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Sample records for neutron scattering applications

  1. 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 ...

  2. 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

  3. 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

  4. 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

  5. 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...

  6. 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...

  7. 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)

  8. 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.

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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

  20. 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...

  1. 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...

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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 + ...

  12. 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, ...

  13. 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 ...

  14. 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 ...

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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 ...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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}.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. (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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. 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.

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

    SciTech Connect (OSTI)

    Xinsheng Ling

    2012-02-02

    The proposed program is an experimental study of the fundamental properties of Abrikosov vortex matter in type-II superconductors. Most superconducting materials used in applications such as MRI are type II and their transport properties are determined by the interplay between random pinning, interaction and thermal fluctuation effects in the vortex state. Given the technological importance of these materials, a fundamental understanding of the vortex matter is necessary. The vortex lines in type-II superconductors also form a useful model system for fundamental studies of a number of important issues in condensed matter physics, such as the presence of a symmetry-breaking phase transition in the presence of random pinning. Recent advances in neutron scattering facilities such as the major upgrade of the NIST cold source and the Spallation Neutron Source are providing unprecedented opportunities in addressing some of the longstanding issues in vortex physics. The core component of the proposed program is to use small angle neutron scattering and Bitter decoration experiments to provide the most stringent test of the Bragg glass theory by measuring the structure factor in both the real and reciprocal spaces. The proposed experiments include a neutron reflectometry experiment to measure the precise Q-dependence of the structure factor of the vortex lattice in the Bragg glass state. A second set of SANS experiments will be on a shear-strained Nb single crystal for testing a recently proposed theory of the stability of Bragg glass. The objective is to artificially create a set of parallel grain boundaries into a Nb single crystal and use SANS to measure the vortex matter diffraction pattern as a function of the changing angle between the applied magnetic field to the grain boundaries. The intrinsic merits of the proposed work are a new fundamental understanding of type-II superconductors on which superconducting technology is based, and a firm understanding of phases

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  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. 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.

  4. 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 ...

  5. 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

  6. 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.)

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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,

  19. 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,

  20. 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.

  1. 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.

  2. 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).

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Neutron Energy Measurements in Radiological Emergency Response Applications

    SciTech Connect (OSTI)

    Sanjoy Mukhopadhyay, Paul Guss, Michael Hornish, Scott Wilde, Tom Stampahar, Michael Reed

    2009-04-30

    We present significant results in recent advances in the determination of neutron energy. Neutron energy measurements are a small but very significant part of radiological emergency response applications. Mission critical information can be obtained by analyzing the neutron energy given off from radioactive materials. In the case of searching for special nuclear materials, neutron energy information from an unknown source can be of paramount importance.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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).

  6. 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).

  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. 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

  8. 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

  9. 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.).

  10. PRODUCTION AND APPLICATIONS OF NEUTRONS USING PARTICLE ACCELERATORS

    SciTech Connect (OSTI)

    David L. Chichester

    2009-11-01

    Advances in neutron science have gone hand in hand with the development and of particle accelerators from the beginning of both fields of study. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and how neutrons interact in matter, but people quickly realized that more tangible uses existed too. Today the diversity of applications for industrial accelerator-based neutron sources is high and so to is the actual number of instruments in daily use is high, and they serve important roles in the fields where they're used. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the early development of neutron-producing particle accelerators, a description of some current industrial accelerator systems, narratives of the fields where neutron-producing particle accelerators are used today, and comments on future trends in the industrial uses of neutron producing particle accelerators.

  11. Aerial Neutron Detection: Neutron Signatures for Nonproliferation and Emergency Response Applications

    SciTech Connect (OSTI)

    Maurer, Richard J.; Stampahar, Thomas G.; Smith, Ethan X.; Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Rourke, Timothy J.; LeDonne, Jeffrey P.; Avaro, Emanuele; Butler, D. Andre; Borders, Kevin L.; Stampahar, Jezabel; Schuck, William H.; Selfridge, Thomas L.; McKissack, Thomas M.; Duncan, William W.; Hendricks, Thane J.

    2012-10-17

    From 2007 to the present, the Remote Sensing Laboratory has been conducting a series of studies designed to expand our fundamental understanding of aerial neutron detection with the goal of designing an enhanced sensitivity detection system for long range neutron detection. Over 35 hours of aerial measurements in a helicopter were conducted for a variety of neutron emitters such as neutron point sources, a commercial nuclear power reactor, nuclear reactor spent fuel in dry cask storage, depleted uranium hexafluoride and depleted uranium metal. The goals of the project were to increase the detection sensitivity of our instruments such that a 5.4 × 104 neutron/second source could be detected at 100 feet above ground level at a speed of 70 knots and to enhance the long-range detection sensitivity for larger neutron sources, i.e., detection ranges above 1000 feet. In order to increase the sensitivity of aerial neutron detection instruments, it is important to understand the dynamics of the neutron background as a function of altitude. For aerial neutron detection, studies have shown that the neutron background primarily originates from above the aircraft, being produced in the upper atmosphere by galactic cosmic-ray interactions with air molecules. These interactions produce energetic neutrons and charged particles that cascade to the earth’s surface, producing additional neutrons in secondary collisions. Hence, the neutron background increases as a function of altitude which is an impediment to long-range neutron detection. In order to increase the sensitivity for long range detection, it is necessary to maintain a low neutron background as a function of altitude. Initial investigations show the variation in the neutron background can be decreased with the application of a cosmic-ray shield. The results of the studies along with a representative data set are presented.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Potential nuclear safeguards applications for neutron generators

    SciTech Connect (OSTI)

    Lindquist, L.O.

    1980-01-01

    Many nuclear safeguards inspection instruments use neutron sources to interrogate the fissile material (commonly /sup 235/U and /sup 239/Pu) to be measured. The neutron sources currently used in these instruments are isotopics such as Californium-252, Americium-Lithium, etc. It is becoming increasingly more difficult to transport isotopic sources from one measurement location to another. This represents a significant problem for the International Atomic Energy Agency (IAEA) safeguards inspectors because they must take their safeguards instruments with them to each nuclear installation to make an independent measurement. Purpose of this paper is to review the possibility of replacing isotopic neutron sources now used in IAEA safeguards instruments with electric neutron sources such as deuterium-tritium (D-T, 14-MeV neutrons) or deuterium-deuterium (D-D, 2-MeV neutrons). The potential for neutron generators to interrogate spent-light water reactor fuel assemblies in storage pools is also reviewed.

  2. 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

  3. 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.

  4. 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)

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

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

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10²more » MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.« less

  19. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

    SciTech Connect (OSTI)

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10² MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.

  20. 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.

  1. 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

  2. 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.

  3. 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...

  4. Compact, energy EFFICIENT neutron source: enabling technology for various applications

    SciTech Connect (OSTI)

    Hershcovitch, A.; Roser, T.

    2009-12-01

    A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.

  5. Production, Distribution, and Applications of Californium-252 Neutron Sources

    SciTech Connect (OSTI)

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    reencapsulators domestically and internationally. Sealed {sup 252}Cf sources are also available for loan to agencies and subcontractors of the U.S. government and to universities for educational, research, and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of {sup 252}Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments, and irradiation of rice to induce genetic mutations.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. Deuterated polyethylene coatings for ultra-cold neutron applications

    SciTech Connect (OSTI)

    Brenner, Th.; Geltenbort, P.; Fierlinger, P.; Gutsmiedl, E.; Hollering, A.; Petzoldt, G.; Ruhstorfer, D.; Stuiber, St.; Taubenheim, B.; Windmayer, D.; Lauer, T.; Schroffenegger, J.; Zechlau, T.; Seemann, K. M.; Soltwedel, O.

    2015-09-21

    We report on the fabrication and use of deuterated polyethylene as a coating material for ultra-cold neutron (UCN) storage and transport. The Fermi potential has been determined to be 214 neV, and the wall loss coefficient η is 1.3 × 10{sup 4} per wall collision. The coating technique allows for a wide range of applications in this field of physics. In particular, flexible and quasi-massless UCN guides with slit-less shutters and seamless UCN storage volumes become possible. These properties enable the use in next-generation measurements of the electric dipole moment of the neutron.

  16. 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.

  17. 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 ...

  18. (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.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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)

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Nickel-based gadolinium alloy for neutron adsorption application...

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 11 ... NEUTRONS; NUCLEAR FUELS; SPENT FUELS; TESTING; THERMAL NEUTRONS; YUCCA MOUNTAIN Word ...

  14. Application of nuclear models to neutron nuclear cross section calculations

    SciTech Connect (OSTI)

    Young, P.G.

    1982-01-01

    Nuclear theory is used increasingly to supplement and extend the nuclear data base that is available for applied studies. Areas where theoretical calculations are most important include the determination of neutron cross sections for unstable fission products and transactinide nuclei in fission reactor or nuclear waste calculations and for meeting the extensive dosimetry, activation, and neutronic data needs associated with fusion reactor development, especially for neutron energies above 14 MeV. Considerable progress has been made in the use of nuclear models for data evaluation and, particularly, in the methods used to derive physically meaningful parameters for model calculations. Theoretical studies frequently involve use of spherical and deformed optical models, Hauser-Feshbach statistical theory, preequilibrium theory, direct-reaction theory, and often make use of gamma-ray strength function models and phenomenological (or microscopic) level density prescriptions. The development, application, and limitations of nuclear models for data evaluation are discussed, with emphasis on the 0.1 to 50 MeV energy range. (91 references).

  15. 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.

  16. Green Zia Application Sandia National Laboratories' Neutron Generator Production Facility

    SciTech Connect (OSTI)

    SAAD, MAX P.; RICHARDSON, ANASTASIA DAWN

    2003-03-01

    The Green Zia Environmental Excellence Program is a voluntary program designed to support and assist all New Mexico businesses to achieve environmental excellence through continuous improvement and effective energy management. The program encourages integration of environmental excellence into business operations and management practices through the establishment of a prevention-based environmental management system. The Neutron Generator Production Facility has participated in the Green Zia Environmental Excellence Program for two years. This document is the submittal application for inclusion in the 2003 Green Zia program year.

  17. Plutonium Measurements with a Fast-Neutron Multiplicity Counter for Nuclear Safeguards Applications

    SciTech Connect (OSTI)

    Jennifer L. Dolan; Marek Flaska; Alexis Poitrasson-Riviere; Andreas Enqvist; Paolo Peerani; David L. Chichester; Sara A. Pozzi

    2014-11-01

    Measurements were performed at the Joint Research Centre in Ispra, Italy to field test a fast-neutron multiplicity counter developed at the University of Michigan. The measurements allowed the illustration of the system’s photon discrimination abilities, efficiency when measuring neutron multiplicity, ability to characterize 240Pueff mass, and performance relative to a currently deployed neutron coincidence counter. This work is motivated by the need to replace and improve upon 3He neutron detection systems for nuclear safeguards applications.

  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

    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.

  19. 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.

  20. 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

  1. 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.

  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. 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.

  4. 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.

  5. Vibrational spectra of light and heavy water with application to neutron cross section calculations

    SciTech Connect (OSTI)

    Damian, J. I. Marquez; Granada, J. R.; Malaspina, D. C.

    2013-07-14

    The design of nuclear reactors and neutron moderators require a good representation of the interaction of low energy (E < 1 eV) neutrons with hydrogen and deuterium containing materials. These models are based on the dynamics of the material, represented by its vibrational spectrum. In this paper, we show calculations of the frequency spectrum for light and heavy water at room temperature using two flexible point charge potentials: SPC-MPG and TIP4P/2005f. The results are compared with experimental measurements, with emphasis on inelastic neutron scattering data. Finally, the resulting spectra are applied to calculation of neutron scattering cross sections for these materials, which were found to be a significant improvement over library data.

  6. 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

  7. 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

  8. Alternative materials to cadmium for neutron absorbers in safeguards applications

    SciTech Connect (OSTI)

    Freeman, Corey R [Los Alamos National Laboratory; Geist, William H [Los Alamos National Laboratory; West, James D [Los Alamos National Laboratory

    2009-01-01

    Cadmium is increasingly difficult to use in safeguards applications because of rising cost and increased safety regulations. This work examines the properties of two materials produced by Ceradyne, inc. that present alternatives to cadmium for neutron shielding. The first is an aluminum metal doped with boron and the second is a boron carbide powder, compressed into a ceramic. Both are enriched in the {sup 10}B isotope. Two sheets of boron doped aluminum (1.1 mm and 5.2mm thick) and one sheet of boron carbide (8.5mm thick) were provided by Ceradyne for testing. An experiment was designed to test the neutron absorption capabilities of these three sheets against two different thicknesses of cadmium (0.6mm and 1.6mm thick). The thinner piece of aluminum boron alloy (1.1mm) performed as well as the cadmium pieces at absorbing neutrons. The thicker aluminum-boron plate provided more shielding than the cadmium sheets and the boron carbide performed best by a relatively large margin. Monte Carlo N-Particle eXtended (MCNPX) transport code modeling of the experiment was performed to provide validaLed computational tools for predicting the behavior of systems in which these materials may be incorporated as alternatives to cadmium. MCNPX calculations predict that approximately 0.17mm of the boron carbide is equivalent to 0.6mm of cadmium. There are drawbacks to these materials that need to be noted when considering using them as replacements for cadmium. Notably, they may need to be thicker than cadmium, and are not malleable, requiring machining to fit any curved forms.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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)

  8. 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.

  9. Quasielastic neutron scattering with in situ humidity control: Water dynamics in uranyl fluoride

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

    Miskowiec, A.; Kirkegaard, M. C.; Herwig, K. W.; Trowbridge, L.; Mamontov, E.; Anderson, B.

    2016-03-04

    The authors confirm that water vapor pressure is the driving thermodynamic force for the conversion of the anhydrous structure to [(UO2F2)(H2O)]7 ? (H2O)4, and they demonstrate the feasibility of extending this approach to aqueous forms of UO2F2+ xH2O. This method has general applicability to systems in which water content itself is a driving variable for structural or dynamical phase transitions.

  10. Analytical evaluation of atomic form factors: Application to Rayleigh scattering

    SciTech Connect (OSTI)

    Safari, L.; Santos, J. P.; Amaro, P.; Jnkl, K.; Fratini, F.

    2015-05-15

    Atomic form factors are widely used for the characterization of targets and specimens, from crystallography to biology. By using recent mathematical results, here we derive an analytical expression for the atomic form factor within the independent particle model constructed from nonrelativistic screened hydrogenic wave functions. The range of validity of this analytical expression is checked by comparing the analytically obtained form factors with the ones obtained within the Hartee-Fock method. As an example, we apply our analytical expression for the atomic form factor to evaluate the differential cross section for Rayleigh scattering off neutral atoms.

  11. Dynamics and structure in complex liquids under shear explored by neutron scattering

    SciTech Connect (OSTI)

    Wolff, Max; Magerl, Andreas; Frick, Bernhard; Zabel, Hartmut

    2005-01-01

    It is well established that the structural order of macromolecules can be affected by the application of shear. For example, triblock copolymers in aqueous solutions are known to aggregate for high concentrations. For increasing temperature the polymer micelles crystallize and offer a model system for the investigation of percolation and crystallization. The crystalline phases rearrange under shear. We correlate the structural assemblages of polymer micelles to the microscopic dynamics of the polymer monomers as well as to the solvent molecules at rest and under shear. We find the monomer dynamics affected by the different arrangements of the polymer micelles in aqueous solutions. For pronounced structural ordering we report on the monomer diffusion to become anisotropic under shear, with the diffusive mode in the direction of the shear gradient being slowed down with respect to that in the direction of the flow.

  12. 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.

  13. 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.

  14. High voltage supply for neutron tubes in well logging applications

    DOE Patents [OSTI]

    Humphreys, D. Russell

    1989-01-01

    A high voltage supply is provided for a neutron tube used in well logging. The "biased pulse" supply of the invention combines DC and "full pulse" techniques and produces a target voltage comprising a substantial negative DC bias component on which is superimposed a pulse whose negative peak provides the desired negative voltage level for the neutron tube. The target voltage is preferably generated using voltage doubling techniques and employing a voltage source which generates bipolar pulse pairs having an amplitude corresponding to the DC bias level.

  15. Application of neutron-activation analysis to geological materials

    SciTech Connect (OSTI)

    Laul, J.C.; Wogman, N.A.

    1980-12-01

    Neutron activation analysis (NAA) is an extremely sensitive, selective, and precise method, which yields a wealth of elemental information from even a small-sized sample. By varying neutron fluxes, irradiation times, decay and counting intervals in instrumental NAA, it is possible to accurately determine about 35 elements in a geological aliquot. When INAA is coupled with coincidence-noncoincidence Ge(Li)-Na(Tl) counting, it enhances the sensitivities of various elements by order of magnitude. The attractive features of INAA are that it is fast, nondestructive and economical.

  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. 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.

  18. 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.

  19. 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 ...

  20. 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...

  1. APPLICATION OF THE FIXED NEUTRON ABSORBER STANDARD ANSI/ANS-8.21

    SciTech Connect (OSTI)

    TOFFER, H.

    2004-07-26

    The specific applications standard, ANSI/ANS-8.21, provides guidance and insight in the use of fixed neutron absorbers. Organizations involved with handling and processing fissionable material will benefit from the systematic guidance provided by the standard in implementing engineered criticality safety controls. Numerous applications have demonstrated the successful implementation of fixed neutron absorbers as engineered safety features replacing administrative controls and substantial increases in mass loading. Upgrading the scope and usefulness of the standard by expanding the appendices is in progress.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. A Wide Range Neutron Detector for Space Nuclear Reactor Applications

    SciTech Connect (OSTI)

    Nassif, Eduardo; Sismonda, Miguel; Matatagui, Emilio; Pretorius, Stephan

    2007-01-30

    We propose here a versatile and innovative solution for monitoring and controlling a space-based nuclear reactor that is based on technology already proved in ground based reactors. A Wide Range Neutron Detector (WRND) allows for a reduction in the complexity of space based nuclear instrumentation and control systems. A ground model, predecessor of the proposed system, has been installed and is operating at the OPAL (Open Pool Advanced Light Water Research Reactor) in Australia, providing long term functional data. A space compatible Engineering Qualification Model of the WRND has been developed, manufactured and verified satisfactorily by analysis, and is currently under environmental testing.

  10. 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