values and R values. This report documents the Panel's assessment of the work presented by Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory (LLNL). Based on the work presented we have seven key observations: (1) Experiments conducted in the 1970s at LANL, some of which were performed in association with a larger, NIST-led, program, have recently been documented. A preliminary assessment of this work, which will be referred to in this document as ILRR-LANL, shows it to be technically sound. (2) LLNL has done a thorough, unbiased review and evaluation of the available literature and is in the process of incorporating the previously unavailable LANL data into its evaluation of key fission product yields. The results of the LLNL effort, which includes a preliminary evaluation of the ILRR-LANL data, have been documented. (3) LANL has also conducted an evaluation of fission product yields for fission spectrum neutrons on plutonium including a meta-analysis of benchmark data as part of a planned upgrade to the ENDF/B compilation. We found that the approach of using meta-analysis provides valuable additional insight for evaluating the sparse data sets involved in this assessment. (4) Both laboratories have provided convincing evidence for energy dependence in the fission product yield of {sup 147}Nd produced from the bombardment of {sup 239}Pu with fission spectrum neutrons over an incident neutron energy range of 0.2 to 1.9 MeV. (5) Consistent, complete, and explicit treatment of

  12. Small-angle neutron scattering analysis of Mn–C clusters in high-manganese 18Mn–0.6C steel

    SciTech Connect (OSTI)

    Kang, Mihyun; Shin, Eunjoo; Woo, Wanchuck; Lee, Young-Kook

    2014-10-15

    Nanometer-scale particles (Mn–C clusters) were analyzed quantitatively using small-angle neutron scattering in 18Mn–0.6C (wt.%) austenite high-manganese steel. The size, number, and volume fraction of the particles were determined as a function of strain (0, 5, 15, 30, 45, 50%) at different temperatures (25 and 100 °C). The diameter of the cluster ranges from 2 to 14 nm in the matrix. The total volume fraction of the cluster significantly increases from 2.7 × 10{sup −6} to 8.7 × 10{sup −6} as the strain increases. Such clustering phenomenon is correlated to the serration behavior under loading in high-manganese steels. - Highlights: • Show Mn-C clustering as function of strain in 18Mn-0.6C TWIP steel. • Determine the size, number, and volume fraction of clusters quantitatively. • Compare the clustering behavior at 25 and 100 °C.

  13. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    SciTech Connect (OSTI)

    Putra, Edy Giri Rachman; Patriati, Arum

    2015-04-16

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  14. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering

    SciTech Connect (OSTI)

    Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; Stanley, Christopher B.; Do, Changwoo; Heller, William T.; Aggarwal, Aneel K.; Callaway, David J.E.; Bu, Zimei

    2015-01-08

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin, which links the CD44 assembled receptor signaling complexes to the cytoskeletal actin and organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered and adopts an autoinhibited conformation, which prevents CD44ct from binding directly to activated Ezrin in solution. Binding to the signaling lipid phosphatidylinositol 4,5-biphosphlate (PIP2) disrupts autoinhibition in CD44ct, and activates CD44ct to associate with Ezrin. Further, using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific hetero-tetramer complex of CD44ct with Ezrin. This study reveals a novel autoregulation mechanism in the cytoplasmic tail of CD44 and the role of PIP2 in mediating the assembly of multimeric CD44ct-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of multimeric PIP2-CD44-Ezrin complexes.

  15. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; Stanley, Christopher B.; Do, Changwoo; Heller, William T.; Aggarwal, Aneel K.; Callaway, David J.E.; Bu, Zimei

    2015-01-08

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin, which links the CD44 assembled receptor signaling complexes to the cytoskeletal actin and organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered and adopts an autoinhibited conformation, which prevents CD44ct from binding directly to activated Ezrin in solution. Binding to the signaling lipid phosphatidylinositol 4,5-biphosphlate (PIP2) disrupts autoinhibition in CD44ct, and activates CD44ct to associate with Ezrin.more » Further, using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific hetero-tetramer complex of CD44ct with Ezrin. This study reveals a novel autoregulation mechanism in the cytoplasmic tail of CD44 and the role of PIP2 in mediating the assembly of multimeric CD44ct-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of multimeric PIP2-CD44-Ezrin complexes.« less

  16. Pressure-Induced Structural Phase Transition in CeNi: X-ray and Neutron Scattering Studies and First-Principles Calculations

    SciTech Connect (OSTI)

    Mirmelstein, A.; Podlesnyak, Andrey A.; dos Santos, Antonio M.; Ehlers, Georg; Kerbel, O.; Matvienko, V.; Sefat, A. S.; Saporov, B.; Halder, G. J.; Tobin, J. G.

    2015-08-03

    The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by x-ray and neutron powder diffraction techniques. It is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P<8 GPa and T<300 K. The observed Cmcm→Pnma structural transition is then analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated with the phase transition.

  17. Pressure-Induced Structural Phase Transition in CeNi: X-ray and Neutron Scattering Studies and First-Principles Calculations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mirmelstein, A.; Podlesnyak, Andrey A.; dos Santos, Antonio M.; Ehlers, Georg; Kerbel, O.; Matvienko, V.; Sefat, A. S.; Saporov, B.; Halder, G. J.; Tobin, J. G.

    2015-08-03

    The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by x-ray and neutron powder diffraction techniques. It is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P<8 GPa and T<300 K. The observed Cmcm→Pnma structural transition is then analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated withmore » the phase transition.« less

  18. Chiral Three-Nucleon Interactions in Light Nuclei, Neutron- α...

    Office of Scientific and Technical Information (OSTI)

    Title: Chiral Three-Nucleon Interactions in Light Nuclei, Neutron- Scattering, and Neutron Matter Authors: Lynn, J. E. ; Tews, I. ; Carlson, J. ; Gandolfi, S. ; Gezerlis, A. ; ...

  19. Category:Neutron Log | Open Energy Information

    Open Energy Info (EERE)

    Looking for the Neutron Log page? For detailed information on Neutron Log, click here. Category:Neutron Log Add.png Add a new Neutron Log Technique Pages in category...

  20. Electroweak Measurements of Neutron Densities in CREX and PREX at JLab, USA

    SciTech Connect (OSTI)

    Horowitz, Charles J. [Indiana U.; Kumar, Krishna S. [UMass; Michaels, Robert W. [JLAB

    2014-02-01

    Measurement of the parity-violating electron scattering asymmetry is an established technique at Jefferson Lab and provides a new opportunity to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively; these are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter ${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces.

  1. Monitoring the dynamics of miscible P3HT:PCBM blends: A quasi elastic neutron scattering study of organic photovoltaic active layers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Etampawala, Thusitha; Ratnaweera, Dilru; Morgan, Brian; Diallo, Souleymane; Mamontov, Eugene; Dadmun, Mark

    2015-02-02

    Our work reports on the detailed molecular dynamic behavior of miscible blends of Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and their pure counterparts by quasi-elastic neutron scattering measurements (QENS). The study provides the measure of relaxation processes on pico-to-nanosecond time scales. A single relaxation process was observed in pure P3HT and PCBM while two relaxation processes, one fast and one slow, were observed in the blends. The fast process was attributed to the dynamics of P3HT while the slow process was correlated to the dynamics of PCBM. The results show that the relaxation process is a balance betweenmore » two opposing effects: increased mobility due to thermal activation of P3HT molecules and decrease mobility due to the presence of PCBM which is correlated to the percent crystallinity of P3HT and local packing density of PCBM in the amorphous phase. The threshold for the domination of the thermally activated relaxation is between 5 and 9 vol.% of PCBM loading. Two distinct spatial dependences of the relaxation processes, in which the crossover length scale depends neither on temperature nor composition, were observed for all the samples. They were attributed to the collective motions of the hexyl side chains and the rotational motions of the C-C single bonds of the side chains. Finally, these results provide an understanding of the effects of PCBM loading and temperature on the dynamics of the polymer-fullerene blends which provides a tool to optimize the efficiency of charge carrier and exciton transport within the organic photovoltaic (OPV) active layer to improve the high performance of organic solar cells.« less

  2. Effect of Protein Incorporation on the Nanostructure of the Bicontinuous Microemulsion Phase of Winsor-III Systems: A Small-Angle Neutron Scattering Study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hayes, Douglas G.; Gomez del Rio, Javier A.; Ye, Ran; Urban, Volker S.; Pingali, Sai Venkatesh; O’Neill, Hugh M.

    2015-01-20

    Small-angle neutron scattering (SANS) analysis using the Teubner₋Strey model has been employed to evaluate the effect of protein incorporation into the middle, bicontinuous microemulsion (BμE) phase of Winsor-III (WIII) systems formed by an aerosol-OT (AOT)/alkyl ethoxylate mixed surfactant system to understand better the extraction of proteins into and out of BμEs and to study the effect of proteins on a system that serves as a biomimetic analog of cell membranes. Under conditions of high salinity, the incorporation of positively charged proteins cytochrome c, lysozyme, and α-chymotrypsin, near their solubilization limit in the BμEs promoted the release of water and oilmore » from the BμEs, a decrease in the quasi-periodic repeat distance (d), an increase in ordering (a decrease in the amphiphilicity factor, fa) for the surfactant monolayers, and a decrease in the surface area per surfactant headgroup, suggesting that the proteins affected the self-assembly of components in the BμE phase and produced Debye shielding of AOTs sulfonate headgroup. For WIII systems possessing lower salinity, cytochrome c reduced the efficiency of surfactant in the BμE phase, noted by increases in d and fa, suggesting that the enzyme and AOT underwent ion pairing. We find that the results of this study demonstrate the importance of ionic strength to modulate proteinsurfactant interactions, which in turn will control the release of proteins encapsulated in the BμEs, relevant to WIII-based protein extraction and controlled release from BμE delivery systems, and demonstrate the utility of BμEs as a model system to understand the effect of proteins on biomembranes.« less

  3. 235U Determination using In-Beam Delayed Neutron Counting Technique at the NRU Reactor

    SciTech Connect (OSTI)

    Andrews, M. T.; Bentoumi, G.; Corcoran, E. C.; Dimayuga, I.; Kelly, D. G.; Li, L.; Sur, B.; Rogge, R. B.

    2015-11-17

    This paper describes a collaborative effort that saw the Royal Military College of Canada (RMC)’s delayed neutron and gamma counting apparatus transported to Canadian Nuclear Laboratories (CNL) for use in the neutron beamline at the National Research Universal (NRU) reactor. Samples containing mg quantities of fissile material were re-interrogated, and their delayed neutron emissions measured. This collaboration offers significant advantages to previous delayed neutron research at both CNL and RMC. This paper details the determination of 235U content in enriched uranium via the assay of in-beam delayed neutron magnitudes and temporal behavior. 235U mass was determined with an average absolute error of ± 2.7 %. This error is lower than that obtained at RMCC for the assay of 235U content in aqueous solutions (3.6 %) using delayed neutron counting. Delayed neutron counting has been demonstrated to be a rapid, accurate, and precise method for special nuclear material detection and identification.

  4. Fundamental neutron physics at LANSCE

    SciTech Connect (OSTI)

    Greene, G.

    1995-10-01

    Modern neutron sources and science share a common origin in mid-20th-century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for studying condensed matter with modern neutron sources being primarily used (and justified) as tools for neutron scattering and materials science research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities performed at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high-flux neutron facilities. Future sources, particularly high-power spallation sources, offer exciting possibilities for continuing this research.

  5. Neutron-deuteron breakup reaction as a tool for studying neutron-neutron interactions

    SciTech Connect (OSTI)

    Konobeevski, E. S., E-mail: konobeev@inr.ru; Zuyev, S. V.; Mordovskoy, M. V.; Potashev, S. I.; Sharapov, I. M. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)] [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

    2013-11-15

    An analysis of the most recent data on the reaction nd {yields} pnn revealed a serious discrepancy between theoretical predictions and cross sections measured for this reaction in various configurations where the role of neutron-neutron interactions is important. In view of this, it seems necessary both to develop theoretical approaches and to obtain new experimental data. For this purpose, a setup for studying the neutron-deuteron breakup reaction was created at the Institute for Nuclear Research on the basis of the neutron beam in the RADEX channel and deuterium targets. This facility makes it possible to perform experiments over a broad region of primary-neutron energies (10-60 MeV) and in various (final-state interaction, quasifree scattering, and spatial-star) configurations. Preliminary results of the respective experiment were obtained for configurations of final-state neutron-neutron interaction and quasifree neutron-neutron scattering.

  6. Neutron Resonance Spectroscopy for the Analysis of Materials and Objects

    SciTech Connect (OSTI)

    Borella, A.; Lampoudis, C.; Schillebeeckx, P.; Kopecky, S.; Postma, H.; Moxon, M.

    2009-12-02

    The presence of resonances in neutron induced reaction cross sections is the basis of the Neutron Resonance Capture (NRCA) and Transmission (NRTA) Analysis techniques. Since resonances can be observed at neutron energies which are specific for each nuclide, they can be used as fingerprints to identify and quantify elements in materials and objects. Both NRCA and NRTA are fully non-destructive methods which determine the bulk elemental composition, do not require any sample preparation and result in a negligible residual activation. In this text we review the technique and present an analysis procedures including one based on a more methodological approach which relies on a full Resonance Shape Analysis (RSA) and accounts directly for the neutron self-shielding, multiple scattering, Doppler broadening and instrumental resolution.

  7. Neutron elastic backscattering with resonance enhancement

    SciTech Connect (OSTI)

    Gomberg, H.J.; McEllistrem, M.T.

    1993-12-31

    Reliable detection of explosives and narcotics depends on generating signatures of compounds which characterize them. Major explosives and also alkaloid narcotics contain unique concentrations of Carbon, Oxygen, and Nitrogen which provide specific elemental ratios and chemical signatures. Neutron-induced reaction methods are rapid and non-invasive means of probing container interiors for special element-ratio signatures which signal the presence of significant amounts of contraband. Among these reactions the highest probabilities occur for neutron from different light elements, allowing determination of relative abundance of these elements. The authors have already demonstrated signature for simulated explosives and simulated narcotics in experimental tests at 1-4 MeV at the University of Kentucky accelerator labs. Intensities of neutron scatter at angles near 150{degrees} from three different elements, C, N, and O, were determined. Fast neutron time-of-flight detection methods enabled measurement of neutron energies, and thus separation of scattering from the different elements. Making measurements on and off strong resonances for specific elements, increases PFD and reduces PFA. Measurements illustrating this resonance enhancement technique will be presented.

  8. Neutron inelastic scattering investigation of the magnetic excitations in Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Br,Cl)

    SciTech Connect (OSTI)

    Crowe, S.J.; Majumdar, S.; Lees, M.R.; Paul, D. McK.; Bewley, R.I.; Levett, S.J.; Ritter, C.

    2005-06-01

    Neutron inelastic scattering investigations have been performed on the spin tetrahedral system Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br). We report the observation of magnetic excitations with a dispersive component in both compounds, associated with the three-dimensional incommensurate magnetic order that develops below T{sub N}{sup Cl}=18.2 K and T{sub N}{sup Br}=11.4 K. The excitation in Cu{sub 2}Te{sub 2}O{sub 5}Cl{sub 2} softens as the temperature approaches T{sub N}{sup Cl}, leaving diffuse quasi-elastic scattering above the transition temperature. In the bromide, the excitations are present well above T{sub N}{sup Br}, which might be attributed to the presence of a degree of low dimensional correlations above T{sub N}{sup Br} in this compound.

  9. A qualitative analysis of the neutron population in fresh and spent fuel assemblies during simulated interrogation using the differential die-away technique

    SciTech Connect (OSTI)

    Tobin, Stephen J.; Lundkvist, Niklas; Goodsell, Alison V.; Grape, Sophie; Hendricks, John S.; Henzl, Vladimir; Swinhoe, Martyn T.

    2015-01-01

    In this study, Monte Carlo simulations were performed for the differential die-away (DDA) technique to analyse the time-dependent behaviour of the neutron population in fresh and spent nuclear fuel assemblies as part of the Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) Project. Simulations were performed to investigate both a possibly portable as well as a permanent DDA instrument. Taking advantage of a custom made modification to the MCNPX code, the variation in the neutron population, simultaneously in time and space, was examined. The motivation for this research was to improve the design of the DDA instrument, as it is be ing considered for possible deployment at the Central Storage of Spent Nuclear Fuel and Encapsulation Plant in Sweden (Clab), as well as to assist in the interpretation of the both simulated and measured signals.

  10. A qualitative analysis of the neutron population in fresh and spent fuel assemblies during simulated interrogation using the differential die-away technique

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tobin, Stephen J.; Lundkvist, Niklas; Goodsell, Alison V.; Grape, Sophie; Hendricks, John S.; Henzl, Vladimir; Swinhoe, Martyn T.

    2015-01-01

    In this study, Monte Carlo simulations were performed for the differential die-away (DDA) technique to analyse the time-dependent behaviour of the neutron population in fresh and spent nuclear fuel assemblies as part of the Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) Project. Simulations were performed to investigate both a possibly portable as well as a permanent DDA instrument. Taking advantage of a custom made modification to the MCNPX code, the variation in the neutron population, simultaneously in time and space, was examined. The motivation for this research was to improve the design of the DDA instrument, as it is bemore » ing considered for possible deployment at the Central Storage of Spent Nuclear Fuel and Encapsulation Plant in Sweden (Clab), as well as to assist in the interpretation of the both simulated and measured signals.« less

  11. Voids in neutron-irradiated metals and alloys

    SciTech Connect (OSTI)

    Hendricks, R.W.

    1980-01-01

    Small-angle x-ray and neutron scattering are powerful analytical tools for investigating long-range fluctuations in electron (x-rays) or magnetic moment (neutrons) densities in materials. In recent years they have yielded valuable information about voids, void size distributions, and swelling in aluminum, aluminum alloys, copper, molybdenum, nickel, nickel-aluminum, niobium and niobium alloys, stainless steels, graphite and silicon carbide. In the case of aluminum, information concerning the shape of the voids and the ratio of specific surface energies was obtained. The technique of small-angle scattering and its application to the study of voids is reviewed in the paper. Emphasis is placed on the conditions which limit the applicability of the technique, on the interpretation of the data, and on a comparison of the results obtained with companion techniques such as transmission electron microscopy and bulk density. 8 figures, 41 references.

  12. Measurement of the structure function of the nearly free neutron using spectator tagging in inelastic H2 ( e, e'ps ) X scattering with CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tkachenko, S.; Baillie, N.; Kuhn, S. E.; Zhang, J.; Arrington, J.; Bosted, P.; Bültmann, S.; Christy, M. E.; Dutta, D.; Ent, R.; et al

    2014-04-24

    In this study, much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x.

  13. Measurement of the nearly free neutron structure function using spectator tagging in inelastic 2H(e,e'p s)X scattering with CLAS

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tkachenko, Svyatoslav; Baillie, Nathan; Kuhn, Sebastian; Zhang, J; Arrington, John; Bosted, Peter; Bueltmann, Stephen; Christy, Michael; Fenker, Howard; Griffioen, Keith; et al

    Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x.

  14. Magnetization of neutron matter

    SciTech Connect (OSTI)

    Bigdeli, M.

    2011-09-21

    In this paper, we compute magnetization of neutron matter at strong magnetic field using the lowest order constrained variational (LOCV) technique.

  15. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    SciTech Connect (OSTI)

    Proffen, Thomas E; Kim, Yiung- Il; Cadars, Sylvian; Shayib, Ramzy; Feigerle, Charles S; Chmelka, Bradley F; Seshadri, Ram

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  16. Processing of Neutron Diffraction Data for Strain Measurement in Geological Materials

    SciTech Connect (OSTI)

    Polsky, Yarom; An, Ke; Anovitz, Lawrence {Larry} M; Bingham, Philip R; Carmichael, Justin R; Dessieux Jr, Luc Lucius

    2014-01-01

    : Conventional rock mechanics testing techniques typically involve the loading of samples and measurement of displacements or strains on the outer boundary of the specimen surface. Neutron diffraction based strain measurement techniques represent a unique and powerful tool for measuring the strain within geological materials under load. The structural variability and non-uniform crystallinity of geological materials, however, create many complexities in the intensity patterns that must be analyzed to quantify strains within the material. The attenuating and scattering properties of the pressure cell housing the sample further add difficulties to the data analysis. This paper describes the methods and processes used to process neutron scattering data for strain measurement in geological materials. It is intended to provide a primer for those in the rock mechanics community that are interested in utilizing this technique along with additional discussion of neutron diffraction experimental factors that may affect data quality.

  17. LANSCE | Lujan Center | Highlights | Neutron Reflectometry (NR...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    composites because the scattering strength is a non-monotonic function of the Z number of a material. Therefore, elements like Cu and Nb provide the necessary neutron...

  18. Spin-phonon coupling and high-pressure phase transitions of RMnO3 (R=Ca and Pr): An inelastic neutron scattering and first-principles study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mishra, S. K.; Gupta, M. K.; Mittal, R.; Kolesnikov, Alexander I.; Chaplot, S. L.

    2016-06-22

    Here, we report inelastic neutron scattering measurements over 7–1251 K in CaMnO3 covering various phase transitions, and over 6–150 K in PrMnO3 covering the magnetic transition. The excitations around 20 meV in CaMnO3 and at 17 meV in PrMnO3 at low temperatures are found to be associated with magnetic origin. We observe coherent magnetic neutron scattering in localized regions in reciprocal space and show it to arise from long-range correlated magnetic spin-waves below the magnetic transition temperature (TN) and short-range stochastic spin-spin fluctuations above TN. In spite of the similarity of the structure of the two compounds, the neutron inelasticmore » spectrum of PrMnO3 exhibits broad features at 150 K unlike well-defined peaks in the spectrum of CaMnO3. This might result from the difference in the nature of interactions in the two compounds (magnetic and Jahn-Teller distortion). Ab initio phonon calculations have been used to interpret the observed phonon spectra. The ab initio calculations at high pressures show that the variations of Mn-O distances are isotropic for CaMnO3 and highly anisotropic for PrMnO3. The calculation in PrMnO3 shows the suppression of Jahn-Teller distortion and simultaneous insulator-to-metal transition. It appears that this transition may not be associated with the occurrence of the tetragonal phase above 20 GPa as reported in the literature, since the tetragonal phase is found to be dynamically unstable, although it is found to be energetically favored over the orthorhombic phase above 20 GPa. CaMnO3 does not show any phase transition up to 60 GPa.« less

  19. Diffuse magnetic neutron scattering in the highly frustrated double perovskite Ba2YRuO6

    SciTech Connect (OSTI)

    Nilsen, Gøran. J.; Thompson, Corey M.; Ehlers, Georg; Marjerrison, Casey A.; Greedan, John E.

    2015-02-23

    Here we investigated diffuse magnetic scattering in the highly frustrated double perovskite Ba2YRuO6 using polarized neutrons. Consistent with previous reports, the material shows two apparent transitions at 47 and 36 K to an eventual type I face-centered-cubic magnetic ground state. The (100) magnetic reflection shows different behavior from the five other observed reflections upon heating from 1.8 K, with the former broadening well beyond the resolution limit near 36 K. Closer examination of the latter group reveals a small, but clear, increase in peak widths between 36 and 47 K, indicating that this regime is dominated by short-range spin correlations. Diffuse magnetic scattering persists above 47 K near the position of (100) to at least 200 K, consistent with strong frustration. Reverse Monte Carlo (RMC) modeling of the diffuse scattering from 45 to 200 K finds that the spin-spin correlations between nearest and next-nearest neighbors are antiferromagnetic and ferromagnetic, respectively, at temperatures near the upper ordering temperature, but both become antiferromagnetic and of similar magnitude above 100 K. The significance of this unusual crossover is discussed in light of the super-superexchange interactions between nearest and next-nearest neighbors in this material and the demands of type I order. The dimensionality of the correlations is addressed by reconstructing the scattering in the (hk0) plane using the RMC spin configurations. This indicates that one-dimensional spin correlations dominate at temperatures close to the first transition. In addition, a comparison between mean-field calculations and (hk0) scattering implies that further neighbor couplings play a significant role in the selection of the ground state. Finally, the results and interpretation are compared with those recently published for monoclinic Sr2YRuO6, and similarities and differences are emphasized.

  20. Spallation Neutron Source (SNS) | U.S. DOE Office of Science (SC)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutron Scattering Facilities » Spallation Neutron Source (SNS) Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Spallation Neutron Source (SNS) High Flux Isotope Reactor (HFIR) Nanoscale Science Research Centers (NSRCs) Projects Accelerator & Detector Research Science Highlights Principal Investigators' Meetings BES Home Neutron Scattering Facilities Spallation Neutron Source (SNS) Print Text Size: A A A

  1. Enhancing Neutron Beam Production with a Convoluted Moderator

    SciTech Connect (OSTI)

    Iverson, Erik B; Baxter, David V; Muhrer, Guenter; Ansell, Stuart; Gallmeier, Franz X; Dalgliesh, Robert; Lu, Wei; Kaiser, Helmut

    2014-10-01

    We describe a new concept for a neutron moderating assembly resulting in the more efficient production of slow neutron beams. The Convoluted Moderator, a heterogeneous stack of interleaved moderating material and nearly transparent single-crystal spacers, is a directionally-enhanced neutron beam source, improving beam effectiveness over an angular range comparable to the range accepted by neutron beam lines and guides. We have demonstrated gains of 50% in slow neutron intensity for a given fast neutron production rate while simultaneously reducing the wavelength-dependent emission time dispersion by 25%, both coming from a geometric effect in which the neutron beam lines view a large surface area of moderating material in a relatively small volume. Additionally, we have confirmed a Bragg-enhancement effect arising from coherent scattering within the single-crystal spacers. We have not observed hypothesized refractive effects leading to additional gains at long wavelength. In addition to confirmation of the validity of the Convoluted Moderator concept, our measurements provide a series of benchmark experiments suitable for developing simulation and analysis techniques for practical optimization and eventual implementation at slow neutron source facilities.

  2. Foil cycling technique for the VESUVIO spectrometer operating in the resonance detector configuration

    SciTech Connect (OSTI)

    Schooneveld, E. M.; Mayers, J.; Rhodes, N. J.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Gorini, G.; Perelli-Cippo, E.; Tardocchi, M.

    2006-09-15

    This article reports a novel experimental technique, namely, the foil cycling technique, developed on the VESUVIO spectrometer (ISIS spallation source) operating in the resonance detector configuration. It is shown that with a proper use of two foils of the same neutron absorbing material it is possible, in a double energy analysis process, to narrow the width of the instrumental resolution of a spectrometer operating in the resonance detector configuration and to achieve an effective subtraction of the neutron and gamma backgrounds. Preliminary experimental results, obtained from deep inelastic neutron scattering measurements on lead, zirconium hydride, and deuterium chloride samples, are presented.

  3. Combined x-ray scattering, radiography, and velocity interferometry/streaked optical pyrometry measurements of warm dense carbon using a novel technique of shock-and-release

    SciTech Connect (OSTI)

    Falk, K.; Collins, L. A.; Kagan, G.; Kress, J. D.; Montgomery, D. S.; Srinivasan, B.; Gamboa, E. J.; Tzeferacos, P.; Benage, J. F.

    2014-05-15

    This work focused on a new application of the shock-and-release technique for equation of state (EOS) measurements. Warm dense matter states at near normal solid density and at temperatures close to 10 eV in diamond and graphite samples were created using a deep release from a laser-driven shock at the OMEGA laser facility. Independent temperature, density, and pressure measurements that do not depend on any theoretical models or simulations were obtained using imaging x-ray Thomson scattering, radiography, velocity interferometry, and streaked optical pyrometry. The experimental results were reproduced by the 2-D FLASH radiation hydrodynamics simulations finding a good agreement. The final EOS measurement was then compared with widely used SESAME EOS models as well as quantum molecular dynamics simulation results for carbon, which were very consistent with the experimental data.

  4. Shifting scintillator neutron detector

    DOE Patents [OSTI]

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

    2014-03-04

    Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

  5. The characterization of metal/ceramic interfaces using specular neutron reflection

    SciTech Connect (OSTI)

    Xiao, P.; Derby, B.; Webster, J.; Penfold, J.

    1997-01-01

    The authors have characterized the chemical composition of three interfaces between metals and a sapphire (Al{sub 2}O{sub 3}) single crystal using specular neutron reflection. The interfaces are Sn/sapphire, Sn/sapphire containing a thin, {approximately}20 nm, Ti interlayer and an interface between sapphire and a Ti-containing Ag-Cu eutectic active braze alloy. The authors have evaluated the neutron reflection results using a multilayer model of the interface. The technique is extremely sensitive to the presence of Ti at the interface being probed because of the negative neutron scattering length of Ti compared with the positive scattering lengths of the other elements present in the systems. The analysis of the data revealed a thin, {approximately}70 nm, titanium suboxide layer t the sapphire/active braze alloy interface, consistent with observations made using other techniques.

  6. Neutron-scattering evidence for a periodically modulated superconducting phase in the underdoped cuprate La1.905Ba0.095CuO4

    SciTech Connect (OSTI)

    Xu, Zhijun; Stock, C.; Chi, Songxue; Kolesnikov, A. I.; Xu, Guangyong I.; Gu, Genda; Tranquada, J. M.

    2014-10-01

    The role of antiferromagnetic spin correlations in high-temperature superconductors remains a matter of debate. We present inelastic neutron-scattering evidence that gapless spin fluctuations coexist with superconductivity in La1.905Ba0.095CuO4. Furthermore, we observe that both the low-energy magnetic spectral weight and the spin incommensurability are enhanced with the onset of superconducting correlations. We propose that the coexistence occurs through intertwining of spatial modulations of the pair wave function and the antiferromagnetic correlations. This proposal is also directly relevant to sufficiently underdoped La2-xSrxCuO4 and YBa2Cu3O6+x.

  7. High power neutron production targets

    SciTech Connect (OSTI)

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  8. High-resolution spectroscopy used to measure inertial confinement fusion neutron spectra on Omega (invited)

    SciTech Connect (OSTI)

    Forrest, C. J.; Radha, P. B.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Pruyne, A.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J. III; Stoeckl, C.; Casey, D. T.; Gatu-Johnson, M.; Gardner, S.

    2012-10-15

    The areal density ({rho}R) of cryogenic DT implosions on Omega is inferred by measuring the spectrum of neutrons that elastically scatter off the dense deuterium (D) and tritium (T) fuel. Neutron time-of-flight (nTOF) techniques are used to measure the energy spectrum with high resolution. High signal-to-background data has been recorded on cryogenic DT implosions using a well-collimated 13.4-m line of sight and an nTOF detector with an advanced liquid scintillator compound. An innovative method to analyze the elastically scattered neutron spectra was developed using well-known cross sections of the DT nuclear reactions. The estimated areal densities are consistent with alternative {rho}R measurements and 1-D simulations.

  9. DOE Science Showcase - Neutron Science Research from DOE Databases | OSTI,

    Office of Scientific and Technical Information (OSTI)

    US Dept of Energy Office of Scientific and Technical Information Neutron Science Research from DOE Databases Additional neutron science research in DOE Databases Information Bridge Neutron scattering research was pioneered in 1946 by ORNL's Clifford G. Shull, winner of 1994 Nobel Prize in Physics. Access Shull's early research records in Energy Citations Database. Neutron scattering research was pioneered in 1946 by ORNL's Clifford G. Shull, winner of 1994 Nobel Prize in Physics. Access

  10. Neutronic reactor

    DOE Patents [OSTI]

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  11. The roles of RIIbeta linker and N-terminal cyclic nucleotide-binding domain in determining the unique structures of Type IIbeta Protein Kinase A. A small angle X-ray and neutron scattering study

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Blumenthal, Donald K.; Copps, Jeffrey; Smith-Nguyen, Eric V.; Zhang, Ping; Heller, William T.; Taylor, Susan S.

    2014-08-11

    Protein kinase A (PKA) is ubiquitously expressed and is responsible for regulating many important cellular functions in response to changes in intracellular cAMP concentrations. Moreover, the PKA holoenzyme is a tetramer (R2:C2), with a regulatory subunit homodimer (R2) that binds and inhibits two catalytic (C) subunits; binding of cAMP to the regulatory subunit homodimer causes activation of the catalytic subunits. Four different R subunit isoforms exist in mammalian cells, and these confer different structural features, subcellular localization, and biochemical properties upon the PKA holoenzymes they form. The holoenzyme containing RIIβ is structurally unique in that the type IIβ holoenzyme ismore » much more compact than the free RIIβ homodimer. We have used small angle x-ray scattering and small angle neutron scattering to study the solution structure and subunit organization of a holoenzyme containing an RIIβ C-terminal deletion mutant (RIIβ(1–280)), which is missing the C-terminal cAMP-binding domain to better understand the structural organization of the type IIβ holoenzyme and the RIIβ domains that contribute to stabilizing the holoenzyme conformation. These results demonstrate that compaction of the type IIβ holoenzyme does not require the C-terminal cAMP-binding domain but rather involves large structural rearrangements within the linker and N-terminal cyclic nucleotide-binding domain of the RIIβ homodimer. The structural rearrangements are significantly greater than seen previously with RIIα and are likely to be important in mediating short range and long range interdomain and intersubunit interactions that uniquely regulate the activity of the type IIβ isoform of PKA.« less

  12. Neutron scattering study of underdoped Ba1-xKxFe₂As₂ (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rotundu, C. R.; Tian, W.; Rule, K. C.; Forrest, T. R.; Zhao, J.; Zarestky, J. L.; Birgeneau, R. J.

    2012-04-04

    We present a combination of elastic neutron scattering measurements in zero and 14.5 T and magnetization measurements in zero and 14 T on underdoped superconducting Ba1-xKxFe₂As₂ (x=0.17), and the same measurements in zero field on a nonsuperconducting crystal with x=0.09. The data suggest that the underdoped materials may not be electronic phase separated but rather have slightly inhomogeneous potassium doping. The temperature dependence of the magnetic order parameter below the transition of the sample with x=0.09 is more gradual than that for the case of the undoped BaFe₂As₂, suggesting that this doping may be in the vicinity of a tricriticalmore » point. We advance therefore the hypothesis that the tricritical point is a common feature of all superconducting 122s. For the x=0.17 sample, while Tc is suppressed from ≈17 to ≈8 K by a magnetic field of 14 T, the intensity of the magnetic Bragg peaks (1 0 3) at 1.2 K is enhanced by 10%, showing competition of superconductivity and antiferromagnetism. The intensity of the magnetic Bragg peaks (1 0 3) in the (Tc, TN) temperature interval remain practically unchanged in 14.5 T within a 10% statistical error. The present results are discussed in the context of the existing literature.« less

  13. Neutron scattering study of underdoped Ba1-xKxFe₂As₂ (x=0.09 and 0.17) self-flux-grown single crystals and the universality of the tricritical point

    SciTech Connect (OSTI)

    Rotundu, C. R.; Tian, W.; Rule, K. C.; Forrest, T. R.; Zhao, J.; Zarestky, J. L.; Birgeneau, R. J.

    2012-04-04

    We present a combination of elastic neutron scattering measurements in zero and 14.5 T and magnetization measurements in zero and 14 T on underdoped superconducting Ba1-xKxFe₂As₂ (x=0.17), and the same measurements in zero field on a nonsuperconducting crystal with x=0.09. The data suggest that the underdoped materials may not be electronic phase separated but rather have slightly inhomogeneous potassium doping. The temperature dependence of the magnetic order parameter below the transition of the sample with x=0.09 is more gradual than that for the case of the undoped BaFe₂As₂, suggesting that this doping may be in the vicinity of a tricritical point. We advance therefore the hypothesis that the tricritical point is a common feature of all superconducting 122s. For the x=0.17 sample, while Tc is suppressed from ≈17 to ≈8 K by a magnetic field of 14 T, the intensity of the magnetic Bragg peaks (1 0 3) at 1.2 K is enhanced by 10%, showing competition of superconductivity and antiferromagnetism. The intensity of the magnetic Bragg peaks (1 0 3) in the (Tc, TN) temperature interval remain practically unchanged in 14.5 T within a 10% statistical error. The present results are discussed in the context of the existing literature.

  14. Neutron diffraction measurements of residual stresses in friction stir welding: a review

    SciTech Connect (OSTI)

    Woo, Wan Chuck [ORNL; Feng, Zhili [ORNL; Wang, Xun-Li [ORNL; David, Stan A [ORNL

    2011-01-01

    Significant amounts of residual stresses are often generated during welding and result in critical degradation of the structural integrity and performance of components. Neutron diffraction has become a well established technique for the determination of residual stresses in welds because of the unique deep penetration, three-dimensional mapping capability, and volume averaged bulk measurements characteristic of the scattering neutron beam. Friction stir welding has gained prominence in recent years. The authors reviewed a number of neutron diffraction measurements of residual stresses in friction stir welds and highlighted examples addressing how the microstructures and residual stresses are correlated with each other. An example of in situ neutron diffraction measurement result shows the evolution of the residual stresses during welding.

  15. A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zylstra, A. B.; Gatu Johnson, M.; Frenje, J. A.; Séguin, F. H.; Rinderknecht, H. G.; Rosenberg, M. J.; Sio, H. W.; Li, C. K.; Petrasso, R. D.; McCluskey, M.; et al

    2014-06-04

    A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is capable of measuring the yield to ~±10% accuracy, and mean neutron energy to ~±50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energymore » uncertainty to ±15-20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ~±25-40 km/s.« less

  16. A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF

    SciTech Connect (OSTI)

    Zylstra, A. B.; Gatu Johnson, M.; Frenje, J. A.; Seguin, F. H.; Rinderknecht, H. G.; Rosenberg, M. J.; Sio, H. W.; Li, C. K.; Petrasso, R. D.; McCluskey, M.; Mastrosimone, D.; Glebov, V. Yu.; Forrest, C.; Stoeckl, C.; Sangster, T. C.

    2014-06-01

    A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is currently capable of measuring the yield to ~10% accuracy, and mean neutron energy to ~50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energy uncertainty to 15-20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ~25-40 km/s.

  17. Neutron and resonant x-ray scattering studies of RNi{sub 2}B{sub 2}C (R = rare earth) single crystals

    SciTech Connect (OSTI)

    Stassis, C.; Goldman, A.I. |

    1996-06-01

    This family of intermetallic compounds is ideal for the study of the interplay between superconductivity and magnetism since, in several of these compounds (Ho, Er, Tm, Dy), superconductivity coexists with magnetic ordering. The most important findings of the scattering studies are (a) in the Ho-compound, a complex magnetic structure characterized by two incommensurate wave vectors, {rvec k}{sub a} = 0.585 {rvec a}* and {rvec k}{sub c} = 0.915 {rvec c}*, exists in the vicinity of 5 K, where the almost reentrant behavior of this compound occurs; (b) an incommensurate magnetic structure with wave vector along {rvec a}*, close to the zone boundary, is observed in several of these compounds; and (c) pronounced soft-phonon behavior was observed for both the acoustic and first optical {Delta}{sub 4}[{xi}00] branches in the superconducting Lu and Ho compounds, a behavior characteristic of strongly coupled conventional superconductors. Furthermore, these phonon anomalies occur at wave vectors close to those of the incommensurate magnetically ordered structures observed in the magnetic compounds of this family. This observation suggests that both the magnetic ordering and phonon softening originate from common nesting features of the Fermi surfaces of these compounds. Band theoretical calculations are in qualitative agreement with these results.

  18. High-Pressure Single-Crystal Neutron Scattering Study of Magnetic and Fe Vacancy Orders in (Tl,Rb)2 Fe4 Se5 Superconductor

    SciTech Connect (OSTI)

    Ye, Feng; Bao, Wei; Chi, Song-Xue; Santos, Antonio M. dos; Molaison, Jamie J.; Fang, Ming-Hu; Wang, Hang-Dong; Mao, Qian-Hui; Wang, Jin-Chen; Liu, Juan-Juan; Sheng, Jie-Ming

    2014-12-01

    We investigate the magnetic and iron vacancy orders in superconducting (Tl,Rb)2Fe4Se5 single-crystals by using a high-pressure neutron diffraction technique. Similar to the temperature effect, the block antiferromagnetic order gradually decreases upon increasing pressure while the Fe vacancy superstructural order remains intact before its precipitous disappearance at the critical pressure Pc = 8.3 GPa. Combined with previously determined Pc for superconductivity, our phase diagram under pressure reveals the concurrence of the block AFM order, the √5 × √5 iron vacancy order and superconductivity for the 245 superconductor. Lastly, a synthesis of current experimental data in a coherent physical picture is attempted.

  19. MnO spin-wave dispersion curves from neutron powder diffraction

    SciTech Connect (OSTI)

    Goodwin, Andrew L.; Dove, Martin T.; Tucker, Matthew G.; Keen, David A.

    2007-02-15

    We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

  20. January 16, 2009: Expansion of Spallation Neutron Source | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 16, 2009: Expansion of Spallation Neutron Source January 16, 2009: Expansion of Spallation Neutron Source January 16, 2009: Expansion of Spallation Neutron Source January 16, 2009 The Department gives its initial approval to begin plans for the Oak Ridge National Laboratory (ORNL) to build a second target station for the Spallation Neutron Source, expanding what is already the world's most powerful pulsed neutron scattering facility. The new station, which will cost approximately $1

  1. Portable Neutron Sensors for Emergency Response Operations

    SciTech Connect (OSTI)

    ,

    2012-06-24

    This article presents the experimental work performed in the area of neutron detector development at the Remote Sensing Laboratory–Andrews Operations (RSL-AO) sponsored by the U.S. Department of Energy, National Nuclear Security Administration (NNSA) in the last four years. During the 1950s neutron detectors were developed mostly to characterize nuclear reactors where the neutron flux is high. Due to the indirect nature of neutron detection via interaction with other particles, neutron counting and neutron energy measurements have never been as precise as gamma-ray counting measurements and gamma-ray spectroscopy. This indirect nature is intrinsic to all neutron measurement endeavors (except perhaps for neutron spin-related experiments, viz. neutron spin-echo measurements where one obtains μeV energy resolution). In emergency response situations generally the count rates are low, and neutrons may be scattered around in inhomogeneous intervening materials. It is also true that neutron sensors are most efficient for the lowest energy neutrons, so it is not as easy to detect and count energetic neutrons. Most of the emergency response neutron detectors are offshoots of nuclear device diagnostics tools and special nuclear materials characterization equipment, because that is what is available commercially. These instruments mostly are laboratory equipment, and not field-deployable gear suited for mobile teams. Our goal is to design and prototype field-deployable, ruggedized, lightweight, efficient neutron detectors.

  2. Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

    SciTech Connect (OSTI)

    Lacy, Jeffrey L

    2009-05-22

    Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically

  3. Neutron scattering study of spin ordering and stripe pinning in superconducting La1.93Sr0.07CuO4

    SciTech Connect (OSTI)

    Jacobsen, H.; Zaliznyak, I. A.; Savici, A. T.; Winn, B. L.; Chang, S.; Hücker, M.; Gu, G. D.; Tranquada, J. M.

    2015-11-20

    The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La1.93Sr0.07CuO4 a superconductor with a transition temperature of Tc = 20 K. At T<< Tc, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below ~ 10 K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO6 octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO2 planes. Moreover, we observed a weak elastic (3 30) superlattice peak that implies a reduced lattice symmetry. The presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped La2-xSrxCuO4. The coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function.

  4. LANSCE | Lujan Center | Instruments | Neutron Radiography

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutron Radiography The recently acquired energy-dispersive neutron imaging detector can be used on various Lujan Center beam-lines to combine scattering with imaging. In most cases, FP5 is the default beam-line for the unique energy-dispersive neutron imaging capabilities, but for instance experiments could benefit from combined diffraction on HIPPO, SMARTS, and NPDF. Please contact Sven Vogel (sven@lanl.gov, 505.667.7016) for further discussions of dedicated or combined energy-dispersive

  5. Neutron-deuteron analyzing power data at 19.0 MeV

    SciTech Connect (OSTI)

    Weisel, G. J.; Tornow, W.; Crowe, B. J. III; Crowell, A. S.; Esterline, J. H.; Howell, C. R.; Kelley, J. H.; Macri, R. A.; Pedroni, R. S.; Walter, R. L.; Witala, H.

    2010-02-15

    Measurements of neutron-deuteron (n-d) analyzing power A{sub y}(theta) at E{sub n}=19.0 MeV are reported at 16 angles from theta{sub c.m.}=46.7 to 152.0 deg. The objective of the experiment is to better characterize the discrepancies between n-d data and the predictions of three-nucleon calculations for neutron energies above 16.0 MeV. The experiment used a shielded neutron source, which produced polarized neutrons via the {sup 2}H(d-vector,n-vector){sup 3}He reaction, a deuterated liquid scintillator center detector (CD) and liquid-scintillator neutron side detectors. A coincidence between the CD and the side detectors isolated the elastic-scattering events. The CD pulse height spectrum associated with each side detector was sorted by using pulse-shape discrimination, time-of-flight techniques, and by removing accidental coincidences. A Monte Carlo computer simulation of the experiment accounted for effects due to finite geometry, multiple scattering, and CD edge effects. The resulting high-precision data (with absolute uncertainties ranging from 0.0022 to 0.0132) have a somewhat lower discrepancy with the predictions of three-body calculations, as compared to those found at lower energies.

  6. Neutron skins and neutron stars

    SciTech Connect (OSTI)

    Piekarewicz, J.

    2013-11-07

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ('PREX') at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in {sup 208}Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.

  7. 2010 Neutron Review: ORNL Neutron Sciences Progress Report

    SciTech Connect (OSTI)

    Bardoel, Agatha A; Counce, Deborah M; Ekkebus, Allen E; Horak, Charlie M; Nagler, Stephen E; Kszos, Lynn A

    2011-06-01

    During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology, and operations. Some topics discussed are: (1) HFIR and SNS Experiments Take Gordon Battelle Awards for Scientific Discovery - Battelle Memorial Institute presented the inaugural Gordon Battelle Prizes for scientific discovery and technology impact in 2010. Battelle awards the prizes to recognize the most significant advancements at national laboratories that it manages or co-manages. (2) Discovery of Element 117 - As part of an international team of scientists from Russia and the United States, HFIR staff played a pivotal role in the discovery by generating the berkelium used to produce the new element. A total of six atoms of ''ununseptium'' were detected in a two-year campaign employing HFIR and the Radiochemical Engineering Development Center at Oak Ridge National Laboratory (ORNL) and the heavy-ion accelerator capabilities at the Joint Institute for Nuclear Research in Dubna, Russia. The discovery of the new element expands the understanding of the properties of nuclei at extreme numbers of protons and neutrons. The production of a new element and observation of 11 new heaviest isotopes demonstrate the increased stability of super-heavy elements with increasing neutron numbers and provide the strongest evidence to date for the existence of an island of enhanced stability for super-heavy elements. (3) Studies of Iron-Based High-Temperature Superconductors - ORNL applied its distinctive capabilities in neutron scattering, chemistry, physics, and computation to detailed studies of the magnetic excitations of iron-based superconductors (iron pnictides and

  8. Neutron guide

    DOE Patents [OSTI]

    Greene, Geoffrey L.

    1999-01-01

    A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

  9. Neutron dosimetry

    DOE Patents [OSTI]

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

  10. OSTIblog Articles in the x-ray scattering Topic | OSTI, US Dept...

    Office of Scientific and Technical Information (OSTI)

    X-ray scattering has been used to gather clues about materials' atomic structures for about a century. Once reactors were built that could provide intense neutron beams, ...

  11. Method for measuring multiple scattering corrections between liquid scintillators

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; Wurtz, R. E.

    2016-04-11

    In this study, a time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.

  12. Neutron scattering study of unconventional superconductors

    SciTech Connect (OSTI)

    Lee, Seunghun

    2014-06-30

    My group’s primary activity at the University of Virginia supported by DOE is to study novel electronic, magnetic, and structural phenomena that emerge out of strong interactions between electrons. Some of these phenomena are unconventional superconductivity, exotic states in frustrated magnets, quantum spin liquid states, and magneto-electricity. The outcome of our research funded by the grant advanced microscopic understanding of the emergence of the collective states in the systems.

  13. Neutron and X-ray Scattering

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to design, discover, and control materials. This research is in anticipation of MaRIE, Los Alamos National Laboratory's proposed Matter-Radiation Interactions in Extremes...

  14. Phase-sensitive two-dimensional neutron shearing interferometer and

    Office of Scientific and Technical Information (OSTI)

    Hartmann sensor (Patent) | SciTech Connect Patent: Phase-sensitive two-dimensional neutron shearing interferometer and Hartmann sensor Citation Details In-Document Search Title: Phase-sensitive two-dimensional neutron shearing interferometer and Hartmann sensor A neutron imaging system detects both the phase shift and absorption of neutrons passing through an object. The neutron imaging system is based on either of two different neutron wavefront sensor techniques: 2-D shearing

  15. Apparatus for measuring a flux of neutrons

    DOE Patents [OSTI]

    Stringer, James L.

    1977-01-01

    A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

  16. NEUTRON IMAGING, RADIOGRAPHY AND TOMOGRAPHY.

    SciTech Connect (OSTI)

    SMITH,G.C.

    2002-03-01

    Neutrons are an invaluable probe in a wide range of scientific, medical and commercial endeavors. Many of these applications require the recording of an image of the neutron signal, either in one-dimension or in two-dimensions. We summarize the reactions of neutrons with the most important elements that are used for their detection. A description is then given of the major techniques used in neutron imaging, with emphasis on the detection media and position readout principle. Important characteristics such as position resolution, linearity, counting rate capability and sensitivity to gamma-background are discussed. Finally, the application of a subset of these instruments in radiology and tomography is described.

  17. Neutron instrumentation for biology

    SciTech Connect (OSTI)

    Mason, S.A.

    1994-12-31

    In the October 1994 round of proposals at the ILL, the external biology review sub- committee was asked to allocate neutron beam time to a wide range of experiments, on almost half the total number of scheduled neutron instruments: on 3 diffractometers, on 3 small angle scattering instruments, and on some 6 inelastic scattering spectrometers. In the 3.5 years since the temporary reactor shutdown, the ILL`s management structure has been optimized, budgets and staff have been trimmed, the ILL reactor has been re-built, and many of the instruments up-graded, many powerful (mainly Unix) workstations have been introduced, and the neighboring European Synchrotron Radiation Facility has established itself as the leading synchrotron radiation source and has started its official user program. The ILL reactor remains the world`s most intense dedicated neutron source. In this challenging context, it is of interest to review briefly the park of ILL instruments used to study the structure and energetics of small and large biological systems. A brief summary will be made of each class of experiments actually proposed in the latest ILL proposal round.

  18. Gamma compensated, self powered neutron detector

    DOE Patents [OSTI]

    Brown, Donald P.

    1977-01-01

    An improved, self-powered, gamma compensated, neutron detector having two electrically conductive concentric cylindrical electrodes and a central rod emitter formed from a material which emits beta particles when bombarded by neutrons. The outer electrode and emitter are maintained at a common potential and the neutron representative current is furnished at the inner cylindrical electrode which serves as a collector. The two concentric cylindrical electrodes are designed to exhibit substantially equal electron emission induced by Compton scattering under neutron bombardment to supply the desired gamma compensation.

  19. Spallation Neutron Source reaches megawatt power

    SciTech Connect (OSTI)

    Dr. William F. Brinkman

    2009-09-30

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  20. Spallation Neutron Source reaches megawatt power

    ScienceCinema (OSTI)

    Dr. William F. Brinkman

    2010-01-08

    The Department of Energy's Spallation Neutron Source (SNS), already the world's most powerful facility for pulsed neutron scattering science, is now the first pulsed spallation neutron source to break the one-megawatt barrier. "Advances in the materials sciences are fundamental to the development of clean and sustainable energy technologies. In reaching this milestone of operating power, the Spallation Neutron Source is providing scientists with an unmatched resource for unlocking the secrets of materials at the molecular level," said Dr. William F. Brinkman, Director of DOE's Office of Science.

  1. Thermal Neutron Detectors with Discrete Anode Pad Readout

    SciTech Connect (OSTI)

    Yu,B.; Schaknowski, N.A., Smith, G.C., DeGeronimo, G., Vernon, E.O.

    2008-10-19

    A new two-dimensional thermal neutron detector concept that is capable of very high rates is being developed. It is based on neutron conversion in {sup 3}He in an ionization chamber (unity gas gain) that uses only a cathode and anode plane; there is no additional electrode such as a Frisch grid. The cathode is simply the entrance window, and the anode plane is composed of discrete pads, each with their own readout electronics implemented via application specific integrated circuits. The aim is to provide a new generation of detectors with key characteristics that are superior to existing techniques, such as higher count rate capability, better stability, lower sensitivity to background radiation, and more flexible geometries. Such capabilities will improve the performance of neutron scattering instruments at major neutron user facilities. In this paper, we report on progress with the development of a prototype device that has 48 x 48 anode pads and a sensitive area of 24cm x 24cm.

  2. ABSTRACT Bayarbadrakh, Baramsai. Neutron Capture Reactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bayarbadrakh, Baramsai. Neutron Capture Reactions on Gadolinium Isotopes. (Under the direction of Dr. G. E. Mitchell and U. Agvaanluvsan). The neutron capture reaction on 155 Gd, 156 Gd and 158 Gd isotopes has been studied with the DANCE calorimeter at Los Alamos Neutron Science Center. The highly segmented calorimeter provided detailed multiplicity distributions of the capture γ-rays. With this information the spins of the neutron capture resonances have been determined. The new technique

  3. Scattering Workshop May 16-17, 2006

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    First Annual SSRL Workshop on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences: Theory and Application Tuesday, May 16 & Wednesday, May 17, 2006...

  4. Transport of thermal neutrons in different forms of liquid hydrogen and the production of intense beams of cold neutrons

    SciTech Connect (OSTI)

    Swaminathan, K.; Tewari, S.P.

    1982-10-01

    From their studies the authors find that the thermal neutron inelastic scattering kernel incorporating the chemical binding energy in liquid hydrogen is able to successfully explain various neutron transport studies such as pulsed neutron and steady-state neutron spectra. For an infinite-sized assembly, D/sub 2/ at 4 K yields a very intense flux of cold and ultracold neutrons. For the practicable finite assembly corresponding to B/sup 2/ = 0.0158 cm/sup -2/, it is found that liquid hydrogen at 11 K gives the most intense beam of cold neutrons.

  5. OSTIblog Articles in the National School on Neutron and X-ray...

    Office of Scientific and Technical Information (OSTI)

    X-ray scattering has been used to gather clues about materials' atomic structures for about a century. Once reactors were built that could provide intense neutron beams, ...

  6. Ultracold neutrons

    SciTech Connect (OSTI)

    Saunders, Alexander

    2015-06-22

    This series of slides describes ultracold neutrons (UCN) and their properties, various UCN sources, and an overview of UCN-based experiments. Numerous diagrams and photographs are included.

  7. Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality

    SciTech Connect (OSTI)

    Nowak, G. Strmer, M.; Horstmann, C.; Kampmann, R.; Hche, D.; Lorenz, U.; Mller, M.; Schreyer, A.; Becker, H.-W.; Haese-Seiller, M.; Moulin, J.-F.; Pomm, M.; Randau, C.; Hall-Wilton, R.

    2015-01-21

    Due to the present shortage of {sup 3}He and the associated tremendous increase of its price, the supply of large neutron detection systems with {sup 3}He becomes unaffordable. Alternative neutron detection concepts, therefore, have been invented based on solid {sup 10}B converters. These concepts require development in thin film deposition technique regarding high adhesion, thickness uniformity and chemical purity of the converter coating on large area substrates. We report on the sputter deposition of highly uniform large-area {sup 10}B{sub 4}C coatings of up to 2??m thickness with a thickness deviation below 4% using the Helmholtz-Zentrum Geesthacht large area sputtering system. The {sup 10}B{sub 4}C coatings are x-ray amorphous and highly adhesive to the substrate. Material analysis by means of X-ray-Photoelectron Spectroscopy, Secondary-Ion-Mass-Spectrometry, and Rutherford-Back-Scattering (RBS) revealed low impurities concentration in the coatings. The isotope composition determined by Secondary-Ion-Mass-Spectrometry, RBS, and inelastic nuclear reaction analysis of the converter coatings evidences almost identical {sup 10}B isotope contents in the sputter target and in the deposited coating. Neutron conversion and detection test measurements with variable irradiation geometry of the converter coating demonstrate an average relative quantum efficiency ranging from 65% to 90% for cold neutrons as compared to a black {sup 3}He-monitor. Thus, these converter coatings contribute to the development of {sup 3}He-free prototype detectors based on neutron grazing incidence. Transferring the developed coating process to an industrial scale sputtering system can make alternative {sup 3}He-free converter elements available for large area neutron detection systems.

  8. FAST NEUTRON SPECTROMETER

    DOE Patents [OSTI]

    Davis, F.J.; Hurst, G.S.; Reinhardt, P.W.

    1959-08-18

    An improved proton recoil spectrometer for determining the energy spectrum of a fast neutron beam is described. Instead of discriminating against and thereby"throwing away" the many recoil protons other than those traveling parallel to the neutron beam axis as do conventional spectrometers, this device utilizes protons scattered over a very wide solid angle. An ovoidal gas-filled recoil chamber is coated on the inside with a scintillator. The ovoidal shape of the sensitive portion of the wall defining the chamber conforms to the envelope of the range of the proton recoils from the radiator disposed within the chamber. A photomultiplier monitors the output of the scintillator, and a counter counts the pulses caused by protons of energy just sufficient to reach the scintillator.

  9. Porous material neutron detector

    DOE Patents [OSTI]

    Diawara, Yacouba; Kocsis, Menyhert

    2012-04-10

    A neutron detector employs a porous material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the porous material layer to further amplify the electrons exiting the porous material layer.

  10. Neutron Log At Alum Area (Moos & Ronne, 2010) | Open Energy Informatio...

    Open Energy Info (EERE)

    Technique Neutron Log Activity Date Usefulness useful DOE-funding Unknown Notes Density, photo-electric factor (PEF), neutron, and gamma ray (GR) logs provided sufficient...

  11. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiplemore » scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.« less

  12. MCViNE- An object oriented Monte Carlo neutron ray tracing simulation package

    SciTech Connect (OSTI)

    Lin, J. Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry L.; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2015-11-28

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. As a result, with simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.

  13. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

  14. Modeling gated neutron images of THD capsules

    SciTech Connect (OSTI)

    Wilson, Douglas Carl; Grim, Gary P; Tregillis, Ian L; Wilke, Mark D; Morgan, George L; Loomis, Eric N; Wilde, Carl H; Oertel, John A; Fatherley, Valerie E; Clark, David D; Schmitt, Mark J; Merrill, Frank E; Wang, Tai - Sen F; Danly, Christopher R; Batha, Steven H; Patel, M; Sepke, S; Hatarik, R; Fittinghoff, D; Bower, D; Marinak, M; Munro, D; Moran, M; Hilko, R; Frank, M; Buckles, R

    2010-01-01

    Time gating a neutron detector 28m from a NIF implosion can produce images at different energies. The brighter image near 14 MeV reflects the size and symmetry of the capsule 'hot spot'. Scattered neutrons, {approx}9.5-13 MeV, reflect the size and symmetry of colder, denser fuel, but with only {approx}1-7% of the neutrons. The gated detector records both the scattered neutron image, and, to a good approximation, an attenuated copy of the primary image left by scintillator decay. By modeling the imaging system the energy band for the scattered neutron image (10-12 MeV) can be chosen, trading off the decayed primary image and the decrease of scattered image brightness with energy. Modeling light decay from EJ399, BC422, BCF99-55, Xylene, DPAC-30, and Liquid A leads to a preference from BCF99-55 for the first NIF detector, but DPAC 30 and Liquid A would be preferred if incorporated into a system. Measurement of the delayed light from the NIF scintillator using implosions at the Omega laser shows BCF99-55 to be a good choice for down-scattered imaging at 28m.

  15. Simplified fast neutron dosimeter

    DOE Patents [OSTI]

    Sohrabi, Mehdi

    1979-01-01

    Direct fast-neutron-induced recoil and alpha particle tracks in polycarbonate films may be enlarged for direct visual observation and automated counting procedures employing electrochemical etching techniques. Electrochemical etching is, for example, carried out in a 28% KOH solution at room temperature by applying a 2000 V peak-to-peak voltage at 1 kHz frequency. Such recoil particle amplification can be used for the detection of wide neutron dose ranges from 1 mrad. to 1000 rads. or higher, if desired.

  16. Neutronic reactor

    DOE Patents [OSTI]

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  17. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  18. Neutron Sources for Standard-Based Testing

    SciTech Connect (OSTI)

    Radev, Radoslav; McLean, Thomas

    2014-11-10

    The DHS TC Standards and the consensus ANSI Standards use 252Cf as the neutron source for performance testing because its energy spectrum is similar to the 235U and 239Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.

  19. Neutron tubes

    DOE Patents [OSTI]

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  20. Neutron source

    DOE Patents [OSTI]

    Cason, J.L. Jr.; Shaw, C.B.

    1975-10-21

    A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

  1. Low-energy parameters of neutron-neutron interaction in the effective-range approximation

    SciTech Connect (OSTI)

    Babenko, V. A.; Petrov, N. M. [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine)

    2013-06-15

    The effect of the mass difference between the charged and neutral pions on the low-energy parameters of nucleon-nucleon interaction in the {sup 1}S{sub 0} state is studied in the effective-range approximation. On the basis of experimental values of the singlet parameters of neutron-proton scattering and the experimental value of the virtual-state energy for the neutron-neutron systemin the {sup 1}S{sub 0} state, the following values were obtained for the neutron-neutron scattering length and effective range: a{sub nn} = -16.59(117) fm and r{sub nn} = 2.83(11) fm. The calculated values agree well with present-day experimental results.

  2. The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source -- Design and Performance

    SciTech Connect (OSTI)

    Ehlers, Georg; Podlesnyak, Andrey A.; Niedziela, Jennifer L.; Iverson, Erik B.; Sokol, Paul E.

    2011-01-01

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  3. The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance

    SciTech Connect (OSTI)

    Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B.; Sokol, P. E.

    2011-08-15

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  4. Elemental characterization of LL-MA radioactive waste packages with the associated particle technique

    SciTech Connect (OSTI)

    Perot, B.; Carasco, C.; Toure, M.; El Kanawati, W.; Eleon, C.

    2011-07-01

    The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R and D program to improve the characterization of long-lived and medium activity (LL-MA) radioactive waste packages with analytical methods and with non-destructive nuclear measurements. This paper concerns fast neutron interrogation with the associated particle technique (APT), which brings 3D information about the waste material composition. The characterization of volume elements filled with iron, water, aluminium, and PVC in bituminized and fibre concrete LL-MA waste packages has been investigated with MCNP [1] and MODAR data analysis software [2]. APT provides usable information about major elements presents in the volumes of interest. However, neutron scattering on hydrogen nuclei spreads the tagged neutron beam out of the targeted volume towards surrounding materials, reducing spatial selectivity. Simulation shows that small less than 1 L targets can be characterised up to the half-radius of a 225 L bituminized drum, the matrix of which is very rich in hydrogen. Deeper characterization in concrete is possible but limited by counting statistics due to photon attenuation in this dense matrix and, unless large inspection volumes are considered, by the lack of spatial selectivity of the tagged neutron beam due to neutron scattering. (authors)

  5. Multigroup computation of the temperature-dependent Resonance Scattering Model (RSM) and its implementation

    SciTech Connect (OSTI)

    Ghrayeb, S. Z.; Ouisloumen, M.; Ougouag, A. M.; Ivanov, K. N.

    2012-07-01

    A multi-group formulation for the exact neutron elastic scattering kernel is developed. This formulation is intended for implementation into a lattice physics code. The correct accounting for the crystal lattice effects influences the estimated values for the probability of neutron absorption and scattering, which in turn affect the estimation of core reactivity and burnup characteristics. A computer program has been written to test the formulation for various nuclides. Results of the multi-group code have been verified against the correct analytic scattering kernel. In both cases neutrons were started at various energies and temperatures and the corresponding scattering kernels were tallied. (authors)

  6. Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.

    2015-07-22

    Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering ???? (nnvv, ppvv, and npvv) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated ???? emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an OPE model. Purpose: To investigate the free ???? cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes nnvv, ppvv, and npvv.

  7. Scattering Dynamics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scattering Dynamics - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced Nuclear

  8. Thermal neutron detection system

    DOE Patents [OSTI]

    Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

    2000-01-01

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  9. Mechanical approach to the neutrons spectra collimation and detection

    SciTech Connect (OSTI)

    Sadeghi, H.; Roshan, M. V.

    2014-11-15

    Neutrons spectra from most of known sources require being collimated for numerous applications; among them one is the Neutron Activation Analysis. High energy neutrons are collimated through a mechanical procedure as one of the most promising methods. The output energy of the neutron beam depends on the velocity of the rotating Polyethylene disks. The collimated neutrons are then measured by an innovative detection technique with high accuracy.

  10. Calculation of the neutron structure function by using A = 3 mirror nuclei and a quark exchange formalism

    SciTech Connect (OSTI)

    Modarres, M.; Zolfagharpour, F.; Yazdanpanah, M.M.

    2005-05-06

    It is demonstrated that the free neutron structure function can be extracted in deep inelastic scattering from A = 3 mirror nuclei i.e. 3He and 3H, and our extracted free neutron structure function agrees with the experiments.

  11. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Wigner, E.P.

    1960-11-22

    A nuclear reactor is described wherein horizontal rods of thermal- neutron-fissionable material are disposed in a body of heavy water and extend through and are supported by spaced parallel walls of graphite.

  12. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  13. The Neutron Imaging System Fielded at the National Ignition Facility

    SciTech Connect (OSTI)

    Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B; Frank, M; Liddick, S N; Moran, M J; Roberson, G P; Weiss, P B; Grim, G P; Aragonez, R J; Archuleta, T N; Batha, S H; Clark, D D; Clark, D J; Danly, C R; Day, R D; Fatherley, V E; Finch, J P; Garcia, F P; Gallegos, R A; Guler, N; Hsu, A H; Jaramillo, S A; Loomis, E N; Mares, D; Martinson, D D; Merrill, F E; Morgan, G L; Munson, C; Murphy, T J; Oertel, J A; Polk, P J; Schmidt, D W; Tregillis, I L; Valdez, A C; Volegov, P L; Wang, T F; Wilde, C H; Wilke, M D; Wilson, D C; Buckles, R A; Cradick, J R; Kaufman, M I; Lutz, S S; Malone, R M; Traille, A

    2011-10-24

    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.

  14. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  15. NEUTRON SOURCES

    DOE Patents [OSTI]

    Richmond, J.L.; Wells, C.E.

    1963-01-15

    A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)

  16. Neutron range spectrometer

    DOE Patents [OSTI]

    Manglos, S.H.

    1988-03-10

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

  17. Narcotics detection using fast-neutron interrogation

    SciTech Connect (OSTI)

    Micklich, B.J.; Fink, C.L.

    1995-12-31

    Fast-neutron interrogation techniques are being investigated for detection of narcotics in luggage and cargo containers. This paper discusses two different fast-neutron techniques. The first uses a pulsed accelerator or sealed-tube source to produce monoenergetic fast neutrons. Gamma rays characteristic of carbon and oxygen are detected and the elemental densities determined. Spatial localization is accomplished by either time of flight or collimators. This technique is suitable for examination of large containers because of the good penetration of the fast neutrons and the low attenuation of the high-energy gamma rays. The second technique uses an accelerator to produce nanosecond pulsed beams of deuterons that strike a target to produce a pulsed beam of neutrons with a continuum of energies. Elemental distributions are obtained by measuring the neutron spectrum after the source neutrons pass through the items being interrogated. Spatial variation of elemental densities is obtained by tomographic reconstruction of projection data obtained for three to five angles and relatively low (2 cm) resolution. This technique is best suited for examination of luggage or small containers with average neutron transmissions greater than about 0.01. Analytic and Monte-Carlo models are being used to investigate the operational characteristics and limitations of both techniques.

  18. Neutron-scattering measurements of spin excitations in LaFeAsO and Ba(Fe0.953Co0.047)2As2: Evidence for a sharp enhancement of spin fluctuations by nematic order [Sharp enhancement of spin fluctuations by nematic order in iron pnictides

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Qiang; Fernandes, Rafael M.; Lamsal, Jagat; Yan, Jiaqiang; Chi, Songxue; Tucker, Gregory S.; Pratt, Daniel K.; Lynn, Jeffrey W.; McCallum, R. W.; Canfield, Paul C.; et al

    2015-02-04

    Inelastic neutron scattering is employed to investigate the impact of electronic nematic order on the magnetic spectra of LaFeAsO and Ba(Fe0.953Co0.047)2As2. These materials are ideal to study the paramagnetic-nematic state, since the nematic order, signaled by the tetragonal-to-orthorhombic transition at TS, sets in well above the stripe antiferromagnetic ordering at TN. We find that the temperature-dependent dynamic susceptibility displays an anomaly at TS followed by a sharp enhancement in the spin-spin correlation length, revealing a strong feedback effect of nematic order on the low-energy magnetic spectrum. As a result, our findings can be consistently described by a model that attributesmore » the structural or nematic transition to magnetic fluctuations, and unveils the key role played by nematic order in promoting the long-range stripe antiferromagnetic order in iron pnictides.« less

  19. Pressure dependence of the exchange interaction in the dimeric single-molecule magnet [Mn{sub 4}O{sub 3}Cl{sub 4}(O{sub 2}CEt){sub 3}(py){sub 3}]{sub 2} from inelastic neutron scattering

    SciTech Connect (OSTI)

    Sieber, A.; Waldmann, O.; Ochsenbein, S. T.; Carver, G.; Guedel, H. U.; Foguet-Albiol, D.; Christou, G.; Mutka, H.; Fernandez-Alonso, F.; Mezouar, M.; Weber, H. P.

    2006-07-01

    The low-lying magnetic excitations in the dimers of single-molecule magnets [Mn{sub 4}O{sub 3}Cl{sub 4}(O{sub 2}CEt){sub 3}(py){sub 3}]{sub 2}, or (Mn{sub 4}){sub 2}, are studied by inelastic neutron scattering as a function of hydrostatic pressure. The anisotropy parameters D and B{sub 0}{sup 4}, which describe each Mn{sub 4} subunit, are essentially pressure independent, while the antiferromagnetic exchange coupling J between the two Mn{sub 4} subunits strongly depends on pressure, with an increase of 42% at 17 kbar. Additional pressure-dependent powder x-ray measurements allow a structural interpretation of the findings.

  20. Precise neutron inelastic cross section measurements

    SciTech Connect (OSTI)

    Negret, Alexandru

    2012-11-20

    The design of a new generation of nuclear reactors requires the development of a very precise neutron cross section database. Ongoing experiments performed at dedicated facilities aim to the measurement of such cross sections with an unprecedented uncertainty of the order of 5% or even smaller. We give an overview of such a facility: the Gamma Array for Inelastic Neutron Scattering (GAINS) installed at the GELINA neutron source of IRMM, Belgium. Some of the most challenging difficulties of the experimental approach are emphasized and recent results are shown.

  1. Los Alamos Neutron Science Center | National Nuclear Security

    National Nuclear Security Administration (NNSA)

    Administration | (NNSA) Los Alamos Neutron Science Center LANSCE provides the scientific community with intense sources of neutrons supporting both civilian and national security applications. The principal sponsors of LANSCE include the DOE, NNSA, Office of Science and Office of Nuclear Energy, Science and Technology. Users conduct research at state-of-the-art facilities within LANSCE. These facilities include the Isotope Production Facility (IPF); the Lujan Neutron Scattering Center (Lujan

  2. Neutron spectrometer for improved SNM search.

    SciTech Connect (OSTI)

    Vance, Andrew L.; Aigeldinger, Georg

    2007-03-01

    With the exception of large laboratory devices with very low sensitivities, a neutron spectrometer have not been built for fission neutrons such as those emitted by special nuclear materials (SNM). The goal of this work was to use a technique known as Capture Gated Neutron Spectrometry to develop a solid-state device with this functionality. This required modifications to trans-stilbene, a known solid-state scintillator. To provide a neutron capture signal we added lithium to this material. This unique triggering signal allowed identification of neutrons that lose all of their energy in the detector, eliminating uncertainties that arise due to partial energy depositions. We successfully implemented a capture gated neutron spectrometer and were able to distinguish an SNM like fission spectrum from a spectrum stemming from a benign neutron source.

  3. New Developments in Proton Radiography at the Los Alamos Neutron Science Center (LANSCE)

    SciTech Connect (OSTI)

    Morris, C. L.; Brown, E. N.; Agee, C.; Bernert, T.; Bourke, M. A. M.; Burkett, M. W.; Buttler, W. T.; Byler, D. D.; Chen, C. F.; Clarke, A. J.; Cooley, J. C.; Gibbs, P. J.; Imhoff, S. D.; Jones, R.; Kwiatkowski, K.; Mariam, F. G.; Merrill, F. E.; Murray, M. M.; Olinger, C. T.; Oro, D. M.; Nedrow, P.; Saunders, A.; Terrones, G.; Trouw, F.; Tupa, D.; Vogan, W.; Winkler, B.; Wang, Z.; Zellner, M. B.

    2015-12-30

    An application of nuclear physics, a facility for using protons for flash radiography, was developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays for flash radiography because of their long mean free path, good position resolution, and low scatter background. Although this facility is primarily used for studying very fast phenomena such as high explosive driven experiments, it is finding increasing application to other fields, such as tomography of static objects, phase changes in materials and the dynamics of chemical reactions. The advantages of protons are discussed, data from some recent experiments will be reviewed and concepts for new techniques are introduced.

  4. Upgrades to the Polarized Neutron Reflectometer Asterix at LANSCE

    SciTech Connect (OSTI)

    Pynn, Roger

    2015-03-16

    We have upgraded the polarized neutron reflectometer, Asterix, at the Lujan Neutron Scattering Center at Los Alamos for the benefit of the research communities that study magnetic and complex-fluid films, both of which play important roles in support of the DOE’s energy mission. The upgrades to the instrument include: • A secondary spectrometer that was integrated with a Huber sample goniometer purchased with other funds just prior to the start of our project. The secondary spectrometer provides a flexible length for the scattered flight path, includes a mechanism to select among 3 alternative polarization analyzers as well as a support for new neutron detectors. Also included is an optic rail for reproducible positioning of components for Spin Echo Scattering Angle Measurement (SESAME). The entire secondary spectrometer is now non-magnetic, as required for neutron Larmor labeling. • A broad-band neutron polarizer for the incident neutron beam based on the V geometry. • A wide-angle neutron polarization analyzer • A 2d position-sensitive neutron detector • Electromagnetic coils (Wollaston prisms) for SESAME plus the associated power supplies, cooling, safety systems and integration into the data acquisition system. The upgrades allowed a nearly effortless transition between configurations required to serve the polarized neutron reflectometry community, users of the 11 T cryomagnet and users of SESAME.

  5. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  6. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  7. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  8. Active neutron multiplicity counting of bulk uranium

    SciTech Connect (OSTI)

    Ensslin, N.; Krick, M.S.; Langner, D.G.; Miller, M.C. )

    1991-01-01

    This paper describes a new nondestructive assay technique being developed to assay bulk uranium containing kilogram quantities of {sup 235}U. The new technique uses neutron multiplicity analysis of data collected with a coincidence counter outfitted with AmLi neutron sources. The authors have calculated the expected neutron multiplicity count rate and assay precision for this technique and will report on its expected performance as a function of detector design characteristics, {sup 235}U sample mass, AmLi source strength, and source-to-sample coupling.

  9. Quark-hadron duality in the free neutron F2 structure function

    SciTech Connect (OSTI)

    Niculescu, Gabriel

    2015-09-01

    The Thomas Jefferson National Accelerator Facility (JLab) experiment BONuS used a novel spectator-tagging technique to measure the inclusive electron-free neutron scattering cross section and extract the F2 structure function. This data was used to reconstruct moments of F2 in the three prominent resonance region and the moments integrated over the entire resonance region. Comparisons of the experimental results with moments obtained from global parton distribution function parametrization seem to suggest that the quark-hadron duality hypothesis holds locally for the neutron in the second and third resonance regions down to Q2 of 1 GeV2; with up to 20% violations observed in the first resonance region.

  10. Neutron Polarization Analysis for Biphasic Solvent Extraction Systems

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Motokawa, Ryuhei; Endo, Hitoshi; Nagao, Michihiro; Heller, William T.

    2016-06-16

    Here we performed neutron polarization analysis (NPA) of extracted organic phases containing complexes, comprised of Zr(NO3)4 and tri-n-butyl phosphate, which enabled decomposition of the intensity distribution of small-angle neutron scattering (SANS) into the coherent and incoherent scattering components. The coherent scattering intensity, containing structural information, and the incoherent scattering compete over a wide range of magnitude of scattering vector, q, specifically when q is larger than q* ≈ 1/Rg, where Rg is the radius of gyration of scatterer. Therefore, it is important to determine the incoherent scattering intensity exactly to perform an accurate structural analysis from SANS data when Rgmore » is small, such as the aforementioned extracted coordination species. Although NPA is the best method for evaluating the incoherent scattering component for accurately determining the coherent scattering in SANS, this method is not used frequently in SANS data analysis because it is technically challenging. In this study, we successfully demonstrated that experimental determination of the incoherent scattering using NPA is suitable for sample systems containing a small scatterer with a weak coherent scattering intensity, such as extracted complexes in biphasic solvent extraction systems.« less

  11. Neutronic reactor

    DOE Patents [OSTI]

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  12. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  13. Structural characterization of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature using neutron powder diffraction and extended X-ray absorption fine structure techniques

    SciTech Connect (OSTI)

    Mansour, A. N.; Wong-Ng, W.; Huang, Q.; Tang, W.; Thompson, A.; Sharp, J.

    2014-08-28

    The structure of Bi{sub 2}Te{sub 3} (Seebeck coefficient Standard Reference Material (SRM™ 3451)) and the related phase Sb{sub 2}Te{sub 3} have been characterized as a function of temperature using the neutron powder diffraction (NPD) and the extended X-ray absorption fine structure (EXAFS) techniques. The neutron structural studies were carried out from 20 K to 300 K for Bi{sub 2}Te{sub 3} and from 10 K to 298 K for Sb{sub 2}Te{sub 3}. The EXAFS technique for studying the local structure of the two compounds was conducted from 19 K to 298 K. Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} are isostructural, with a space group of R3{sup ¯}m. The structure consists of repeated quintuple layers of atoms, Te2-M-Te1-M-Te2 (where M = Bi or Sb) stacking along the c-axis of the unit cell. EXAFS was used to examine the bond distances and static and thermal disorders for the first three shells of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} as a function of temperature. The temperature dependencies of thermal disorders were analyzed using the Debye and Einstein models for lattice vibrations. The Debye and Einstein temperatures for the first two shells of Bi{sub 2}Te{sub 3} are similar to those of Sb{sub 2}Te{sub 3} within the uncertainty in the data. However, the Debye and Einstein temperatures for the third shell of Bi-Bi are significantly lower than those of the third shell of Sb-Sb. The Einstein temperature for the third shell is consistent with a soft phonon mode in both Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3}. The lower Einstein temperature of Bi-Bi relative to Sb-Sb is consistent with the lower value of thermal conductivity of Bi{sub 2}Te{sub 3} relative to Sb{sub 2}Te{sub 3}.

  14. Molecular-beam scattering

    SciTech Connect (OSTI)

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  15. Methods for absorbing neutrons

    DOE Patents [OSTI]

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  16. Scintillation neutron detectors

    SciTech Connect (OSTI)

    Davidson, J.B.

    1984-01-01

    Two basic types of scintillation area neutron detectors are reviewed. The first is the prompt detector which uses photomultipliers to convert the neutron scintillations to electrical pulses. These signals are combined in weighting or encoding circuits to give event location. Several embodiments of the weighted and coded scintillator approach are mentioned. The second type of scintillation detector is based on television techniques and has a delayed readout. In this method all the light (or as much as possible) is either focused with a fast lens or is coupled by being put in direct contact with the fiber-optic faceplate of an image intensifier tube. The light from the phosphor screen is intensified and coupled to a television camera tube instead of a photomultiplier, and further amplification is produced in the camera tube by accelerating the photoelectrons in order to produce secondary electrons. (LEW)

  17. Neutron reflecting supermirror structure

    DOE Patents [OSTI]

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

  18. Neutron reflecting supermirror structure

    DOE Patents [OSTI]

    Wood, J.L.

    1992-12-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

  19. Simulation of Neutron Backscattering applied to organic material detection

    SciTech Connect (OSTI)

    Forero, N. C.; Cruz, A. H.; Cristancho, F.

    2007-10-26

    The Neutron Backscattering technique is tested when performing the task of localizing hydrogenated explosives hidden in soil. Detector system, landmine, soil and neutron source are simulated with Geant4 in order to obtain the number of neutrons detected when several parameters like mine composition, relative position mine-source and soil moisture are varied.0.

  20. Direct observation of quark-hadron duality in the free neutron F2 structure function

    SciTech Connect (OSTI)

    Niculescu, I.; Niculescu, G.; Melnitchouk, W.; Arrington, J.; Christy, M. E.; Ent, R.; Griffioen, K. A.; Kalantarians, N.; Keppel, C. E.; Kuhn, S.; Tkachenko, S.; Zhang, J.

    2015-05-21

    Using data from the recent BONuS experiment at Jefferson Lab, which utilized a novel spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F2 structure function. In addition, the data are used to reconstruct the lowest few (N = 2, 4 and 6) moments of F2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark--hadron duality holds locally for the neutron in the second and third resonance regions down to Q2 ≈ 1 GeV2, with violations possibly up to 20% observed in the first resonance region.

  1. Versatile module for experiments with focussing neutron guides

    SciTech Connect (OSTI)

    Adams, T.; Pfleiderer, C.; Bni, P. [Physik-Department, Technische Universitt Mnchen, D-85748 Garching (Germany); Brandl, G.; Chacon, A.; Wagner, J. N.; Rahn, M.; Mhlbauer, S.; Georgii, R. [Physik-Department, Technische Universitt Mnchen, D-85748 Garching (Germany); Heinz Maier-Leibnitz Zentrum, FRM II, Technische Universitt Mnchen, D-85748 Garching (Germany)

    2014-09-22

    We report the development of a versatile module that permits fast and reliable use of focussing neutron guides under varying scattering angles. A simple procedure for setting up the module and neutron guides is illustrated by typical intensity patterns to highlight operational aspects as well as typical parasitic artefacts. Combining a high-precision alignment table with separate housings for the neutron guides on kinematic mounts, the change-over between neutron guides with different focussing characteristics requires no readjustments of the experimental setup. Exploiting substantial gain factors, we demonstrate the performance of this versatile neutron scattering module in a study of the effects of uniaxial stress on the domain populations in the transverse spin density wave phase of single crystal Cr.

  2. Neutron activation analysis and gamma ray spectrometry

    SciTech Connect (OSTI)

    Lyon, W.S. . Analytical Chemistry Div.)

    1989-11-01

    The authors present scientometric study of the citations and publication data. It shows the present state of neutron activation analysis (NAA) and applied nuclear chemistry as compared to other analytical techniques.

  3. (International Collaboration on Advanced Neutron Sources)

    SciTech Connect (OSTI)

    Hayter, J.B.

    1990-11-08

    The International Collaboration on Advanced Neutron Sources was started about a decade ago with the purpose of sharing information throughout the global neutron community. The collaboration has been extremely successful in optimizing the use of resources, and the discussions are open and detailed, with reasons for failure shared as well as reasons for success. Although the meetings have become increasingly oriented toward pulsed neutron sources, many of the neutron instrumentation techniques, such as the development of better monochromators, fast response detectors and various data analysis methods, are highly relevant to the Advanced Neutron Source (ANS). I presented one paper on the ANS, and another on the neutron optical polarizer design work which won a 1989 R D-100 Award. I also gained some valuable design ideas, in particular for the ANS hot source, in discussions with individual researchers from Canada, Western Europe, and Japan.

  4. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Vernon, H.C.

    1959-01-13

    A neutronic reactor of the heterogeneous, fluid cooled tvpe is described. The reactor is comprised of a pressure vessel containing the moderator and a plurality of vertically disposed channels extending in spaced relationship through the moderator. Fissionable fuel material is placed within the channels in spaced relationship thereto to permit circulation of the coolant fluid. Separate means are provided for cooling the moderator and for circulating a fluid coolant thru the channel elements to cool the fuel material.

  5. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams

    SciTech Connect (OSTI)

    Zheng Yuanshui; Liu Yaxi; Zeidan, Omar; Schreuder, Andries Niek; Keole, Sameer

    2012-06-15

    Purpose: Neutron exposure is of concern in proton therapy, and varies with beam delivery technique, nozzle design, and treatment conditions. Uniform scanning is an emerging treatment technique in proton therapy, but neutron exposure for this technique has not been fully studied. The purpose of this study is to investigate the neutron dose equivalent per therapeutic dose, H/D, under various treatment conditions for uniform scanning beams employed at our proton therapy center. Methods: Using a wide energy neutron dose equivalent detector (SWENDI-II, ThermoScientific, MA), the authors measured H/D at 50 cm lateral to the isocenter as a function of proton range, modulation width, beam scanning area, collimated field size, and snout position. They also studied the influence of other factors on neutron dose equivalent, such as aperture material, the presence of a compensator, and measurement locations. They measured H/D for various treatment sites using patient-specific treatment parameters. Finally, they compared H/D values for various beam delivery techniques at various facilities under similar conditions. Results: H/D increased rapidly with proton range and modulation width, varying from about 0.2 mSv/Gy for a 5 cm range and 2 cm modulation width beam to 2.7 mSv/Gy for a 30 cm range and 30 cm modulation width beam when 18 Multiplication-Sign 18 cm{sup 2} uniform scanning beams were used. H/D increased linearly with the beam scanning area, and decreased slowly with aperture size and snout retraction. The presence of a compensator reduced the H/D slightly compared with that without a compensator present. Aperture material and compensator material also have an influence on neutron dose equivalent, but the influence is relatively small. H/D varied from about 0.5 mSv/Gy for a brain tumor treatment to about 3.5 mSv/Gy for a pelvic case. Conclusions: This study presents H/D as a function of various treatment parameters for uniform scanning proton beams. For similar treatment

  6. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities,more » the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.« less

  7. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    SciTech Connect (OSTI)

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

  8. Scattering Workshop May 16-17, 2006

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Workshop on Synchrotron X-ray Scattering Techniques in Materials and Environmental Sciences: Theory and Application. group shot on the steps of bldg 41 (Click image for a hi-res version) Date: May 16 (Lectures) May 17 (Hands-on practical session) Location: SSRL Overview: Modern synchrotron-based X-ray scattering (SR-XRS) techniques offer the ability to probe nano- and atomic-scale structures and order/disorder relationships that critically govern the properties of advanced technological and

  9. Research Techniques

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Techniques Research Techniques Print Coming Soon

  10. SHARP Neutronics Expanded

    Broader source: Energy.gov [DOE]

    The SHARP neutronics module, PROTEUS, includes neutron and gamma transport solvers and cross-section processing tools as well as the capability for depletion and fuel cycle analysis.

  11. NEUTRON SOURCE

    DOE Patents [OSTI]

    Reardon, W.A.; Lennox, D.H.; Nobles, R.G.

    1959-01-13

    A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.

  12. NEUTRON COUNTER

    DOE Patents [OSTI]

    Curtis, C.D.; Carlson, R.L.; Tubinis, M.P.

    1958-07-29

    An ionization chamber instrument is described for cylindrical electrodes with an ionizing gag filling the channber. The inner electrode is held in place by a hermetic insulating seal at one end of the outer electrode, the other end of the outer electrode being closed by a gas filling tube. The outer surface of the inner electrode is coated with an active material which is responsive to neutron bombardment, such as uranium235 or boron-10, to produce ionizing radiations in the gas. The transverse cross sectional area of the inner electrode is small in relation to that of the channber whereby substantially all of the radiations are directed toward the outer electrode.

  13. Analysis of the neutron time-of-flight spectra from inertial confinement fusion experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hatarik, R.; Sayre, D. B.; Caggiano, J. A.; Phillips, T.; Eckart, M. J.; Bond, E. J.; Cerjan, C.; Grim, G. P.; Hartouni, E. P.; Knauer, J. P.; et al

    2015-11-12

    For a long time, neutron time-of-flight diagnostics been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d+t→n+α (DT) and d+d→n+³He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, which is also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (Tion) and cold fuel areal density. We explain such novel methodologies used to determine neutron yield, apparent Tion and DSR.

  14. Analysis of the neutron time-of-flight spectra from inertial confinement fusion experiments

    SciTech Connect (OSTI)

    Hatarik, R.; Sayre, D. B.; Caggiano, J. A.; Phillips, T.; Eckart, M. J.; Bond, E. J.; Cerjan, C.; Grim, G. P.; Hartouni, E. P.; Knauer, J. P.; Mcnaney, J. M.; Munro, D. H.

    2015-11-12

    For a long time, neutron time-of-flight diagnostics been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d+t→n+α (DT) and d+d→n+³He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, which is also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (Tion) and cold fuel areal density. We explain such novel methodologies used to determine neutron yield, apparent Tion and DSR.

  15. Conducting Polymers for Neutron Detection

    SciTech Connect (OSTI)

    Kimblin, Clare; Miller, Kirk; Vogel, Bob; Quam, Bill; McHugh, Harry; Anthony, Glen; Mike, Grover

    2007-12-01

    Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number.

  16. The synchronous active neutron detection assay system

    SciTech Connect (OSTI)

    Pickrell, M.M.; Kendall, P.K.

    1994-08-01

    We have begun to develop a novel technique for active neutron assay of fissile material in spent nuclear fuel. This approach will exploit a 14-MeV neutron generator developed by Schlumberger. The technique, termed synchronous active neutron detection (SAND), follows a method used routinely in other branches of physics to detect very small signals in presence of large backgrounds. Synchronous detection instruments are widely available commercially and are termed ``lock-in`` amplifiers. We have implemented a digital lock-in amplifier in conjunction with the Schlumberger neutron generator to explore the possibility of synchronous detection with active neutrons. The Schlumberger system can operate at up to a 50% duty factor, in effect, a square wave of neutron yield. Results are preliminary but promising. The system is capable of resolving the fissile material contained in a small fraction of the fuel rods in a cold fuel assembly; it also appears resilient to background neutron interference. The interrogating neutrons appear to be non-thermal and penetrating. Work remains to fully explore relevant physics and optimize instrument design.

  17. Compound Refractive Lenses for Thermal Neutron Applications

    SciTech Connect (OSTI)

    Gary, Charles K.

    2013-11-12

    This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 μm which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

  18. The Neutron Imaging Diagnostic at NIF

    SciTech Connect (OSTI)

    Merrill, F E; Buckles, R; Clark, D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherly, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H

    2012-10-01

    A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of ICF implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

  19. The neutron imaging diagnostic at NIF (invited)

    SciTech Connect (OSTI)

    Merrill, F. E.; Clark, D. D.; Danly, C. R.; Drury, O. B.; Fatherley, V. E.; Gallegos, R.; Grim, G. P.; Guler, N.; Loomis, E. N.; Martinson, D. D.; Mares, D.; Morley, D. J.; Morgan, G. L.; Oertel, J. A.; Tregillis, I. L.; Volegov, P. L.; Wilde, C. H.; Wilson, D. C.; Bower, D.; Dzenitis, J. M.; and others

    2012-10-15

    A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

  20. On-the-fly generation of differential resonance scattering probability distribution functions for Monte Carlo codes

    SciTech Connect (OSTI)

    Sunny, E. E.; Martin, W. R. [University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor MI 48109 (United States)

    2013-07-01

    Current Monte Carlo codes use one of three models to model neutron scattering in the epithermal energy range: (1) the asymptotic scattering model, (2) the free gas scattering model, or (3) the S({alpha},{beta}) model, depending on the neutron energy and the specific Monte Carlo code. The free gas scattering model assumes the scattering cross section is constant over the neutron energy range, which is usually a good approximation for light nuclei, but not for heavy nuclei where the scattering cross section may have several resonances in the epithermal region. Several researchers in the field have shown that using the free gas scattering model in the vicinity of the resonances in the lower epithermal range can under-predict resonance absorption due to the up-scattering phenomenon. Existing methods all involve performing the collision analysis in the center-of-mass frame, followed by a conversion back to the laboratory frame. In this paper, we will present a new sampling methodology that (1) accounts for the energy-dependent scattering cross sections in the collision analysis and (2) acts in the laboratory frame, avoiding the conversion to the center-of-mass frame. The energy dependence of the scattering cross section was modeled with even-ordered polynomials to approximate the scattering cross section in Blackshaw's equations for the moments of the differential scattering PDFs. These moments were used to sample the outgoing neutron speed and angle in the laboratory frame on-the-fly during the random walk of the neutron. Results for criticality studies on fuel pin and fuel assembly calculations using these methods showed very close comparison to results using the reference Doppler-broadened rejection correction (DBRC) scheme. (authors)

  1. Enabling Explosives and Contraband Detection with Neutron Resonant Attenuation. Year 1 of 3 Summary

    SciTech Connect (OSTI)

    Sweany, Melinda

    2015-10-01

    Material Identification by Resonant Attenuation is a technique that measures the energy-dependent attenuation of 1-10 MeV neutrons as they pass through a sample. Elemental information is determined from the neutron absorption resonances unique to each element. With sufficient energy resolution, these resonances can be used to categorize a wide range of materials, serving as a powerful discrimination technique between explosives, contraband, and other materials. Our proposed system is unique in that it simultaneously down-scatters and time tags neutrons in scintillator detectors oriented between a d-T generator and sample. This allows not only for energy measurements without pulsed neutron beams, but for sample interrogation over a large range of relevant energies, vastly improving scan times. Our system’s core advantage is a potential breakthrough ability to provide detection discrimination of threat materials by their elemental composition (e.g. water vs. hydrogen peroxide) without opening the container. However, several technical and computational challenges associated with this technique have yet to be addressed. There are several open questions: what is the sensitivity to different materials, what scan times are necessary, what are the sources of background, how do each of these scale as the detector system is made larger, and how can the system be integrated into existing scanning technology to close current detection gaps? In order to prove the applicability of this technology, we will develop a validated model to optimize the design and characterize the uncertainties in the measurement, and then test the system in a real-world scenario. This project seeks to perform R&D and laboratory tests that demonstrate proof of concept (TRL 3) to establishing an integrated system and evaluating its performance (TRL 4) through both laboratory tests and a validated detector model. The validated model will allow us to explore our technology’s benefits to explosive

  2. Neutron Generators for Spent Fuel Assay

    SciTech Connect (OSTI)

    Ludewigt, Bernhard A

    2010-12-30

    The Next Generation Safeguards Initiative (NGSI) of the U.S. DOE has initiated a multi-lab/university collaboration to quantify the plutonium (Pu) mass in, and detect the diversion of pins from, spent nuclear fuel (SNF) assemblies with non-destructive assay (NDA). The 14 NDA techniques being studied include several that require an external neutron source: Delayed Neutrons (DN), Differential Die-Away (DDA), Delayed Gammas (DG), and Lead Slowing-Down Spectroscopy (LSDS). This report provides a survey of currently available neutron sources and their underlying technology that may be suitable for NDA of SNF assemblies. The neutron sources considered here fall into two broad categories. The term 'neutron generator' is commonly used for sealed devices that operate at relatively low acceleration voltages of less than 150 kV. Systems that employ an acceleration structure to produce ion beam energies from hundreds of keV to several MeV, and that are pumped down to vacuum during operation, rather than being sealed units, are usually referred to as 'accelerator-driven neutron sources.' Currently available neutron sources and future options are evaluated within the parameter space of the neutron generator/source requirements as currently understood and summarized in section 2. Applicable neutron source technologies are described in section 3. Commercially available neutron generators and other source options that could be made available in the near future with some further development and customization are discussed in sections 4 and 5, respectively. The pros and cons of the various options and possible ways forward are discussed in section 6. Selection of the best approach must take a number of parameters into account including cost, size, lifetime, and power consumption, as well as neutron flux, neutron energy spectrum, and pulse structure that satisfy the requirements of the NDA instrument to be built.

  3. Cryogenic Neutron Protein Crystallography: routine methods and potential benefits

    SciTech Connect (OSTI)

    Weiss, Kevin L; Tomanicek, Stephen J; NG, Joseph D

    2014-01-01

    The use of cryocooling in neutron diffraction has been hampered by several technical challenges such as the need for specialized equipment and techniques. Recently we have developed and deployed equipment and strategies that allow for routine neutron data collection on cryocooled crystals using off the shelf components. This system has several advantages, compared to a closed displex cooling system such as fast cooling coupled with easier crystal mounting and centering. The ability to routinely collect cryogenic neutron data for analysis will significantly broaden the range of scientific questions that can be examined by neutron protein crystallography. Cryogenic neutron data collection for macromolecules has recently become available at the new Biological Diffractometer BIODIFF at FRM II and the Macromolecular Diffractometer (MaNDi) at the Spallation Neutron Source, Oak Ridge National Laboratory. To evaluate the benefits of a cryocooled neutron structure we collected a full neutron data set on the BIODIFF instrument on a Toho-1 lactamase structure at 100K.

  4. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Stewart, H.B.

    1958-12-23

    A nuclear reactor of the type speclfically designed for the irradiation of materials is discussed. In this design a central cyllndrical core of moderating material ls surrounded by an active portlon comprlsed of an annular tank contalning fissionable material immersed ln a liquid moderator. The active portion ls ln turn surrounded by a reflector, and a well ls provided in the center of the core to accommodate the materlals to be irradiated. The over-all dimensions of the core ln at least one plane are equal to or greater than twice the effective slowing down length and equal to or less than twlce the effective diffuslon length for neutrons in the core materials.

  5. NEUTRONIC REACTORS

    DOE Patents [OSTI]

    Wigner, E.P.; Young, G.J.

    1958-10-14

    A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

  6. Deuterium density profile determination at JET using a neutron camera and a neutron spectrometer

    SciTech Connect (OSTI)

    Eriksson, J. Castegnetti, G.; Conroy, S.; Ericsson, G.; Hellesen, C.; Giacomelli, L.

    2014-11-15

    In this work we estimate the fuel ion density profile in deuterium plasmas at JET, using the JET neutron camera, the neutron time-of-flight spectrometer TOFOR, and fusion reactivities modeled by the transport code TRANSP. The framework has been tested using synthetic data, which showed that the density profile could be reconstructed with an average accuracy of the order of 10 %. The method has also been applied to neutron measurements from a neutral beam heated JET discharge, which gave n{sub d}/n{sub e} ? 0.6 0.3 in the plasma core and n{sub d}/n{sub e} ? 0.4 0.3 towards the edge. Correction factors for detector efficiencies, neutron attenuation, and back-scattering are not yet included in the analysis; future work will aim at refining the estimated density.

  7. Neutron reflecting supermirror structure

    DOE Patents [OSTI]

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

  8. Phase-sensitive two-dimensional neutron shearing interferometer and Hartmann sensor

    SciTech Connect (OSTI)

    Baker, Kevin

    2015-12-08

    A neutron imaging system detects both the phase shift and absorption of neutrons passing through an object. The neutron imaging system is based on either of two different neutron wavefront sensor techniques: 2-D shearing interferometry and Hartmann wavefront sensing. Both approaches measure an entire two-dimensional neutron complex field, including its amplitude and phase. Each measures the full-field, two-dimensional phase gradients and, concomitantly, the two-dimensional amplitude mapping, requiring only a single measurement.

  9. Neutron Imaging Calibration to Measure Void Fraction

    SciTech Connect (OSTI)

    Geoghegan, Patrick J; Bilheux, Hassina Z; Sharma, Vishaldeep; Fricke, Brian A

    2015-01-01

    Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.

  10. A Program to Calculate Fast Neutron Data for Structural Materials.

    Energy Science and Technology Software Center (OSTI)

    1990-11-09

    Version 00 Based on the unified model the UNIFY code is used for the calculation of the fast neutron data for structural materials, which involves: (1) cross section- total cross section, all kinds of reactions channels, the cross section of the discrete levels and continuum emission, (2) angular distribution- elastic scattering angular distribution and its Legendre coefficients and transition matrix elements,the Legendre coefficients of the discrete levels in the inelastic scattering channels, (3) energy spectra,more » (4) double differential cross section of the inelastic channel and of the neutron outgoing channels.« less

  11. Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

    SciTech Connect (OSTI)

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.

    2015-07-22

    Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering ΝΝνν¯ (nnvv¯, ppvv¯, and npvv¯) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated ΝΝνν¯ emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an OPE model. Purpose: To investigate the free ΝΝνν¯ cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes nnvv¯, ppvv¯, and npvv¯.

  12. Continuous Energy MC Neutron/Photon

    Energy Science and Technology Software Center (OSTI)

    1991-10-10

    VIM solves the three-dimensional steady-state multiplication eigenvalue or fixed source neutron or photon (VIM3.0) transport problem using continuous energy-dependent nuclear data. It was designed for the analysis of fast critical experiments. In VIM3.0, the photon interactions i.e., pair production, coherent and incoherent scattering, and photoelectric events, and photon heating are tallied by group, region, and isotope.

  13. Combination neutron-gamma ray detector

    DOE Patents [OSTI]

    Stuart, Travis P.; Tipton, Wilbur J.

    1976-10-26

    A radiation detection system capable of detecting neutron and gamma events and distinguishing therebetween. The system includes a detector for a photomultiplier which utilizes a combination of two phosphor materials, the first of which is in the form of small glass beads which scintillate primarily in response to neutrons and the second of which is a plastic matrix which scintillates in response to gammas. A combination of pulse shape and pulse height discrimination techniques is utilized to provide an essentially complete separation of the neutron and gamma events.

  14. Neutron range spectrometer

    DOE Patents [OSTI]

    Manglos, Stephen H.

    1989-06-06

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

  15. NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

    1958-09-01

    This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

  16. Fast neutron environments.

    SciTech Connect (OSTI)

    Buchheit, Thomas Edward; Kotula, Paul Gabriel; Lu, Ping; Brewer, Luke N.; Goods, Steven Howard; Foiles, Stephen Martin; Puskar, Joseph David; Hattar, Khalid Mikhiel; Doyle, Barney Lee; Boyce, Brad Lee; Clark, Blythe G.

    2011-10-01

    The goal of this LDRD project is to develop a rapid first-order experimental procedure for the testing of advanced cladding materials that may be considered for generation IV nuclear reactors. In order to investigate this, a technique was developed to expose the coupons of potential materials to high displacement damage at elevated temperatures to simulate the neutron environment expected in Generation IV reactors. This was completed through a high temperature high-energy heavy-ion implantation. The mechanical properties of the ion irradiated region were tested by either micropillar compression or nanoindentation to determine the local properties, as a function of the implantation dose and exposure temperature. In order to directly compare the microstructural evolution and property degradation from the accelerated testing and classical neutron testing, 316L, 409, and 420 stainless steels were tested. In addition, two sets of diffusion couples from 316L and HT9 stainless steels with various refractory metals. This study has shown that if the ion irradiation size scale is taken into consideration when developing and analyzing the mechanical property data, significant insight into the structural properties of the potential cladding materials can be gained in about a week.

  17. Neutron multiplicity measurements with 3He alternative: Straw neutron detectors

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Wolff, Ronald; Detwiler, Ryan; Maurer, Richard; Mitchell, Stephen; Guss, Paul; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as ‘‘ship effect ’’) and to the complicated nature of the neutron scattering in that environment. A prototype neutron detector was built using 10B as the converter in a special form factor called ‘‘straws’’ that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and

  18. Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

    SciTech Connect (OSTI)

    Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; Detweiler, Ryan; Maurer, Richard J.; Mitchell, Stephen E.; Guss, Paul P.; Lacy, Jeffrey L.; Sun, Liang; Athanasiades, Athanasios

    2015-01-27

    Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics

  19. Development of multichannel low-energy neutron spectrometer

    SciTech Connect (OSTI)

    Arikawa, Y. Nagai, T.; Abe, Y.; Kojima, S.; Sakata, S.; Inoue, H.; Utsugi, M.; Iwasa, Y.; Sarukura, N.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Murata, T.

    2014-11-15

    A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments.

  20. Design and Demonstration of a Quasi-monoenergetic Neutron Source

    SciTech Connect (OSTI)

    Joshi, T.; Sangiorgio, Samuele; Mozin, Vladimir V.; Norman, E. B.; Sorensen, Peter F.; Foxe, Michael P.; Bench, G.; Bernstein, A.

    2014-03-05

    The design of a neutron source capable of producing 24 and 70 keV neutron beams with narrow energy spread is presented. The source exploits near-threshold kinematics of the 7Li(p,n)7Be reaction while taking advantage of the interference `notches' found in the scattering cross-sections of iron. The design was implemented and characterized at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Alternative lters such as vanadium and manganese are also explored and the possibility of studying the response of di*erent materials to low-energy nuclear recoils using the resultant neutron beams is discussed.

  1. Relativistic mean field calculations in neutron-rich nuclei

    SciTech Connect (OSTI)

    Gangopadhyay, G.; Bhattacharya, Madhubrata [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Roy, Subinit [Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata- 700 064 (India)

    2014-08-14

    Relativistic mean field calculations have been employed to study neutron rich nuclei. The Lagrange's equations have been solved in the co-ordinate space. The effect of the continuum has been effectively taken into account through the method of resonant continuum. It is found that BCS approximation performs as well as a more involved Relativistic Continuum Hartree Bogoliubov approach. Calculations reveal the possibility of modification of magic numbers in neutron rich nuclei. Calculation for low energy proton scattering cross sections shows that the present approach reproduces the density in very light neutron rich nuclei.

  2. Measurement of uranium and plutonium in solid waste by passive photon or neutron counting and isotopic neutron source interrogation

    SciTech Connect (OSTI)

    Crane, T.W.

    1980-03-01

    A summary of the status and applicability of nondestructive assay (NDA) techniques for the measurement of uranium and plutonium in 55-gal barrels of solid waste is reported. The NDA techniques reviewed include passive gamma-ray and x-ray counting with scintillator, solid state, and proportional gas photon detectors, passive neutron counting, and active neutron interrogation with neutron and gamma-ray counting. The active neutron interrogation methods are limited to those employing isotopic neutron sources. Three generic neutron sources (alpha-n, photoneutron, and /sup 252/Cf) are considered. The neutron detectors reviewed for both prompt and delayed fission neutron detection with the above sources include thermal (/sup 3/He, /sup 10/BF/sub 3/) and recoil (/sup 4/He, CH/sub 4/) proportional gas detectors and liquid and plastic scintillator detectors. The instrument found to be best suited for low-level measurements (< 10 nCi/g) is the /sup 252/Cf Shuffler. The measurement technique consists of passive neutron counting followed by cyclic activation using a /sup 252/Cf source and delayed neutron counting with the source withdrawn. It is recommended that a waste assay station composed of a /sup 252/Cf Shuffler, a gamma-ray scanner, and a screening station be tested and evaluated at a nuclear waste site. 34 figures, 15 tables.

  3. Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2

    SciTech Connect (OSTI)

    1996-05-01

    The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

  4. Thermal stability of photovoltaic a-Si:H determined by neutron reflectometry

    SciTech Connect (OSTI)

    Qviller, A. J. Haug, H.; You, C. C.; Hasle, I. M.; Marstein, E. S.; Frommen, C.; Hauback, B. C.; Dennison, A. J. C.; Vorobiev, A.; streng, E.; Fjellvg, H.; Hjrvarsson, B.

    2014-12-08

    Neutron and X-ray reflectometry were used to determine the layer structure and hydrogen content of thin films of amorphous silicon (a-Si:H) deposited onto crystalline silicon (Si) wafers for surface passivation in solar cells. The combination of these two reflectometry techniques is well suited for non-destructive probing of the structure of a-Si:H due to being able to probe buried interfaces and having sub-nanometer resolution. Neutron reflectometry is also unique in its ability to allow determination of density gradients of light elements such as hydrogen (H). The neutron scattering contrast between Si and H is strong, making it possible to determine the H concentration in the deposited a-Si:H. In order to correlate the surface passivation properties supplied by the a-Si:H thin films, as quantified by obtainable effective minority carrier lifetime, photoconductance measurements were also performed. It is shown that the minority carrier lifetime falls sharply when H has been desorbed from a-Si:H by annealing.

  5. Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1

    SciTech Connect (OSTI)

    Marzec, B.

    1996-05-01

    The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

  6. Neutron streak camera

    DOE Patents [OSTI]

    Wang, C.L.

    1983-09-13

    Disclosed is an apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon. 4 figs.

  7. Neutron streak camera

    DOE Patents [OSTI]

    Wang, Ching L.

    1983-09-13

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  8. Layered semiconductor neutron detectors

    DOE Patents [OSTI]

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  9. Neutron streak camera

    DOE Patents [OSTI]

    Wang, C.L.

    1981-05-14

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  10. Organic metal neutron detector

    DOE Patents [OSTI]

    Butler, M.A.; Ginley, D.S.

    1984-11-21

    A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

  11. Neutronic Reactor Design to Reduce Neutron Loss

    DOE Patents [OSTI]

    Miles, F. T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall. The wall is surrounded by successive layers of pure fertile material and moderator containing fertile material. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. Since the steel has a smaller capture cross section for the fast neutrons, greater nunnbers of neutrons will pass into the blanket, thereby increasing the over-all efficiency of the reactor. (AEC)

  12. NEUTRONIC REACTOR DESIGN TO REDUCE NEUTRON LOSS

    DOE Patents [OSTI]

    Mills, F.T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall which is surrounded by successive layers of pure fertile material and fertile material having moderator. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. As the steel has a smaller capture cross-section for the fast neutrons, then greater numbers of the neutrons will pass into the blanket thereby increasing the over-all efficiency of the reactor.

  13. Toward a Taxonomy of the Denatured State: Small Angle Scattering Studies of Unfolded Proteins

    SciTech Connect (OSTI)

    Millett, I.S.; Doniach, S.; Plaxco, K.W. (Stanford); (UCSB)

    2005-02-15

    Despite the critical role the unfolded state plays in defining protein folding kinetics and thermodynamics (Berg et al., 2002; Dunker, 2002; Shortle, 2002; Wright and Dyson, 2002), our understanding of its detailed structure remains rather rudimentary; the heterogeneity of the unfolded ensemble renders difficult or impossible its study by traditional, atomic-level structural methods. Consequently, recent years have seen a significant expansion of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) techniques that provide direct, albeit rotationally and time-averaged, measures of the geometric properties of the unfolded ensemble. These studies have reached a critical mass, allowing us for the first time to define general observations regarding the nature of the geometry - and possibly the chemistry and physics - of unfolded proteins.

  14. Dose equivalent neutron dosimeter

    DOE Patents [OSTI]

    Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

    1983-01-01

    A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

  15. Ultrafast neutron detector

    DOE Patents [OSTI]

    Wang, C.L.

    1985-06-19

    A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

  16. Neutron dose equivalent meter

    DOE Patents [OSTI]

    Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

    1996-01-01

    A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

  17. ULTRASONIC NEUTRON DOSIMETER

    DOE Patents [OSTI]

    Truell, R.; de Klerk, J.; Levy, P.W.

    1960-02-23

    A neutron dosimeter is described which utilizes ultrasonic waves in the megacycle region for determination of the extent of neutron damage in a borosilicate glass through ultrasonic wave velocity and attenuation measurements before and after damage.

  18. Recent improvements in Thomson scattering data analysis

    SciTech Connect (OSTI)

    Tillack, M.S.; Lazarus, E.A.

    1980-04-01

    A new profile analysis package for use with the Thomson scattering data on ISX-B has recently been implemented. The primary feature of this package is a weighted least squares fitting of temperature and density data to generate a representative curve, as opposed to the previous hand-fitting technique. The changes will automate the manner in which data are transmitted and manipulated, without affecting the calculational techniques previously used. The computer programs have also been used to estimate the sensitivity of various plasma quantities to the accuracy of the Thomson scattering data.

  19. Intense fusion neutron sources

    SciTech Connect (OSTI)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-15

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 10{sup 15}-10{sup 21} neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 10{sup 20} neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the

  20. Neutrons - 88-Inch Cyclotron

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Neutrons Neutron beams are available at the 88-Inch Cyclotron. Available energies range of from 8 to 30 MeV, with fluxes of up to 1E8 neutrons/cm^2/sec. For more information, please contact Mike Johnson via e-mail at MBJohnson@lbl.gov, or by phone at at (510) 486-4389.

  1. Advanced neutron absorber materials

    DOE Patents [OSTI]

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  2. Prototype Neutron Energy Spectrometer

    SciTech Connect (OSTI)

    Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

    2010-06-16

    The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production [ship effect], [a, n] reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

  3. Arsenic activation neutron detector

    DOE Patents [OSTI]

    Jacobs, E.L.

    1980-01-28

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  4. Arsenic activation neutron detector

    DOE Patents [OSTI]

    Jacobs, Eddy L.

    1981-01-01

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  5. Environment scattering in GADRAS.

    SciTech Connect (OSTI)

    Thoreson, Gregory G.; Mitchell, Dean James; Theisen, Lisa Anne; Harding, Lee T.

    2013-09-01

    Radiation transport calculations were performed to compute the angular tallies for scattered gamma-rays as a function of distance, height, and environment. Green's Functions were then used to encapsulate the results a reusable transformation function. The calculations represent the transport of photons throughout scattering surfaces that surround sources and detectors, such as the ground and walls. Utilization of these calculations in GADRAS (Gamma Detector Response and Analysis Software) enables accurate computation of environmental scattering for a variety of environments and source configurations. This capability, which agrees well with numerous experimental benchmark measurements, is now deployed with GADRAS Version 18.2 as the basis for the computation of scattered radiation.

  6. A radial collimator for a time-of-flight neutron spectrometer

    SciTech Connect (OSTI)

    Stone, M. B.; Abernathy, D. L. [Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Niedziela, J. L.; Loguillo, M. J.; Overbay, M. A. [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-08-15

    We have engineered and installed a radial collimator for use in the scattered beam of a neutron time-of-flight spectrometer at a spallation neutron source. The radial collimator may be used with both thermal and epithermal neutrons, reducing the detected scattering intensity due to material outside of the sample region substantially. The collimator is located inside of the sample chamber of the instrument, which routinely cycles between atmospheric conditions and cryogenic vacuum. The oscillation and support mechanism of the collimator allow it to be removed from use without breaking vacuum. We describe here the design and characterization of this radial collimator.

  7. Semiconductor neutron detector

    DOE Patents [OSTI]

    Ianakiev, Kiril D.; Littlewood, Peter B.; Blagoev, Krastan B.; Swinhoe, Martyn T.; Smith, James L.; Sullivan, Clair J.; Alexandrov, Boian S.; Lashley, Jason Charles

    2011-03-08

    A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

  8. Organic metal neutron detector

    DOE Patents [OSTI]

    Butler, Michael A.; Ginley, David S.

    1987-01-01

    A device for detecting neutrons comprises a layer of conductive polymer sandwiched between electrodes, which may be covered on each face with a neutron transmissive insulating material layer. Conventional electrodes are used for a non-imaging integrating total neutron fluence-measuring embodiment, while wire grids are used in an imaging version of the device. The change in conductivity of the polymer after exposure to a neutron flux is determined in either case to provide the desired data. Alternatively, the exposed conductive polymer layer may be treated with a chemical reagent which selectively binds to the sites altered by neutrons to produce an image of the flux detected.

  9. High energy neutron dosimeter

    DOE Patents [OSTI]

    Rai, K.S.F.

    1994-01-11

    A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

  10. PERSONNEL NEUTRON DOSIMETER

    DOE Patents [OSTI]

    Fitzgerald, J.J.; Detwiler, C.G. Jr.

    1960-05-24

    A description is given of a personnel neutron dosimeter capable of indicating the complete spectrum of the neutron dose received as well as the dose for each neutron energy range therein. The device consists of three sets of indium foils supported in an aluminum case. The first set consists of three foils of indium, the second set consists of a similar set of indium foils sandwiched between layers of cadmium, whereas the third set is similar to the second set but is sandwiched between layers of polyethylene. By analysis of all the foils the neutron spectrum and the total dose from neutrons of all energy levels can be ascertained.

  11. High energy neutron dosimeter

    DOE Patents [OSTI]

    Sun, Rai Ko S.F. (Albany, CA)

    1994-01-01

    A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

  12. Neutron activation analysis system

    DOE Patents [OSTI]

    Taylor, M.C.; Rhodes, J.R.

    1973-12-25

    A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

  13. Stable Difference Schemes for the Neutron Transport Equation

    SciTech Connect (OSTI)

    Ashyralyev, Allaberen; Taskin, Abdulgafur

    2011-09-22

    The initial boundary value problem for the neutron transport equation is considered. The first and second orders of accuracy difference schemes for the approximate solution of this problem are presented. In applications, the stability estimates for solutions of difference schemes for the approximate solution of the neutron transport equation are obtained. Numerical techniques are developed and algorithms are tested on an example in MATLAB.

  14. Improving Neutron Measurement Capabilities; Expanding the Limits of Correlated Neutron Counting

    SciTech Connect (OSTI)

    Santi, Peter Angelo; Geist, William H.; Dougan, Arden

    2015-11-05

    A number of technical and practical limitations exist within the neutron correlated counting techniques used in safeguards, especially within the algorithms that are used to process and analyze the detected neutron signals. A multi-laboratory effort is underway to develop new and improved analysis and data processing algorithms based on fundamental physics principles to extract additional or more accurate information about nuclear material bearing items.

  15. Compton scattering overview

    SciTech Connect (OSTI)

    Hartemann, F V

    2008-12-01

    An overview of linear and nonlinear Compton scattering is presented, along with a comparison with Thomson scattering. Two distinct processes play important roles in the nonlinear regime: multi-photon interactions, leading to the generation of harmonics, and radiation pressure, yielding a downshift of the radiated spectral features. These mechanisms, their influence on the source brightness, and different modeling strategies are also briefly discussed.

  16. Parity Violation in Electron Scattering

    SciTech Connect (OSTI)

    Beise, Elizabeth

    2007-10-26

    About thirty years ago, electron scattering from nucleons was used [1] to identify, and then measure, the properties of the weak interaction, the only force of nature known to violate the symmetry parity. The basic technique has not fundamentally changed, which is to look for a small asymmetry in count rate from scattering a polarized electron beam from an unpolarized target. Since then, parity-violating (PV) electron scattering has developed substantially, a result of significant improvements in polarized electron beams, accelerator advancements, and developments in cryogenic targets that make it possible to carry out experiments with much higher statistical precision. In the last decade PV experiments have focused on using the complementary electron-quark flavor coupling of the weak interaction to identify and place limits on contributions of strange quark-antiquark pairs to the charge and magnetism of the proton. This observable provides a unique window into the structure of the proton since strange quark contributions can arise only from the sea of quarks and gluons that are responsible for the vast majority of the nucleon's mass. This paper will report on recent results aimed at this goal, along with a brief overview of future directions.

  17. Measurement of vibrational, gas, and rotational temperatures of H{sub 2} (X{sup 1} {sigma}{sub g}{sup +}) in radio frequency inductive discharge plasma by multiplex coherent anti-Stokes Raman scattering spectroscopy technique

    SciTech Connect (OSTI)

    Shakhatov, V.A.; De Pascale, O.; Capitelli, M.; Hassouni, K.; Lombardi, G.; Gicquel, A.

    2005-02-01

    Translational, rotational, and vibrational temperatures of H{sub 2} in radio frequency inductive discharge plasmas at pressures and power release ranges, respectively, of 0.5-8 torr and 0.5-2 W/cm{sup 3} have been measured by using multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopy. Computational codes have been developed to determine the rotational and vibrational temperatures and to analyze H{sub 2} CARS spectrum for nonequilibrium conditions. The results show a decrease of the vibrational temperature from 4250 to 2800 K by increasing the pressure from 0.5 to 8 torr and a corresponding increase of the rotational temperature from 525 to 750 K.

  18. NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR

    DOE Patents [OSTI]

    Young, G.J.

    1959-06-30

    The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

  19. Neutron inelastic scattering in natural Pb as a background in...

    Office of Scientific and Technical Information (OSTI)

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  20. Theoretical modeling for neutron elastic scattering angular distributi...

    Office of Scientific and Technical Information (OSTI)

    Publication: United States Language: English Subject: 29 ENERGY PLANNING, POLICY AND ECONOMY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION...