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Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Three-dimensional boron particle loaded thermal neutron detector  

DOE Patents [OSTI]

Three-dimensional boron particle loaded thermal neutron detectors utilize neutron sensitive conversion materials in the form of nano-powders and micro-sized particles, as opposed to thin films, suspensions, paraffin, etc. More specifically, methods to infiltrate, intersperse and embed the neutron nano-powders to form two-dimensional and/or three-dimensional charge sensitive platforms are specified. The use of nano-powders enables conformal contact with the entire charge-collecting structure regardless of its shape or configuration.

Nikolic, Rebecca J.; Conway, Adam M.; Graff, Robert T.; Kuntz, Joshua D.; Reinhardt, Catherine; Voss, Lars F.; Cheung, Chin Li; Heineck, Daniel

2014-09-09T23:59:59.000Z

2

Neutron detector  

DOE Patents [OSTI]

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.

Stephan, Andrew C. (Knoxville, TN); Jardret; Vincent D. (Powell, TN)

2011-04-05T23:59:59.000Z

3

Thermal Neutron Detectors with Discrete Anode Pad Readout  

SciTech Connect (OSTI)

A new two-dimensional thermal neutron detector concept that is capable of very high rates is being developed. It is based on neutron conversion in {sup 3}He in an ionization chamber (unity gas gain) that uses only a cathode and anode plane; there is no additional electrode such as a Frisch grid. The cathode is simply the entrance window, and the anode plane is composed of discrete pads, each with their own readout electronics implemented via application specific integrated circuits. The aim is to provide a new generation of detectors with key characteristics that are superior to existing techniques, such as higher count rate capability, better stability, lower sensitivity to background radiation, and more flexible geometries. Such capabilities will improve the performance of neutron scattering instruments at major neutron user facilities. In this paper, we report on progress with the development of a prototype device that has 48 x 48 anode pads and a sensitive area of 24cm x 24cm.

Yu,B.; Schaknowski, N.A., Smith, G.C., DeGeronimo, G., Vernon, E.O.

2008-10-19T23:59:59.000Z

4

Thermal neutron detection system  

DOE Patents [OSTI]

According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

2000-01-01T23:59:59.000Z

5

Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers  

SciTech Connect (OSTI)

We propose a technique for thermal neutron detection, based on a {sup 6}Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

Barbagallo, Massimo; Greco, Giuseppe; Scire, Carlotta; Scire, Sergio [INFN Laboratori Nazionali del Sud, via S. Sofia 62, 95125 Catania (Italy); Ansaldo Nucleare S.p.A., corso Perrone 25, 16161 Genova (Italy); Cosentino, Luigi; Pappalardo, Alfio; Finocchiaro, Paolo [INFN Laboratori Nazionali del Sud, via S. Sofia 62, 95125 Catania (Italy); Montereali, Rosa Maria; Vincenti, Maria Aurora [ENEA C.R. Frascati, Via Enrico Fermi, 45, 00044 Frascati, Roma (Italy)

2010-09-15T23:59:59.000Z

6

An investigation of the elimination of detector perturbations in pure thermal neutron fluxes  

E-Print Network [OSTI]

AN INVESTIGATION OF THE ELIMINATION OF DETECTOR PERTURBATIONS IN PURE THERMAL NEUTRON FLUXES A Thesis By Donald Everett Feltz Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1963 Major Subject Nuclear Engineering AN INVESTIGATION OF THE ELIMINATION OF DETECTOR PERTURBATIONS IN PURE THERMAL NEUTRON FLUXES A Thesis By Donald E~rerett Fettz Approx~ed as to style...

Feltz, Donald Everett

2012-06-07T23:59:59.000Z

7

Rhodium self-powered neutron detector as a suitable on-line thermal neutron flux monitor in BNCT treatments  

SciTech Connect (OSTI)

Purpose: A rhodium self-powered neutron detector (Rh SPND) has been specifically developed by the Comision Nacional de Energia Atomica (CNEA) of Argentina to measure locally and in real time thermal neutron fluxes in patients treated with boron neutron capture therapy (BNCT). In this work, the thermal and epithermal neutron response of the Rh SPND was evaluated by studying the detector response to two different reactor spectra. In addition, during clinical trials of the BNCT Project of the CNEA, on-line neutron flux measurements using the specially designed detector were assessed. Methods: The first calibration of the detector was done with the well-thermalized neutron spectrum of the CNEA RA-3 reactor thermal column. For this purpose, the reactor spectrum was approximated by a Maxwell-Boltzmann distribution in the thermal energy range. The second calibration was done at different positions along the central axis of a water-filled cylindrical phantom, placed in the mixed thermal-epithermal neutron beam of CNEA RA-6 reactor. In this latter case, the RA-6 neutron spectrum had been well characterized by both calculation and measurement, and it presented some marked differences with the ideal spectrum considered for SPND calibrations at RA-3. In addition, the RA-6 neutron spectrum varied with depth in the water phantom and thus the percentage of the epithermal contribution to the total neutron flux changed at each measurement location. Local (one point-position) and global (several points-positions) and thermal and mixed-field thermal neutron sensitivities were determined from these measurements. Thermal neutron flux was also measured during BNCT clinical trials within the irradiation fields incident on the patients. In order to achieve this, the detector was placed on patient's skin at dosimetric reference points for each one of the fields. System stability was adequate for this kind of measurement. Results: Local mixed-field thermal neutron sensitivities and global thermal and mixed-field thermal neutron sensitivities derived from measurements performed at the RA-6 were compared and no significant differences were found. Global RA-6-based thermal neutron sensitivity showed agreement with pure thermal neutron sensitivity measurements performed in the RA-3 spectrum. Additionally, the detector response proved nearly unchanged by differences in neutron spectra from real (RA-6 BNCT beam) and ideal (considered for calibration calculations at RA-3) neutron source descriptions. The results confirm that the special design of the Rh SPND can be considered as having a pure thermal response for neutron spectra with epithermal-to-thermal flux ratios up to 12%. In addition, the linear response of the detector to thermal flux allows the use of a mixed-field thermal neutron sensitivity of 1.95 {+-} 0.05 x 10{sup -21} A n{sup -1}{center_dot}cm{sup 2}{center_dot}s. This sensitivity can be used in spectra with up to 21% epithermal-to-thermal flux ratio without significant error due to epithermal neutron and gamma induced effects. The values of the measured fluxes in clinical applications had discrepancies with calculated results that were in the range of -25% to +30%, which shows the importance of a local on-line independent measurement as part of a treatment planning quality control system. Conclusions: The usefulness of the CNEA Rh SPND for the on-line local measurement of thermal neutron flux on BNCT patients has been demonstrated based on an appropriate neutron spectra calibration and clinical applications.

Miller, Marcelo E.; Sztejnberg, Manuel L.; Gonzalez, Sara J.; Thorp, Silvia I.; Longhino, Juan M.; Estryk, Guillermo [Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429 (Argentina); Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429, Argentina and CONICET, Av. Rivadavia 1917, Ciudad de Buenos Aires 1033 (Argentina); Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429 (Argentina)

2011-12-15T23:59:59.000Z

8

Numerical Simulations of Pillar Structured Solid State Thermal Neutron Detector Efficiency and Gamma Discrimination  

SciTech Connect (OSTI)

This work reports numerical simulations of a novel three-dimensionally integrated, {sup 10}boron ({sup 10}B) and silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and {sup 7}Li) created from the neutron - {sup 10}B reaction. In this work, the effect of both the 3-D geometry (including pillar diameter, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the measurement results. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.

Conway, A; Wang, T; Deo, N; Cheung, C; Nikolic, R

2008-06-24T23:59:59.000Z

9

High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation  

DOE Patents [OSTI]

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

1987-02-27T23:59:59.000Z

10

Layered semiconductor neutron detectors  

DOE Patents [OSTI]

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Mao, Samuel S; Perry, Dale L

2013-12-10T23:59:59.000Z

11

Fiber optic thermal/fast neutron and gamma ray scintillation detector  

DOE Patents [OSTI]

A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

Neal, John S. (Knoxville, TN); Mihalczo, John T (Oak Ridge, TN)

2007-10-30T23:59:59.000Z

12

Neutron coincidence detectors employing heterogeneous materials  

DOE Patents [OSTI]

A neutron detector relies upon optical separation of different scintillators to measure the total energy and/or number of neutrons from a neutron source. In pulse mode embodiments of the invention, neutrons are detected in a first detector which surrounds the neutron source and in a second detector surrounding the first detector. An electronic circuit insures that only events are measured which correspond to neutrons first detected in the first detector followed by subsequent detection in the second detector. In spectrometer embodiments of the invention, neutrons are thermalized in the second detector which is formed by a scintillator-moderator and neutron energy is measured from the summed signals from the first and second detectors.

Czirr, J. Bartley (Mapleton, UT); Jensen, Gary L. (Orem, UT)

1993-07-27T23:59:59.000Z

13

Ultrafast neutron detector  

DOE Patents [OSTI]

A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

Wang, C.L.

1985-06-19T23:59:59.000Z

14

THERMAL NEUTRON BACKSCATTER IMAGING.  

SciTech Connect (OSTI)

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

2004-10-16T23:59:59.000Z

15

Semiconductor neutron detector  

DOE Patents [OSTI]

A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

Ianakiev, Kiril D. (Los Alamos, NM); Littlewood, Peter B. (Cambridge, GB); Blagoev, Krastan B. (Arlington, VA); Swinhoe, Martyn T. (Los Alamos, NM); Smith, James L. (Los Alamos, NM); Sullivan, Clair J. (Los Alamos, NM); Alexandrov, Boian S. (Los Alamos, NM); Lashley, Jason Charles (Santa Fe, NM)

2011-03-08T23:59:59.000Z

16

Pocked surface neutron detector  

DOE Patents [OSTI]

The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

2003-04-08T23:59:59.000Z

17

Pulsed neutron detector  

DOE Patents [OSTI]

A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

Robertson, deceased, J. Craig (late of Albuquerque, NM); Rowland, Mark S. (Livermore, CA)

1989-03-21T23:59:59.000Z

18

Shifting scintillator neutron detector  

DOE Patents [OSTI]

Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

2014-03-04T23:59:59.000Z

19

Porous material neutron detector  

DOE Patents [OSTI]

A neutron detector employs a porous material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the porous material layer to further amplify the electrons exiting the porous material layer.

Diawara, Yacouba (Oak Ridge, TN); Kocsis, Menyhert (Venon, FR)

2012-04-10T23:59:59.000Z

20

Solid state neutron detector array  

DOE Patents [OSTI]

A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors. 7 figs.

Seidel, J.G.; Ruddy, F.H.; Brandt, C.D.; Dulloo, A.R.; Lott, R.G.; Sirianni, E.; Wilson, R.O.

1999-08-17T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Solid state neutron detector array  

DOE Patents [OSTI]

A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors.

Seidel, John G. (Pittsburgh, PA); Ruddy, Frank H. (Monroeville, PA); Brandt, Charles D. (Mount Lebanon, PA); Dulloo, Abdul R. (Pittsburgh, PA); Lott, Randy G. (Pittsburgh, PA); Sirianni, Ernest (Monroeville, PA); Wilson, Randall O. (Greensburg, PA)

1999-01-01T23:59:59.000Z

22

Directional Response of Microstructure Solid State Thermal Neutron Detectors Justin Dingleya  

E-Print Network [OSTI]

, such as the inclusion of micron and sub-micron scale structures4,5 and the development of solar-cell type devices application of these devices; the detector (or detector stack) would need to be covered by or encapsulated

Danon, Yaron

23

Neutron detectors comprising boron powder  

SciTech Connect (OSTI)

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

2013-05-21T23:59:59.000Z

24

Ion chamber based neutron detectors  

DOE Patents [OSTI]

A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

2014-12-16T23:59:59.000Z

25

Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object  

DOE Patents [OSTI]

The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

Crane, Thomas W. (Los Alamos, NM)

1986-01-01T23:59:59.000Z

26

A novel solid-state self powered neutron detector Nicholas LiCausi*a  

E-Print Network [OSTI]

A novel solid-state self powered neutron detector Nicholas LiCausi*a , Justin Dingleyb , Yaron procedures. Keywords: Neutron detector, thermal neutrons, solid-state detector, DRIE, computer simulations 1 source and could be entirely self-powered. With no moving parts it would be robust and work in a variety

Danon, Yaron

27

Optimization of a neutron detector design using adjoint transport simulation  

SciTech Connect (OSTI)

A synthetic aperture approach has been developed and investigated for Special Nuclear Materials (SNM) detection in vehicles passing a checkpoint at highway speeds. SNM is postulated to be stored in a moving vehicle and detector assemblies are placed on the road-side or in chambers embedded below the road surface. Neutron and gamma spectral awareness is important for the detector assembly design besides high efficiencies, so that different SNMs can be detected and identified with various possible shielding settings. The detector assembly design is composed of a CsI gamma-ray detector block and five neutron detector blocks, with peak efficiencies targeting different energy ranges determined by adjoint simulations. In this study, formulations are derived using adjoint transport simulations to estimate detector efficiencies. The formulations is applied to investigate several neutron detector designs for Block IV, which has its peak efficiency in the thermal range, and Block V, designed to maximize the total neutron counts over the entire energy spectrum. Other Blocks detect different neutron energies. All five neutron detector blocks and the gamma-ray block are assembled in both MCNP and deterministic simulation models, with detector responses calculated to validate the fully assembled design using a 30-group library. The simulation results show that the 30-group library, collapsed from an 80-group library using an adjoint-weighting approach with the YGROUP code, significantly reduced the computational cost while maintaining accuracy. (authors)

Yi, C.; Manalo, K.; Huang, M.; Chin, M.; Edgar, C.; Applegate, S.; Sjoden, G. [Georgia Inst. of Technology, Gilhouse Boggs Bldg., 770 State St, Atlanta, GA 30332-0745 (United States)

2012-07-01T23:59:59.000Z

28

ATRC Neutron Detector Testing Quick Look Report  

SciTech Connect (OSTI)

As part of the Advanced Test Reactor (ATR) National Scientific User Facility (NSUF) program, a joint Idaho State University (ISU) / French Alternative Energies and Atomic Energy Commission (CEA) / Idaho National Laboratory (INL) project was initiated in FY-10 to investigate the feasibility of using neutron sensors to provide online measurements of the neutron flux and fission reaction rate in the ATR Critical Facility (ATRC). A second objective was to provide initial neutron spectrum and flux distribution information for physics modeling and code validation using neutron activation based techniques in ATRC as well as ATR during depressurized operations. Detailed activation spectrometry measurements were made in the flux traps and in selected fuel elements, along with standard fission rate distribution measurements at selected core locations. These measurements provide additional calibration data for the real-time sensors of interest as well as provide benchmark neutronics data that will be useful for the ATR Life Extension Program (LEP) Computational Methods and V&V Upgrade project. As part of this effort, techniques developed by Prof. George Imel will be applied by Idaho State University (ISU) for assessing the performance of various flux detectors to develop detailed procedures for initial and follow-on calibrations of these sensors. In addition to comparing data obtained from each type of detector, calculations will be performed to assess the performance of and reduce uncertainties in flux detection sensors and compare data obtained from these sensors with existing integral methods employed at the ATRC. The neutron detectors required for this project were provided to team participants at no cost. Activation detectors (foils and wires) from an existing, well-characterized INL inventory were employed. Furthermore, as part of an on-going ATR NSUF international cooperation, the CEA sent INL three miniature fission chambers (one for detecting fast flux and two for detecting thermal flux) with associated electronics for assessment. In addition, Prof. Imel, ISU, has access to an inventory of Self-Powered Neutron Detectors (SPNDs) with a range of response times as well as Back-to-Back (BTB) fission chambers from prior research he conducted at the Transient REActor Test Facility (TREAT) facility and Neutron RADiography (NRAD) reactors. Finally, SPNDs from the National Atomic Energy Commission of Argentina (CNEA) were provided in connection with the INL effort to upgrade ATR computational methods and V&V protocols that are underway as part of the ATR LEP. Work during fiscal year 2010 (FY10) focussed on design and construction of Experiment Guide Tubes (EGTs) for positioning the flux detectors in the ATRC N-16 locations as well as obtaining ATRC staff concurrence for the detector evaluations. Initial evaluations with CEA researchers were also started in FY10 but were cut short due to reactor reliability issues. Reactor availability issues caused experimental work to be delayed during FY11/12. In FY13, work resumed; and evaluations were completed. The objective of this "Quick Look" report is to summarize experimental activities performed from April 4, 2013 through May 16, 2013.

Troy C. Unruh; Benjamin M. Chase; Joy L. Rempe

2013-08-01T23:59:59.000Z

29

IMPROVEMENTS IN CODED APERTURE THERMAL NEUTRON IMAGING.  

SciTech Connect (OSTI)

A new thermal neutron imaging system has been constructed, based on a 20-cm x 17-cm He-3 position-sensitive detector with spatial resolution better than 1 mm. New compact custom-designed position-decoding electronics are employed, as well as high-precision cadmium masks with Modified Uniformly Redundant Array patterns. Fast Fourier Transform algorithms are incorporated into the deconvolution software to provide rapid conversion of shadowgrams into real images. The system demonstrates the principles for locating sources of thermal neutrons by a stand-off technique, as well as visualizing the shapes of nearby sources. The data acquisition time could potentially be reduced two orders of magnitude by building larger detectors.

VANIER,P.E.

2003-08-03T23:59:59.000Z

30

Neutrino Physics with Thermal Detectors  

SciTech Connect (OSTI)

The investigation of fundamental neutrino properties like its mass and its nature calls for the design of a new generation of experiments. High sensitivity, high energy resolution, and versatility together with the possibility of a simple multiplexing scheme are the key features of future detectors for these experiments. Thermal detectors can combine all these features. This paper reviews the status and the perspectives for what concerns the application of this type of detectors to neutrino physics, focusing on direct neutrino mass measurements and neutrinoless double beta decay searches.

Nucciotti, A. [Dipartimento di Fisica, Universita di Milano Bicocca and INFN Sezione di Milano-Bicocca Piazza della Scienza, 3, 20126 Milano (Italy)

2009-11-09T23:59:59.000Z

31

Neutron detector using sol-gel absorber  

DOE Patents [OSTI]

An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

Hiller, John M. (Oak Ridge, TN); Wallace, Steven A. (Oak Ridge, TN); Dai, Sheng (Knoxville, TN)

1999-01-01T23:59:59.000Z

32

Lithium Loaded Glass Fiber Neutron Detector Tests  

SciTech Connect (OSTI)

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. Reported here are the results of tests of the lithium-loaded glass fibers option. This testing measured the neutron detection efficiency and gamma ray rejection capabilities of a small system manufactured by Nucsafe (Oak Ridge, TN).

Ely, James H.; Erikson, Luke E.; Kouzes, Richard T.; Lintereur, Azaree T.; Stromswold, David C.

2009-11-12T23:59:59.000Z

33

Development of A Self Biased High Efficiency Solid-State Neutron Detector for MPACT Applications  

SciTech Connect (OSTI)

Neutron detection is an important aspect of materials protection, accounting, and control for transmutation (MPACT). Currently He-3 filled thermal neutron detectors are utilized in many applications; these detectors require high-voltage bias for operation, which complicates the system when multiple detectors are used. In addition, due to recent increase in homeland security activity and the nuclear renaissance, there is a shortage of He-3, and these detectors become more expensive. Instead, cheap solid-state detectors that can be mass produced like any other computer chips will be developed. The new detector does not require a bias for operation, has low gamma sensitivity, and a fast response. The detection system is based on a honeycomb-like silicon device, which is filled with B-10 as the neutron converter; while a silicon p-n diode (i.e., solar cell type device) formed on the thin silicon wall of the honeycomb structure detects the energetic charged particles emitted from the B-10 conversion layer. Such a detector has ~40% calculated thermal neutron detection efficiency with an overall detector thickness of about 200 ?m. Stacking of these devices allows over 90% thermal neutron detection efficiency. The goal of the proposed research is to develop a high-efficiency, low-noise, self-powered solid-state neutron detector system based on the promising results of the existing research program. A prototype of this solid-state neutron detector system with sufficient detector size (up to 8-inch diam., but still portable and inexpensive) and integrated with interface electronics (e.g., preamplifier) will be designed, fabricated, and tested as a coincidence counter for MPACT applications. All fabrications proposed are based on silicon-compatible processing; thus, an extremely cheap detector system could be massively produced like any other silicon chips. Such detectors will revolutionize current neutron detection systems by providing a solid-state alternative to traditional gas-based neutron detectors.

Danon, Yaron; Bhat, Ishwara; Jian-Qiang Lu, James

2013-09-03T23:59:59.000Z

34

Neutron Position Sensitive Detectors for the ESS  

E-Print Network [OSTI]

The European Spallation Source (ESS) in Lund, Sweden will become the world's leading neutron source for the study of materials. The instruments are being selected from conceptual proposals submitted by groups from around Europe. These instruments present numerous challenges for detector technology in the absence of the availability of Helium-3, which is the default choice for detectors for instruments built until today and due to the extreme rates expected across the ESS instrument suite. Additionally a new generation of source requires a new generation of detector technologies to fully exploit the opportunities that this source provides. The detectors will be sourced from partners across Europe through numerous in-kind arrangements; a process that is somewhat novel for the neutron scattering community. This contribution presents briefly the current status of detectors for the ESS, and outlines the timeline to completion. For a conjectured instrument suite based upon instruments recommended for construction, ...

Kirstein, Oliver; Stefanescu, Irina; Etxegarai, Maddi; Anastasopoulos, Michail; Fissum, Kevin; Gulyachkina, Anna; Höglund, Carina; Imam, Mewlude; Kanaki, Kalliopi; Khaplanov, Anton; Kittelmann, Thomas; Kolya, Scott; Nilsson, Björn; Ortega, Luis; Pfeiffer, Dorothea; Piscitelli, Francesco; Ramos, Judith Freita; Robinson, Linda; Scherzinger, Julius

2014-01-01T23:59:59.000Z

35

Author's personal copy Microstructured semiconductor neutron detectors  

E-Print Network [OSTI]

neutron cross section of 6 LiF is 57:51 cmÃ?1 with a mass density of 2:54 g cmÃ?3 . When thermal neutrons area of the shallow channels will increase the overall detection efficiency, which is only partially true. It is actually both the extended surface area and the increased probability that reaction

Shultis, J. Kenneth

36

Measurements of the Thermal Neutron Scattering Kernel  

E-Print Network [OSTI]

Measurements of the Thermal Neutron Scattering Kernel Li (Emily) Liu, Yaron Danon, Bjorn Becker and discussions Problems and Future study Questions #12;3 M. Mattes and J. Keinert, Thermal Neutron Scattering experimental data used was from 1973-1974! M. Mattes and J. Keinert, Thermal Neutron Scattering Data

Danon, Yaron

37

Cylindrical Detector and Preamplifier Design for Detecting Neutrons  

E-Print Network [OSTI]

neutrons because the recoil protons do not cross the detectors. Proportional counters simulating different site-sizes can be used to get a better neutron dose equivalent measurement since the range and stopping power of protons generated by neutrons...

Xia, Zhenghua

2010-01-14T23:59:59.000Z

38

Proposed experiment to measure {gamma}-rays from the thermal neutron capture of gadolinium  

SciTech Connect (OSTI)

Gadolinium-157 ({sup 157}Gd) has the largest thermal neutron capture cross section among any stable nuclei. The thermal neutron capture yields {gamma}-ray cascade with total energy of about 8 MeV. Because of these characteristics, Gd is applied for the recent neutrino detectors. Here, we propose an experiment to measure the multiplicity and the angular correlation of {gamma}-rays from the Gd neutron capture. With these information, we expect the improved identification of the Gd neutron capture.

Yano, Takatomi; Ou, I.; Izumi, T.; Yamaguchi, R.; Mori, T.; Sakuda, M. [Department of Physics, Okayama University, Okayama, 700-8530 (Japan)

2012-11-12T23:59:59.000Z

39

High efficiency proportional neutron detector with solid liner internal structures  

DOE Patents [OSTI]

A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.

Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

2014-08-05T23:59:59.000Z

40

Thermal Neutron Imaging in an Active Interrogation Environment  

SciTech Connect (OSTI)

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutron-emitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier, Peter E. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Forman, Leon [Ion Focus Technology, Inc., Miller Place, NY 11764 (United States); Norman, Daren R. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2009-03-10T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Diagnostic of fusion neutrons on JET tokamak using diamond detector  

SciTech Connect (OSTI)

In 2011-2012, an experimental campaign with a significant yield of fusion neutrons was carried out on the JET tokamak. During this campaign the facility was equipped with two diamond detectors based on natural and artificial CVD diamond. These detectors were designed and manufactured in State Research Center of Russian Federation TRINITI. The detectors measure the flux of fast neutrons with energies above 0.2 MeV. They have been installed in the torus hall and the distance from the center of plasma was about 3 m. For some of the JET pulses in this experiment, the neutron flux density corresponded to the operational conditions in collimator channels of ITER Vertical Neutron Camera. The main objective of diamond monitors was the measurement of total fast neutron flux at the detector location and the estimation of the JET total neutron yield. The detectors operate as threshold counters. Additionally a spectrometric measurement channel has been configured that allowed us to distinguish various energy components of the neutron spectrum. In this paper we describe the neutron signal measuring and calibration procedure of the diamond detector. Fluxes of DD and DT neutrons at the detector location were measured. It is shown that the signals of total neutron yield measured by the diamond detector correlate with signals measured by the main JET neutron diagnostic based on fission chambers with high accuracy. This experiment can be considered as a successful test of diamond detectors in ITER-like conditions.

Nemtsev, G.; Amosov, V.; Marchenko, N.; Meshchaninov, S.; Rodionov, R. [Institution Project center ITER, Moscow (Russian Federation); Popovichev, S. [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon, OXON, OX14 3DB (United Kingdom); Collaboration: JET EFDA Conbributors

2014-08-21T23:59:59.000Z

42

Hand Held Neutron Detector Development for Physics and Security Applications  

E-Print Network [OSTI]

neutrons are slowed to thermal using hydrogenous material such as polyethylene where the thermal neutrons are easily captured by either a gadolinium or boron source. Both boron and gadolinium release ionizing radiation in the form of alpha and gammas upon...

Campbell, Caitlin E

2013-10-04T23:59:59.000Z

43

Thermal neutron imaging in an active interrogation environment  

SciTech Connect (OSTI)

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier,P.E.; Forman, L., and Norman, D.R.

2009-03-10T23:59:59.000Z

44

Thermal neutron shield and method of manufacture  

DOE Patents [OSTI]

A thermal neutron shield comprising boron shielding panels with a high percentage of the element Boron. The panel is least 46% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of boron shielding panels which includes enriching the pre-cursor mixture with varying grit sizes of Boron Carbide.

Metzger, Bert Clayton; Brindza, Paul Daniel

2014-03-04T23:59:59.000Z

45

Thermal neutron shield and method of manufacture  

DOE Patents [OSTI]

A thermal neutron shield comprising concrete with a high percentage of the element Boron. The concrete is least 54% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of Boron loaded concrete which includes enriching the concrete mixture with varying grit sizes of Boron Carbide.

Brindza, Paul Daniel; Metzger, Bert Clayton

2013-05-28T23:59:59.000Z

46

Determination of thermal neutron capture gamma yields  

E-Print Network [OSTI]

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01T23:59:59.000Z

47

Determination of thermal neutron capture gamma yields.  

E-Print Network [OSTI]

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01T23:59:59.000Z

48

High sensitivity, solid state neutron detector  

DOE Patents [OSTI]

An apparatus (200) for detecting slow or thermal neutrons (160) including an alpha particle-detecting layer (240) that is a hydrogenated amorphous silicon p-i-n diode structure. The apparatus includes a bottom metal contact (220) and a top metal contact (250) with the diode structure (240) positioned between the two contacts (220, 250) to facilitate detection of alpha particles (170). The apparatus (200) includes a neutron conversion layer (230) formed of a material containing boron-10 isotopes. The top contact (250) is pixilated with each contact pixel extending to or proximate to an edge of the apparatus to facilitate electrical contacting. The contact pixels have elongated bodies to allow them to extend across the apparatus surface (242) with each pixel having a small surface area to match capacitance based upon a current spike detecting circuit or amplifier connected to each pixel. The neutron conversion layer (860) may be deposited on the contact pixels (830) such as with use of inkjet printing of nanoparticle ink.

Stradins, Pauls; Branz, Howard M.; Wang, Qi; McHugh, Harold R.

2013-10-29T23:59:59.000Z

49

Neutron capture measurement on {sup 173}Lu at LANSCE with DANCE detector  

SciTech Connect (OSTI)

The (n,{gamma}) cross section on the unstable {sup 173}Lu(t{sub 1/2} = 1.37y) has been measured from thermal energy up to 200 eV at Los Alamos Neutron Science Center (LANSCE) with The Detector for Advanced Neutron Capture Experiements (DANCE). The main aim of this study is to validate and optimize reaction models for unstable nucleus. A preliminary capture yield will be presented in this paper.

Theroine, C.; Ebran, A.; Meot, V.; Roig, O. [CEA DAM DIF, F-91297 Arpajon (France); Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Nortier, F. M.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Viera, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-06-10T23:59:59.000Z

50

A Novel Detector for High Neutron Flux Measurements  

SciTech Connect (OSTI)

Measuring alpha particles from a neutron induced break-up reaction with a mass spectrometer can be an excellent tool for detecting neutrons in a high neutron flux environment. Break-up reactions of {sup 6}Li and {sup 12}C can be used in the detection of slow and fast neutrons, respectively. A high neutron flux detection system that integrates the neutron energy sensitive material and helium mass spectrometer has been developed. The description of the detector configuration is given and it is soon to be tested at iThemba LABS, South Africa.

Singo, T. D.; Wyngaardt, S. M. [Department of Physics, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa); Papka, P. [Department of Physics, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa); Nuclear Physics group, iThemba labs, P. O. Box 722, Somerset West 7129 (South Africa); Dobson, R. T. [Department of Mechanical and Mechatronic Engineering, University of Stellenbosch, Private bag X1, Matieland, Stellenbosch (South Africa)

2010-01-05T23:59:59.000Z

51

Compound Refractive Lenses for Thermal Neutron Applications  

SciTech Connect (OSTI)

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 ?m which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

Gary, Charles K.

2013-11-12T23:59:59.000Z

52

Selective Filtration of Gadolinium Trichloride for Use in Neutron Detection in Large Water Cherenkov Detectors  

SciTech Connect (OSTI)

Water Cherenkov detectors have been used for many years as inexpensive, effective detectors for neutrino interactions and nucleon decay searches. While many important measurements have been made with these detectors a major drawback has been their inability to detect the absorption of thermal neutrons. We believe an inexpensive, effective technique could be developed to overcome this situation via the addition to water of a solute with a large neutron cross section and energetic gamma daughters which would make neutrons detectable. Gadolinium seems an excellent candidate especially since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially-available gadolinium trichloride, GdCl{sub 3}. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields a gamma cascade which would be easily seen in detectors like Super-Kamiokande. We have been investigating the use of GdCl{sub 3} as a possible upgrade for the Super-Kamiokande detector with a view toward improving its performance as a detector for atmospheric neutrinos, supernova neutrinos, wrong-sign solar neutrinos, reactor neutrinos, proton decay, and also as a target for the coming T2K long-baseline neutrino experiment. This focused study of selective water filtration and GdCl{sub 3} extraction techniques, conducted at UC Irvine, followed up on highly promising benchtop-scale and kiloton-scale work previously carried out with the assistance of 2003 and 2005 Advanced Detector Research Program grants.

Vagins, Mark R.

2013-04-10T23:59:59.000Z

53

Liquid Argon Cryogenic Detector Calibration by Inelastic Scattering of Neutrons  

E-Print Network [OSTI]

A method for calibration of cryogenic liquid argon detector response to recoils with certain energy -8.2 keV - is proposed. The method utilizes a process of inelastic scattering of monoenergetic neutrons produced by fusion DD neutron generator. Features of kinematics of inelastic scattering cause sufficient (forty times) increase in count rate of useful events relative to traditional scheme exploited elastic scattering with the same recoil energy and compatible energy resolution. The benefits of the proposed scheme of calibration most well implemented with the use of tagged neutron generator as a neutron source that allows to eliminate background originated from casual coincidence of signals on cryogenic detector and additional detector of scattered neutrons.

Sergey Polosatkin; Evgeny Grishnyaev; Alexander Dolgov

2014-07-10T23:59:59.000Z

54

Neutron Interactions as Seen by A Segmented Germanium Detector  

E-Print Network [OSTI]

The GERmanium Detector Array, GERDA, is designed for the search for ``neutrinoless double beta decay'' (0-nu-2-beta) with germanium detectors enriched in Ge76. An 18-fold segmented prototype detector for GERDA Phase II was exposed to an AmBe neutron source to improve the understanding of neutron induced backgrounds. Neutron interactions with the germanium isotopes themselves and in the surrounding materials were studied. Segment information is used to identify neutron induced peaks in the recorded energy spectra. The Geant4 based simulation package MaGe is used to simulate the experiment. Though many photon peaks from germanium isotopes excited by neutrons are correctly described by Geant4, some physics processes were identified as being incorrectly treated or even missing.

I. Abt; A. Caldwell; K. Kroeninger; J. Liu; X. Liu; B. Majorovits

2007-11-14T23:59:59.000Z

55

Neutron detectors comprising ultra-thin layers of boron powder  

SciTech Connect (OSTI)

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material having a thickness of from about 50 nm to about 250 nm and comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehul; Morris, Christopher

2013-07-23T23:59:59.000Z

56

A thermal neutron source imager using coded apertures  

SciTech Connect (OSTI)

To facilitate the process of re-entry vehicle on-site inspections, it would be useful to have an imaging technique which would allow the counting of deployed multiple nuclear warheads without significant disassembly of a missile`s structure. Since neutrons cannot easily be shielded without massive amounts of materials, they offer a means of imaging the separate sources inside a sealed vehicle. Thermal neutrons carry no detailed spectral information, so their detection should not be as intrusive as gamma ray imaging. A prototype device for imaging at close range with thermal neutrons has been constructed using an array of {sup 3}He position-sensitive gas proportional counters combined with a uniformly redundant coded aperture array. A sealed {sup 252}Cf source surrounded by a polyethylene moderator is used as a test source. By means of slit and pinhole experiments, count rates of image-forming neutrons (those which cast a shadow of a Cd aperture on the detector) are compared with the count rates for background neutrons. The resulting ratio, which limits the available image contrast, is measured as a function of distance from the source. The envelope of performance of the instrument is defined by the contrast ratio, the angular resolution, and the total count rate as a function of distance from the source. These factors will determine whether such an instrument could be practical as a tool for treaty verification.

Vanier, P.E.; Forman, L.; Selcow, E.C.

1995-08-01T23:59:59.000Z

57

NEUTRON DETECTION EFFICIENCY OF THE CLAS12 DETECTOR  

E-Print Network [OSTI]

of the Jefferson Lab 12 GeV upgrade, to obtain a preliminary estimate of it's neutron detection efficiency (NDE). Knowledge of the NDE of a detector is important for calculating systematic uncertainty of neutron measurements, so knowledge of NDE is essential. An important experiment requiring knowledge of NDE is measuring

Gilfoyle, Jerry

58

Neutron counting and gamma spectroscopy with PVT detectors.  

SciTech Connect (OSTI)

Radiation portals normally incorporate a dedicated neutron counter and a gamma-ray detector with at least some spectroscopic capability. This paper describes the design and presents characterization data for a detection system called PVT-NG, which uses large polyvinyl toluene (PVT) detectors to monitor both types of radiation. The detector material is surrounded by polyvinyl chloride (PVC), which emits high-energy gamma rays following neutron capture reactions. Assessments based on high-energy gamma rays are well suited for the detection of neutron sources, particularly in border security applications, because few isotopes in the normal stream of commerce have significant gamma ray yields above 3 MeV. Therefore, an increased count rate for high-energy gamma rays is a strong indicator for the presence of a neutron source. The sensitivity of the PVT-NG sensor to bare {sup 252}Cf is 1.9 counts per second per nanogram (cps/ng) and the sensitivity for {sup 252}Cf surrounded by 2.5 cm of polyethylene is 2.3 cps/ng. The PVT-NG sensor is a proof-of-principal sensor that was not fully optimized. The neutron detector sensitivity could be improved, for instance, by using additional moderator. The PVT-NG detectors and associated electronics are designed to provide improved resolution, gain stability, and performance at high-count rates relative to PVT detectors in typical radiation portals. As well as addressing the needs for neutron detection, these characteristics are also desirable for analysis of the gamma-ray spectra. Accurate isotope identification results were obtained despite the common impression that the absence of photopeaks makes data collected by PVT detectors unsuitable for spectroscopic analysis. The PVT detectors in the PVT-NG unit are used for both gamma-ray and neutron detection, so the sensitive volume exceeds the volume of the detection elements in portals that use dedicated components to detect each type of radiation.

Mitchell, Dean James; Brusseau, Charles A.

2011-06-01T23:59:59.000Z

59

Ship Effect Measurements With Fiber Optic Neutron Detector  

SciTech Connect (OSTI)

The main objectives of this research project was to assemble, operate, test and characterize an innovatively designed scintillating fiber optic neutron radiation detector manufactured by Innovative American Technology with possible application to the Department of Homeland Security screening for potential radiological and nuclear threats at US borders (Kouzes 2004). One goal of this project was to make measurements of the neutron ship effect for several materials. The Virginia State University DOE FaST/NSF summer student-faculty team made measurements with the fiber optic radiation detector at PNNL above ground to characterize the ship effect from cosmic neutrons, and underground to characterize the muon contribution.

King, Kenneth L.; Dean, Rashe A.; Akbar, Shahzad; Kouzes, Richard T.; Woodring, Mitchell L.

2010-08-10T23:59:59.000Z

60

High-efficiency neutron detectors and methods of making same  

DOE Patents [OSTI]

Neutron detectors, advanced detector process techniques and advanced compound film designs have greatly increased neutron-detection efficiency. One embodiment of the detectors utilizes a semiconductor wafer with a matrix of spaced cavities filled with one or more types of neutron reactive material such as 10B or 6LiF. The cavities are etched into both the front and back surfaces of the device such that the cavities from one side surround the cavities from the other side. The cavities may be etched via holes or etched slots or trenches. In another embodiment, the cavities are different-sized and the smaller cavities extend into the wafer from the lower surfaces of the larger cavities. In a third embodiment, multiple layers of different neutron-responsive material are formed on one or more sides of the wafer. The new devices operate at room temperature, are compact, rugged, and reliable in design.

McGregor, Douglas S.; Klann, Raymond

2007-01-16T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy  

E-Print Network [OSTI]

Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials.

Mor, I; Bar, D; Feldman, G; Goldberg, M B; Katz, D; Sayag, E; Shmueli, I; Cohen, Y; Tal, A; Vagish, Z; Bromberger, B; Dangendorf, V; Mugai, D; Tittelmeier, K; Weierganz, M

2009-01-01T23:59:59.000Z

62

Diamond detector for high rate monitors of fast neutrons beams  

SciTech Connect (OSTI)

A fast neutron detection system suitable for high rate measurements is presented. The detector is based on a commercial high purity single crystal diamond (SDD) coupled to a fast digital data acquisition system. The detector was tested at the ISIS pulsed spallation neutron source. The SDD event signal was digitized at 1 GHz to reconstruct the deposited energy (pulse amplitude) and neutron arrival time; the event time of flight (ToF) was obtained relative to the recorded proton beam signal t{sub 0}. Fast acquisition is needed since the peak count rate is very high ({approx}800 kHz) due to the pulsed structure of the neutron beam. Measurements at ISIS indicate that three characteristics regions exist in the biparametric spectrum: i) background gamma events of low pulse amplitudes; ii) low pulse amplitude neutron events in the energy range E{sub dep}= 1.5-7 MeV ascribed to neutron elastic scattering on {sup 12}C; iii) large pulse amplitude neutron events with E{sub n} < 7 MeV ascribed to {sup 12}C(n,{alpha}){sup 9}Be and 12C(n,n')3{alpha}.

Giacomelli, L.; Rebai, M.; Cippo, E. Perelli; Tardocchi, M.; Fazzi, A.; Andreani, C.; Pietropaolo, A.; Frost, C. D.; Rhodes, N.; Schooneveld, E.; Gorini, G. [Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, and Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Milano (Italy); Energy Department, Politecnico di Milano, Milano (Italy); Dipartimento di Fisica, Centro NAST, Universita degli Studi di Roma Tor Vergata, Roma (Italy); STFC, ISIS facility, Rutherford Appleton Laboratory, Chilton Didcot Oxfordshire (United Kingdom); Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, and Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Milano (Italy)

2012-06-19T23:59:59.000Z

63

Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles  

SciTech Connect (OSTI)

A gamma-free neutron-sensitive scintillator is needed to enhance radiaition sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source.

Steven Wallace

2007-08-28T23:59:59.000Z

64

Directionally Sensitive Neutron Detector For Homeland Security Applications  

E-Print Network [OSTI]

might be able to overcome many of these limitations. This thesis presents a method to create a directionally sensitive neutron detector using a unique characteristic of 10B. This characteristic is the Doppler broadening of the de-excitation gamma-ray...

Spence, Grant

2012-02-14T23:59:59.000Z

65

NEUTRON STAR ENVELOPES AND THERMAL RADIATION FROM THE MAGNETIC SURFACE  

E-Print Network [OSTI]

NEUTRON STAR ENVELOPES AND THERMAL RADIATION FROM THE MAGNETIC SURFACE in: C. Kouveliotou, J. van.Petersburg, Russia Abstract. The thermal structure of neutron star envelopes is discussed with emphasis on analytic on the opacities and the thermal structure is further reviewed in view of the application to pulsar cooling

66

Rocky Flats Neutron Detector Testing at Valduc, France  

SciTech Connect (OSTI)

Recent program requirements of the US Department of Energy/NNSA have led to a need for a criticality accident alarm system to be installed at a newly activated facility. The Criticality Safety Group of the Lawrence Livermore National Laboratory (LLNL) was able to recover and store for possible future use approximately 200 neutron criticality detectors and 20 master alarm panels from the former Rocky Flats Plant in Golden, Colorado when the plant was closed. The Criticality Safety Group participated in a facility analysis and evaluation, the engineering design and review process, as well as the refurbishment, testing, and recalibration of the Rocky Flats criticality alarm system equipment to be used in the new facility. In order to demonstrate the functionality and survivability of the neutron detectors to the effects of an actual criticality accident, neutron detector testing was performed at the French CEA Valduc SILENE reactor from October 7 to October 19, 2010. The neutron detectors were exposed to three criticality events or pulses generated by the SILENE reactor. The first excursion was performed with a bare or unshielded reactor, and the second excursion was made with a lead shielded/reflected reactor, and the third excursion with a polyethylene reflected core. These tests of the Rocky Flats neutron detectors were performed as a part of the 2010 Criticality Accident Alarm System Benchmark Measurements at the SILENE Reactor. The principal investigators for this series of experiments were Thomas M. Miller and John C. Wagner of the Oak Ridge National Laboratory, with Nicolas Authier and Nathalie Baclet of CEA Valduc. Several other organizations were also represented, including the Y-12 National Security Complex, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, CEA Saclay, and Babcock International Group.

Kim, S S; Dulik, G M

2011-01-03T23:59:59.000Z

67

Thermal-neutron capture in light nuclei  

SciTech Connect (OSTI)

We have made considerable progress toward the goal of carrying out thermal-neutron capture {gamma}-ray measurements on all stable isotopes below A=60. Information processed till now has significantly augmented the existing knowledge on the detailed nuclear level structure of many light nuclides. Most of this knowledge comes from our {gamma}-ray energies, level placements, and branching ratios of secondary transitions between low-lying states. Spectroscopic information is also contained in the cross sections of the primary transitions originating from the capturing state. This is deduced from the success of ``direct`` theories of neutron capture for many nuclides, especially those of light and near closed-shell character. 23 refs, 1 tab, 3 figs.

Raman, S. [Oak Ridge National Lab., TN (United States); Jurney, E.T.; Lynn, J.E. [Los Alamos National Lab., NM (United States)

1996-10-01T23:59:59.000Z

68

Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source  

SciTech Connect (OSTI)

Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically, probably at a small fraction of the cost of He-3 detectors. In addition to neutron scattering science, the fully developed base technology can be used as a rugged, low-cost neutron detector in area monitoring and surveying. Radiation monitors are used in a number of other settings for occupational and environmental radiation safety. Such a detector can also be used in environmental monitoring and remote nuclear power plant monitoring. For example, the Department of Energy could use it to characterize nuclear waste dumps, coordinate clean-up efforts, and assess the radioactive contaminants in the air and water. Radiation monitors can be used to monitor the age and component breakdown of nuclear warheads and to distinguish between weapons and reactor grade plutonium. The UN's International Atomic Energy Agency (IAEA) uses radiation monitors for treaty verification, remote monitoring, and enforcing the non-proliferation of nuclear weapons. As part of treaty verification, monitors can be used to certify the contents of containers during inspections. They could be used for portal monitoring to secure border checkpoints, sea ports, air cargo centers, public parks, sporting venues, and key government buildings. Currently, only 2% of all sea cargo shipped is inspected for radiation sources. In addition, merely the presence of radiation is detected and nothing is known about the radioactive source until further testing. The utilization of radiation monitors with neutron sensitivity and capability of operation in hostile port environments would increase the capacity and effectiveness of the radioactive scanning processes.

Lacy, Jeffrey L

2009-05-22T23:59:59.000Z

69

Novel Boron-10-based detectors for Neutron Scattering Science  

E-Print Network [OSTI]

Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rate capability, spatial resolution and cost-e?ectiveness, are only a few examples of the features that must be improved to ful?fill the new requirements. On the other hand, 3He technology could still satisfy the detector requirements for large area applications (50m^2), however, because of the present 3He shortage that the world is experiencing, this is not practical anymore. The recent detector advances (the Multi-Grid and the Multi-Blade prototypes) developed in the framework of the collaboration between the Institut Laue...

Piscitelli, Francesco

2015-01-01T23:59:59.000Z

70

Solid state neutron detector and method for use  

DOE Patents [OSTI]

Crystals of lithium tetraborate or alpha-barium borate had been found to be neutron detecting materials. The crystals are prepared using known crystal growing techniques, wherein the process does not include the common practice of using a fluxing agent, such as sodium oxide or sodium fluoride, to reduce the melting temperature of the crystalline compound. Crystals prepared by this method can be sliced into thin single or polycrystalline wafers, or ground to a powder and prepared as a sintered compact or a print paste, and then configured with appropriate electronic hardware, in order to function as neutron detectors.

Doty, F. Patrick (Livermore, CA); Zwieback, Ilya (New Milford, NJ); Ruderman, Warren (Demarest, NJ)

2002-01-01T23:59:59.000Z

71

Neutron detector for fusion reaction-rate measurements  

SciTech Connect (OSTI)

We have developed a fast, sensitive neutron detector for recording the fusion reaction-rate history of inertial-confinement fusion (ICF) experiments. The detector is based on the fast rise-time of a commercial plastic scintillator (BC-422) and has a response < 25-ps FWHM. A thin piece of scintillator material acts as a neutron-to- light converter. A zoom lens images light from the scintillator surface to a high-speed (15 ps) optical streak camera for recording. The zoom lens allows the scintillator to be positioned between 1 and 50 cm from a target. The camera simulaneously records an optical fiducial pulse which allows the camera time base to be calibrated relative to the incident laser power. Bursts of x rays formed by focusing 20-ps, 2.5-TW laser pulses onto gold disk targets demonstrate the detector resolution to be < 25 ps. We have recorded burn histories for deuterium/tritium-filled targets producing as few as 3 {times} 10{sup 7} neutrons.

Lerche, R.A.; Phillion, D.W.; Tietbohl, G.L.

1993-09-03T23:59:59.000Z

72

Non-destructive assay of mechanical components using gamma-rays and thermal neutrons  

SciTech Connect (OSTI)

This work presents the results obtained in the inspection of several mechanical components through neutron and gamma-ray transmission radiography. The 4.46 Multiplication-Sign 10{sup 5} n.cm{sup -2}.s{sup -1} thermal neutron flux available at the main port of the Argonauta research reactor in Instituto de Engenharia Nuclear has been used as source for the neutron radiographic imaging. The 412 keV {gamma}-ray emitted by {sup 198}Au, also produced in that reactor, has been used as interrogation agent for the gamma radiography. Imaging Plates - IP specifically designed to operate with thermal neutrons or with X-rays have been employed as detectors and storage devices for each of these radiations.

Souza, Erica Silvani; Avelino, Mila R. [PPG-EM/UERJ, R. Sao Francisco Xavier, 524, Maracana - Rio de Janeiro - RJ (Brazil); Almeida, Gevaldo L. de; Souza, Maria Ines S. [IEN/CNEN, Rua Helio de Almeida, 75, Ilha do Fundao, Rio de Janeiro - RJ (Brazil)

2013-05-06T23:59:59.000Z

73

Non-streaming high-efficiency perforated semiconductor neutron detectors, methods of making same and measuring wand and detector modules utilizing same  

DOE Patents [OSTI]

Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

McGregor, Douglas S. (Riley, KS); Shultis, John K. (Manhattan, KS); Rice, Blake B. (Manhattan, KS); McNeil, Walter J. (Winnfield, KS); Solomon, Clell J. (Wichita, KS); Patterson, Eric L. (Manhattan, KS); Bellinger, Steven L. (Manhattan, KS)

2010-12-21T23:59:59.000Z

74

NOVEL Al2O3:C,Mg FLUORESCENT NUCLEAR TRACK DETECTORS FOR PASSIVE NEUTRON DOSIMETRY  

E-Print Network [OSTI]

NOVEL Al2O3:C,Mg FLUORESCENT NUCLEAR TRACK DETECTORS FOR PASSIVE NEUTRON DOSIMETRY G. Jeff Sykora1 in the development of a fluorescent nuclear track detector (FNTD) for neutron and heavy charged particle dosimetry for neutron dosimetry because they have 100% n/g dis- crimination. For instance, CR-39 plastic nuclear track

75

Thermal Neutron Capture y's (CapGam)  

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

The National Nuclear Data Center (NNDC) presents two tables showing energy and photon intensity with uncertainties of gamma rays as seen in thermal-neutron capture.  One table is organized in ascending order of gamma energy, and the second is organized by Z, A of the target. In the energy-ordered table the three strongest transitions are indicated in each case. The nuclide given is the target nucleus in the capture reaction. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. %I? (per 100 n-captures) for the strongest transition is given, where known. All data are taken from the Evaluated Nuclear Structure Data File (ENSDF), a computer file of evaluated nuclear structure data and from the eXperimental Unevaluated Nuclear Data List (XUNDL). (Specialized Interface)

76

Measurement of delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons  

SciTech Connect (OSTI)

The delayed-neutron yield from thermal-neutron-induced fission of the {sup 237}Np nucleus was measured using a sample periodically exposed to a pulsed neutron beam with subsequent detection of neutrons during the time intervals between pulses. The experiment was realized on an Isomer-M setup mounted in the IBR-2 pulsed reactor channel equipped with a mirror neutron guide. The setup and the experimental procedure are described, the background sources are thoroughly analyzed, and the experimental data are presented. The total delayed-neutron yield from {sup 237}Np fission induced by thermal neutrons is {nu}{sub d} = 0.0110 {+-} 0.0009. This study was performed at the Frank Laboratory of Neutron Physics (JINR, Dubna)

Gundorin, N. A.; Zhdanova, K. V.; Zhuchko, V. E.; Pikelner, L. B., E-mail: plb@nf.jinr.ru; Rebrova, N. V.; Salamatin, I. M.; Smirnov, V. I.; Furman, V. I. [Joint Institute for Nuclear Research (Russian Federation)

2007-06-15T23:59:59.000Z

77

[sup 3]He neutron detector performance in mixed neutron gamma environments  

SciTech Connect (OSTI)

A test program of the performance of 3He neutron proportional detectors with varying gas pressures, and their response to lligh level gamma-ray exposure in a mixed neutrodgamma environment, ha$ been performed Our intent was to identie the optimal gas pressure to reduce the gamma-ray sensitivity of these detectors. These detectors were manufxtured using materials to minimize their gamma response. Earlier work focused on 3He fill pressures of four atmospheres and above, whereas the present work focuses on a wider range of pressures. Tests have shown that reducing the .filling pressure will M e r increase the gamma-ray dose range in which the detectors can be operated.

Johnson, N. H. (Nathan H.); Beddingfield, D. H. (David H.)

2002-01-01T23:59:59.000Z

78

X-Ray Energy Responses of Silicon Tomography Detectors Irradiated with Fusion Produced Neutrons  

SciTech Connect (OSTI)

In order to clarify the effects of fusion-produced neutron irradiation on silicon semiconductor x-ray detectors, the x-ray energy responses of both n- and p-type silicon tomography detectors used in the Joint European Torus (JET) tokamak (n-type) and the GAMMA 10 tandem mirror (p-type) are studied using synchrotron radiation at the Photon Factory of the National Laboratory for High Energy Accelerator Research Organization (KEK). The fusion neutronics source (FNS) of Japan Atomic Energy Research Institute (JAERI) is employed as well-calibrated D-T neutron source with fluences from 10{sup 13} to 10{sup 15} neutrons/cm{sup 2} onto these semiconductor detectors. Different fluence dependence is found between these two types of detectors; that is, (i) for the n-type detector, the recovery of the degraded response is found after the neutron exposure beyond around 10{sup 13} neutrons/cm{sup 2} onto the detector. A further finding is followed as a 're-degradation' by a neutron irradiation level over about 10{sup 14} neutrons/cm{sup 2}. On the other hand, (ii) the energy response of the p-type detector shows only a gradual decrease with increasing neutron fluences. These properties are interpreted by our proposed theory on semiconductor x-ray responses in terms of the effects of neutrons on the effective doping concentration and the diffusion length of a semiconductor detector.

Kohagura, J. [Plasma Research Centre, University of Tsukuba (Japan); Cho, T. [Plasma Research Centre, University of Tsukuba (Japan); Hirata, M. [Plasma Research Centre, University of Tsukuba (Japan); Numakura, T. [Plasma Research Centre, University of Tsukuba (Japan); Yokoyama, N. [Plasma Research Centre, University of Tsukuba (Japan); Fukai, T. [Plasma Research Centre, University of Tsukuba (Japan); Tomii, Y. [Plasma Research Centre, University of Tsukuba (Japan); Tokioka, S. [Plasma Research Centre, University of Tsukuba (Japan); Miyake, Y. [Plasma Research Centre, University of Tsukuba (Japan); Kiminami, S. [Plasma Research Centre, University of Tsukuba (Japan); Shimizu, K. [Plasma Research Centre, University of Tsukuba (Japan); Miyoshi, S. [Plasma Research Centre, University of Tsukuba (Japan); Hirano, K. [High Energy Accelerator Research Organization (Japan); Yoshida, M. [Japan Atomic Energy Research Institute (Japan); Yamauchi, M. [Japan Atomic Energy Research Institute (Japan); Kondoh, T. [Japan Atomic Energy Research Institute (Japan); Nishitani, T. [Japan Atomic Energy Research Institute (Japan)

2005-01-15T23:59:59.000Z

79

RIS-M-2247 A CALORIMETRIC THERMAL NEUTRON DOSEMETER  

E-Print Network [OSTI]

DOSIMETRY, NEUTRON FLUX, SILICON, THERMAL NEUTRONS. UDC 621.039.556 : 539.12.08 ISBN 87-550-0720-1 ISSN 0418, porperties which are not obtained by ordinary instruments when exposed to -he ra- diation fields in a nuclear

80

A NOVEL MICROMEGAS DETECTOR FOR IN-CORE NUCLEAR REACTOR NEUTRON FLUX MEASUREMENTS  

E-Print Network [OSTI]

1 A NOVEL MICROMEGAS DETECTOR FOR IN-CORE NUCLEAR REACTOR NEUTRON FLUX MEASUREMENTS S. ANDRIAMONJE Talence Cedex, France Future fast nuclear reactors designed for energy production and transmutation to neutron detection inside nuclear reactor is given. The advantage of this detector over conventional

Paris-Sud XI, Université de

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81

Deuterium-tritium neutron yield measurements with the 4.5 m neutron-time-of-flight detectors at NIF  

SciTech Connect (OSTI)

The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator/photodetector neutron-time-of-flight (nTOF) detectors for measuring deuterium-deuterium (DD) and DT neutron yields. The detectors provided consistent neutron yield (Y{sub n}) measurements from below 10{sup 9} (DD) to nearly 10{sup 15} (DT). The detectors initially demonstrated detector-to-detector Y{sub n} precisions better than 5%, but lacked in situ absolute calibrations. Recent experiments at NIF now have provided in situ DT yield calibration data that establish the absolute sensitivity of the 4.5 m differential tissue harmonic imaging (DTHI) detector with an accuracy of {+-}10% and precision of {+-}1%. The 4.5 m nTOF calibration measurements also have helped to establish improved detector impulse response functions and data analysis methods, which have contributed to improving the accuracy of the Y{sub n} measurements. These advances have also helped to extend the usefulness of nTOF measurements of ion temperature and downscattered neutron ratio (neutron yield 10-12 MeV divided by yield 13-15 MeV) with other nTOF detectors.

Moran, M. J.; Bond, E. J.; Clancy, T. J.; Eckart, M. J.; Khater, H. Y. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Glebov, V. Yu. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States)

2012-10-15T23:59:59.000Z

82

Phenomenological Model for Predicting the Energy Resolution of Neutron-Damaged Coaxial HPGe Detectors  

SciTech Connect (OSTI)

The peak energy resolution of germanium detectors deteriorates with increasing neutron fluence. This is due to hole capture at neutron-created defects in the crystal which prevents the full energy of the gamma-ray from being recorded by the detector. A phenomenological model of coaxial HPGe detectors is developed that relies on a single, dimensionless parameter that is related to the probability for immediate trapping of a mobile hole in the damaged crystal. As this trap parameter is independent of detector dimensions and type, the model is useful for predicting energy resolution as a function of neutron fluence.

C. DeW. Van Siclen; E. H. Seabury; C. J. Wharton; A. J. Caffrey

2012-10-01T23:59:59.000Z

83

Neutron star envelopes and thermal radiation from the magnetic surface  

E-Print Network [OSTI]

The thermal structure of neutron star envelopes is discussed with emphasis on analytic results. Recent progress on the effect of chemical constitution and high magnetic fields on the opacities and the thermal structure is further reviewed in view of the application to pulsar cooling and magnetars.

J. Ventura; A. Y. Potekhin

2001-03-31T23:59:59.000Z

84

Yields of delayed-neutron groups in thermal-neutron fission of sup 229 Th  

SciTech Connect (OSTI)

Absolute yields of five delayed-neutron groups in thermal-neutron fission of {sup 229}Th have been determined for the first time. A significant discrepancy is noted between the experimental yields of delayed neutrons of the fourth group and the corresponding theoretical values. From the results of the experimental studies, corrections have been determined for even--odd effects in the charge distributions of the yields of fragment nuclides.

Gudkov, A.N.; Koldobskii, A.B.; Krivasheev, S.V.; Lebedev, N.A.; Pchelin, V.A. (Moscow Engineering-Physics Institute (SU))

1989-06-01T23:59:59.000Z

85

Neutron detection and multiplicity counting using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array  

SciTech Connect (OSTI)

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array. Boron-loaded plastic combines neutron moderation (H) and detection ({sup 10}B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Both of these characteristics address a fundamental limitation of thermal-neutron multiplicity counters, where {sup 3}He proportional counters are embedded in a polyethylene matrix. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on a pulse-by-pulse basis using custom integrator and timing circuits. In addition, a custom time-tag module was used to provide a time for each detector event. Analysis of the combined energy and time event stream was performed by calibrating each detector`s response and filtering based on the presence of a simultaneous energy deposition corresponding to the {sup 10}B(n,alpha) reaction products in the plastic scintillator (93 keV{sub ee}) and the accompanying neutron-capture gamma ray in the bismuth germanate (478 keV). Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates. Proof-of-principle measurements were conducted with a variety of gamma-ray and neutron sources including {sup 137}Cs, {sup 54}Mn, AmLi, and {sup 252}Cf. Results of this study indicate that a neutron-capture probability of {approximately}10% and a die-away time of {approximately}10 {micro}s are possible with a 4-detector array with a detector volume of 1600 cm{sup 3}. Simulations were performed that indicate neutron-capture probabilities on the order of 50% and die-away times of less than 4 {micro}s are realistically achievable. While further study will be required for practical application of such a detection system, the results obtained in this investigation are encouraging and may lead to a new class of high-efficiency, short die-away time neutron multiplicity counters capable of extending current nondestructive assay methods for special nuclear materials.

Miller, M.C.

1998-03-01T23:59:59.000Z

86

Neutron Slowing Down in a Detector with Absorption Sara A. Pozzi*  

E-Print Network [OSTI]

Neutron Slowing Down in a Detector with Absorption Sara A. Pozzi* Oak Ridge National Laboratory, P of scattering collisions undergone by fast neutrons as they slow down until they are absorbed was presented realistic case of neutron slowing down in a homogeneous mixture. The formulas are derived and evaluated

Pázsit, Imre

87

Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency  

E-Print Network [OSTI]

Self-powered micro-structured solid state neutron detector with very low leakage current and high helps to reduce the gammas sensitivity. The neutron detec- tion efficiency of such detectors mainly, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon

Danon, Yaron

88

Thermal neutron imaging support with other laboratories BL06-IM-TNI  

SciTech Connect (OSTI)

The goals of this project are: (1) detect and locate a source of thermal neutrons; (2) distinguish a localized source from uniform background; (3) show shape and size of thermalizing material; (4) test thermal neutron imager in active interrogation environment; and (5) distinguish delayed neutrons from prompt neutrons.

Vanier,P.E.

2008-06-17T23:59:59.000Z

89

Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA  

SciTech Connect (OSTI)

A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

Glebov, V. Yu.; Forrest, C.; Knauer, J. P.; Pruyne, A.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J. III; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Caggiano, J. A.; Carman, M. L.; Clancy, T. J.; Hatarik, R.; McNaney, J.; Zaitseva, N. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-10-15T23:59:59.000Z

90

Multidimensional thermal structure of magnetized neutron star envelopes  

E-Print Network [OSTI]

Recently launched x-ray telescopes have discovered several candidate isolated neutron stars. The thermal radiation from these objects may potentially constrain our understanding of nuclear physics in a realm inaccessible to terrestrial experiments. To translate the observed fluxes from neutron stars into constraints, one needs precise calculations of the heat transfer through the thin insulating envelopes of neutron stars. We describe models of the thermal structure of the envelopes of neutron stars with magnetic fields up to 10^{14} G. Unlike earlier work, we infer the properties of envelope models in two dimensions and precisely account for the quantization of the electron phase space. Both dipole and uniformly magnetized envelopes are considered.

Jeremy S. Heyl; Lars Hernquist

1998-08-12T23:59:59.000Z

91

Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors  

SciTech Connect (OSTI)

This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermaliation 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.

Hawari, Ayman; Ougouag, Abderrafi

2014-07-08T23:59:59.000Z

92

A new neutron time-of-flight detector for fuel-areal-density measurements on OMEGA  

SciTech Connect (OSTI)

A new neutron time-of-flight (nTOF) detector for fuel-areal-density measurements in cryogenic DT implosions was installed on the OMEGA Laser System. The nTOF detector has a cylindrical thin-wall, stainless-steel, 8-in.-diam, 4-in.-thick cavity filled with an oxygenated liquid xylene scintillator. Four gated photomultiplier tubes (PMTs) with different gains are used to measure primary DT and D{sub 2} neutrons, down-scattered neutrons in nT and nD kinematic edge regions, and to study tertiary neutrons in the same detector. The nTOF detector is located 13.4 m from target chamber center in a well-collimated line of sight. The design details of the nTOF detector, PMT optimization, and test results on OMEGA will be presented.

Glebov, V. Yu., E-mail: vgle@lle.rochester.edu; Forrest, C. J.; Marshall, K. L.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2014-11-15T23:59:59.000Z

93

Fission signal detection using helium-4 gas fast neutron scintillation detectors  

SciTech Connect (OSTI)

We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

Lewis, J. M., E-mail: lewisj@ufl.edu; Kelley, R. P.; Jordan, K. A. [Nuclear Engineering Program, University of Florida, Gainesville, Florida 32611 (United States); Murer, D. [Arktis Radiation Detectors Ltd., 8045 Zurich (Switzerland)

2014-07-07T23:59:59.000Z

94

A Cargo Inspection System for Special Nuclear Material (SNM) Based on Associated Particle Neutron Generators and Liquid-Kr Detectors  

SciTech Connect (OSTI)

A feasibility analysis is presented of a cargo inspection system based on neutron-induced fission followed by the coincident detection of multiple prompt fission gamma rays as a signature of Special Nuclear Material (SNM). The system does not require gamma ray spectroscopy and would be capable of distinguishing U-238 from U-235 using the ratio of signals from two modes of detection: thermal neutron capture induced fission and fast neutron-induced fission. The system utilizes two deuterium-tritium (DT) associated particle neutron generators, each capable of 10{sup 9} neutrons/s at 14.1 MeV, with sub-nanosecond timing resolution ZnO:Ga alpha detectors. The expected {approx}1 MeV prompt gamma rays are detected using liquid krypton (LKr) detectors with sub-nanosecond timing resolution ({approx}600 ps) and high detection efficiency. The expected SNM signal and randomly correlated background rates are discussed using Monte Carlo N-Particle (MCNP) code.

Koltick, David S.; Kane, Steven Z. [Purdue University Applied Physics Laboratory 740 Navco Dr., Lafayette, IN 47906 (United States)

2009-03-10T23:59:59.000Z

95

Measurement of Neutron and Muon Fluxes 100~m Underground with the SciBath Detector  

SciTech Connect (OSTI)

The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. Initially conceived as a fine-grained charged particle detector for neutrino studies that could image charged particle tracks in all directions, it is also sensitive to fast neutrons (15-200 MeV). In fall of 2011 the apparatus performed a three month run to measure cosmic-induced muons and neutrons 100~meters underground in the FNAL MINOS near-detector area. Data from this run has been analyzed and resulted in measurements of the cosmic muon flux as \

Garrison, Lance

2014-01-01T23:59:59.000Z

96

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation  

SciTech Connect (OSTI)

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Ruffner, Judith A. (Albuquerque, NM); Bullington, Jeff A. (Albuquerque, NM); Clem, Paul G. (Albuquerque, NM); Warren, William L. (Albuquerque, NM); Brinker, C. Jeffrey (Albuquerque, NM); Tuttle, Bruce A. (Albuquerque, NM); Schwartz, Robert W. (Seneca, SC)

1999-01-01T23:59:59.000Z

97

Designing and testing the neutron source deployment system and calibration plan for a dark matter detector  

E-Print Network [OSTI]

In this thesis, we designed and tested a calibration and deployment system for the MiniCLEAN dark matter detector. The deployment system uses a computer controlled winch to lower a canister containing a neutron source into ...

Westerdale, Shawn (Shawn S.)

2011-01-01T23:59:59.000Z

98

Statistical theory of thermal evolution of neutron stars  

E-Print Network [OSTI]

Thermal evolution of neutron stars is known to depend on the properties of superdense matter in neutron star cores. We suggest a statistical analysis of isolated cooling middle-aged neutron stars and old transiently accreting quasi-stationary neutron stars warmed up by deep crustal heating in low-mass X-ray binaries. The method is based on simulations of the evolution of stars of different masses and on averaging the results over respective mass distributions. This gives theoretical distributions of isolated neutron stars in the surface temperature--age plane and of accreting stars in the photon thermal luminosity--mean mass accretion rate plane to be compared with observations. This approach permits to explore not only superdense matter but also the mass distributions of isolated and accreting neutron stars. We show that the observations of these stars can be reasonably well explained by assuming the presence of the powerful direct Urca process of neutrino emission in the inner cores of massive stars, introd...

Beznogov, M V

2014-01-01T23:59:59.000Z

99

Response of neutron-irradiated RPV steels to thermal annealing  

SciTech Connect (OSTI)

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the fracture toughness properties that have been degraded by neutron irradiation. This paper summarizes experimental results of work performed at the Oak Ridge National Laboratory (ORNL) to study the annealing response of several irradiated RPV steels.

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

1997-03-01T23:59:59.000Z

100

Thermal neutron flux perturbation due to indium foils in water  

E-Print Network [OSTI]

press) 13. Axford, R. A. , and Day, G. M. , personnel communication. 14. Ritchie, R. H. , Thermal Neutron Flux De ression, Health Physics Division Annual Prog. Rep. July, 1958, ORNL-2806, p. 133. 27 i 5, Walker, J. V. , "The Measurement of Absolute... Fluxes in Water and Graphite, " 'ORNL- 2842, 204 (f959). ...

Stinson, Ronald Calvin

1961-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors  

SciTech Connect (OSTI)

The neutron field parameters (fluence and energy distribution) at a specific location outside the JET Torus Hall have been measured by means of super-heated fluid detectors (or 'bubble detectors') in combination with an independent, time-of-flight, technique. The bubble detector assemblies were placed at the end of a vertical line of sight at about 16 m from the tokamak mid plane. Spatial distributions of the neutron fluence along the radial and toroidal directions have been obtained using two-dimensional arrays of bubble detectors. Using a set of three bubble detector spectrometers the neutron energy distribution was determined over a broad energy range, from about 10 keV to above 10 MeV, with an energy resolution of about 30% at 2.5 MeV. The very broad energy response allowed for the identification of energy features far from the main fusion component (around 2.45 MeV for deuterium discharges).

Gherendi, M.; Craciunescu, T.; Pantea, A. [Association EURATOM-MEdC, National Institute for Laser, Plasma and Radiation Physics, Magurele (Romania); Zoita, V. L. [Association EURATOM-MEdC, National Institute for Laser, Plasma and Radiation Physics, Magurele (Romania); EFDA-JET CSU Culham, Culham Science Centre, Abingdon (United Kingdom); Johnson, M. Gatu; Hellesen, C.; Conroy, S. [Association EURATOM-VR, Uppsala University, Uppsala (Sweden); Baltog, I. [Association EURATOM-MEdC, National Institute for Material Physics, Magurele (Romania); Edlington, T.; Kiptily, V.; Popovichev, S. [Association EURATOM-CCFE, Culham Science Centre, Abingdon (United Kingdom); Murari, A. [EFDA-JET CSU Culham, Culham Science Centre, Abingdon (United Kingdom); Association EURATOM-ENEA, RFX, Padova (Italy); Collaboration: JET EFDA Contributors

2012-10-15T23:59:59.000Z

102

Thermal structure and cooling of neutron stars with magnetized envelopes  

E-Print Network [OSTI]

The thermal structure of neutron stars with magnetized envelopes is studied using modern physics input. The relation between the internal (T_i) and local surface temperatures is calculated and fitted by analytic expressions for magnetic field strengths B from 0 to 10^{16} G and arbitrary inclination of the field lines to the surface. The luminosity of a neutron star with dipole magnetic field is calculated and fitted as a function of B, T_i, stellar mass and radius. In addition, we simulate cooling of neutron stars with magnetized envelopes. In particular, we analyse ultramagnetized envelopes of magnetars and also the effects of the magnetic field of the Vela pulsar on the determination of critical temperatures of neutron and proton superfluids in its core.

A. Y. Potekhin; D. G. Yakovlev

2001-06-19T23:59:59.000Z

103

Fabrication and Characterization of a Conduction Cooled Thermal Neutron Filter  

SciTech Connect (OSTI)

Installation of a conduction cooled thermal (low-energy) neutron filter in an existing domestic test reactor would provide the U.S. the capability to test new reactor fuels and materials for advanced fast (high-energy) reactor concepts. A composite consisting of Al3Hf-Al has been proposed for the neutron filter due to both the neutron filtering properties of hafnium and the conducting capabilities of aluminum. Knowledge of the thermal conductivity of the Al3Hf-Al composite is essential for the design of the filtering system. The present objectives are to identify a suitable fabrication technique and to measure the thermophysical properties of the Al3Hf intermetallic, which has not been done previous to this study. A centrifugal casting method was used to prepare samples of Al3Hf. X-ray diffraction and Rietveld analysis were conducted to determine the structural make-up of each of the samples. Thermophysical properties were measured as follows: specific heat by a differential scanning calorimeter (DSC), thermal diffusivity by a laser flash thermal diffusivity measuring system, thermal expansion by a dilatometer, and thermal conductivity was calculated based on the previous measurements. All measurements were acquired over a temperature range of 90°C - 375°C with some measurements outside these bounds. The average thermal conductivity of the intermetallic Al3Hf (~7 at.% Hf) was found to be ~ 41 W/m-K for the given temperature range. This information fills a knowledge gap in the thermophysical properties of the intermetallic Al3Hf with the specified percentage of hafnium. A model designed to predict composite properties was used to calculate a thermal conductivity of ~177 W/m-K for an Al3Hf-Al composite with 23 vol% Al3Hf. This calculation was based upon the average thermal conductivity of Al3Hf over the specified temperature range.

Heather Wampler; Adam Gerth; Heng Ban; Donna Post Guillen; Douglas Porter; Cynthia Papesch

2010-06-01T23:59:59.000Z

104

The uTPC Method: Improving the Position Resolution of Neutron Detectors Based on MPGDs  

E-Print Network [OSTI]

Due to the Helium-3 crisis, alternatives to the standard neutron detection techniques are becoming urgent. In addition, the instruments of the European Spallation Source (ESS) require advances in the state of the art of neutron detection. The instruments need detectors with excellent neutron detection efficiency, high-rate capabilities and unprecedented spatial resolution. The Macromolecular Crystallography instrument (NMX) requires a position resolution in the order of 200 um over a wide angular range of incoming neutrons. Solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are proposed to meet the new requirements. Charged particles rising from the neutron capture have usually ranges larger than several millimetres in gas. This is apparently in contrast with the requirements for the position resolution. In this paper, we present an analysis technique, new in the field of neutron detection, based on the Time Projection Chamber (TPC) concept. Using a standard Single-GEM with the catho...

Pfeiffer, Dorothea; Birch, Jens; Hall-Wilton, Richard; Höglund, Carina; Hultman, Lars; Iakovidis, George; Oliveri, Eraldo; Oksanen, Esko; Ropelewski, Leszek; Thuiner, Patrik

2015-01-01T23:59:59.000Z

105

Data from the Versatile Array of Neutron Detectors at Low Energy (VANDLE) will impact modeling of processes occurring in neutron-rich  

E-Print Network [OSTI]

Data from the Versatile Array of Neutron Detectors at Low Energy (VANDLE) will impact modeling of processes occurring in neutron-rich environments ·The energies of beta-delayed neutrons emitted from 25 strong feeding to high-lying states that emit high energy neutrons while others have broad distributions

106

Comparison of SEM and Optical Analysis of DT Neutron Tracks in CR-39 Detectors  

SciTech Connect (OSTI)

A solid state nuclear track detector, CR-39, was exposed to DT neutrons. After etching, the resultant tracks were analyzed using both an optical microscope and a scanning electron microscope (SEM). In this communication, both methods of analyzing DT neutron tracks are discussed.

P.A. Mosier-Boss, L.P.G. Forsley, P. Carbonnelle, M.S. Morey, J.R. Tinsley, J. P. Hurley, F.E. Gordon

2012-01-01T23:59:59.000Z

107

A NEW HIGH ENERGY RESOLUTION NEUTRON TRANSMISSION DETECTOR SYSTEM AT THE GAERTTNER LINAC LABORATORY  

E-Print Network [OSTI]

Laboratory P.O. Box 1072, Schenectady, New York 12301-1072 A new high energy resolution modular neutronA NEW HIGH ENERGY RESOLUTION NEUTRON TRANSMISSION DETECTOR SYSTEM AT THE GAERTTNER LINAC LABORATORY capabilities at the Laboratory in and above the resolved resonance energy region from 1 keV to 600 ke

Danon, Yaron

108

Cross-Fertilization between Spallation Neutron Source and Third Generation Synchrotron Radiation Detectors  

SciTech Connect (OSTI)

Suffering presently from relatively low source strengths compared to synchrotron radiation investigations, neutron scattering methods will greatly benefit from the increase of instantaneous flux attained at the next generation of pulsed spallation neutron sources. In particular at ESS, the strongest projected source, the counting rate load on the detectors will rise by factors of up to 50-150 in comparison with present generic instruments. For these sources the detector requirements overlap partly with those for modern synchrotron radiation detectors as far as counting rate capability and two-dimensional position resolution are concerned. In this paper, examples of the current and forthcoming detector development, comprising e.g. novel solutions for low-pressure micro-strip gas chamber detectors, for silicon micro-strip detectors and for the related front-end ASICs and data acquisition (DAQ) systems, are summarized, which will be of interest for detection of synchrotron radiation as well.

Gebauer, B.; Schulz, Ch.; Alimov, S.S.; Wilpert, Th. [Hahn-Meitner-Instiut Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Levchanovsky, F.V. [Hahn-Meitner-Instiut Berlin, Glienicker Str. 100, 14109 Berlin (Germany); Frank Laboratory of Neutron Physics, Joint Institute of Nuclear Research, 141980 Dubna (Russian Federation); Litvinenko, E.I.; Nikiforov, A.S. [Frank Laboratory of Neutron Physics, Joint Institute of Nuclear Research, 141980 Dubna (Russian Federation)

2004-05-12T23:59:59.000Z

109

Neutron and gamma detector using an ionization chamber with an integrated body and moderator  

DOE Patents [OSTI]

A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. A conductive neutron-capturing layer is disposed on the interior surface of the cathode and a plastic housing surrounds the cathode. A plastic lid is attached to the housing and encloses the interior volume of the cathode forming an ionization chamber, into the center of which an anode extends from the plastic lid. A working gas is disposed within the ionization chamber and a high biasing voltage is connected to the cathode. Processing electronics are coupled to the anode and process current pulses which are converted into Gaussian pulses, which are either counted as neutrons or integrated as gammas, in response to whether pulse amplitude crosses a neutron threshold. The detector according to the invention may be readily fabricated into single or multilayer detector arrays.

Ianakiev, Kiril D.; Swinhoe, Martyn T.; Lestone, John Paul

2006-07-18T23:59:59.000Z

110

Quiescent thermal emission from neutron stars in LMXBs  

E-Print Network [OSTI]

We monitored the quiescent thermal emission from neutron stars in low-mass X-ray binaries after active periods of intense activity in x-rays (outbursts). The theoretical modeling of the thermal relaxation of the neutron star crust may be used to establish constraints on the crust composition and transport properties, depending on the astrophysical scenarios assumed. We numerically simulated the thermal evolution of the neutron star crust and compared them with inferred surface temperatures for five sources: MXB 1659-29, KS 1731-260, EXO 0748-676, XTE J1701-462 and IGR J17480-2446. We find that the evolution of MXB 1659-29, KS 1731-260 and EXO 0748-676 can be well described within a deep crustal cooling scenario. Conversely, we find that the other two sources can only be explained with models beyond crustal cooling. For the peculiar emission of XTE J1701-462 we propose alternative scenarios such as residual accretion during quiescence, additional heat sources in the outer crust, and/or thermal isolation of the inner crust due to a buried magnetic field. We also explain the very recent reported temperature of IGR J17480-2446 with an additional heat deposition in the outer crust from shallow sources.

Anabela Turlione; Deborah N. Aguilera; José A. Pons

2015-02-19T23:59:59.000Z

111

Computational characterization and experimental validation of the thermal neutron source for neutron capture therapy research at the University of Missouri  

SciTech Connect (OSTI)

Parameter studies, design calculations and neutronic performance measurements have been completed for a new thermal neutron beamline constructed for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational models used for the final beam design and performance evaluation are based on coupled discrete-ordinates and Monte Carlo techniques that permit detailed modeling of the neutron transmission properties of the filtering crystals with very few approximations. Validation protocols based on neutron activation spectrometry measurements and rigorous least-square adjustment techniques show that the beam produces a neutron spectrum that has the anticipated level of thermal neutron flux and a somewhat higher than expected, but radio-biologically insignificant, epithermal neutron flux component. (authors)

Broekman, J. D. [University of Missouri, Research Reactor Center, 1513 Research Park Drive, Columbia, MO 65211-3400 (United States); Nigg, D. W. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Hawthorne, M. F. [University of Missouri, International Institute of Nano and Molecular Medicine, 1514 Research Park Dr., Columbia, MO 65211-3450 (United States)

2013-07-01T23:59:59.000Z

112

Accurate Development of Thermal Neutron Scattering Cross Section Libraries  

SciTech Connect (OSTI)

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.

Hawari, Ayman; Dunn, Michael

2014-06-10T23:59:59.000Z

113

Event-by-event study of neutron observables in spontaneous and thermal fission  

SciTech Connect (OSTI)

The event-by-event fission model FREYA is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view towards possible applications for SNM detection. We have shown that event-by-event models of fission, such as FREYA, provide a powerful tool for studying fission neutron correlations. Our results demonstrate that these correlations are significant and exhibit a dependence on the fissioning nucleus. Since our method is phenomenological in nature, good input data are especially important. Some of the measurements employed in FREYA are rather old and statistics limited. It would be useful to repeat some of these studies with modern detector techniques. In addition, most experiments made to date have not made simultaneous measurements of the fission products and the prompt observables, such as neutron and photons. Such data, while obviously more challenging to obtain, would be valuable for achieving a more complete understanding of the fission process.

Vogt, R; Randrup, J

2011-09-14T23:59:59.000Z

114

Thermal conductivity changes upon neutron transmutation of {sup 10}B doped diamond  

SciTech Connect (OSTI)

{sup 10}B doped p-type diamond samples were subjected to neutron transmutation reaction using thermal neutron flux of 0.9 × 10{sup 13} cm{sup ?2} s{sup ?1} and fast neutron flux of 0.09 × 10{sup 13} cm{sup ?2} s{sup ?1}. Another sample of epilayer grown on type IIa (110) single crystal diamond substrate was subjected to equal thermal and fast neutron flux of 10{sup 14}?cm{sup ?2} s{sup ?1}. The defects in the diamond samples were previously characterized by different methods. In the present work, thermal conductivity of these diamond samples was determined at room temperature by transient thermoreflectance method. The thermal conductivity change in the samples as a function of neutron fluence is explained by the phonon scattering from the point defects and disordered regions. The thermal conductivity of the diamond samples decreased more rapidly initially and less rapidly for larger neutron fluence. In addition, the thermal conductivity in type IIb diamond decreased less rapidly with thermal neutron fluence compared to the decrease in type IIa diamond subjected to fast neutron fluence. It is concluded that the rate of production of defects during transmutation reaction is slower when thermal neutrons are used. The thermal conductivity of epilayer of diamond subjected to high thermal and fast neutron fluence is associated with the covalent carbon network in the composite structure consisting of disordered carbon and sp{sup 2} bonded nanocrystalline regions.

Jagannadham, K., E-mail: jag-kasichainula@ncsu.edu [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Verghese, K. [Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Butler, J. E. [Code 6174, Naval research Laboratory, Washington, District of Columbia 20375 (United States)

2014-08-28T23:59:59.000Z

115

An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons  

E-Print Network [OSTI]

We describe a novel photon detector which operates under an intense flux of neutrons. It is composed of lead-aerogel sandwich counter modules. Its salient features are high photon detection efficiency and blindness to neutrons. As a result of Monte Carlo (MC) simulations, the efficiency for photons with the energy larger than 1 GeV is expected to be higher than 99.5% and that for 2 GeV/$c$ neutrons less than 1%. The performance on the photon detection under such a large flux of neutrons was measured for a part of the detector. It was confirmed that the efficiency to photons with the energy $>$1 GeV was consistent with the MC expectation within 8.2% uncertainty.

Y. Maeda; N. Kawasaki; T. Masuda; H. Morii; D. Naito; Y. Nakajima; H. Nanjo; T. Nomura; N. Sasao; S. Seki; K. Shiomi; T. Sumida; Y. Tajima

2014-12-22T23:59:59.000Z

116

An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons  

E-Print Network [OSTI]

We describe a novel photon detector which operates under an intense flux of neutrons. It is composed of lead-aerogel sandwich counter modules. Its salient features are high photon detection efficiency and blindness to neutrons. As a result of Monte Carlo (MC) simulations, the efficiency for photons with the energy larger than 1 GeV is expected to be higher than 99.5% and that for 2 GeV/$c$ neutrons less than 1%. The performance on the photon detection under such a large flux of neutrons was measured for a part of the detector. It was confirmed that the efficiency to photons with the energy $>$1 GeV was consistent with the MC expectation within 8.2% uncertainty.

Maeda, Y; Masuda, T; Morii, H; Naito, D; Nakajima, Y; Nanjo, H; Nomura, T; Sasao, N; Seki, S; Shiomi, K; Sumida, T; Tajima, Y

2014-01-01T23:59:59.000Z

117

Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis  

SciTech Connect (OSTI)

Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

Xie Xufei; Zhang Xing; Yuan Xi; Chen Jinxiang; Li Xiangqing; Zhang Guohui; Fan Tieshuan [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing (China); Yuan Guoliang; Yang Jinwei; Yang Qingwei [Southwestern Institute of Physics, Chengdu (China)

2012-09-15T23:59:59.000Z

118

The prototype of a detector for monitoring the cosmic radiation neutron flux on ground  

SciTech Connect (OSTI)

This work presents a comparison between the results of experimental tests and Monte Carlo simulations of the efficiency of a detector prototype for on-ground monitoring the cosmic radiation neutron flux. The experimental tests were made using one conventional {sup 241}Am-Be neutron source in several incidence angles and the results were compared to that ones obtained with a Monte Carlo simulation made with MCNPX Code.

Lelis Goncalez, Odair; Federico, Claudio Antonio; Mendes Prado, Adriane Cristina; Galhardo Vaz, Rafael; Tizziani Pazzianotto, Mauricio [Instituto de Estudos Avancados - IEAv/DCTA - Sao Jose dos Campos, SP (Brazil); Semmler, Renato [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP - Sao Paulo, SP (Brazil)

2013-05-06T23:59:59.000Z

119

Analog and digital dynamic compensation techniques for delayed self-powered neutron detectors  

SciTech Connect (OSTI)

This paper reports on analog and digital methods developed to compensate for the time delay associated with rhodium self-powered neutron detector signals. This delay is caused by the decay of the neutron-activated rhodium and results in a current signal with unfavorable time response characteristics. The compensating analog method is based on the use of lead-lag networks to eliminate undesirable poles and zeros. The digital method takes digitized signals and numerically solves the inverse kinetics equation that relates reactor flux to the detector current at all earlier times. These methods were tested in a realistic reactor environment, and the results illustrate the accuracy achieved using each method.

Yusuf, S.O.; Wehe, D.K. (Univ. of Michigan, Dept. of Nuclear Engineering, Ann Arbor, MI (US))

1990-12-01T23:59:59.000Z

120

Electro-optic Laser-Sampled Neutron Detector  

SciTech Connect (OSTI)

A new method of detecting radiation which can allow for long distance measurements is being investigated. The device is primarily for neutrons detection althought it could, in principle, be used for gamma ray detection. The neutron detection medium is a solid, transparent, electro-optical material, such as lithium niobate, lithium tantalite, or barium borate. Crystals of these materials act as optical gates to laser light, allowing light to pass through only when a neutron interaction occurs in the crystal. Typical light detection devices, such as CCD cameras or photomultiplier tubes, can be used to signal when light passes through the crystal. The overall goal of the project is to investigate the feasibility of such devices for the detection of neutron radiation and to quantify their capabilities and limitations.

J. Kenneth Shultis; Douglas McGregor

2009-11-30T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Forward fitting of experimental data from a NE213 neutron detector installed with the magnetic proton recoil upgraded spectrometer at JET  

SciTech Connect (OSTI)

In this paper, we present the results obtained from the data analysis of neutron spectra measured with a NE213 liquid scintillator at JET. We calculated the neutron response matrix of the instrument combining MCNPX simulations, a generic proton light output function measured with another detector and the fit of data from ohmic pulses. For the analysis, we selected a set of pulses with neutral beam injection heating (NBI) only and we applied a forward fitting procedure of modeled spectral components to extract the fraction of thermal neutron emission. The results showed the same trend of the ones obtained with the dedicated spectrometer TOFOR, even though the values from the NE213 analysis were systematically higher. This discrepancy is probably due to the different lines of sight of the two spectrometers (tangential for the NE213, vertical for TOFOR). The uncertainties on the thermal fraction estimates were from 4 to 7 times higher than the ones from the TOFOR analysis.

Binda, F., E-mail: federico.binda@physics.uu.se; Ericsson, G.; Eriksson, J.; Hellesen, C.; Conroy, S.; Sundén, E. Andersson [Department of Physics and Astronomy, EURATOM-VR Association, Uppsala University, Uppsala (Sweden); Collaboration: JET-EFDA Team

2014-11-15T23:59:59.000Z

122

Multi-Grid Boron-10 detector for large area applications in neutron scattering science  

E-Print Network [OSTI]

The present supply of 3He can no longer meet the detector demands of the upcoming ESS facility and continued detector upgrades at current neutron sources. Therefore viable alternative technologies are required to support the development of cutting-edge instrumentation for neutron scattering science. In this context, 10B-based detectors are being developed by collaboration between the ESS, ILL, and Link\\"{o}ping University. This paper reports on progress of this technology and the prospects applying it in modern neutron scattering experiments. The detector is made-up of multiple rectangular gas counter tubes coated with B4C, enriched in 10B. An anode wire reads out each tube, thereby giving position of conversion in one of the lateral co-ordinates as well as in depth of the detector. Position resolution in the remaining co-ordinate is obtained by segmenting the cathode tube itself. Boron carbide films have been produced at Link\\"{o}ping University and a detector built at ILL. The characterization study is presented in this paper, including measurement of efficiency, effects of the fill gas species and pressure, coating thickness variation on efficiency and sensitivity to gamma-rays.

Ken Andersen; Thierry Bigault; Jens Birch; Jean-Claude Buffet; Jonathan Correa; Patrick van Esch; Bruno Guerard; Richard Hall-Wilton; Lars Hultman; Carina Höglund; Jens Jensen; Anton Khaplanov; Oliver Kirstein; Francesco Piscitelli; Christian Vettier

2012-09-04T23:59:59.000Z

123

Advanced Neutron Source Reactor thermal analysis of fuel plate defects  

SciTech Connect (OSTI)

The Advanced Neutron Source Reactor (ANSR) is a research reactor designed to provide the highest continuous neutron beam intensity of any reactor in the world. The present technology for determining safe operations were developed for the High Flux Isotope Reactor (HFIR). These techniques are conservative and provide confidence in the safe operation of HFIR. However, the more intense requirements of ANSR necessitate the development of more accurate, but still conservative, techniques. This report details the development of a Local Analysis Technique (LAT) that provides an appropriate approach. Application of the LAT to two ANSR core designs are presented. New theories of the thermal and nuclear behavior of the U{sub 3}Si{sub 2} fuel are utilized. The implications of lower fuel enrichment and of modifying the inspection procedures are also discussed. Development of the computer codes that enable the automate execution of the LAT is included.

Giles, G.E.

1995-08-01T23:59:59.000Z

124

Neutron superfluidity in strongly magnetic interiors of neutron stars and its effect on thermal evolution  

E-Print Network [OSTI]

The possibility of a neutron m=2-superfluid in the interior of neutron stars is investigated. This pairing state is energetically favoured in strong magnetic fields ($H\\sim 10^{16}-10^{17}$ G). Because of the node in the angular-dependent energy gap along the field direction the neutrino emissivity is only suppressed polynomially as function in $T/T_{c}$ instead of exponentially, as it is obtained for a nodeless pairing state. The effect of this pairing state on the thermal evolution of neutron stars is studied, and its outcome is compared with the evolution of ``normal'', i.e. nodeless, superfluid and non-superfluid neutron stars, and also with observations. We find that particularly the predicted surface temperatures of the enhanced cooling scenario considerably change and come into agreement with temperatures deduced from observational data within the hydrogen atmosphere model. Furthermore the surface temperature depends on the magnetic field strength as an additional parameter aside from the neutron star mass. The latter is however only operative in the case of the intermediate cooling scenario.

Ch. Schaab; F. Weber; M. K. Weigel

1998-04-20T23:59:59.000Z

125

Thermal Design of the Mu2e Detector Solenoid  

SciTech Connect (OSTI)

The reference design for a superconducting Detector Solenoid (DS) for the Mu2e experiment has been completed. The main functions of the DS are to provide a graded field in the region of the stopping target which ranges from 2 T to 1 T and a uniform precision magnetic field of 1 T in a volume large enough to house a tracker downstream of the stopping target. The inner diameter of the magnet cryostat is 1.9 m and the length is 10.9 m. The gradient section of the magnet is about 4 m long and the spectrometer section with a uniform magnetic field is about 6 m long. The inner cryostat wall supports the stopping target, tracker, calorimeter and other equipment installed in the DS. This warm bore volume is under vacuum during operation. It is sealed on one end by the muon beam stop, while it is open on the other end where it interfaces with the Transport Solenoid. The operating temperature of the magnetic coil is 4.7 K and is indirectly cooled with helium flowing in a thermosiphon cooling scheme. This paper describes the thermal design of the solenoid, including the design aspects of the thermosiphon for the coil cooling, forced flow cooling of the thermal shields with 2 phase LN2 (Liquid Nitrogen) and the transient studies of the cool down of the cold mass as well.

Dhanaraj, Nandhini; Wands, Bob; Buehler, Marc; Feher, Sandor; Page, Thomas M; Peterson, Thomas; Schmitt, Richard L

2014-12-18T23:59:59.000Z

126

Compounds for neutron radiation detectors and systems thereof  

DOE Patents [OSTI]

One embodiment includes a material exhibiting an optical response signature for neutrons that is different than an optical response signature for gamma rays, said material exhibiting performance comparable to or superior to stilbene in terms of distinguishing neutrons from gamma rays, wherein the material is not stilbene. Another embodiment includes a substantially pure crystal exhibiting an optical response signature for neutrons that is different than an optical response signature for gamma rays, the substantially pure crystal comprising a material selected from a group consisting of: 1-1-4-4-tetraphenyl-1-3-butadiene; 2-fluorobiphenyl-4-carboxylic acid; 4-biphenylcarboxylic acid; 9-10-diphenylanthracene; 9-phenylanthracene; 1-3-5-triphenylbenzene; m-terphenyl; bis-MSB; p-terphenyl; diphenylacetylene; 2-5-diphenyoxazole; 4-benzylbiphenyl; biphenyl; 4-methoxybiphenyl; n-phenylanthranilic acid; and 1-4-diphenyl-1-3-butadiene.

Payne, Stephen A.; Stoeffl, Wolfgang; Zaitseva, Natalia P.; Cherepy, Nerine J.; Carman, M. Leslie

2013-06-11T23:59:59.000Z

127

Thermal Neutron Capture for Nuclei A = 3 - 20  

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

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128

Compounds for neutron radiation detectors and systems thereof  

DOE Patents [OSTI]

A material according to one embodiment exhibits an optical response signature for neutrons that is different than an optical response signature for gamma rays, said material exhibiting performance comparable to or superior to stilbene in terms of distinguishing neutrons from gamma rays, wherein the material is not stilbene, the material comprising a molecule selected from a group consisting of: two or more benzene rings, one or more benzene rings with a carboxylic acid group, one or more benzene rings with at least one double bound adjacent to said benzene ring, and one or more benzene rings for which at least one atom in the benzene ring is not carbon.

Payne, Stephen A; Stoeffl, Wolfgang; Zaitseva, Natalia P; Cherepy, Nerine J; Carman, M. Leslie

2014-05-27T23:59:59.000Z

129

Detecting gravitational waves from mountains on neutron stars in the Advanced Detector Era  

E-Print Network [OSTI]

Rapidly rotating Neutron Stars (NSs) in Low Mass X-ray Binaries (LMXBs) are thought to be interesting sources of Gravitational Waves (GWs) for current and next generation ground based detectors, such as Advanced LIGO and the Einstein Telescope. The main reason is that many of the NS in these systems appear to be spinning well below their Keplerian breakup frequency, and it has been suggested that torques associated with GW emission may be setting the observed spin period. This assumption has been used extensively in the literature to assess the strength of the likely gravitational wave signal. There is now, however, a significant amount of theoretical and observation work that suggests that this may not be the case, and that GW emission is unlikely to be setting the spin equilibrium period in many systems. In this paper we take a different starting point and predict the GW signal strength for two physical mechanisms that are likely to be at work in LMXBs: crustal mountains due to thermal asymmetries and magnetically confined mountains. We find that thermal crustal mountains in transient LMXBs are unlikely to lead to detectable GW emission, while persistent systems are good candidates for detection by Advanced LIGO and by the Einstein Telescope. Detection prospects are pessimistic for the magnetic mountain case, unless the NS has a buried magnetic field of $B\\approx 10^{12}$ G, well above the typically inferred exterior dipole fields of these objects. Nevertheless, if a system were to be detected by a GW observatory, cyclotron resonant scattering features in the X-ray emission could be used to distinguish between the two different scenarios.

Brynmor Haskell; Maxim Priymak; Alessandro Patruno; Manuel Oppenoorth; Andrew Melatos; Paul Lasky

2015-01-24T23:59:59.000Z

130

Neutron-Deuteron System and Photon Polarization Parameter at Thermal Neutron Energies  

E-Print Network [OSTI]

Effective Field Theory(EFT) is, the unique, model independent and systematic low-energy version of QCD for processes involving momenta below the pion mass. A low-energy photo-nuclear observable in three-body systems, photon polarization parameter at thermal neutron energies is calculated by using pionless EFT up to next-to-next to leading order(N$^2$LO). In order to make a comparative study of this model, we compared our results for photon polarization parameter with the realistic Argonne $v_{18}$ two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions. Three-body currents give small but significant contributions to some of the observables in the neutron-deuteron radiative capture cross section at thermal neutron energies. In this formalism the three-nucleon forces are needed up to N$^2$LO for cut-off independent results. Our result converges order by order in low energy expansion and also cut-off independent at this order.

H. Sadeghi

2007-04-28T23:59:59.000Z

131

ahumada motion detector: Topics by E-print Network  

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

We show data from a new type of detector that can be used to determine the neutron flux, the energy distribution, and the direction of motion neutron for both fast and thermal...

132

3D neutronic/thermal-hydraulic coupled analysis of MYRRHA  

SciTech Connect (OSTI)

The current tendency in multiphysics calculations applied to reactor physics is the use of already validated computer codes, coupled by means of an iterative approach. In this paper such an approach is explained concerning neutronics and thermal-hydraulics coupled analysis with MCNPX and COBRA-IV codes using a driver program and file exchange between codes. MCNPX provides the neutronic analysis of heterogeneous nuclear systems, both in critical and subcritical states, while COBRA-IV is a subchannel code that can be used for rod bundles or core thermal-hydraulics analysis. In our model, the MCNP temperature dependence of nuclear data is handled via pseudo-material approach, mixing pre-generated cross section data set to obtain the material with the desired cross section temperature. On the other hand, COBRA-IV has been updated to allow for the simulation of liquid metal cooled reactors. The coupled computational tool can be applied to any geometry and coolant, as it is the case of single fuel assembly, at pin-by-pin level, or full core simulation with the average pin of each fuel-assembly. The coupling tool has been applied to the critical core layout of the SCK-CEN MYRRHA concept, an experimental LBE cooled fast reactor presently in engineering design stage. (authors)

Vazquez, M.; Martin-Fuertes, F. [CIEMAT, Avda. Complutense 40, 28040 Madrid (Spain)

2012-07-01T23:59:59.000Z

133

Yield of delayed neutrons in the thermal-neutron-induced reaction {sup 245}Cm(n, f)  

SciTech Connect (OSTI)

The yield of delayed neutrons, v{sub d}, from thermal-neutron-induced fission of {sup 245}Cm is measured. Experiments aimed at studying the properties of delayed neutrons from the fission of some reactor isotopes and initiated in 1997 were continued at the upgraded Isomer-M facility by a method according to which a periodic irradiation of a sample with a pulsed neutron beam from the IBR-2 reactor was accompanied by recording emitted neutrons in the intervals between the pulses. The accuracy of the resulting total delayed-neutron yield v{sub d} = (0.64 {+-} 0.02)% is two times higher than that in previous measurements. This work was performed at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (JINR, Dubna).

Andrianov, V. R. [Joint Institute for Nuclear Research (Russian Federation); Vyachin, V. N. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Gundorin, N. A. [Joint Institute for Nuclear Research (Russian Federation); Druzhinin, A. A. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Zhdanova, K. V.; Lihachev, A. N.; Pikelner, L. B.; Rebrova, N. V.; Salamatin, I. M.; Furman, V. I. [Joint Institute for Nuclear Research (Russian Federation)

2008-10-15T23:59:59.000Z

134

Spin-dependent scattering and absorption of thermal neutrons on dynamically polarized nuclei  

E-Print Network [OSTI]

957 Spin-dependent scattering and absorption of thermal neutrons on dynamically polarized nuclei H neutrons and polarized nuclei have been used to measure spin-dependent scattering lengths and absorption cross sections of slow (S-wave) neutrons on nuclei. In order to obtain those scattering lengths

Paris-Sud XI, Université de

135

A large area plastic scintillator detector array for fast neutron measurements  

E-Print Network [OSTI]

A large area plastic scintillator detector array(~ 1 m x1m) has been set up for fast neutron spectroscopy at the BARC-TIFR Pelletron laboratory, Mumbai. The energy, time and position response has been measured for electrons using radioactive sources and for mono-energetic neutrons using the 7Li(p,n1)7Be*(0.429 MeV) reaction at proton energies between 6.3 and 19 MeV. A Monte Carlo simulation of the energy dependent efficiency of the array for neutron detection is in agreement with the 7Li(p,n1) measurements. The array has been used to measure the neutron spectrum, in the energy range of 4-12 MeV, in the reaction 12C+ 93Nb at E(12C)= 40 MeV. This is in reasonable agreement with a statistical model calculation.

P. C. Rout; D. R. Chakrabarty; V. M. Datar; Suresh Kumar; E. T. Mirgule; A. Mitra; V. Nanal; R. Kujur

2008-09-04T23:59:59.000Z

136

Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus  

SciTech Connect (OSTI)

The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/? discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.

Giacomelli, L. [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom) [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Department of Physics, Università degli Studi di Milano-Bicocca, Milano (Italy); Conroy, S. [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom) [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Gorini, G. [Department of Physics, Università degli Studi di Milano-Bicocca, Milano (Italy)] [Department of Physics, Università degli Studi di Milano-Bicocca, Milano (Italy); Horton, L.; Murari, A.; Popovichev, S.; Syme, D. B. [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)] [JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2014-02-15T23:59:59.000Z

137

Neutron detector using lithiated glass-scintillating particle composite -  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas Conchas recoveryLaboratory | NationalJohn Cyber SecurityAlamosExtending ourNewsNeutronEnergy

138

LENDA, a Low Energy Neutron Detector Array for experiments with radioactive beams in inverse kinematics  

E-Print Network [OSTI]

The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight (TOF) spectrometer developed at the National Superconducting Cyclotron Lab- oratory (NSCL) for use in inverse kinematics experiments with rare isotope beams. Its design has been motivated by the need to study the spin-isospin response of unstable nuclei using (p, n) charge-exchange reactions at intermediate energies (> 100 MeV/u). It can be used, however, for any reaction study that involves emission of low energy neutrons (150 keV - 10 MeV). The array consists of 24 plastic scintillator bars and is capable of registering the recoiling neutron energy and angle with high detection efficiency. The neutron energy is determined by the time-of-flight technique, while the position of interaction is deduced using the timing and energy information from the two photomultipliers of each bar. A simple test setup utilizing radioactive sources has been used to characterize the array. Results of test measurements are compared with simulations. A neutron energy threshold of 20 % for neutrons below 4 MeV have been obtained.

G. Perdikakis; M. Sasano; Sam M. Austin; D. Bazin; C. Caesar; S. Cannon; J. M. Deaven; H. J. Doster; C. J. Guess; G. W. Hitt; J. Marks; R. Meharchand; D. T. Nguyen; D. Peterman; A. Prinke; M. Scott; Y. Shimbara; K. Thorne; L. Valdez; R. G. T. Zegers

2012-05-21T23:59:59.000Z

139

Characterization of a Li-6 loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection  

E-Print Network [OSTI]

The characterization of a liquid scintillator incorporating an aqueous solution of enriched lithium chloride to produce a scintillator with 0.40% Li-6 is presented, including the performance of the scintillator in terms of its optical properties and neutron response. The scintillator was incorporated into a fast neutron spectrometer, and the light output spectra from 2.5 MeV, 14.1 MeV, and Cf-252 neutrons were measured using capture-gated coincidence techniques. The spectrometer was operated without coincidence to perform thermal neutron measurements. Possible improvements in spectrometer performance are discussed.

C. D. Bass; E. J. Beise; H. Breuer; C. R. Heimbach; T. Langford; J. S. Nico

2013-02-07T23:59:59.000Z

140

A silicon photomultiplier readout for time of flight neutron spectroscopy with {gamma}-ray detectors  

SciTech Connect (OSTI)

The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of {gamma}-detection based on the new device.

Pietropaolo, A.; Gorini, G. [Dipartimento di Fisica ''G. Occhialini'' and CNISM, Universita Degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Festa, G.; Andreani, C.; De Pascale, M. P.; Reali, E. [Dipartimento di Fisica and Centro NAST, Universita degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133, Roma (Italy); Grazzi, F. [Istituto dei Sistemi Complessi-Consiglio Nazionale delle Ricerche, Via Madonna del Piano n.10, I-50019 Sesto Fiorentino, Firenze (Italy); Schooneveld, E. M. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

2009-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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141

YALINA-booster subcritical assembly pulsed-neutron e xperiments: detector dead time and apatial corrections.  

SciTech Connect (OSTI)

In almost every detector counting system, a minimal dead time is required to record two successive events as two separated pulses. Due to the random nature of neutron interactions in the subcritical assembly, there is always some probability that a true neutron event will not be recorded because it occurs too close to the preceding event. These losses may become rather severe for counting systems with high counting rates, and should be corrected before any utilization of the experimental data. This report examines the dead time effects for the pulsed neutron experiments of the YALINA-Booster subcritical assembly. The nonparalyzable model is utilized to correct the experimental data due to dead time. Overall, the reactivity values are increased by 0.19$ and 0.32$ after the spatial corrections for the YALINA-Booster 36% and 21% configurations respectively. The differences of the reactivities obtained with He-3 long or short detectors at the same detector channel diminish after the dead time corrections of the experimental data for the 36% YALINA-Booster configuration. In addition, better agreements between reactivities obtained from different experimental data sets are also observed after the dead time corrections for the 21% YALINA-Booster configuration.

Cao, Y.; Gohar, Y.; Nuclear Engineering Division

2010-10-11T23:59:59.000Z

142

Measurements of possible type inversion in silicon junction detectors by fast neutron irradiation  

SciTech Connect (OSTI)

The successful application of silicon position sensitive detectors in experiments at the SSC or LHC depends on an accurate assessment of the radiation tolerance of this detector species. In particular, fast neutrons (E{sub av} = 1 MeV) produce bulk displacement damage that is projected, from estimated fluences, to cause increased generation (leakage) current, charge collection deficiencies, resistivity changes and possibly semiconductor type change or inversion. Whereas the leakage current increase was believed to be the major concern for estimated fluences of 10{sup 12} n/cm{sup 2} experiment year at the initial SSC luminosity of 10{sup 33}/cm{sup 2}-sec, increased luminosity and exposure time has raised the possible exposure to 10{sup 14} n/cm{sup 2}, which opens the door for the several other radiation effects suggested above to play observable and significant roles in detector degradation or change. 17 refs., 19 figs.

Li, Z.; Kraner, H.W.

1991-05-01T23:59:59.000Z

143

THERMAL STRUCTURE AND COOLING OF SUPERFLUID NEUTRON STARS WITH ACCRETED MAGNETIZED ENVELOPES  

E-Print Network [OSTI]

THERMAL STRUCTURE AND COOLING OF SUPERFLUID NEUTRON STARS WITH ACCRETED MAGNETIZED ENVELOPES envelopes composed of accreted material, using updated thermal conductivities of plasmas in quantizing is determined by the equation of state (EOS) and thermal conductivity of matter in the heat-blanketing envelope

144

THERMAL STRUCTURE AND COOLING OF SUPERFLUID NEUTRON STARS WITH ACCRETED MAGNETIZED ENVELOPES  

E-Print Network [OSTI]

THERMAL STRUCTURE AND COOLING OF SUPERFLUID NEUTRON STARS WITH ACCRETED MAGNETIZED ENVELOPES envelopes composed of accreted material, using updated thermal conductivities of plasmas in quantizing is determined by the equation of state (EOS) and thermal conductivity of matter in the heat­blanketing envelope

145

Nuclear Instruments and Methods in Physics Research A 540 (2005) 464469 Fusion neutron detector calibration using a table-top laser  

E-Print Network [OSTI]

Nuclear Instruments and Methods in Physics Research A 540 (2005) 464­469 Fusion neutron detector is designed for observing fusion neutrons at the Z accelerator in Sandia National Laboratories. Nuclear fusion Keywords: Cluster; Laser; Fusion; Neutron; Calibration; Detector 1. Introduction One of the principal

Ditmire, Todd

146

Waste Package Neutron Absorber, Thermal Shunt, and Fill Gas Selection Report  

SciTech Connect (OSTI)

Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials evaluated were essentially boron-containing stainless steels. Two candidates were evaluated for the thermal shunt material. The fill gas candidates were common gases such as helium, argon, nitrogen, carbon dioxide, and dry air. Based on the performance of each candidate against the criteria, the following selections were made: Neutron absorber--Neutronit A978; Thermal shunt--Aluminum 6061 or 6063; and Fill gas--Helium.

V. Pasupathi

2000-01-28T23:59:59.000Z

147

Characterization of a Li-6 loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection  

E-Print Network [OSTI]

We present the characterization of a liquid scintillator incorporating an aqueous solution of enriched lithium chloride to produce a scintillator with 0.40% Li-6. We report on its performance in terms of optical properties and neutron response. We incorporated the scintillator into a spectrometer and measured the light output spectra from 2.5 MeV, 14 MeV, and Cf-252 neutrons using capture-gated coincidence techniques. We operated the spectrometer without coincidence to perform thermal neutron measurements. We discuss possible improvements in spectrometer performance.

Bass, C D; Breuer, H; Heimbach, C R; Langford, T; Nico, J S

2012-01-01T23:59:59.000Z

148

Prospects For High Frequency Burst Searches Following Binary Neutron Star Coalescence With Advanced Gravitational Wave Detectors  

E-Print Network [OSTI]

The equation of state plays a critical role in the physics of the merger of two neutron stars. Recent numerical simulations with microphysical equation of state suggest the outcome of such events depends on the mass of the neutron stars. For less massive systems, simulations favor the formation of a hypermassive, quasi-stable neutron star, whose oscillations produce a short, high frequency burst of gravitational radiation. Its dominant frequency content is tightly correlated with the radius of the neutron star, and its measurement can be used to constrain the supranuclear equation of state. In contrast, the merger of higher mass systems results in prompt gravitational collapse to a black hole. We have developed an algorithm which combines waveform reconstruction from a morphology-independent search for gravitational wave transients with Bayesian model selection, to discriminate between post-merger scenarios and accurately measure the dominant oscillation frequency. We demonstrate the efficacy of the method using a catalogue of simulated binary merger signals in data from LIGO and Virgo, and we discuss the prospects for this analysis in advanced ground-based gravitational wave detectors. From the waveforms considered in this work and assuming an optimally oriented source, we find that the post-merger neutron star signal may be detectable by this technique to $\\sim 10\\text{--}25$\\,Mpc. We also find that we successfully discriminate between the post-merger scenarios with $\\sim 95\\%$ accuracy and determine the dominant oscillation frequency of surviving post-merger neutron stars to within $\\sim 10$\\,Hz, averaged over all detected signals. This leads to an uncertainty in the estimated radius of a non-rotating 1.6\\,M$_{\\odot}$ reference neutron star of $\\sim 100\\,$m.

J. Clark; A. Bauswein; L. Cadonati; H. -T. Janka; C. Pankow; N. Stergioulas

2014-06-20T23:59:59.000Z

149

Measuring Muon-Induced Neutrons with Liquid Scintillation Detector at Soudan Mine  

E-Print Network [OSTI]

We report a direct detection of muon-induced high energy neutrons with a 12-liter neutron detector fabricated with EJ-301 liquid scintillator operating at Soudan Mine for about two years. The detector response to energy from a few MeV up to $\\sim$ 20 MeV has been calibrated using radioactive sources and cosmic-ray muons. Subsequently, we have calculated the scintillation efficiency for nuclear recoils, up to a few hundred MeV, using Birks' law in the Monte Carlo simulation. Data from an exposure of 655.1 days were analyzed and neutron-induced recoil events were observed in the energy region from 4 MeV to 50 MeV, corresponding to fast neutrons with kinetic energy up to a few hundred MeV, depending on the scattering angle. Combining with the Monte Carlo simulation, the muon-induced fast neutron flux is determined to be $(2.3 \\pm 0.52 (sta.) \\pm 0.99 (sys.) ) \\times10^{-9}$ cm$^{-2}$s$^{-1}$ (E$_{n}$ $>$ 20 MeV), in a reasonable agreement with the model prediction. The muon flux is found to be ($1.65\\pm 0.02 (sta.) \\pm 0.1 (sys.) ) \\times10^{-7}$ cm$^{-2}$s$^{-1}$ (E$_{\\mu}$ $>$ 1 GeV), consistent with other measurements. As a result, the muon-induced high energy gamma-ray flux is simulated to be 7.08 $\\times$10$^{-7}$cm$^{-2}$s$^{-1}$ (E$_{\\gamma}$ $>$ 1 MeV) for the depth of Soudan.

C. Zhang; D. -M. Mei

2014-11-26T23:59:59.000Z

150

A First Comparison of the responses of a He4-based fast-neutron detector and a NE-213 liquid-scintillator reference detector  

E-Print Network [OSTI]

A first comparison has been made between the pulse-shape discrimination characteristics of a novel He4-based pressurized scintillation detector and a NE-213 liquid-scintillator reference detector using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquid-scintillator reference cell produced a wide range of scintillation-light yields in response to the gamma-ray field of the source. In stark contrast, the He4-based detector registered a maximum scintillation-light yield of 750 keVee to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750 keVee was excellent in the case of the He4-based detector, and above 750 keVee its signal was unambiguously neutron.

Jebali, R; Annand, J R M; Chandra, R; Davatz, G; Fissum, K G; Friederich, H; Gendotti, U; Hall-Wilton, R; Håkansson, E; Kanaki, K; Lundin, M; Murer, D; Nilsson, B; Rosborg, A; Svensson, H

2015-01-01T23:59:59.000Z

151

A First Comparison of the responses of a He4-based fast-neutron detector and a NE-213 liquid-scintillator reference detector  

E-Print Network [OSTI]

A first comparison has been made between the pulse-shape discrimination characteristics of a novel He4-based pressurized scintillation detector and a NE-213 liquid-scintillator reference detector using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquid-scintillator reference cell produced a wide range of scintillation-light yields in response to the gamma-ray field of the source. In stark contrast, the He4-based detector registered a maximum scintillation-light yield of 750 keVee to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750 keVee was excellent in the case of the He4-based detector, and above 750 keVee its signal was unambiguously neutron.

R. Jebali; J. Scherzinger; J. R. M. Annand; R. Chandra; G. Davatz; K. G. Fissum; H. Friederich; U. Gendotti; R. Hall-Wilton; E. Håkansson; K. Kanaki; M. Lundin; D. Murer; B. Nilsson; A. Rosborg; H. Svensson

2015-02-13T23:59:59.000Z

152

NEUTRONIC AND THERMAL HYDRAULIC DESIGNS OF ANNULAR FUEL FOR HIGH POWER DENSITY BWRS  

E-Print Network [OSTI]

As a promising new fuel for high power density light water reactors, the feasibility of using annular fuel for BWR services is explored from both thermal hydraulic and neutronic points of view. Keeping the bundle size ...

Morra, P.

153

Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems  

SciTech Connect (OSTI)

Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

2013-10-01T23:59:59.000Z

154

MEASURING THE COOLING OF THE NEUTRON STAR IN CASSIOPEIA A WITH ALL CHANDRA X-RAY OBSERVATORY DETECTORS  

SciTech Connect (OSTI)

The thermal evolution of young neutron stars (NSs) reflects the neutrino emission properties of their cores. Heinke and Ho measured a 3.6% ± 0.6% decay in the surface temperature of the Cassiopeia A (Cas A) NS between 2000 and 2009, using archival data from the Chandra X-ray Observatory ACIS-S detector in Graded mode. Page et al. and Shternin et al. attributed this decay to enhanced neutrino emission from a superfluid neutron transition in the core. Here we test this decline, combining analysis of the Cas A NS using all Chandra X-ray detectors and modes (HRC-S, HRC-I, ACIS-I, ACIS-S in Faint mode, and ACIS-S in Graded mode) and adding a 2012 May ACIS-S Graded mode observation, using the most current calibrations (CALDB 4.5.5.1). We measure the temperature changes from each detector separately and test for systematic effects due to the nearby filaments of the supernova remnant. We find a 0.92%-2.0% decay over 10 yr in the effective temperature, inferred from HRC-S data, depending on the choice of source and background extraction regions, with a best-fit decay of 1.0% ± 0.7%. In comparison, the ACIS-S Graded data indicate a temperature decay of 3.1%-5.0% over 10 yr, with a best-fit decay of 3.5% ± 0.4%. Shallower observations using the other detectors yield temperature decays of 2.6% ± 1.9% (ACIS-I), 2.1% ± 1.0% (HRC-I), and 2.1% ± 1.9% (ACIS-S Faint mode) over 10 yr. Our best estimate indicates a decline of 2.9% ± 0.5%{sub stat} ± 1.0{sub sys}% over 10 yr. The complexity of the bright and varying supernova remnant background makes a definitive interpretation of archival Cas A Chandra observations difficult. A temperature decline of 1%-3.5% over 10 yr would indicate extraordinarily fast cooling of the NS that can be regulated by superfluidity of nucleons in the stellar core.

Elshamouty, K. G.; Heinke, C. O.; Sivakoff, G. R. [Department of Physics, University of Alberta, CCIS 4-181, Edmonton AB T6G 2E1 (Canada); Ho, W. C. G. [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom); Shternin, P. S.; Yakovlev, D. G. [Ioffe Physical Technical Institute, Politekhnicheskaya 26, 194021 St Petersburg (Russian Federation); Patnaude, D. J.; David, L., E-mail: alshamou@ualberta.ca [Harvard-Smithsonian Centre for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-11-01T23:59:59.000Z

155

Fissile material detector  

DOE Patents [OSTI]

A detector for fissile materials which provides for integrity monitoring of fissile materials and can be used for nondestructive assay to confirm the presence of a stable content of fissile material in items. The detector has a sample cavity large enough to enable assay of large items of arbitrary configuration, utilizes neutron sources fabricated in spatially extended shapes mounted on the endcaps of the sample cavity, incorporates a thermal neutron filter insert with reflector properties, and the electronics module includes a neutron multiplicity coincidence counter.

Ivanov, Alexander I. (Dubna, RU); Lushchikov, Vladislav I. (Dubna, RU); Shabalin, Eugeny P. (Dubna, RU); Maznyy, Nikita G. (Dubna, RU); Khvastunov, Michael M. (Dubna, RU); Rowland, Mark (Alamo, CA)

2002-01-01T23:59:59.000Z

156

Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system  

DOE Patents [OSTI]

A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

2013-02-12T23:59:59.000Z

157

Fabrication and characterization of a lithium-glass-based composite neutron detector  

E-Print Network [OSTI]

A novel composite, scintillating material intended for neutron detection and composed of small (1.5 mm) cubes of KG2-type lithium glass embedded in a matrix of scintillating plastic has been developed in the form of a 2.2"-diameter, 3.1"-tall cylindrical prototype loaded with $(5.82 \\pm 0.02)%$ lithium glass by mass. The response of the material when exposed to ${}^{252}$Cf fission neutrons and various $\\gamma$-ray sources has been studied; using the charge-integration method for pulse shape discrimination, good separation between neutron and $\\gamma$-ray events is observed and intrinsic efficiencies of $(5.88 \\pm 0.78)\\times 10^{-3}$ and $(7.80 \\pm 0.77)\\times 10^{-5}$ for ${}^{252}$Cf fission neutrons and ${}^{60}$Co $\\gamma$ rays are obtained; an upper limit for the sensitivity to ${}^{137}$Cs $\\gamma$ rays is determined to be $lithium glass can be detected in coincidence with a preceding elastic scattering event in the plastic scintillator; with this coincidence requirement, the intrinsic efficiency of the prototype detector for ${}^{60}$Co $\\gamma$ rays is $(9.65 \\pm 4.07)\\times 10^{-7}$ while its intrinsic efficiency for unmoderated ${}^{252}$Cf fission neutrons is $(2.21 \\pm 0.29)\\times 10^{-3}$. Through use of subregion-integration ratios in addition to the coincidence requirement, the efficiency for $\\gamma$ rays from ${}^{60}$Co is reduced to $(2.56 \\pm 3.15) \\times 10^{-7}$ while the ${}^{252}$Cf fission neutron efficiency becomes $(1.63 \\pm 0.22) \\times 10^{-3}$.

G. C. Rich; K. Kazkaz; H. P. Martinez; T. Gushue

2014-10-13T23:59:59.000Z

158

Characterization of Monoenergetic Neutron Reference Fields with a High Resolution Diamond Detector  

E-Print Network [OSTI]

A novel radiation detector based on an artificial single crystal diamond was used to characterize in detail the energy distribution of neutron reference fields at the Physikalisch-Technische Bundesanstalt (PTB) and their contamination with charged particles. The monoenergetic reference fields at PTB in the neutron energy range from 1.5 MeV up to 19 MeV are generated by proton and deuteron beams impinging on solid and gas targets of tritium and deuterium. The energy of the incoming particles and the variation of the angle under which the measurement is performed produce monoenergetic reference fields with different mean energies and line shapes. In this paper we present high resolution neutron spectrometry measurements of different monoenergetic reference fields. The results are compared with calculated spectra taking into account the actual target parameters. Line structures in the order of 80 keV for a neutron energy of 9 MeV were resolved. The shift of the mean energy and the increasing of the width of the ...

Zimbal, A; Nolte, R; Schuhmacher, H

2009-01-01T23:59:59.000Z

159

Y-12 neutron detector wins prestigious R&D 100 Award | Y-12 National  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered energy consumption byAbout SRNL Home SRNLSecurity Complex neutron detector wins

160

Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays  

SciTech Connect (OSTI)

High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

2002-01-30T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Monitoring the Thermal Power of Nuclear Reactors with a Prototype Cubic Meter Antineutrino Detector  

E-Print Network [OSTI]

In this paper, we estimate how quickly and how precisely a reactor's operational status and thermal power can be monitored over hour to month time scales, using the antineutrino rate as measured by a cubic meter scale detector. Our results are obtained from a detector we have deployed and operated at 25 meter standoff from a reactor core. This prototype can detect a prompt reactor shutdown within five hours, and monitor relative thermal power to three percent within seven days. Monitoring of short-term power changes in this way may be useful in the context of International Atomic Energy Agency's (IAEA) Reactor Safeguards Regime, or other cooperative monitoring regimes.

A. Bernstein; N. S. Bowden; A. Misner; T. Palmer

2008-04-30T23:59:59.000Z

162

Characterization of the Neutron Detector Upgrade to the GP-SANS and BIO-SANS Instruments at HFIR  

SciTech Connect (OSTI)

Over the past year, new 1 m x 1 m neutron detectors have been installed at both the General Purpose SANS (GP-SANS) and the Bio-SANS instruments at HFIR, each intended as an upgrade to provide improved high rate capability. This paper presents the results of characterization studies performed in the detector test laboratory, including position resolution, linearity and background, as well as a preliminary look at high count rate performance.

Berry, Kevin D [ORNL; Bailey, Katherine M [ORNL; Beal, Justin D [ORNL; Diawara, Yacouba [ORNL; Funk, Loren L [ORNL; Hicks, J Steve [ORNL; Jones, Amy Black [ORNL; Littrell, Ken [ORNL; Summers, Randy [ORNL; Urban, Volker S [ORNL; Vandergriff, David H [ORNL; Johnson, Nathan [GE Energy Services; Bradley, Brandon [GE Energy Services

2012-01-01T23:59:59.000Z

163

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation  

SciTech Connect (OSTI)

Uncooled pyroelectric IR imaging systems, such as night vision goggles, offer important strategic advantages in battlefield scenarios and reconnaissance surveys. Until now, the current technology for fabricating these devices has been limited by low throughput and high cost which ultimately limit the availability of these sensor devices. We have developed and fabricated an alternative design for pyroelectric IR imaging sensors that utilizes a multilayered thin film deposition scheme to create a monolithic thin film imaging element on an active silicon substrate for the first time. This approach combines a thin film pyroelectric imaging element with a thermally insulating SiO{sub 2} aerogel thin film to produce a new type of uncooled IR sensor that offers significantly higher thermal, spatial, and temporal resolutions at a substantially lower cost per unit. This report describes the deposition, characterization and optimization of the aerogel thermal isolation layer and an appropriate pyroelectric imaging element. It also describes the overall integration of these components along with the appropriate planarization, etch stop, adhesion, electrode, and blacking agent thin film layers into a monolithic structure. 19 refs., 8 figs., 6 tabs.

Ruffner, J.A.; Clem, P.G.; Tuttle, B.A. [and others

1998-01-01T23:59:59.000Z

164

NEUTRINO PHYSICS WITH THERMAL DETECTORS A. ALESSANDRELLO, C. BROFFERIO, O. CREMONESI, E. FIORINI,  

E-Print Network [OSTI]

of California, Berkeley CA 94720, USA We present the status of our experiments with thermal detectors applied;#12;-0#23;). In the light of the recent hints on atmospheric, solar and reactor neutrino oscillations, 1 both the neutrino sensitivity. Intuitively one expects #1;T #25; E=C and therefore any material with a low heat capacity C can

165

A novel method for modeling the neutron time of flight detector response in current mode to inertial confinement fusion experiments (invited)  

SciTech Connect (OSTI)

A novel method for modeling the neutron time of flight (nTOF) detector response in current mode for inertial confinement fusion experiments has been applied to the on-axis nTOF detectors located in the basement of the Z-Facility. It will be shown that this method can identify sources of neutron scattering, and is useful for predicting detector responses in future experimental configurations, and for identifying potential sources of neutron scattering when experimental set-ups change. This method can also provide insight on how much broadening neutron scattering contributes to the primary signals, which is then subtracted from them. Detector time responses are deconvolved from the signals, allowing a transformation from dN/dt to dN/dE, extracting neutron spectra at each detector location; these spectra are proportional to the absolute yield.

Nelson, A. J.; Cooper, G. W. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ruiz, C. L.; Chandler, G. A.; Fehl, D. L.; Hahn, K. D.; Leeper, R. J.; Smelser, R.; Torres, J. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)

2012-10-15T23:59:59.000Z

166

Heat blanketing envelopes and thermal radiation of strongly magnetized neutron stars  

E-Print Network [OSTI]

Strong (B >> 10^9 G) and superstrong (B > 10^{14} G) magnetic fields profoundly affect many thermodynamic and kinetic characteristics of dense plasmas in neutron star envelopes. In particular, they produce strongly anisotropic thermal conductivity in the neutron star crust and modify the equation of state and radiative opacities in the atmosphere, which are major ingredients of the cooling theory and spectral atmosphere models. As a result, both the radiation spectrum and the thermal luminosity of a neutron star can be affected by the magnetic field. We briefly review these effects and demonstrate the influence of magnetic field strength on the thermal structure of an isolated neutron star, putting emphasis on the differences brought about by the superstrong fields and high temperatures of magnetars. For the latter objects, it is important to take proper account of a combined effect of the magnetic field on thermal conduction and neutrino emission at densities \\rho > 10^{10} g cm^{-3}. We show that the neutrino emission puts a B-dependent upper limit on the effective surface temperature of a cooling neutron star.

A. Y. Potekhin; G. Chabrier; D. G. Yakovlev

2007-09-04T23:59:59.000Z

167

Elemental composition of nickel silicide layers using thermal and fast neutrons  

SciTech Connect (OSTI)

Metal silicides are important contact materials used in the manufacture of semiconductor devices. The presence of impurities has been observed to alter or control the formation of the silicide during fabrication and to influence critically the thermal and electrical performance characteristics of the metal-semiconductor interface. The purpose of this investigation has been to use neutron activation analysis (NAAA), relying on both thermal and fast neutrons, to determine relative concentrations of nickel and impurity elements in nickel silicide/silicon systems. 5 refs., 2 figs., 1 tab.

McGuire, S.C.; Wong, K.; Silcox, J. (Cornell Univ., Ithaca, NY (United States))

1992-01-01T23:59:59.000Z

168

Measurement on the thermal neutron capture cross section of w-180  

E-Print Network [OSTI]

We have measured the thermal neutron capture cross section for w-180 nucleus. There is only one previous data on this cross section with a value of 30 $^{+300%}_{-100%}$ barn. To consider w-181 as a low energy neutrino source, the thermal neutron capture cross section should be measured more precisely to estimate the production rate of w-181 inside a nuclear reactor. We measured the cross section of w-180 with a natural tungsten foil and obtained a new value of 21.9 $\\pm$ 2.5 barn

W. G. Kang; Y. D. Kim; J. I. Lee; I. S. Hahn; A. R. Kim; H. J. Kim

2007-04-24T23:59:59.000Z

169

Measurement of the thermal neutron capture cross section of {sup 180}W  

SciTech Connect (OSTI)

We measured the thermal neutron capture cross section for the {sup 180}W nucleus. There is only one previous measurement with regard to this cross section, and it yielded a value of 30 -100%+300% b. To determine whether {sup 181}W is an appropriate low energy neutrino source, the thermal neutron capture cross section should be measured more precisely to estimate the production rate of {sup 181}W inside a nuclear reactor. We measured the cross section of {sup 180}W using a natural tungsten foil and obtained a value of 22.6{+-}1.7 b.

Kang, W. G.; Kim, Y. D.; Lee, J. I.; Hahn, I. S.; Kim, A. R.; Kim, H. J. [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of); Department of Science Education, Ewha Woman's University, Seoul 120-750 (Korea, Republic of); Physics Department, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

2007-12-15T23:59:59.000Z

170

Study on generating of thermal neutron scattering cross sections for LiH  

SciTech Connect (OSTI)

LiH is designated as a promising moderator and shielding material because of its low density, high melting point and large fraction of H atoms. However, lack of the thermal neutron cross sections of LiH makes numerical calculation deviate from experimental data to some extent. As a result, it is necessary to study LiH thermal kernel effect. The phonon property of LiH has been investigated by first-principles calculations using the plane-wave pseudo potential method with CASTEP code. The scattering law and the thermal neutron scattering cross sections for Li and H have been generated using this distribution. The results have been compared with zirconium hydride data. The GASKET and NJOY/LEAPR codes have been used in the calculation of scattering law, whose results have been compared with the reference; the discrepancy mainly comes from phonon spectrums and its expansion. LEAPR had the capability to compute scattering through larger energy and momentum transfers than GASKET did. By studying LiH phonon spectrum and constructing the model of LiH thermal kernel and scattering matrix, the ACE format LiH thermal neutron cross sections for MCNP software could be made and used for reactor Neutronics calculation. (authors)

Wang, L.; Jiang, X.; Zhao, Z.; Chen, L. [Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

2013-07-01T23:59:59.000Z

171

Condensed Surfaces of Magnetic Neutron Stars, Thermal Surface Emission, and Particle Acceleration Above Pulsar Polar Caps  

E-Print Network [OSTI]

For sufficiently strong magnetic fields and/or low temperatures, the neutron star surface may be in a condensed state with little gas or plasma above it. Such surface condensation can significantly affect the thermal emission from isolated neutron stars, and may lead to the formation of a charge-depleted acceleration zone ("vacuum gap") in the magnetosphere above the stellar polar cap. Using the latest results on the cohesive property of magnetic condensed matter, we quantitatively determine the conditions for surface condensation and vacuum gap formation in magnetic neutron stars. We find that condensation can occur if the thermal energy kT of the neutron star surface is less than about 8% of its cohesive energy Q_s, and that a vacuum gap can form if the neutron star's rotation axis and magnetic moment point in opposite directions and kT is less than about 4% of Q_s. Thus, vacuum gap accelerators may exist for some neutron stars. Motivated by this result, we also study the physics of pair cascades in the vacuum gap model for photon emission by accelerating electrons and positrons due to both curvature radiation and resonant/nonresonant inverse Compton scattering. Our calculations of the condition of cascade-induced vacuum breakdown and the related pulsar death line/boundary generalize previous works to the superstrong field regime. We find that inverse Compton scatterings do not produce a sufficient number of high energy photons in the gap and thus do not lead to pair cascades for most neutron star parameters. We discuss the implications of our results for the recent observations of neutron star thermal radiation as well as for the detection/non-detection of radio emission from high-B pulsars and magnetars.

Zach Medin; Dong Lai

2008-01-18T23:59:59.000Z

172

Neutron Scattering Facility for Characterization of CRESST and EURECA Detectors at mK Temperatures  

E-Print Network [OSTI]

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) is an experiment located at the Gran Sasso underground laboratory and aimed at the direct detection of dark matter in the form of WIMPs. The setup has just completed a one year commissioning run in 2007 and is presently starting a physics run with an increased target mass. Scintillating $\\mathrm{CaWO_4}$ single crystals, operated at temperatures of a few millikelvin, are used as target to detect the tiny nuclear recoil induced by a WIMP. The powerful background identification and rejection of $\\alpha$, e$^{-}$ and $\\gamma$ events is realized via the simultaneous measurement of a phonon and a scintillation signal generated in the $\\mathrm{CaWO_4}$ crystal. However, neutrons could still be misidentified as a WIMP signature. Therefore, a detailed understanding of the individual recoil behaviour in terms of phonon generation and scintillation light emission due to scattering on Ca, O or W nuclei, respectively, is mandatory. The only setup which allows to perform such measurements at the operating temperature of the CRESST detectors has been installed at the Maier-Leibnitz-Accelerator Laboratory in Garching and is presently being commissioned. The design of this neutron scattering facility is such that it can also be used for other target materials, e.g. $\\mathrm{ZnWO_4}$, $\\mathrm{PbWO_4}$ and others as foreseen in the framework of the future multitarget tonne-scale experiment EURECA (European Underground Rare Event Calorimeter Array).

J. -C. Lanfranchi; C. Ciemniak; C. Coppi; F. von Feilitzsch; A. Gütlein; H. Hagn; C. Isaila; J. Jochum; M. Kimmerle; S. Pfister; W. Potzel; W. Rau; S. Roth; K. Rottler; C. Sailer; S. Scholl; I. Usherov; W. Westphal

2008-10-01T23:59:59.000Z

173

The Use of a Multichannel Analyzer to Investigate Effects of Experimental Factors on Gross-Counting Gamma and Neutron Detectors  

SciTech Connect (OSTI)

Radiation detection technology is invaluable to many fields of study in identifying nuclear materials. However, many detectors use gross-counting methods that give only a relative count rate. Without a spectrum (information on counts over time vs energy), it can be more difficult to discern if an alarm is false, innocent, or real. In particular, we would like to understand better the effect of experimental factors (i.e., external conditions and equipment parameters) on detector data, with possible implications for false alarms. To more thoroughly characterize detector technology, a multichannel analyzer (MCA) was used to record spectra from neutron (helium-3 tubes) and gamma (photomultiplier tubes) gross-counting detectors. Several factors could affect the signal-to-noise ratio of sources. For example, we examined the effects of neutron detector high voltage setting on the appearance of a californium-252 spectrum, the effect of discriminator values on integrated counts in neutron detection, and the effect of gain changes on the gamma spectra from several sources. Possible implications of ambient temperature of the experiment on the data collected will be discussed. The input impedance of the MCA must be considered to ensure that data are not affected by the measurement itself. Moreover, a calibration on the MCA was performed to verify the conversion of a MCA channel number to a voltage. In summary, the series of source spectra collected on an MCA with a variety of experimental conditions allow us to understand factors that affect data better, and assure us that gross-counting neutron and gamma detectors will have minimal false alarms.

Volz, Heather M. [Los Alamos National Laboratory; Rennie, John A. [Los Alamos National Laboratory; Lovejoy, Christopher M. [Los Alamos National Laboratory; Martinez, Diana E. R [Los Alamos National Laboratory; Dempsey, Michael A. [Los Alamos National Laboratory; Livesay, Jake [ORNL; Lousteau, Angela [ORNL

2012-07-12T23:59:59.000Z

174

The fast neutron fluence and the activation detector activity calculations using the effective source method and the adjoint function  

SciTech Connect (OSTI)

This paper describes the application of effective source in forward calculations and the adjoint method to the solution of fast neutron fluence and activation detector activities in the reactor pressure vessel (RPV) and RPV cavity of a VVER-440 reactor. Its objective is the demonstration of both methods on a practical task. The effective source method applies the Boltzmann transport operator to time integrated source data in order to obtain neutron fluence and detector activities. By weighting the source data by time dependent decay of the detector activity, the result of the calculation is the detector activity. Alternatively, if the weighting is uniform with respect to time, the result is the fluence. The approach works because of the inherent linearity of radiation transport in non-multiplying time-invariant media. Integrated in this way, the source data are referred to as the effective source. The effective source in the forward calculations method thereby enables the analyst to replace numerous intensive transport calculations with a single transport calculation in which the time dependence and magnitude of the source are correctly represented. In this work, the effective source method has been expanded slightly in the following way: neutron source data were performed with few group method calculation using the active core calculation code MOBY-DICK. The follow-up neutron transport calculation was performed using the neutron transport code TORT to perform multigroup calculations. For comparison, an alternative method of calculation has been used based upon adjoint functions of the Boltzmann transport equation. Calculation of the three-dimensional (3-D) adjoint function for each required computational outcome has been obtained using the deterministic code TORT and the cross section library BGL440. Adjoint functions appropriate to the required fast neutron flux density and neutron reaction rates have been calculated for several significant points within the RPV and RPV cavity of the VVER-440 reacto rand located axially at the position of maximum power and at the position of the weld. Both of these methods (the effective source and the adjoint function) are briefly described in the present paper. The paper also describes their application to the solution of fast neutron fluence and detectors activities for the VVER-440 reactor. (authors)

Hep, J.; Konecna, A.; Krysl, V.; Smutny, V. [Calculation Dept., Skoda JS plc, Orlik 266, 31606 Plzen (Czech Republic)

2011-07-01T23:59:59.000Z

175

Thermal structure and cooling of superfluid neutron stars with accreted magnetized envelopes  

E-Print Network [OSTI]

We study the thermal structure of neutron stars with magnetized envelopes composed of accreted material, using updated thermal conductivities of plasmas in quantizing magnetic fields, as well as equation of state and radiative opacities for partially ionized hydrogen in strong magnetic fields. The relation between the internal and local surface temperatures is calculated and fitted by an analytic function of the internal temperature, magnetic field strength, angle between the field lines and the normal to the surface, surface gravity, and the mass of the accreted material. The luminosity of a neutron star with a dipole magnetic field is calculated for various values of the accreted mass, internal temperature, and magnetic field strength. Using these results, we simulate cooling of superfluid neutron stars with magnetized accreted envelopes. We consider slow and fast cooling regimes, paying special attention to very slow cooling of low-mass superfluid neutron stars. In the latter case, the cooling is strongly affected by the combined effect of magnetized accreted envelopes and neutron superfluidity in the stellar crust. Our results are important for interpretation of observations of isolated neutron stars hottest for their age, such as RX J0822-43 and PSR B1055-52.

A. Y. Potekhin; D. G. Yakovlev; G. Chabrier; O. Y. Gnedin

2003-09-17T23:59:59.000Z

176

Analysis of the effective delayed neutron fraction in the coupled fast-thermal system HERBE  

SciTech Connect (OSTI)

The results of measurements {beta}{sub eff} and {beta}{sub eff}/{Lambda} and calculation results based on various sets of evaluated six-group delayed neutron parameters for the coupled fast-thermal system HERBE are shown in this paper.

Milosevic, M.; Pesic, M.; Avdic, S.; Nikolic, D. [Institute of Nuclear Sciences, Beograd (Yugoslavia)

1994-12-31T23:59:59.000Z

177

Advances in thermal hydraulic and neutronic simulation for reactor analysis and safety  

SciTech Connect (OSTI)

This paper describes several large-scale computational models developed at Argonne National Laboratory for the simulation and analysis of thermal-hydraulic and neutronic events in nuclear reactors and nuclear power plants. The impact of advanced parallel computing technologies on these computational models is emphasized.

Tentner, A.M.; Blomquist, R.N.; Canfield, T.R.; Ewing, T.F.; Garner, P.L.; Gelbard, E.M.; Gross, K.C.; Minkoff, M.; Valentin, R.A.

1993-03-01T23:59:59.000Z

178

DIRECTIONAL DETECTION OF A NEUTRON SOURCE.  

SciTech Connect (OSTI)

Advantages afforded by the development of new directional neutron detectors and imagers are discussed. Thermal neutrons have mean free paths in air of about 20 meters, and can be effectively imaged using coded apertures. Fission spectrum neutrons have ranges greater than 100 meters, and carry enough energy to scatter at least twice in multilayer detectors which can yield both directional and spectral information. Such strategies allow better discrimination between a localized spontaneous fission source and the low, but fluctuating, level of background neutrons generated by cosmic rays. A coded aperture thermal neutron imager will be discussed as well as a proton-recoil double-scatter fast-neutron directional detector with time-of-flight energy discrimination.

VANIER, P.E.; FORMAN, L.

2006-10-23T23:59:59.000Z

179

Detectors  

DOE Patents [OSTI]

The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

Orr, Christopher Henry (Calderbridge, GB); Luff, Craig Janson (Calderbridge, GB); Dockray, Thomas (Calderbridge, GB); Macarthur, Duncan Whittemore (Los Alamos, NM); Bounds, John Alan (Los Alamos, NM); Allander, Krag (Los Alamos, NM)

2002-01-01T23:59:59.000Z

180

Reconstructing the neutron-star equation of state with gravitational-wave detectors from a realistic population of inspiralling binary neutron stars  

E-Print Network [OSTI]

Gravitational-wave observations of inspiralling binary neutron star systems can be used to measure the neutron-star equation of state (EOS) through the tidally induced shift in the waveform phase that depends on the tidal deformability parameter $\\lambda$. Previous work has shown that $\\lambda$, a function of the neutron-star EOS and mass, is measurable by Advanced LIGO for a single event when including tidal information up to the merger frequency. In this work, we describe a method for stacking measurements of $\\lambda$ from multiple inspiral events to measure the EOS. We use Markov chain Monte Carlo simulations to estimate the parameters of a 4-parameter piecewise polytrope EOS that matches theoretical EOS models to a few percent. We find that, for "realistic" event rates ($\\sim 40$ binary neutron star inspiral events per year with signal-to-noise ratio $> 8$ in a single Advanced LIGO detector), combining a year of gravitational-wave data from a three-detector network with the constraints from causality and recent high mass neutron-star measurements, the EOS above nuclear density can be measured to better than a factor of two in pressure in most cases. We also find that in the mass range $1M_\\odot$--$2M_\\odot$, the neutron-star radius can be measured to better than $\\pm 1$ km and the tidal deformability can be measured to better than $\\pm 1 \\times 10^{36}$ g cm$^2$ s$^2$ (10%--50% depending on the EOS and mass). The overwhelming majority of this information comes from the loudest $\\sim 5$ events. Current uncertainties in the post-Newtonian waveform model, however, lead to systematic errors in the EOS measurement that are as large as the statistical errors, and more accurate waveform models are needed to minimize this error.

Benjamin D. Lackey; Leslie Wade

2014-10-31T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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181

NEUTRON AND NON-NEUTRON NUCLEAR DATA FOR RADIATION DOSIMETRY  

SciTech Connect (OSTI)

NEUTRON NUCLEAR DATA THAT IS USED IN REACTOR DOSIMETRY INCLUDE THERMAL NEUTRON CROSS SECTIONS AND NEUTRON RESONANCE INTEGRALS, FISSION SPECTRUM AVERAGED CROSS SECTIONS FOR REACTIONS ON A TARGET NUCLEUS. NON-NEUTRON NUCLEAR DATA USED IN REACTOR DOSIMETRY INCLUDE ISOTOPIC COMPOSITIONS OF TARGET NUCLIDES AND RADIOACTIVE HALF-LIVES, GAMMA-RAY ENERGIES AND INTENSITIES OF REACTION PRODUCT NUCLIDES. ALL OF THESE DATA ARE PERIODICALLY EVALUATED AND RECOMMENDED VALUES ARE PROVIDED IN THE HANDBOOK OF CHEMISTRY AND PHYSICS. THE LATEST RECOMMENDED VALUES ARE DISCUSSED AND THEY ARE CONTRASTED WITH SOME EARLIER NUCLEAR DATA, WHICH WAS PROVIDED WITH NEUTRON DETECTOR FOILS.

HOLDEN,N.E.

1999-09-10T23:59:59.000Z

182

Benchmark validation comparisons of measured and calculated delayed neutron detector responses for a pulsed photonuclear assessment technique  

SciTech Connect (OSTI)

An MCNPX-based calculational methodology has been developed to numerically simulate the complex electron–photon–neutron transport problem for the active interrogation system known as the pulsed photonuclear assessment (PPA) technique. The PPA technique uses a pulsed electron accelerator to generate bremsstrahlung photons in order to fission nuclear materials. Delayed neutron radiation is then detected with helium-3 neutron detectors as evidence of the nuclear material presence. Two experimental tests were designed, setup and run to generate experimental data for benchmarking purposes. The first test irradiated depleted uranium in air, and the second test, depleted uranium in a simulated cargo container (plywood pallet), using 10 MeV electron pulses. Time-integrated, post-flash, delayed neutron counts were measured and compared to calculated count predictions in order to benchmark the calculational methodology and computer models. Comparisons between the experimental measurements and numerical predictions of the delayed neutron detector responses resulted in reasonable experiment/calculated ratios of 1.42 and 1.06 for the two tests. High-enriched uranium (HEU) predictions were also made with the benchmarked models.

J. W. Sterbentz; J. L. Jones; W. Y. Yoon; D. R. Norman; K. J. Haskell

2007-08-01T23:59:59.000Z

183

Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel  

DOE Patents [OSTI]

The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor.

Schreiber, Roger B. (Penn Twp., PA); Fero, Arnold H. (New Kensington, PA); Sejvar, James (Murrysville, PA)

1997-01-01T23:59:59.000Z

184

Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel  

DOE Patents [OSTI]

The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor. 8 figs.

Schreiber, R.B.; Fero, A.H.; Sejvar, J.

1997-12-16T23:59:59.000Z

185

Predicting the sensitivity of the beryllium/scintillator layer neutron detector using Monte Carlo and experimental response functions  

SciTech Connect (OSTI)

A methodology for obtaining empirical curves relating absolute measured scintillation light output to beta energy deposited is presented. Output signals were measured from thin plastic scintillator using NIST traceable beta and gamma sources and MCNP5 was used to model the energy deposition from each source. Combining the experimental and calculated results gives the desired empirical relationships. To validate, the sensitivity of a beryllium/scintillator-layer neutron activation detector was predicted and then exposed to a known neutron fluence from a Deuterium-Deuterium fusion plasma (DD). The predicted and the measured sensitivity were in statistical agreement.

Styron, J. D., E-mail: jdstyro@sandia.gov; Cooper, G. W.; Carpenter, Ken; Bonura, M. A. [Department of Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ruiz, C. L.; Hahn, K. D.; Chandler, G. A.; Nelson, A. J.; Torres, J. A.; McWatters, B. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

2014-11-15T23:59:59.000Z

186

Neutronic and thermal design considerations for heat-pipe reactors  

SciTech Connect (OSTI)

SABRE (Space-Arena Baseline Reactor) is a 100-kW/sub e/, heat-pipe-cooled, beryllium-reflected, fast reactor that produces heat at a temperature of 1500/sup 0/K and radiatively transmits it to high-temperature thermoelectric (TE) conversion elements. The use of heat pipes for core heat removal eliminates single-point failure mechanisms in the reactor cooling system, and provides minimal temperature drop radiative coupling to the TE array, as well as automatic, self-actuating removal of reactor afterheat. The question of how the failure of a fuel module heat pipe will affect neighboring fuel modules in the core is discussed, as is fission density peaking that occurs at the core/reflector interface. Results of neutronic calculations of the control margin available are described. Another issue that is addressed is that of helium generation in the heat pipes from neutron reactions in the core with the heat pipe fluid. Finally, the growth potential of the SABRE design to much higher powers is examined.

Ranken, W.A.; Koenig, D.R.

1983-01-01T23:59:59.000Z

187

Materials Development for Boron Phosphide Based Neutron Detectors: Final Technical Report  

SciTech Connect (OSTI)

The project goal was to improve the quality of boron phosphide (BP) by optimizing its epitaxial growth on single crystal substrates and by producing bulk BP single crystals with low dislocation densities. BP is potentially a good semiconductor for high efficiency solid state neutron detectors by combining neutron capture and charge creation within the same volume. The project strategy was to use newly available single crystal substrates, silicon carbide and aluminum nitride, engineered to produce the best film properties. Substrate variables included the SiC polytype, crystallographic planes, misorientation of the substrate surface (tilt direction and magnitude) from the major crystallographic plane, and surface polarity (Si and C). The best films were (111)BP on silicon-face (0001) 4H-SiC misoriented 4° in the [1-100] direction, and BP on (100) and (111) 3C-SiC/Si; these substrates resulted in films that were free of in-plane twin defects, as determined by x-ray topography. The impact of the deposition temperature was also assessed: increasing the temperature from 1000 °C to 1200 °C produced films that were more ordered and more uniform, and the size of individual grains increased by more than a factor of twenty. The BP films were free of other compounds such as icosahedral boron phosphide (B12P2) over the entire temperature range, as established by Raman spectroscopy. The roughness of the BP films was reduced by increasing the phosphine to diborane ratio from 50 to 200. Bulk crystals were grown by reacting boron dissolved in nickel with phosphorus vapor to precipitate BP. Crystals with dimensions up to 2 mm were produced.

Edgar, James Howard [Ksnsas State University

2014-09-12T23:59:59.000Z

188

Neutronic and thermal calculation of blanket for high power operating condition of fusion reactor  

SciTech Connect (OSTI)

Internal (breeding region) structures of ceramic breeder blanket to accommodate high power operating conditions such as a DEMO reactor have been investigated. The conditions considered here are the maximum neutron wall load of 2.8 MW/m{sup 2} at outboard midplane corresponding to a fusion power of 3.0 GW and the coolant temperature of 200{degrees}C. Structure of a blanket is based on the layered pebble bed concept, which has been proposed by Japan since the ITER CDA. Lithium oxide with 50% enriched {sup 6}Li is used in a shape of small spherical pebbles which are filled in a 316SS can avoid its compatibility issue with Be. Beryllium around the breeder can is filled also in a shape of spherical pebbles which works not only as a neutron multiplier but also as a thermal resistant layer to maintain breeder temperature for effective in-situ tritium recovery. Diameters and packing fractions of both pebbles are {<=} 1 mm and 65%, respectively. A layer of block Be between cooling panels is introduced as a neutron multiplier (not as the thermal resistant layer) to enhance tritium breeding performance. Inlet temperature of water coolant is 200{degrees}C to meet the high temperature conditioning requirement to the first wall which is one of walls of the blanket vessel. Neutronics calculations have been carried out by one-dimensional transport code, and thermal calculations have also been carried out by one-dimensional slab code.

Sagawa, H.; Shimakawa, S.; Kuroda, T. [Oarai Research Establishement of JAERI, Ibaraki (Japan)] [and others

1994-12-31T23:59:59.000Z

189

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux  

DOE Patents [OSTI]

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

Bowman, C.D.

1992-11-03T23:59:59.000Z

190

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux  

DOE Patents [OSTI]

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

Bowman, Charles D. (Los Alamos, NM)

1992-01-01T23:59:59.000Z

191

The measurement of absolute thermal neutron flux using liquid scintillation counting techniques  

E-Print Network [OSTI]

was computed as the square root of the sum of the squares of the individual errors . The flux at the same location in the core and at the same reactor power level was measured by the conventional technique of gold foil 34 activation. This measurement... back to 1932 when the neutron was discovered by Chadwick. With the advent of the nuclear reactor in 1942 the problem of absolute neutron flux determination became increasingly important. Since the operating power of a thermal reactor is directly...

Walker, Jack Vernon

2012-06-07T23:59:59.000Z

192

A Thermal Discrete Element Analysis of EU Solid Breeder Blanket subjected to Neutron Irradiation  

E-Print Network [OSTI]

Due to neutron irradiation, solid breeder blankets are subjected to complex thermo-mechanical conditions. Within one breeder unit, the ceramic breeder bed is composed of spherical-shaped lithium orthosilicate pebbles, and as a type of granular material, it exhibits strong coupling between temperature and stress fields. In this paper, we study these thermo-mechanical problems by developing a thermal discrete element method (Thermal-DEM). This proposed simulation tool models each individual ceramic pebble as one element and considers grain-scale thermo-mechanical interactions between elements. A small section of solid breeder pebble bed in HCPB is modelled using thousands of individual pebbles and subjected to volumetric heating profiles calculated from neutronics under ITER-relevant conditions. We consider heat transfer at the grain-scale between pebbles through both solid-to-solid contacts and the interstitial gas phase, and we calculate stresses arising from thermal expansion of pebbles. The overall effective conductivity of the bed depends on the resulting compressive stress state during the neutronic heating. The thermal-DEM method proposed in this study provides the access to the grain-scale information, which is beneficial for HCPB design and breeder material optimization, and a better understanding of overall thermo-mechanical responses of the breeder units under fusion-relevant conditions.

Yixiang Gan; Francisco Hernandez; Dorian Hanaor; Ratna Annabattula; Marc Kamlah; Pavel Pereslavtsev

2014-06-17T23:59:59.000Z

193

On the analysis method of effective delayed neutron fraction at thermal neutron systems  

SciTech Connect (OSTI)

The effective delayed neutron fraction (beta-effective) was numerically analyzed with different analysis methods, and their effects on the results were investigated. The cores investigated in this study were light-water moderated low enriched UO{sub 2} lattices, of which the beta-effective had been reported. The effects of transport/diffusion calculation, energy group collapsing, and change of nuclear data library were studied. The study showed that the diffusion calculation with coarse group cross section gave smaller beta-effective than the transport one with fine group cross section, although the difference was not so large, about 2%. On the other hand, the change of nuclear data library from JENDL-3.3 to ENDF/B-VI.8 gave a significant difference, over than 4%. In comparisons with the experiments, it was indicated that the delayed neutron data in JENDL-3.3 are more reliable than those in ENDF/B-VI.8. (authors)

Nakajima, K.; Unesaki, H. [Research Reactor Inst., Kyoto Univ., Asashiro-Nishi 2, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2006-07-01T23:59:59.000Z

194

A FLUKA Study of $\\beta$-delayed Neutron Emission for the Ton-size DarkSide Dark Matter Detector  

E-Print Network [OSTI]

In the published cosmogenic background study for a ton-sized DarkSide dark matter search, only prompt neutron backgrounds coincident with cosmogenic muons or muon induced showers were considered, although observation of the initiating particle(s) was not required. The present paper now reports an initial investigation of the magnitude of cosmogenic background from $\\beta$-delayed neutron emission produced by cosmogenic activity in DarkSide. The study finds a background rate for $\\beta$-delayed neutrons in the fiducial volume of the detector on the order of < 0.1 event/year. However, detailed studies are required to obtain more precise estimates. The result should be compared to a radiogenic background event rate from the PMTs inside the DarkSide liquid scintillator veto of 0.2 events/year.

Empl, Anton

2014-01-01T23:59:59.000Z

195

Secondary fusion coupled deuteron/triton transport simulation and thermal-to-fusion neutron convertor measurement  

SciTech Connect (OSTI)

A Monte Carlo tool RSMC (Reaction Sequence Monte Carlo) was developed to simulate deuteron/triton transportation and reaction coupled problem. The 'Forced particle production' variance reduction technique was used to improve the simulation speed, which made the secondary product play a major role. The mono-energy 14 MeV fusion neutron source was employed as a validation. Then the thermal-to-fusion neutron convertor was studied with our tool. Moreover, an in-core conversion efficiency measurement experiment was performed with {sup 6}LiD and {sup 6}LiH converters. Threshold activation foils was used to indicate the fast and fusion neutron flux. Besides, two other pivotal parameters were calculated theoretically. Finally, the conversion efficiency of {sup 6}LiD is obtained as 1.97x10{sup -4}, which matches well with the theoretical result. (authors)

Wang, G. B.; Wang, K. [Department of Engineering Physics, Tsinghua University, Beijing, 100084 (China); Liu, H. G.; Li, R. D. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900 (China)

2013-07-01T23:59:59.000Z

196

Self-regulating neutron coincidence counter  

DOE Patents [OSTI]

A device for accurately measuring the mass of /sup 240/Pu and /sup 239/Pu in a sample having arbitrary moderation and mixed with various contaminants. The device utilizes a thermal neutron well counter which has two concentric rings of neutron detectors separated by a moderating material surrounding the well. Neutron spectroscopic information derived by the two rings of detectors is used to measure the quantity of /sup 239/Pu and /sup 240/Pu in device which corrects for background radiation, deadtime losses of the detector and electronics and various other constants of the system.

Baron, N.

1980-06-16T23:59:59.000Z

197

Method of assaying uranium with prompt fission and thermal neutron borehole logging adjusted by borehole physical characteristics. [Patient application  

DOE Patents [OSTI]

Uranium formations are assayed by prompt fission neutron logging techniques. The uranium in the formation is proportional to the ratio of epithermal counts to thermal or epithermal dieaway. Various calibration factors enhance the accuracy of the measurement.

Barnard, R.W.; Jensen, D.H.

1980-11-05T23:59:59.000Z

198

Nuclear Instruments and Methods in Physics Research A 562 (2006) 380388 Modeling solid-state boron carbide low energy neutron detectors  

E-Print Network [OSTI]

carbide low energy neutron detectors C. Lundstedta,b , A. Harkena,c , E. Daya,c , B.W. Robertsona,c , S types of solid-state boron carbide detector. These results provide the basis for distinguishing between-section. At the University of Nebraska, Lincoln (UNL), a semiconducting form of boron carbide has been developed over

199

A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic rays  

SciTech Connect (OSTI)

An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF’s) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.

Bonura, M. A.; Cooper, G. W.; Nelson, A. J.; Styron, J. D. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ruiz, C. L., E-mail: clruiz@sandia.gov; Fehl, D. L.; Chandler, G.; Hahn, K. D.; Torres, J. A. [Sandia National Laboratories, Diagnostics and Target Physics, Albuquerque, New Mexico 87111 (United States)

2014-11-15T23:59:59.000Z

200

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten  

SciTech Connect (OSTI)

Accurately estimating tritium retention in plasma facing components (PFCs) and minimizing its uncertainty are key safety issues for licensing future fusion power reactors. D-T fusion reactions produce 14.1 MeV neutrons that activate PFCs and create radiation defects throughout the bulk of the material of these components. Recent studies show that tritium migrates and is trapped in bulk (>> 10 µm) tungsten beyond the detection range of nuclear reaction analysis technique [1-2], and thermal desorption spectroscopy (TDS) technique becomes the only established diagnostic that can reveal hydrogen isotope behavior in in bulk (>> 10 µm) tungsten. Radiation damage and its recovery mechanisms in neutron-irradiated tungsten are still poorly understood, and neutron-irradiation data of tungsten is very limited. In this paper, systematic investigations with repeated plasma exposures and thermal desorption are performed to study defect annealing and thermal desorption of deuterium in low dose neutron-irradiated tungsten. Three tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to high flux (ion flux of (0.5-1.0)x1022 m-2s-1 and ion fluence of 1x1026 m-2) deuterium plasma at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy (TDS) was performed with a ramp rate of 10 °C/min up to 900 °C, and the samples were annealed at 900 °C for 0.5 hour. These procedures were repeated three (for 100 and 200 °C samples) and four (for 500 °C sample) times to uncover damage recovery mechanisms and its effects on deuterium behavior. The results show that deuterium retention decreases approximately 90, 75, and 66 % for 100, 200, and 500 °C, respectively after each annealing. When subjected to the same TDS recipe, the desorption temperature shifts from 800 °C to 600 °C after 1st annealing for the sample exposed to TPE at 500 °C. Tritium Migration Analysis Program (TMAP) analysis reveals that the detrapping energy decreases from 1.8 eV to 1.4 eV, indicating the changes in trapping mechanisms. This paper also summarizes deuterium behavior studies in HFIR neutron-irradiated tungsten under US-Japan TITAN program.

Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

2014-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Simulation of optical configurations and signal processing methods in Anger-type neutron-position scintillation detector  

SciTech Connect (OSTI)

The spatial linearity and resolution of Anger-type neutron-position scintillation detectors are studied using a semi-empirical model. Detector optics with either an air gap or optical grease between the scintillator and the dispersive light guide are considered. Three signal processing methods which truncate signals from PMT's distant from the scintillation are compared with the linear resistive weighting method. Air gap optics yields a 15% improvement in spatial resolution and 50% reduction in differential and integral nonlinearity relative to grease coupled optics, using linear processing. Using signal truncation instead of linear processing improves the resolution 15-20% for the air gap and 20-30% for the grease coupling case. Thus, the initial discrepancy in the resolution between the two optics nearly vanished, however the linearity of the grease coupled system is still significantly poorer.

Roche, C.T.; Strauss, M.G.; Brenner, R.

1984-01-01T23:59:59.000Z

202

Comparison of discrete and continuous thermal neutron scattering treatments in MCNP5  

SciTech Connect (OSTI)

The standard discrete thermal neutron S({alpha},{beta}) scattering treatment in MCNP5 is compared with a continuous S({alpha},{beta}) scattering treatment using a criticality suite of 119 benchmark cases and ENDF/B-VII.0 nuclear data. In the analysis, six bound isotopes are considered: beryllium metal, graphite, hydrogen in water, hydrogen in polyethylene, beryllium in beryllium oxide and oxygen in beryllium oxide. Overall, there are only small changes in the eigenvalue (k{sub eff}) between discrete and continuous treatments. In the comparison of 64 cases that utilize S({alpha},{beta}) scattering, 62 agreed at the 95% confidence level, and the 2 cases with differences larger than 3 {sigma} agreed within 1 {sigma} when more neutrons were run in the calculations. The results indicate that the changes in eigenvalue between continuous and discrete treatments are random, small, and well within the uncertainty of measured data for reactor criticality experiments. (authors)

Pavlou, A. T. [Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Brown, F. B. [Los Alamos National Laboratory, Monte Carlo Codes Group, MS A143, PO Box 1663, Los Alamos, NM 87545 (United States); Martin, W. R. [Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Kiedrowski, B. C. [Los Alamos National Laboratory, Monte Carlo Codes Group, MS A143, PO Box 1663, Los Alamos, NM 87545 (United States)

2012-07-01T23:59:59.000Z

203

Neutronics and thermal design analyses of US solid breeder blanket for ITER  

SciTech Connect (OSTI)

The US Solid Breeder Blanket is designed to produce the necessary tritium required for the ITER operation and to operate at power reactor conditions as much as possible. Safety, low tritium inventory, reliability, flexibility cost, and minimum R D requirements are the other design criteria. To satisfy these criteria, the produced tritium is recovered continuously during operation and the blanket coolant operates at low pressure. Beryllium multiplier material is used to control the solid-breeder temperature. Neutronics and thermal design analyses were performed in an integrated manner to define the blanket configuration. The reference parameters of ITER including the operating scenarios, the neutron wall loading distribution and the copper stabilizer are included in the design analyses. Several analyses were performed to study the impact of the reactor parameters, blanket dimensions, material characteristics, and heat transfer coefficient at the material interfaces on the blanket performance. The design analyses and the results from the different studies are summarized. 6 refs., 3 figs., 3 tabs.

Gohar, Y.; Billone, M.; Attaya, H. (Argonne National Lab., IL (USA)); Sawan, M. (Wisconsin Univ., Madison, WI (USA))

1990-09-01T23:59:59.000Z

204

Deterministic Multigroup Modeling of Thermal Effect on Neutron Scattering by Heavy Nuclides.  

E-Print Network [OSTI]

??The principal physical phenomenon underlying the computation of neutron spectra is the nuclear reaction in which neutrons lose or gain energy, i.e., the neutron scattering… (more)

Ghrayeb, Shadi

2013-01-01T23:59:59.000Z

205

Coupled neutronic and thermal-hydraulic code benchmark activities at the International Nuclear Safety Center.  

SciTech Connect (OSTI)

Two realistic benchmark problems are defined and used to assess the performance of coupled thermal-hydraulic and neutronic codes used in simulating dynamic processes in VVER-1000 and RBMK reactor systems. One of the problems simulates a design basis accident involving the ejection of three control and protection system rods from a VVER-1000 reactor. The other is based on a postulated rod withdrawal from an operating RBMK reactor. Preliminary results calculated by various codes are compared. While these results show significant differences, the intercomparisons performed so far provide a basis for further evaluation of code limitations and modeling assumptions.

Podlazov, L. N.

1998-07-29T23:59:59.000Z

206

Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector  

E-Print Network [OSTI]

A large heat load caused by thermal radiation through a metal shield pipe was observed in a cooling test of a cryostat for a prototype of a cryogenic interferometric gravitational wave detector. The heat load was approximately 1000 times larger than the value calculated by the Stefan-Boltzmann law. We studied this phenomenon by simulation and experiment and found that it was caused by the conduction of thermal radiation in a metal shield pipe.

Takayuki Tomaru; Masao Tokunari; Kazuaki Kuroda; Takashi Uchiyama; Akira Okutomi; Masatake Ohashi; Hiroyuki Kirihara; Nobuhiro Kimura; Yoshio Saito; Nobuaki Sato; Takakazu Shintomi; Toshikazu Suzuki; Tomiyoshi Haruyama; Shinji Miyoki; Kazuhiro Yamamoto; Akira Yamamoto

2007-11-06T23:59:59.000Z

207

Experiments and Simulations of the Use of Time-Correlated Thermal Neutron Counting to Determine the Multiplication of an Assembly of Highly Enriched Uranium  

SciTech Connect (OSTI)

A series of experiments and numerical simulations using thermal-neutron time-correlated measurements has been performed to determine the neutron multiplication, M, of assemblies of highly enriched uranium available at Idaho National Laboratory. The experiments used up to 14.4 kg of highly-enriched uranium, including bare assemblies and assemblies reflected with high-density polyethylene, carbon steel, and tungsten. A small 252Cf source was used to initiate fission chains within the assembly. Both the experiments and the simulations used 6-channel and 8-channel detector systems, each consisting of 3He proportional counters moderated with polyethylene; data was recorded in list mode for analysis. 'True' multiplication values for each assembly were empirically derived using basic neutron production and loss values determined through simulation. A total of one-hundred and sixteen separate measurements were performed using fifty-seven unique measurement scenarios, the multiplication varied from 1.75 to 10.90. This paper presents the results of these comparisons and discusses differences among the various cases.

David L. Chichester; Mathew T. Kinlaw; Scott M. Watson; Jeffrey M. Kalter; Eric C. Miller; William A. Noonan

2014-11-01T23:59:59.000Z

208

Hidden explosives detector employing pulsed neutron and x-ray interrogation  

DOE Patents [OSTI]

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Schultz, Frederick J. (Oak Ridge, TN); Caldwell, John T. (Los Alamos, NM)

1993-01-01T23:59:59.000Z

209

Hidden explosives detector employing pulsed neutron and x-ray interrogation  

DOE Patents [OSTI]

Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

Schultz, F.J.; Caldwell, J.T.

1993-04-06T23:59:59.000Z

210

Measurement of neutron capture on $^{48}$Ca at thermal and thermonuclear energies  

E-Print Network [OSTI]

At the Karlsruhe pulsed 3.75\\,MV Van de Graaff accelerator the thermonuclear $^{48}$Ca(n,$\\gamma$)$^{49}$Ca(8.72\\,min) cross section was measured by the fast cyclic activation technique via the 3084.5\\,keV $\\gamma$-ray line of the $^{49}$Ca-decay. Samples of CaCO$_3$ enriched in $^{48}$Ca by 77.87\\,\\% were irradiated between two gold foils which served as capture standards. The capture cross-section was measured at the neutron energies 25, 151, 176, and 218\\,keV, respectively. Additionally, the thermal capture cross-section was measured at the reactor BR1 in Mol, Belgium, via the prompt and decay $\\gamma$-ray lines using the same target material. The $^{48}$Ca(n,$\\gamma$)$^{49}$Ca cross-section in the thermonuclear and thermal energy range has been calculated using the direct-capture model combined with folding potentials. The potential strengths are adjusted to the scattering length and the binding energies of the final states in $^{49}$Ca. The small coherent elastic cross section of $^{48}$Ca+n is explained through the nuclear Ramsauer effect. Spectroscopic factors of $^{49}$Ca have been extracted from the thermal capture cross-section with better accuracy than from a recent (d,p) experiment. Within the uncertainties both results are in agreement. The non-resonant thermal and thermonuclear experimental data for this reaction can be reproduced using the direct-capture model. A possible interference with a resonant contribution is discussed. The neutron spectroscopic factors of $^{49}$Ca determined from shell-model calculations are compared with the values extracted from the experimental cross sections for $^{48}$Ca(d,p)$^{49}$Ca and $^{48}$Ca(n,$\\gamma$)$^{49}$Ca.

H. Beer; C. Coceva; P. V. Sedyshev; Yu. P. Popov; H. Herndl; R. Hofinger; P. Mohr; H. Oberhummer

1996-08-07T23:59:59.000Z

211

Solution-grown crystals for neutron radiation detectors, and methods of solution growth  

DOE Patents [OSTI]

A method according to one embodiment includes growing an organic crystal from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. A method according to another embodiment includes growing an organic crystal from solution, the organic crystal being large enough to exhibit a detectable signal response signature for neutrons from a radioactive source. An organic crystal according to another embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source, wherein the organic crystal has a length of greater than about 1 mm in one dimension.

Zaitseva, Natalia P.; Hull, Giulia; Cherepy, Nerine J.; Payne, Stephen A.; Stoeffl, Wolfgang

2012-06-26T23:59:59.000Z

212

INVESTIGATION OF NEW MATERIALS AND DETECTORS USING THE ELECTROSTATIC ACCELERATOR AND NEUTRON GENERATOR BEAMS  

E-Print Network [OSTI]

GENERATOR BEAMS V.M.Lebedev, V.A.Smolin, I.M.Kotina, A.G.Krivchitch, Yu.F.Biryulin 1 , V.I.Ivanov­Omskii 1 with the energy of 1.6 MeV and a neutron generator with 14 MeV monoenergetic neutrons [1-3] - were used for a wide was very actually, especially, of oxygen content due to the largest mobility of these atoms in YBa 2 Cu 3 O

Titov, Anatoly

213

Proceedings of the OECD/CSNI workshop on transient thermal-hydraulic and neutronic codes requirements  

SciTech Connect (OSTI)

This is a report on the CSNI Workshop on Transient Thermal-Hydraulic and Neutronic Codes Requirements held at Annapolis, Maryland, USA November 5-8, 1996. This experts` meeting consisted of 140 participants from 21 countries; 65 invited papers were presented. The meeting was divided into five areas: (1) current and prospective plans of thermal hydraulic codes development; (2) current and anticipated uses of thermal-hydraulic codes; (3) advances in modeling of thermal-hydraulic phenomena and associated additional experimental needs; (4) numerical methods in multi-phase flows; and (5) programming language, code architectures and user interfaces. The workshop consensus identified the following important action items to be addressed by the international community in order to maintain and improve the calculational capability: (a) preserve current code expertise and institutional memory, (b) preserve the ability to use the existing investment in plant transient analysis codes, (c) maintain essential experimental capabilities, (d) develop advanced measurement capabilities to support future code validation work, (e) integrate existing analytical capabilities so as to improve performance and reduce operating costs, (f) exploit the proven advances in code architecture, numerics, graphical user interfaces, and modularization in order to improve code performance and scrutibility, and (g) more effectively utilize user experience in modifying and improving the codes.

Ebert, D.

1997-07-01T23:59:59.000Z

214

The Influence of Thermal Pressure on Equilibrium Models of Hypermassive Neutron Star Merger Remnants  

E-Print Network [OSTI]

The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state, angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (~5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically-symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear equations of state, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parametrized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger.

J. D. Kaplan; C. D. Ott; E. P. O'Connor; K. Kiuchi; L. Roberts; M. Duez

2014-06-01T23:59:59.000Z

215

Simulated Performance of the Integrated Passive Neutron Albedo Reactivity and Self-Interrogation Neutron Resonance Densitometry Detector Designed for Spent Fuel Measurement at the Fugen Reactor in Japan  

SciTech Connect (OSTI)

An integrated nondestructive assay instrument, which combined the Passive Neutron Albedo Reactivity (PNAR) and the Self-Interrogation Neutron Resonance Densitometry (SINRD) techniques, is the research focus for a collaborative effort between Los Alamos National Laboratory (LANL) and the Japanese Atomic Energy Agency as part of the Next Generation Safeguard Initiative. We will quantify the anticipated performance of this experimental system in two physical environments: (1) At LANL we will measure fresh Low Enriched Uranium (LEU) assemblies for which the average enrichment can be varied from 0.2% to 3.2% and for which Gd laced rods will be included. (2) At Fugen we will measure spent Mixed Oxide (MOX-B) and LEU spent fuel assemblies from the heavy water moderated Fugen reactor. The MOX-B assemblies will vary in burnup from {approx}3 GWd/tHM to {approx}20 GWd/tHM while the LEU assemblies ({approx}1.9% initial enrichment) will vary from {approx}2 GWd/tHM to {approx}7 GWd/tHM. The estimated count rates will be calculated using MCNPX. These preliminary results will help the finalization of the hardware design and also serve a guide for the experiment. The hardware of the detector is expected to be fabricated in 2012 with measurements expected to take place in 2012 and 2013. This work is supported by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

Ulrich, Timothy J. II [Los Alamos National Laboratory; Lafleur, Adrienne M. [Los Alamos National Laboratory; Menlove, Howard O. [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory; Tobin, Stephen J. [Los Alamos National Laboratory; Seya, Michio [Los Alamos National Laboratory; Bolind, Alan M. [Los Alamos National Laboratory

2012-07-16T23:59:59.000Z

216

Delayed neutron emission measurements for U-235 and Pu-239  

E-Print Network [OSTI]

The delayed neutron emission rates of U-235 and Pu-239 samples were measured accurately from a thermal fission reaction. A Monte Carlo calculation using the Geant4 code was used to demonstrate the neutron energy independence of the detector used...

Chen, Yong

2009-05-15T23:59:59.000Z

217

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.  

SciTech Connect (OSTI)

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

2007-12-01T23:59:59.000Z

218

Solution-grown crystals for neutron radiation detectors, and methods of solution growth  

DOE Patents [OSTI]

An organic crystal according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. Methods of making such crystals are also provided.

Zaitseva, Natalia; Carman, M Leslie; Payne, Steve

2014-10-28T23:59:59.000Z

219

Methods for absorbing neutrons  

DOE Patents [OSTI]

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)

2012-07-24T23:59:59.000Z

220

Position sensitive detection of neutrons in high radiation background field  

SciTech Connect (OSTI)

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high ? and e{sup ?} radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 ?m{sup 2}) spectroscopic Timepix detector adapted for neutron detection utilizing very thin {sup 10}B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10{sup ?4}.

Vavrik, D., E-mail: vavrik@itam.cas.cz [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, Prague (Czech Republic); Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Prague 9 (Czech Republic); Jakubek, J.; Pospisil, S. [Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Prague 9 (Czech Republic)] [Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Prague 9 (Czech Republic); Vacik, J. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, 250 68 Prague, Czech Republic (Czech Republic)] [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, 250 68 Prague, Czech Republic (Czech Republic)

2014-01-15T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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221

Exposure of nuclear track emulsion to thermal neutrons, heavy ions and muons  

E-Print Network [OSTI]

Physical analysis of exposures of test samples of reproduced nuclear track emulsion (NTE) is presented. In boron enriched NTE the angular and energy correlations of products of the reaction induced by thermal neutrons n$_{th} + ^{10}B \\rightarrow ^{7}Li + (\\gamma) + \\alpha$ are studied. NTE was exposed to ions $^{86}Kr^{+17}$ and $^{124}Xe^{+26}$ of energy about 1.2 A MeV. Measurements of the heavy ion ranges of in NTE allowed one to determine their energy on a basis of the SRIM model. Nuclear stars of large multiplicity of target nuclei are observed in exposure of NTE to ultrarelativistic $\\mu$-mesons. The kinematical characteristics of the events of splitting of carbon nuclei into three $\\alpha$-particles studied in this exposure point to a nuclear diffractive mechanism of interactions.

D. A. Artemenkov; V. Bradnova; A. A. Zaitsev; P. I. Zarubin; I. G. Zarubina; R. R. Kattabekov; K. Z. Mamatkulov; V. V. Rusakova

2014-07-17T23:59:59.000Z

222

Space nuclear-power reactor design based on combined neutronic and thermal-fluid analyses  

SciTech Connect (OSTI)

The design and performance analysis of a space nuclear-power system requires sophisticated analytical capabilities such as those developed during the nuclear rocket propulsion (Rover) program. In particular, optimizing the size of a space nuclear reactor for a given power level requires satisfying the conflicting requirements of nuclear criticality and heat removal. The optimization involves the determination of the coolant void (volume) fraction for which the reactor diameter is a minimum and temperature and structural limits are satisfied. A minimum exists because the critical diameter increases with increasing void fraction, whereas the reactor diameter needed to remove a specified power decreases with void fraction. The purpose of this presentation is to describe and demonstrate our analytical capability for the determination of minimum reactor size. The analysis is based on combining neutronic criticality calculations with OPTION-code thermal-fluid calculations.

Koenig, D.R.; Gido, R.G.; Brandon, D.I.

1985-01-01T23:59:59.000Z

223

Safety analysis of high pressure 3He-filled micro-channels for thermal neutron detection.  

SciTech Connect (OSTI)

This document is a safety analysis of a novel neutron detection technology developed by Sandia National Laboratories. This technology is comprised of devices with tiny channels containing high pressure {sup 3}He. These devices are further integrated into large scale neutron sensors. Modeling and preliminary device testing indicates that the time required to detect the presence of special nuclear materials may be reduced under optimal conditions by several orders of magnitude using this approach. Also, these devices make efficient use of our {sup 3}He supply by making individual devices more efficient and/or extending the our limited {sup 3}He supply. The safety of these high pressure devices has been a primary concern. We address these safety concerns for a flat panel configuration intended for thermal neutron detection. Ballistic impact tests using 3 g projectiles were performed on devices made from FR4, Silicon, and Parmax materials. In addition to impact testing, operational limits were determined by pressurizing the devices either to failure or until they unacceptably leaked. We found that (1) sympathetic or parasitic failure does not occur in pressurized FR4 devices (2) the Si devices exhibited benign brittle failure (sympathetic failure under pressure was not tested) and (3) the Parmax devices failed unacceptably. FR4 devices were filled to pressures up to 4000 + 100 psig, and the impacts were captured using a high speed camera. The brittle Si devices shattered, but were completely contained when wrapped in thin tape, while the ductile FR4 devices deformed only. Even at 4000 psi the energy density of the compressed gas appears to be insignificant compared to the impact caused by the incoming projectile. In conclusion, the current FR4 device design pressurized up to 4000 psi does not show evidence of sympathetic failure, and these devices are intrinsically safe.

Ferko, Scott M.; Galambos, Paul C.; Derzon, Mark Steven; Renzi, Ronald F.

2008-11-01T23:59:59.000Z

224

Measurement of neutron spectra for determining dose equivalent rates at the Texas A&M University Nuclear Science Center  

E-Print Network [OSTI]

. Also, placement of the detector in a low flux neutron environment adjacent to the area to be characterized could be utilized. These recommendations are reasonable for measurements taken at commercial power plants in areas where personnel exposure... reactions in this region, He 3 10 proportional counters have been proposed by Brackenbush (Br84) to measure neutron spectra up to 1 MeV. The He detector is surrounded by a thermal neutron absorber to maximize the sensitivity at the low end...

Sanza, Bruce Jerome

2012-06-07T23:59:59.000Z

225

Thermal-hydraulic criteria for the APT tungsten neutron source design  

SciTech Connect (OSTI)

This report presents the thermal-hydraulic design criteria (THDC) developed for the tungsten neutron source (TNS). The THDC are developed for the normal operations, operational transients, and design-basis accidents. The requirements of the safety analyses are incorporated into the design criteria, consistent with the integrated safety management and the safety-by-design philosophy implemented throughout the APT design process. The phenomenology limiting the thermal-hydraulic design and the confidence level requirements for each limit are discussed. The overall philosophy of the uncertainty analyses and the confidence level requirements also are presented. Different sets of criteria are developed for normal operations, operational transients, anticipated accidents, unlikely accidents, extremely unlikely accidents, and accidents during TNS replacement. In general, the philosophy is to use the strictest criteria for the high-frequency events. The criteria is relaxed as the event frequencies become smaller. The THDC must be considered as a guide for the design philosophy and not as a hard limit. When achievable, design margins greater than those required by the THDC must be used. However, if a specific event sequence cannot meet the THDC, expensive design changes are not necessary if the single event sequence results in sufficient margin to safety criteria and does not challenge the plant availability or investment protection considerations.

Pasamehmetoglu, K.

1998-03-01T23:59:59.000Z

226

A novel method for modeling the neutron time of flight (nTOF) detector response in current mode to inertial confinement fusion experiments.  

SciTech Connect (OSTI)

There are several machines in this country that produce short bursts of neutrons for various applications. A few examples are the Zmachine, operated by Sandia National Laboratories in Albuquerque, NM; the OMEGA Laser Facility at the University of Rochester in Rochester, NY; and the National Ignition Facility (NIF) operated by the Department of Energy at Lawrence Livermore National Laboratory in Livermore, California. They all incorporate neutron time of flight (nTOF) detectors which measure neutron yield, and the shapes of the waveforms from these detectors contain germane information about the plasma conditions that produce the neutrons. However, the signals can also be %E2%80%9Cclouded%E2%80%9D by a certain fraction of neutrons that scatter off structural components and also arrive at the detectors, thereby making analysis of the plasma conditions more difficult. These detectors operate in current mode - i.e., they have no discrimination, and all the photomultiplier anode charges are integrated rather than counted individually as they are in single event counting. Up to now, there has not been a method for modeling an nTOF detector operating in current mode. MCNPPoliMiwas developed in 2002 to simulate neutron and gammaray detection in a plastic scintillator, which produces a collision data output table about each neutron and photon interaction occurring within the scintillator; however, the postprocessing code which accompanies MCNPPoliMi assumes a detector operating in singleevent counting mode and not current mode. Therefore, the idea for this work had been born: could a new postprocessing code be written to simulate an nTOF detector operating in current mode? And if so, could this process be used to address such issues as the impact of neutron scattering on the primary signal? Also, could it possibly even identify sources of scattering (i.e., structural materials) that could be removed or modified to produce %E2%80%9Ccleaner%E2%80%9D neutron signals? This process was first developed and then applied to the axial neutron time of flight detectors at the ZFacility mentioned above. First, MCNPPoliMi was used to model relevant portions of the facility between the source and the detector locations. To obtain useful statistics, variance reduction was utilized. Then, the resulting collision output table produced by MCNPPoliMi was further analyzed by a MATLAB postprocessing code. This converted the energy deposited by neutron and photon interactions in the plastic scintillator (i.e., nTOF detector) into light output, in units of MeVee%D1%84 (electron equivalent) vs time. The time response of the detector was then folded into the signal via another MATLAB code. The simulated response was then compared with experimental data and shown to be in good agreement. To address the issue of neutron scattering, an %E2%80%9CIdeal Case,%E2%80%9D (i.e., a plastic scintillator was placed at the same distance from the source for each detector location) with no structural components in the problem. This was done to produce as %E2%80%9Cpure%E2%80%9D a neutron signal as possible. The simulated waveform from this %E2%80%9CIdeal Case%E2%80%9D was then compared with the simulated data from the %E2%80%9CFull Scale%E2%80%9D geometry (i.e., the detector at the same location, but with all the structural materials now included). The %E2%80%9CIdeal Case%E2%80%9D was subtracted from the %E2%80%9CFull Scale%E2%80%9D geometry case, and this was determined to be the contribution due to scattering. The time response was deconvolved out of the empirical data, and the contribution due to scattering was then subtracted out of it. A transformation was then made from dN/dt to dN/dE to obtain neutron spectra at two different detector locations.

Nelson, Alan J. [University of New Mexico, Albuquerque, NM; Cooper, Gary Wayne [University of New Mexico, Albuquerque, NM; Ruiz, Carlos L.; Chandler, Gordon Andrew; Fehl, David Lee; Hahn, Kelly Denise; Leeper, Ramon Joe; Smelser, Ruth Marie; Torres, Jose A.

2013-09-01T23:59:59.000Z

227

Tests of the radiation hardness of VLSI Integrated Circuits and Silicon Strip Detectors for the SSC (Superconducting Super Collider) under neutron, proton, and gamma irradiation  

SciTech Connect (OSTI)

As part of a program to develop a silicon strip central tracking detector system for the Superconducting Super Collider (SSC) we are studying the effects of radiation damage in silicon detectors and their associated front-end readout electronics. We report on the results of neutron and proton irradiations at the Los Alamos National Laboratory (LANL) and {gamma}-ray irradiations at UC Santa Cruz (UCSC). Individual components on single-sided AC-coupled silicon strip detectors and on test structures were tested. Circuits fabricated in a radiation hard CMOS process and individual transistors fabricated using dielectric isolation bipolar technology were also studied. Results indicate that a silicon strip tracking detector system should have a lifetime of at least one decade at the SSC. 17 refs., 17 figs.

Ziock, H.J.; Milner, C.; Sommer, W.F. (Los Alamos National Lab., NM (USA)); Carteglia, N.; DeWitt, J.; Dorfan, D.; Hubbard, B.; Leslie, J.; O'Shaughnessy, K.F.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E. (California Univ., Santa Cruz, CA (USA). Inst. for Particle Physics); Ellison, J.A. (California Univ., Riverside, CA (USA)); Ferguson, P. (Missouri Univ., Rolla, MO (USA)); Giubellino

1990-01-01T23:59:59.000Z

228

Design and performance considerations for perforated semiconductor thermal-neutron detectors  

E-Print Network [OSTI]

. The ðn; g� reactions yield numerous low energy conversion electrons, with a general distribution ranging]. As a result, the reaction products from Gd are mostly low energy conversion electrons which can easily.K. Shultis, D.S. McGregor � S.M.A.R.T. Laboratory, Department of Mechanical and Nuclear Engineering, 3002

Shultis, J. Kenneth

229

Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections and Astrophysical Reaction Rates Calculated from Major Evaluated Data Libraries  

E-Print Network [OSTI]

We present calculations of neutron thermal cross sections, Westcott factors, resonance integrals, Maxwellianaveraged cross sections and astrophysical reaction rates for 843 ENDF materials using data from the major evaluated nuclear libraries and European activation file. Extensive analysis of newly-evaluated neutron reaction cross sections, neutron covariances, and improvements in data processing techniques motivated us to calculate nuclear industry and neutron physics quantities, produce s-process Maxwellian-averaged cross sections and astrophysical reaction rates, systematically calculate uncertainties, and provide additional insights on currently available neutron-induced reaction data. Nuclear reaction calculations are discussed and new results are presented.

Pritychenko, B

2012-01-01T23:59:59.000Z

230

BWR transient analysis using neutronic / thermal hydraulic coupled codes including uncertainty quantification  

SciTech Connect (OSTI)

The KIT is involved in the development and qualification of best estimate methodologies for BWR transient analysis in cooperation with industrial partners. The goal is to establish the most advanced thermal hydraulic system codes coupled with 3D reactor dynamic codes to be able to perform a more realistic evaluation of the BWR behavior under accidental conditions. For this purpose a computational chain based on the lattice code (SCALE6/GenPMAXS), the coupled neutronic/thermal hydraulic code (TRACE/PARCS) as well as a Monte Carlo based uncertainty and sensitivity package (SUSA) has been established and applied to different kind of transients of a Boiling Water Reactor (BWR). This paper will describe the multidimensional models of the plant elaborated for TRACE and PARCS to perform the investigations mentioned before. For the uncertainty quantification of the coupled code TRACE/PARCS and specifically to take into account the influence of the kinetics parameters in such studies, the PARCS code has been extended to facilitate the change of model parameters in such a way that the SUSA package can be used in connection with TRACE/PARCS for the U and S studies. This approach will be presented in detail. The results obtained for a rod drop transient with TRACE/PARCS using the SUSA-methodology showed clearly the importance of some kinetic parameters on the transient progression demonstrating that the coupling of a best-estimate coupled codes with uncertainty and sensitivity tools is very promising and of great importance for the safety assessment of nuclear reactors. (authors)

Hartmann, C.; Sanchez, V. [Karlsruhe Inst. of Technology (KIT), Inst. for Neutron Physics and Reactor Technology INR, Hermann-vom-Helmholtz-Platz-1, D-76344 Eggenstein-Leopoldshafen (Germany); Tietsch, W. [Westinghouse Electric Germany GmbH, Mannheim (Germany); Stieglitz, R. [Karlsruhe Inst. of Technology (KIT), Inst. for Neutron Physics and Reactor Technology INR, Hermann-vom-Helmholtz-Platz-1, D-76344 Eggenstein-Leopoldshafen (Germany)

2012-07-01T23:59:59.000Z

231

Ultra Wide Band RFID Neutron Tags for Nuclear Materials Monitoring  

SciTech Connect (OSTI)

Recent advancements in the ultra-wide band Radio Frequency Identification (RFID) technology and solid state pillar type neutron detectors have enabled us to move forward in combining both technologies for advanced neutron monitoring. The LLNL RFID tag is totally passive and will operate indefinitely without the need for batteries. The tag is compact, can be directly mounted on metal, and has high performance in dense and cluttered environments. The LLNL coin-sized pillar solid state neutron detector has achieved a thermal neutron detection efficiency of 20% and neutron/gamma discrimination of 1E5. These performance values are comparable to a fieldable {sup 3}He based detector. In this paper we will discuss features about the two technologies and some potential applications for the advanced safeguarding of nuclear materials.

Nekoogar, F; Dowla, F; Wang, T

2010-01-27T23:59:59.000Z

232

A Combined Neutronic-Thermal Hydraulic Model of CERMET NTR Reactor  

SciTech Connect (OSTI)

Abstract. Two different CERMET fueled Nuclear Thermal Propulsion reactors were modeled to determine the optimum coolant channel surface area to volume ratio required to cool a 25,000 lbf rocket engine operating at a specific impulse of 940 seconds. Both reactor concepts were computationally fueled with hexagonal cross section fuel elements having a flat-to-flat distance of 3.51 cm and containing 60 vol.% UO2 enriched to 93wt.%U235 and 40 vol.% tungsten. Coolant channel configuration consisted of a 37 coolant channel fuel element and a 61 coolant channel model representing 0.3 and 0.6 surface area to volume ratios respectively. The energy deposition from decelerating fission products and scattered neutrons and photons was determined using the MCNP monte carlo code and then imported into the STAR-CCM+ computational fluid dynamics code. The 37 coolant channel case was shown to be insufficient in cooling the core to a peak temperature of 3000 K; however, the 61 coolant channel model shows promise for maintaining a peak core temperature of 3000 K, with no more refinements to the surface area to volume ratio. The core was modeled to have a power density of 9.34 GW/m3 with a thrust to weight ratio of 5.7.

Jonathan A. Webb; Brian Gross; William T. Taitano

2011-02-01T23:59:59.000Z

233

Implementing a search for aligned-spin neutron star -- black hole systems with advanced ground based gravitational wave detectors  

E-Print Network [OSTI]

We study the effect of spins on searches for gravitational waves from compact binary coalescences in realistic simulated early advanced LIGO data. We construct a detection pipeline including matched filtering, signal-based vetoes, a coincidence test between different detectors, and an estimate of the rate of background events. We restrict attention to neutron star--black hole (NS-BH) binary systems, and we compare a search using non-spinning templates to one using templates that include spins aligned with the orbital angular momentum. To run the searches we implement the binary inspiral matched-filter computation in PyCBC, a new software toolkit for gravitational-wave data analysis. We find that the inclusion of aligned-spin effects significantly increases the astrophysical reach of the search. Considering astrophysical NS-BH systems with non-precessing black hole spins, for dimensionless spin components along the orbital angular momentum uniformly distributed in $(-1, 1)$, the sensitive volume of the search with aligned-spin templates is increased by $\\sim 50\\%$ compared to the non-spinning search; for signals with aligned spins uniformly distributed in the range $(0.7,1)$, the increase in sensitive volume is a factor of $\\sim 10$.

Tito Dal Canton; Alexander H. Nitz; Andrew P. Lundgren; Alex B. Nielsen; Duncan A. Brown; Thomas Dent; Ian W. Harry; Badri Krishnan; Andrew J. Miller; Karl Wette; Karsten Wiesner; Joshua L. Willis

2014-10-27T23:59:59.000Z

234

Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques  

SciTech Connect (OSTI)

The liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC) use expanded perlite as thermal insulation. Some of the perlite may have compacted over time, compromising the thermal performance and also the structural integrity of the tanks. Neutrons can readily penetrate through the 1.75 cm outer steel shell and through the entire 120 cm thick perlite zone. Neutrons interactions with materials produce characteristic gamma rays which are then detected. In compacted perlite the count rates in the individual peaks in the gamma ray spectrum will increase. Portable neutron generators can produce neutron simultaneous fluxes in two energy ranges: fast (14 MeV) and thermal (25 meV). Fast neutrons produce gamma rays by inelastic scattering which is sensitive to Si, Al, Fe and O. Thermal neutrons produce gamma rays by radiative capture in prompt gamma neutron activation (PGNA), which is sensitive to Si, Al, Na, K and H among others. The results of computer simulations using the software MCNP and measurements on a test article suggest that the most promising approach would be to operate the system in time-of-flight mode by pulsing the neutron generator and observing the subsequent die away curve in the PGNA signal.

Livingston, R. A. [Materials Science and Engineering Dept., U. of Maryland, College Park, MD (United States); Schweitzer, J. S. [Physics Dept., U. of Connecticut, Storrs (United States); Parsons, A. M. [Goddard Space Flight Center, Greenbelt (United States); Arens, E. E. [John F. Kennedy Space Center, FL (United States)

2014-02-18T23:59:59.000Z

235

Low-energy neutron detector based upon lithium lanthanide borate scintillators  

DOE Patents [OSTI]

An apparatus for detecting neutrons includes a cerium activated scintillation crystal containing .sup.10 B, with the scintillation crystal emitting light in response to .alpha. particles emitted from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus also includes a gamma scintillator positioned adjacent the crystal and which generates light in response to gamma rays emitted from the decay of Li*. The apparatus further includes a first and a second light-to-electronic signal converter each positioned to respectively receive light from the crystal and the gamma scintillator, and each respectively outputting first and second electronic signals representative of .alpha. particles from the .sup.10 B(n,.alpha.)Li* reaction and gamma rays from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus includes a coincidence circuit connected to receive the first and second signals and which generates a coincidence signal when the first and second signals coincide. The apparatus also includes a data analyzer for receiving an additional signal from at least one of the first and second converters, and for operating in response to the coincidence signal.

Czirr, John B. (Mapleton, UT)

1998-01-01T23:59:59.000Z

236

Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE  

SciTech Connect (OSTI)

Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

Jandel, Marian [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

237

Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE  

SciTech Connect (OSTI)

Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) events from (n,f) events. The first direct observation of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Couture, A.; Haight, R. C.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A. [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

2009-01-28T23:59:59.000Z

238

E-Print Network 3.0 - asymmetric thermal neutron Sample Search...  

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

2106533431 Large Scale Experimental Facilities at RRL Nuclear Research Reactor 5 MW power Neutron... Scattering Facilities ... Source: National Center for Scientific Research...

239

Thermal up-scattering of very cold and ultra-cold neutrons in solid deuterium  

E-Print Network [OSTI]

The work presented in this thesis forms part of a program at the Paul Scherrer Institute (PSI) to construct a high intensity superthermal ultra-cold neutron (UCN) source based on solid deuterium as UCN production medium. We carried out a set of experiments to gain a better understanding of the properties and the behaviour of solid deuterium as a cold neutron moderator and ultra-cold neutron converter. We present the measurements of the total neutron cross section as obtained by transmission studies with very cold neutrons and ultra-cold neutrons in solid deuterium. The experimental set-up and the methods of data analysis are described and also the procedure of preparing the solid deuterium samples is given. The neutron transmission studies are supported by optical investigation of the crystal and by Raman spectroscopy. We have thus characterised the temperature dependence of the neutron transmission through solid deuterium and we have been able to identify the role that coherent neutron scattering plays for the investigated deuterium samples.

Malgorzata Kasprzak

2004-07-26T23:59:59.000Z

240

Radiative Thermal Noise for Transmissive Optics in Gravitational-Wave Detectors  

E-Print Network [OSTI]

Radiative losses have traditionally been neglected in the calculation of thermal noise of transmissive optical elements because for the most commonly used geometries they are small compared to losses due to thermal conduction. We explore the use of such transmissive optical elements in extremely noise-sensitive environments such as the arm cavities of future gravitational-wave interferometers. This drives us to a geometry regime where radiative losses are no longer negligible. In this paper we derive the thermo-refractive noise associated with such radiative losses and compare it to other known sources of thermal noise.

Sheila Dwyer; Stefan W. Ballmer

2014-08-07T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Neutron absorption detector  

DOE Patents [OSTI]

A method of detecting an activator, the method including impinging a receptor material that is not predominately water and lacks a photoluminescent material with an activator and generating Cherenkov effect light due to the activator impinging the receptor material. The method further including identifying a characteristic of the activator based on the light.

Bell, Zane William (Oak Ridge, TN); Boatner, Lynn Allen (Oak Ridge, TN)

2011-05-31T23:59:59.000Z

242

Contribution of nano-scale effects to the total efficiency of converters of thermal neutrons on the basis of gadolinium foils  

E-Print Network [OSTI]

We study the influence of nano-scale layers of converters made from natural gadolinium and its 157 isotope into the total efficiency of registration of thermal neutrons. Our estimations show that contribution of low-energy Auger electrons with the runs about nanometers in gadolinium, to the total efficiency of neutron converters in this case is essential and results in growth of the total efficiency of converters. The received results are in good consent to the experimental data.

D. A. Abdushukurov; D. V. Bondarenko; Kh. Kh. Muminov; D. Yu. Chistyakov

2008-02-04T23:59:59.000Z

243

Description of TASHA: Thermal Analysis of Steady-State-Heat Transfer for the Advanced Neutron Source Reactor  

SciTech Connect (OSTI)

This document describes the code used to perform Thermal Analysis of Steady-State-Heat-Transfer for the Advanced Neutron Source (ANS) Reactor (TASHA). More specifically, the code is designed for thermal analysis of the fuel elements. The new code reflects changes to the High Flux Isotope Reactor steady-state thermal-hydraulics code. These changes were aimed at both improving the code`s predictive ability and allowing statistical thermal-hydraulic uncertainty analysis to be performed. A significant portion of the changes were aimed at improving the correlation package in the code. This involved incorporating more recent correlations for both single-phase flow and two-phase flow thermal limits, including the addition of correlations to predict the phenomenon of flow excursion. Since the code was to be used in the design of the ANS, changes were made to allow the code to predict limiting powers for a variety of thermal limits, including critical heat flux, flow excursion, incipient boiling, oxide spallation, maximum centerline temperature, and surface temperature equal to the saturation temperature. Statistical uncertainty analysis also required several changes to the code itself as well as changes to the code input format. This report describes these changes in enough detail to allow the reader to interpret code results and also to understand where the changes were made in the code programming. This report is not intended to be a stand alone report for running the code, however, and should be used in concert with the two previous reports published on the original code. Sample input and output files are also included to help accomplish these goals. In addition, a section is included that describes requirements for a new, more modem code that the project planned to develop.

Morris, D.G.; Chen, N.C.; Nelson, W.R.; Yoder, G.L.

1996-10-01T23:59:59.000Z

244

Development of a plasma panel radiation detector  

SciTech Connect (OSTI)

This article reports on the development and experimental results of commercial plasma display panels adapted for their potential use as micropattern gas radiation detectors. The plasma panel sensor (PPS) design and materials include glass substrates, metal electrodes and inert gas mixtures which provide a physically robust, hermetically sealed device. Plasma display panels used as detectors were tested with cosmic ray muons, beta rays and gamma rays, protons, and thermal neutrons. The results demonstrated rise times and time resolution of a few nanoseconds, as well as sub-millimeter spatial resolution compatible with the pixel pitch.

Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Bensimon, B [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Friedman, Dr. Peter S. [Integrated Sensors, LLC; Levin, Daniel S. [University of Michigan; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Wetzel, R. [University of Michigan; Zhou, Bing [University of Michigan; Anderson, T [GE Measurement and Control Solutions; McKinny, K [GE Measurement and Control Solutions; Bentefour, E [Ion Beam Applications

2014-01-01T23:59:59.000Z

245

Development of a plasma panel radiation detector  

E-Print Network [OSTI]

This article reports on the development and experimental results of commercial plasma display panels adapted for their potential use as micropattern gas radiation detectors. The plasma panel sensors (PPS) design an materials include glass substrates, metal electrodes and inert gas mixtures which provide a physically robust, hermetically-sealed device. Plasma display panels used as detectors were tested with cosmic ray muons, beta rays and gamma rays, protons and thermal neutrons. The results demonstrated rise times and time resolution of a few nanoseconds, as well as sub-millimeter spatial resolution compatible with the pixel pitch.

R. Ball; J. R. Beene; M. Ben-Moshe; Y. Benhammou; R. Bensimon; J. W. Chapman; E. Etzion; C. Ferretti; P. S. Friedman; D. S. Levin; Y. Silver; R. L. Varner; C. Weaverdyck; R. Wetzel; B. Zhou; T. Anderson; K. McKinny; E. H. Bentefour

2014-06-14T23:59:59.000Z

246

Gamma and neutron detection modeling in the nuclear detection figure of merit (NDFOM) portal  

SciTech Connect (OSTI)

The Nuclear Detection Figure Of Merit (NDFOM) portal is a database of objects and algorithms for evaluating the performance of radiation detectors to detect nuclear material. This paper describes the algorithms used to model the physics and mathematics of radiation detection. As a first-principles end-to-end analysis system, it starts with the representation of the gamma and neutron spectral fluxes, which are computed with the particle and radiation transport code MCNPX. The gamma spectra emitted by uranium, plutonium, and several other materials of interest are described. The impact of shielding and other intervening material is computed by the method of build-up factors. The interaction of radiation with the detector material is computed by a detector response function approach. The construction of detector response function matrices based on MCNPX simulation runs is described in detail. Neutron fluxes are represented in a three group formulation to treat differences in detector sensitivities to thermal, epithermal, and fast neutrons.

Stroud, Phillip D [Los Alamos National Laboratory; Saeger, Kevin J [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

247

Fast neutron imaging device and method  

DOE Patents [OSTI]

A fast neutron imaging apparatus and method of constructing fast neutron radiography images, the apparatus including a neutron source and a detector that provides event-by-event acquisition of position and energy deposition, and optionally timing and pulse shape for each individual neutron event detected by the detector. The method for constructing fast neutron radiography images utilizes the apparatus of the invention.

Popov, Vladimir; Degtiarenko, Pavel; Musatov, Igor V.

2014-02-11T23:59:59.000Z

248

The energy spectrum of delayed neutrons from thermal neutron induced fission of sup 2 sup 3 sup 5 U and its analytical approximation  

E-Print Network [OSTI]

The energy spectrum of the delayed neutrons is the poorest known of all input data required in the calculation of the effective delayed neutron fractions. In addition to delayed neutron spectra based on the aggregate spectrum measurements there are two different approaches for deriving the delayed neutron energy spectra. Both of them are based on the data related to the delayed neutron spectra from individual precursors of delayed neutrons. In present work these two different data sets were compared with the help of an approximation by gamma-function. The choice of this approximation function instead of the Maxwellian or evaporation type of distribution is substantiated.

Doroshenko, A Y; Tarasko, M Z

2001-01-01T23:59:59.000Z

249

The development and demonstration of a thermal neutron radiography facility utilizing the TAMU NSC TRIGA reactor  

E-Print Network [OSTI]

an object without permanently changing or destroying the object being inspected. X ? rays and gamma rays are probably the most widely used radiations in the above applications; however, the use of beams of neutrons is becoming more prevalent. Radiography... useful results, the attenuation of radiation per unit thickness of material must depend upon the physical or atomic characteristics of the material. X-rays and gamma rays are absorbed within the objects by various interactions with the elec- tronic...

Lorenz, Robert Wayne

1972-01-01T23:59:59.000Z

250

Analysis of the OECD/NRC BWR Turbine Trip Transient Benchmark with the Coupled Thermal-Hydraulics and Neutronics Code TRAC-M/PARCS  

SciTech Connect (OSTI)

An analysis of the Peach Bottom Unit 2 Turbine Trip 2 (TT2) experiment has been performed using the U.S. Nuclear Regulatory Commission coupled thermal-hydraulics and neutronics code TRAC-M/PARCS. The objective of the analysis was to assess the performance of TRAC-M/PARCS on a BWR transient with significance in two-phase flow and spatial variations of the neutron flux. TRAC-M/PARCS results are found to be in good agreement with measured plant data for both steady-state and transient phases of the benchmark. Additional analyses of four fictitious extreme scenarios are performed to provide a basis for code-to-code comparisons and comprehensive testing of the thermal-hydraulics/neutronics coupling. The obtained results of sensitivity studies on the effect of direct moderator heating on transient simulation indicate the importance of this modeling aspect.

Lee, Deokjung [Purdue University (United States); Downar, Thomas J. [Purdue University (United States); Ulses, Anthony [U.S. Nuclear Regulatory Commission (United States); Akdeniz, Bedirhan [Pennsylvania State University (United States); Ivanov, Kostadin N. [Pennsylvania State University (United States)

2004-10-15T23:59:59.000Z

251

CSRL-V ENDF/B-V 227-group neutron cross-section library and its application to thermal-reactor and criticality safety benchmarks  

SciTech Connect (OSTI)

Characteristics and contents of the CSRL-V (Criticality Safety Reference Library based on ENDF/B-V data) 227-neutron-group AMPX master and pointwise cross-section libraries are described. Results obtained in using CSRL-V to calculate performance parameters of selected thermal reactor and criticality safety benchmarks are discussed.

Ford, W.E. III; Diggs, B.R.; Knight, J.R.; Greene, N.M.; Petrie, L.M.; Webster, C.C.; Westfall, R.M.; Wright, R.Q.; Williams, M.L.

1982-01-01T23:59:59.000Z

252

Radiative neutron capture on 9be, 14c, 14n, 15n and 16o at thermal and astrophysical energies  

E-Print Network [OSTI]

The total cross sections of the radiative neutron capture processes on 9Be, 14C, 14N, 15N, and 16O are described in the framework of the modified potential cluster model with the classification of orbital states according to Young tableaux. The continued interest in the study of these reactions is due, on the one hand, to the important role played by this process in the analysis of many fundamental properties of nuclei and nuclear reactions, and, on the other hand, to the wide use of the capture cross section data in the various applications of nuclear physics and nuclear astrophysics, and, also, to the importance of the analysis of primordial nucleosynthesis in the Universe. This article is devoted to the description of results for the processes of the radiative neutron capture on certain light atomic nuclei at thermal and astrophysical energies. The considered capture reactions are not part of stellar thermonuclear cycles, but involve in the reaction chains of inhomogeneous Big Bang models.

Sergey Dubovichenko; Albert Dzhazairov-Kakhramanov; Nadezhda Afanasyeva

2014-01-28T23:59:59.000Z

253

Measurement of the energy, multiplicity and angular correlation of ?-rays from the thermal neutron capture reaction Gd(n, ?) using JPARC-ANNRI  

SciTech Connect (OSTI)

We conducted an experiment using the JPARC-ANNRI spectrometer to measure the energy, multiplicity and correlation of ?-rays from the neutron capture of natural gadolinium. We incorporated the GEANT4 Monte Carlo (MC) simulation into the detector, and compared the data with the results of the MC simulation. We report our data analysis and compare our data with those obtained by the MC simulation.

Ou, Iwa; Yamada, Yoshiyuki; Yano, Takatomi; Mori, Takaaki; Kayano, Tsubasa; Sakuda, Makoto [Department of Physics, Okayama University, Okayama, 700-8530 (Japan); Kimura, Atsushi; Harada, Hideo [Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai, Naka, Ibaraki 319-1195 (Japan)

2014-05-02T23:59:59.000Z

254

Effects of neutron irradiation on thermal conductivity of SiC-based composites and monolithic ceramics  

SciTech Connect (OSTI)

A variety of SiC-based composites and monolithic ceramics were characterized by measuring their thermal diffusivity in the unirradiated, thermal annealed, and irradiated conditions over the temperature range 400 to 1,000 C. The irradiation was conducted in the EBR-II to doses of 33 and 43 dpa-SiC (185 EFPD) at a nominal temperature of 1,000 C. The annealed specimens were held at 1,010 C for 165 days to approximately duplicate the thermal exposure of the irradiated specimens. Thermal diffusivity was measured using the laser flash method, and was converted to thermal conductivity using density data and calculated specific heat values. Exposure to the 165 day anneal did not appreciably degrade the conductivity of the monolithic or particulate-reinforced composites, but the conductivity of the fiber-reinforced composites was slightly degraded. The crystalline SiC-based materials tested in this study exhibited thermal conductivity degradation of irradiation, presumably caused by the presence of irradiation-induced defects. Irradiation-induced conductivity degradation was greater at lower temperatures, and was typically more pronounced for materials with higher unirradiated conductivity. Annealing the irradiated specimens for one hour at 150 C above the irradiation temperature produced an increase in thermal conductivity, which is likely the result of interstitial-vacancy pair recombination. Multiple post-irradiation anneals on CVD {beta}-SiC indicated that a portion of the irradiation-induced damage was permanent. A possible explanation for this phenomenon was the formation of stable dislocation loops at the high irradiation temperature and/or high dose that prevented subsequent interstitial/vacancy recombination.

Senor, D.J.; Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States); Moore, C.E. [Auburn Univ., AL (United States); Trimble, D.J. [Westinghouse Hanford Co., Richland, WA (United States); Woods, J.J. [Lockheed Martin, Schenectady, NY (United States)

1996-06-01T23:59:59.000Z

255

Effects of neutron irradiation on thermal conductivity of SiC-based composites and monolithic ceramics  

SciTech Connect (OSTI)

A variety of SiC-based composites and monolithic ceramics were characterized by measuring their thermal diffusivity in the unirradiated, thermal annealed, and irradiated conditions over the temperature range 400 to 1,000 C. The irradiation was conducted in the EBR-II to doses of 33 and 43 dpa-SiC (185 EFPD) at a nominal temperature of 1,000 C. The annealed specimens were held at 1,010 C for 165 days to approximately duplicate the thermal exposure of the irradiated specimens. Thermal diffusivity was measured using the laser flash method, and was converted to thermal conductivity using density data and calculated specific heat values. Exposure to the 165 day anneal did not appreciably degrade the conductivity of the monolithic or particulate-reinforced composites, but the conductivity of the fiber-reinforced composites was slightly degraded. The crystalline SiC-based materials tested in this study exhibited thermal conductivity degradation after irradiation, presumably caused by the presence of irradiation-induced defects. Irradiation-induced conductivity degradation was greater at lower temperatures, and was typically more pronounced for materials with higher unirradiated conductivity. Annealing the irradiated specimens for one hour at 150 C above the irradiation temperature produced an increase in thermal conductivity, which is likely the result of interstitial-vacancy pair recombination. Multiple post-irradiation anneals on CVD {beta}-SiC indicated that a portion of the irradiation-induced damage was permanent. A possible explanation for this phenomenon was the formation of stable dislocation loops at the high irradiation temperature and/or high dose that prevented subsequent interstitial/vacancy recombination.

Senor, D.J.; Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States); Moore, C.E. [Auburn Univ., AL (United States); Trimble, D.J. [Westinghouse Hanford Co., Richland, WA (United States); Woods, J.J. [Lockheed Martin, Schenectady, NY (United States)

1997-05-01T23:59:59.000Z

256

Measurement of the Neutron Spectrum of a DD Electronic Neutron Generator  

SciTech Connect (OSTI)

A Cuttler-Shalev (C-S) 3He proportional counter has been used to measure the energy spectrum of neutrons from a portable deuterium-deuterium electronic neutron generator. To improve the analysis of results from the C-S detector digital pulse shape analysis techniques have been used to eliminate neutron recoil artifacts in the recorded data. Data was collected using a 8-GHz, 10-bit waveform digitizer with its full scale corresponding to approximately 6-MeV neutrons. The measurements were made with the detector axis perpendicular to the direction of ions in the ENG in a plane 0.5-m to the side of the ENG, measuring neutrons emitted at an angle from 87.3? to 92.7? with respect to the path of ions in the ENG. The system demonstrated an energy resolution of approximately 0.040 MeV for the thermal peak and approximately 0.13 MeV at the DD neutron energy. In order to achieve the ultimate resolution capable with this type of detector it is clear that a higher-precision digitizer will be needed.

D. L. Chichester; J. T. Johnson; E. H. Seabury

2010-08-01T23:59:59.000Z

257

Silicon drift detector based X-ray spectroscopy diagnostic system for the study of non-thermal electrons at Aditya tokamak  

SciTech Connect (OSTI)

Silicon drift detector based X-ray spectrometer diagnostic was developed to study the non-thermal electron for Aditya tokamak plasma. The diagnostic was mounted on a radial mid plane port at the Aditya. The objective of diagnostic includes the estimation of the non-thermal electron temperature for the ohmically heated plasma. Bi-Maxwellian plasma model was adopted for the temperature estimation. Along with that the study of high Z impurity line radiation from the ECR pre-ionization experiments was also aimed. The performance and first experimental results from the new X-ray spectrometer system are presented.

Purohit, S., E-mail: pshishir@ipr.res.in; Joisa, Y. S.; Raval, J. V.; Ghosh, J.; Tanna, R.; Shukla, B. K.; Bhatt, S. B. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

2014-11-15T23:59:59.000Z

258

Plasma Panel Based Radiation Detectors  

SciTech Connect (OSTI)

The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels (PDPs). It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in PDPs, it uses non-reactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (< 50 m RMS) and low cost. In this paper we report here on prototype PPS experimental results in detecting betas, protons and cosmic muons, and we extrapolate on the PPS potential for applications including detection of alphas, heavy-ions at low to medium energy, thermal neutrons and X-rays.

Friedman, Dr. Peter S. [Integrated Sensors, LLC; Varner Jr, Robert L [ORNL; Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Bentefour, E [Ion Beam Applications; Levin, Daniel S. [University of Michigan; Moshe, M. [Tel Aviv University; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Zhou, Bing [University of Michigan

2013-01-01T23:59:59.000Z

259

GADRAS Detector Response Function.  

SciTech Connect (OSTI)

The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

2014-11-01T23:59:59.000Z

260

Thermal-hydraulic performance of a water-cooled tungsten-rod target for a spallation neutron source  

SciTech Connect (OSTI)

A thermal-hydraulic (T-H) analysis is conducted to determine the feasibility and limitations of a water-cooled tungsten-rod target at powers of 1 MW and above. The target evaluated has a 10-cm x 10-cm cross section perpendicular to the beam axis, which is typical of an experimental spallation neutron source - both for a short-pulse spallation source and long-pulse spallation source. This report describes the T-H model and assumptions that are used to evaluate the target. A 1-MW baseline target is examined, and the results indicate that this target should easily handle the T-H requirements. The possibility of operating at powers >1 MW is also examined. The T-H design is limited by the condition that the coolant does not boil (actual limits are on surface subcooling and wall heat flux); material temperature limits are not approached. Three possible methods of enhancing the target power capability are presented: reducing peak power density, altering pin dimensions, and improving coolant conditions (pressure and temperature). Based on simple calculations, it appears that this target concept should have little trouble reaching the 2-MW range (from a purely T-H standpoint), and possibly much higher powers. However, one must keep in mind that these conclusions are based solely on thermal-hydraulics. It is possible, and perhaps likely, that target performance could be limited by structural issues at higher powers, particularly for a short-pulse spallation source because of thermal shock issues.

Poston, D.I.

1997-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Design and development of a 3He replacement safeguards neutron counter based on 10B-lined proportional detector technology  

SciTech Connect (OSTI)

This presentation represents an overview of the experimental evaluation of a boron-lined proportional technology performed within an NA-241 sponsored project on testing of boron-lined proportional counters for the purpose of replacement of {sup 3}He technologies. The presented boron-lined technology will be utilized in a design of a full scale safeguards neutron coincidence counter. The design considerations and the Monte Carlo performance predictions for the counter are also presented.

Henzlova, Daniela [Los Alamos National Laboratory; Evans, Louise [Los Alamos National Laboratory; Menlove, Howard O. [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory; Rael, Carlos D. [Los Alamos National Laboratory; Martinez, Isaac P. [Los Alamos National Laboratory; Marlow, Johnna B. [Los Alamos National Laboratory

2012-07-16T23:59:59.000Z

262

Seismology of adolescent neutron stars: Accounting for thermal effects and crust elasticity  

E-Print Network [OSTI]

We study the oscillations of relativistic stars, incorporating key physics associated with internal composition, thermal gradients and crust elasticity. Our aim is to develop a formalism which is able to account for the state-of-the-art understanding of the complex physics associated with these systems. As a first step, we build models using a modern equation of state including composition gradients and density discontinuities associated with internal phase-transitions (like the crust-core transition and the point where muons first appear in the core). In order to understand the nature of the oscillation spectrum, we carry out cooling simulations to provide realistic snapshots of the temperature distribution in the interior as the star evolves through adolescence. The associated thermal pressure is incorporated in the perturbation analysis, and we discuss the presence of $g$-modes arising as a result of thermal effects. We also consider interface modes due to phase-transitions and the gradual formation of the star's crust and the emergence of a set of shear modes.

C. J. Krüger; W. C. G. Ho; N. Andersson

2014-08-20T23:59:59.000Z

263

activation detectors application: Topics by E-print Network  

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

scattering science is still growing its instruments' power and the neutron flux a detector must tolerate is increasing. For small area detectors the main effort is to expand...

264

Vacuum photodiode detectors for soft x-ray ITER plasma tomography  

SciTech Connect (OSTI)

A special type of vacuum photodiode detector (VPD) for x-ray tomography of (ITER) plasma is described. Laboratory experiments demonstrate that VPD has high sensitivity to thermal x-rays and low sensitivity to hard gamma rays and neutrons. It was shown that in ITER environment the signal due to thermal x-rays will surpass the background signal by more than a factor of 100.

Gott, Yu.V.; Stepanenko, M.M. [RRC, Nuclear Fusion Institute, Kurchatov sq.1, Moscow, 123182 (Russian Federation)

2005-07-15T23:59:59.000Z

265

Innovative and Advanced Coupled Neutron Transport and Thermal Hydraulic Method (Tool) for the Design, Analysis and Optimization of VHTR/NGNP Prismatic Reactors  

SciTech Connect (OSTI)

This project will develop a 3D, advanced coarse mesh transport method (COMET-Hex) for steady- state and transient analyses in advanced very high-temperature reactors (VHTRs). The project will lead to a coupled neutronics and thermal hydraulic (T/H) core simulation tool with fuel depletion capability. The computational tool will be developed in hexagonal geometry, based solely on transport theory without (spatial) homogenization in complicated 3D geometries. In addition to the hexagonal geometry extension, collaborators will concurrently develop three additional capabilities to increase the code’s versatility as an advanced and robust core simulator for VHTRs. First, the project team will develop and implement a depletion method within the core simulator. Second, the team will develop an elementary (proof-of-concept) 1D time-dependent transport method for efficient transient analyses. The third capability will be a thermal hydraulic method coupled to the neutronics transport module for VHTRs. Current advancements in reactor core design are pushing VHTRs toward greater core and fuel heterogeneity to pursue higher burn-ups, efficiently transmute used fuel, maximize energy production, and improve plant economics and safety. As a result, an accurate and efficient neutron transport, with capabilities to treat heterogeneous burnable poison effects, is highly desirable for predicting VHTR neutronics performance. This research project’s primary objective is to advance the state of the art for reactor analysis.

Rahnema, Farzad; Garimeela, Srinivas; Ougouag, Abderrafi; Zhang, Dingkang

2013-11-29T23:59:59.000Z

266

The IPNS resonance detector spectrometer  

SciTech Connect (OSTI)

In the resonance detector method of neutron spectroscopy, a foil is placed in the scattered neutron beam and scattered neutrons having the resonance energy are detected by detecting the capture gammas resulting from the resonance absorption of the neutrons. A prototype resonance detector spectrometer called the Electron Volt Spectrometer (EVS) has been built and operated. The instrument is described, the current understanding of the background of the instrument is discussed, software developed to simulate the detector efficiency is described and compared with experimental results, and a test of the use of foil-thickness difference techniques to improve resolution is presented. (LEW)

Crawford, R.K.

1986-01-01T23:59:59.000Z

267

Neutron computed tomography  

E-Print Network [OSTI]

to make the Donner Algorithms run. TABLE OF CONTEliiTS CHAPTF. . R I NEI. TRON RADIOGRAPHY . I. 1 Background . I. 2 Theory . l. 3 Neutron Beam Characterization I. 4 Image Detectors . COMPI'TED TOMOGRAPHY . Il I Background . II. 2 Notation II. 3... data which is generated by rays traveling (and being attenuated) in straight lines. However in neutron radiography, what is measured is, to most extents, the levels of neutrons which are not attenuated. Neutrons are particles. They scatter...

Russell, Clifford Marlow

2012-06-07T23:59:59.000Z

268

Fission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U  

SciTech Connect (OSTI)

We describe measurements of fission product data at Los Alamos that are important for determining the number of fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The fission-spectrum measurements were made using a fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of fission-product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing fission of 400-600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4-1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of fission product yields in different fuel and neutron environments (Q-values) and fission product yields in fission spectrum neutron environments for {sup 99}Mo, {sup 95}Zr, {sup 137}Cs, {sup 140}Ba, {sup 141,143}Ce, and {sup 147}Nd. Modest incident-energy dependence exists for the {sup 147}Nd fission product yield; this is discussed in the context of models for fission that include thermal and dynamical effects. The fission product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying fission products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by {approx}5-7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated fission-spectrum fission product yields that were carried over to the ENDF/B-VII.0 library, except for {sup 99}Mo where the present results are about 4%-relative higher for neutrons incident on {sup 239}Pu and {sup 235}U. Additionally, our results illustrate the importance of representing the incident energy dependence of fission product yields over the fast neutron energy range for high-accuracy work, for example the {sup 147}Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.

Selby, H.D., E-mail: hds@lanl.go [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mac Innes, M.R.; Barr, D.W.; Keksis, A.L.; Meade, R.A.; Burns, C.J.; Chadwick, M.B.; Wallstrom, T.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2010-12-15T23:59:59.000Z

269

Proton recoil scintillator neutron rem meter  

DOE Patents [OSTI]

A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

Olsher, Richard H. (Los Alamos, NM); Seagraves, David T. (Los Alamos, NM)

2003-01-01T23:59:59.000Z

270

Neutron streak camera  

DOE Patents [OSTI]

Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

Wang, C.L.

1981-05-14T23:59:59.000Z

271

PHYSICAL REVIEW C 83, 064612 (2011) Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced  

E-Print Network [OSTI]

. Chadwick,3 and Y. Danon2 1 T-2 Nuclear Theory Group, Los Alamos National Laboratory, Los Alamos, New Mexico-CP, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA (Received 4 April 2011; published 23, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail

Danon, Yaron

272

Derivation of nuclear parameters for delayed neutron detector measurements for D-D and D-T plasma operation at the Joint European Torus  

SciTech Connect (OSTI)

The first attempt to calculate the parameters for [sup 238]U and [sup 232]Th used in the analysis of delayed neutron counter measurements of the total neutron yield from deuterium-tritium (D-T) plasmas is described. The nuclear theory of systematics is employed, together with nuclear data from the literature. As a check on the methods used, the delayed neutron parameters were also calculated for deuterium-deuterium plasma conditions; the resulting neutron yields agreed within [+-]7% with the results obtained using the experimentally calibrated delayed neutron counter assemblies. After the calculations were completed, the first D-T plasma experiment was performed at the Joint European Torus (JET). Delayed neutron measurements were made using [sup 232]Th samples. The calculated delayed neutron parameters gave neutron yields that agreed within [+-]8% with those obtained with conventional activation methods, using iron and silicon samples. 30 refs., 5 figs., 8 tabs.

Angelone, M. (JET Joint Undertaking Abingdon, Oxon (United Kingdom))

1993-08-01T23:59:59.000Z

273

R-matrix analysis of the {sup 240}Pu neutron cross sections in the thermal to 5700 eV energy range  

SciTech Connect (OSTI)

Resonance analysis of high resolution neutron transmission data and of fission cross sections were performed in the neutron energy range from the thermal regions to 5,700 eV by using the Reich-Moore Bayesian code SAMMY. The experimental data base is described and the method of analysis is given. The experimental data were carefully examined in order to identify more resonances than those found in the current evaluated data files. The statistical properties of the resonance parameters are given. A new set of the average values of the parameters is proposed, which could be used for calculation of the average cross sections in the unresolved resonance region. The resonance parameters are available IN ENDF-6 format at the national or international data centers.

Derrien, H. [OECD, Paris (France). Nuclear Energy Agency Data Bank; Bouland, O. [Commissariat Energie Atomique, Saint Paul-lez-Durance (France). Centre d`Etudes; Larson, N.M.; Leal, L.C. [Oak Ridge National Lab., TN (United States)

1997-08-01T23:59:59.000Z

274

Three Mile Island Unit 1 Main Steam Line Break Three-Dimensional Neutronics/Thermal-Hydraulics Analysis: Application of Different Coupled Codes  

SciTech Connect (OSTI)

A comprehensive analysis of the double ended main steam line break (MSLB) accident assumed to occur in the Babcock and Wilcox Three Mile Island Unit 1 (TMI-1) has been carried out at the Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione of the University of Pisa, Italy, in cooperation with the University of Zagreb, Croatia. The overall activity has been completed within the framework of the participation in the Organization for Economic Cooperation and Development-Committee on the Safety of Nuclear Installations-Nuclear Science Committee pressurized water reactor MSLB benchmark.Thermal-hydraulic system codes (various versions of Relap5), three-dimensional (3-D) neutronics codes (Parcs, Quabbox, and Nestle), and one subchannel code (Cobra) have been adopted for the analysis. Results from the following codes (or code versions) are assumed as reference:1. Relap5/mod3.2.2, beta version, coupled with the 3-D neutron kinetics Parcs code parallel virtual machine (PVM) coupling2. Relap5/mod3.2.2, gamma version, coupled with the 3-D neutron kinetics Quabbox code (direct coupling)3. Relap5/3D code coupled with the 3-D neutron kinetics Nestle code.The influence of PVM and of direct coupling is also discussed.Boundary and initial conditions of the system, including those relevant to the fuel status, have been supplied by Pennsylvania State University in cooperation with GPU Nuclear Corporation (the utility, owner of TMI) and the U.S. Nuclear Regulatory Commission. The comparison among the results obtained by adopting the same thermal-hydraulic nodalization and the coupled code version is discussed in this paper.The capability of the control rods to recover the accident has been demonstrated in all the cases as well as the capability of all the codes to predict the time evolution of the assigned transient. However, one stuck control rod caused some 'recriticality' or 'return to power' whose magnitude is largely affected by boundary and initial conditions.

D'Auria, Francesco [Universita di Pisa (Italy); Moreno, Jose Luis Gago [Universidad Politecnica de Barcelona (Spain); Galassi, Giorgio Maria [Universita di Pisa (Italy); Grgic, Davor [University of Zagreb (Croatia); Spadoni, Antonino [Universita di Pisa (Italy)

2003-05-15T23:59:59.000Z

275

Review of the Development and Testing of a New Family of Boron and Gadolinium-Bearing Dual Thermal Neutron Absorbing Alloys - 13026  

SciTech Connect (OSTI)

The development of a new class of Fe-based thermal neutron absorbing alloys (patent pending) containing both natural boron (B) and gadolinium (Gd) is reviewed. Testing has shown that Ar and N inert gas atomized powder metallurgy (PM) variants offer superior processability coupled with improved mechanical properties that exhibit reduced anisotropy and reduced corrosion rates compared to conventional cast/wrought processed material. PM processing results in a microstructure containing a uniform distribution of second phase borides and gadolinides, and the morphology of the gadolinides prevents the formation low melting point Gd-bearing phases at solidifying austenite boundaries. The new T316-based materials containing both B and Gd exhibit superior corrosion resistance compared to straight B-bearing T304 materials. By keeping the B content < 1 weight percent (%) and using Gd to attain an equivalent B (B{sub Eq}) content higher than that achievable through the use of B only, the new materials exhibit superior ductility, toughness and bendability as a result of significantly reduced area fraction of Cr-rich M{sub 2}B borides. Limiting the total area fraction of second phase particles to < 22% insures a product with superior bendability. By restricting B to < 1% and using Gd up to 2.5%, B{sub Eq} levels approaching 12% can be attained that provide a cost effective improvement in thermal neutron absorption capability compared to using B-10 enriched boron. The new materials can be easily bent during fabrication compared to existing metal matrix composite materials while offering similar thermal neutron absorption capability. Production lots containing B{sub Eq} levels of 4.0 and 7.5% (Micro-Melt{sup R} DuoSorb{sup TM} 316NU-40 and 75, respectively) are in the process of being fabricated for customer trial material. (authors)

Schmidt, M.L.; Del Corso, G.J.; Klankowski, K.A. [Carpenter Tech., Corp., P.O. Box 14662, Reading PA 19612-4662 (United States)] [Carpenter Tech., Corp., P.O. Box 14662, Reading PA 19612-4662 (United States); Lherbier, L.W.; Novotnak, D.J. [Carpenter Powder Products, 600 Mayer St., Bridgeville, PA 15017 (United States)] [Carpenter Powder Products, 600 Mayer St., Bridgeville, PA 15017 (United States)

2013-07-01T23:59:59.000Z

276

A study of the morphological and cytological changes in Century Patna 231 and Bluebonnet 50 rice varieties resulting from X-ray and thermal neutron radiation  

E-Print Network [OSTI]

a PQ > I CQ *H -P 1 oas2 a O ? > ir\\ 1x1 oS E?*i U 0 1 S . N c o uYOf to C\\i vD O rH vO ?? c^ \\ 0^ o in m ?? COvflOn ? ? ? ?lA v?> t> "* CV O C V - J to H ( ^ O tO to% ? ? ? ? 0? 0 0 r H >4- C\\ v O C ^ v O........................................ 40 1 E. Century Patna 231 - Thermal Neutrons for 25 hours...................................4*5 DISCUSSION.............................................48 Meiotic disturbance in normal Century Patna 231....... 4*8 Types of chromosome pairing...

Hasanuzzaman, Shah Muhammad

1959-01-01T23:59:59.000Z

277

Requirements, possible alternatives & international NEUTRON SCATTERING  

E-Print Network [OSTI]

Requirements, possible alternatives & international NEUTRON SCATTERING DETECTORS for Rob Dimeo NIST neutron scattering instruments are the most demanding require background low #12;#12;The Helium-3 Supply Crisis ­ Alternative Techniques to Helium-3 based Detectors for Neutron Scattering Applications

Dimeo, Robert M.

278

Neutron dose equivalent meter  

DOE Patents [OSTI]

A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

Olsher, Richard H. (Los Alamos, NM); Hsu, Hsiao-Hua (Los Alamos, NM); Casson, William H. (Los Alamos, NM); Vasilik, Dennis G. (Los Alamos, NM); Kleck, Jeffrey H. (Menlo Park, CA); Beverding, Anthony (Foster City, CA)

1996-01-01T23:59:59.000Z

279

arXiv:physics/0408090v214Mar2005 Complex Impedance as a Diagnostic Tool for Characterizing Thermal Detectors  

E-Print Network [OSTI]

the thermometer to a heat sink. The simple model treated in most analytical descrip- tions consists of a lumped and complex de- tectors, along with the thermometer temperature sensi- tivity and thermometer voltage (or16­18 in the thermome- ter and a thermal resistance between the absorber and thermometer. We begin

Wisconsin at Madison, University of

280

Thermal neutron diffraction determination of the magnetic structure of EuCu{sub 2}Ge{sub 2}  

SciTech Connect (OSTI)

The magnetic structure of EuCu{sub 2}Ge{sub 2} has been determined by flat-plate neutron powder diffraction. Two magnetic phases are present in the neutron diffraction pattern at 3.5?K. They have the same moment, within error, and a common transition temperature. Both {sup 151}Eu and {sup 153}Eu Mössbauer spectroscopy show that the two magnetic phases belong to the same crystallographic phase. Both phases can be modelled by planar helimagnetic structures: one with a propagation vector of [0.654(1), 0, 0], the other with a propagation vector of [0.410(1), 0.225(1), 0].

Rowan-Weetaluktuk, W. N.; Ryan, D. H., E-mail: dhryan@physics.mcgill.ca [Department of Physics, and Centre for the Physics of Materials, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8 (Canada); Lemoine, P. [Laboratoire CRISMAT, ENSICAEN, UMR 6508 CNRS, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 4 (France); Cadogan, J. M. [School of Physical, Environmental and Mathematical Sciences, UNSW Canberra at the Australian Defence Force Academy, Canberra BC 2610 (Australia)

2014-05-07T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

A more accurate and penetrating method to measure the enrichment and mass of UF6 storage containers using passive neutron self-interrogation  

SciTech Connect (OSTI)

This paper describes an unattended mode neutron measurement that can provide the enrichment of the uranium in UF{sub 6} cylinders. The new passive neutron measurement provides better penetration into the uranium mass than prior gamma-ray enrichment measurement methods. The Passive Neutron Enrichment Monitor (PNEM) provides a new measurement technique that uses passive neutron totals and coincidence counting together with neutron self-interrogation to measure the enrichment in the cylinders. The measurement uses the neutron rates from two detector pods. One of the pods has a bare polyethylene surface next to the cylinder and the other polyethylene surface is covered with Cd to prevent thermal neutrons from returning to the cylinder. The primary neutron source from the enriched UF{sub 6} is the alpha-particle decay from the {sub 234}U that interacts with the fluorine to produce random neutrons. The singles neutron counting rate is dominated by the {sub 234}U neutrons with a minor contribution from the induced fissions in the {sub 235}U. However, the doubles counting rate comes primarily from the induced fissions (i.e., multiplication) in the {sub 235}U in enriched uranium. The PNEM concept makes use of the passive neutrons that are initially produced from the {sub 234}U reactions that track the {sub 235}U enrichment during the enrichment process. The induced fission reactions from the thermal-neutron albedo are all from the {sub 235}U and provide a measurement of the {sub 235}U. The Cd ratio has the desirable feature that all of the thermal-neutron-induced fissions in {sub 235}U are independent of the original neutron source. Thus, the ratio is independent of the uranium age, purity, and prior reactor history.

Menlove, Howard O [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

282

Report to the DOE nuclear data committee. [EV RANGE 10-100; CROSS SECTIONS; PHOTONEUTRONS; NEUTRONS; GAMMA RADIATION; COUPLED CHANNEL THEORY; DIFFERENTIAL CROSS SECTIONS; MEV RANGE 01-10; ; CAPTURE; GAMMA SPECTRA; THERMAL NEUTRONS; COMPUTER CALCULATIONS; DECAY; FISSION PRODUCTS; FISSION YIELD; SHELL MODELS; NUCLEAR DATA COLLECTIONS  

SciTech Connect (OSTI)

Topics covered include: studies of (n, charged particle) reactions with 14 to 15 MeV neutrons; photoneutron cross sections for /sup 15/N; neutron radiative capture; Lane-model analysis of (p,p) and (n,n) scattering on the even tin isotopes; neutron scattering cross sections for /sup 181/Ta, /sup 197/Au, /sup 209/Bi, /sup 232/Th, and /sup 238/U inferred from proton scattering and charge exchange cross sections; neutron-induced fission cross sections of /sup 245/Cm and /sup 242/Am; fission neutron multiplicities for /sup 245/Cm and /sup 242/Am; the transport of 14 MeV neutrons through heavy materials 150 < A < 208; /sup 249/Cm energy levels from measurement of thermal neutron capture gamma rays; /sup 231/Th energy levels from neutron capture gamma ray and conversion electron spectroscopy; new measurements of conversion electron binding energies in berkelium and californium; nuclear level densities; relative importance of statistical vs. valence neutron capture in the mass-90 region; determination of properties of short-lived fission products; fission yield of /sup 87/Br and /sup 137/I from 15 nuclei ranging from /sup 232/Th to /sup 249/Cf; evaluation of charged particle data for the ECPL library; evaluation of secondary charged-particle energy and angular distributions for ENDL; and evaluated nuclear structure libraries derived from the table of isotopes. (GHT)

Struble, G.L.; Haight, R.C.

1981-03-01T23:59:59.000Z

283

Analytical and experimental investigations of the behavior of thermal neutrons in lattices of uranium metal rods in heavy water  

E-Print Network [OSTI]

Measurements of the intracellular distribution of the activation of foils by neutrons were made in lattices of 1/4-inch diameter, 1.03% U-235, uranium rods moderated by heavy water, with bare and cadmium-covered foils of ...

Simms, Richard

1963-01-01T23:59:59.000Z

284

Negative Thermal Expansion in ZrW{sub 2}O{sub 8}: Mechanisms, Rigid Unit Modes, and Neutron Total Scattering  

SciTech Connect (OSTI)

The local structure of the low-temperature ordered phase of the negative thermal expansion (NTE) material ZrW{sub 2}O{sub 8} has been investigated by reverse Monte Carlo (RMC) modeling of neutron total scattering data. We obtain, for the first time, quantitative measurements of the extent to which the WO{sub 4} and ZrO{sub 6} polyhedra move as rigid units, and we show that these values are consistent with the predictions of rigid unit mode theory. We suggest that rigid unit modes are associated with the NTE. Our results do not support a recent interpretation of x-ray-absorption fine structure spectroscopy data in terms of a larger rigid structural component involving the Zr-O-W linkage.

Tucker, Matthew G. [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom); ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Goodwin, Andrew L.; Dove, Martin T. [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom); Keen, David A. [Physics Department, Oxford University, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Wells, Stephen A. [Biological Physics, Bateman Physical Sciences Building, Arizona State University, Tempe, Arizona 85287-1504 (United States); Evans, John S.O. [Department of Chemistry, University Science Laboratories, South Road, Durham DH1 3LE (United Kingdom)

2005-12-16T23:59:59.000Z

285

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U  

E-Print Network [OSTI]

The Coulomb effects hypothesis is used to interpret even-odd effects of maximum total kinetic energy as a function of mass and charge of fragments from thermal neutron induced fission of 235U. Assuming spherical fragments at scission, the Coulomb interaction energy between fragments (C_sph) is higher than the Q-value, the available energy. Therefore at scission the fragments must be deformed, so that the Coulomb interaction energy does not exceed the Q-value. The fact that the even-odd effects in the maximum total kinetic energy as a function of the charge and mass, respectively, are lower than the even-odd effects of Q is consistent with the assumption that odd mass fragments are softer than the even-even fragments. Even-odd effects of charge distribution in super asymmetric fragmentation also are interpreted with the Coulomb effect hypothesis. Because the difference between C_sph and Q increases with asymmetry, fragmentations require higher total deformation energy to occur. Higher deformation energy of the fragments implies lower free energy to break pairs of nucleons. This explains why in the asymmetric fragmentation region, the even-odd effects of the distribution of proton number and neutron number increases with asymmetry. Based on a similar reasoning, a prediction of a relatively high even-odd effect in symmetric fragmentations is proposed.

Modesto Montoya

2015-03-23T23:59:59.000Z

286

Semiconductor radiation detector  

DOE Patents [OSTI]

A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

Bell, Zane W. (Oak Ridge, TN); Burger, Arnold (Knoxville, TN)

2010-03-30T23:59:59.000Z

287

E-Print Network 3.0 - accelerator-based boron neutron Sample...  

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

University Collection: Materials Science ; Physics 46 A novel solid-state self powered neutron detector Nicholas LiCausi*a Summary: . For the nuclear physics and neutron boron...

288

Protons hog the momentum in neutron-rich nuclei | Argonne National...  

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

a greater fraction of the protons than neutrons to have high momentum in relatively neutron-rich nuclei. The CLAS detector completely surrounds an experimental target and is...

289

Portable neutron spectrometer and dosimeter  

DOE Patents [OSTI]

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Waechter, David A. (Los Alamos, NM); Erkkila, Bruce H. (Los Alamos, NM); Vasilik, Dennis G. (Los Alamos, NM)

1985-01-01T23:59:59.000Z

290

neutron density. The neutron density (nn) of the source was modeled by solving the simul-  

E-Print Network [OSTI]

neutron density. The neutron density (nn) of the source was modeled by solving the simul- taneousT is the thermal neutron velocity, l is the decay constant, Ns is the s-process abun- dance, bsÃ? is the maxwellian-averaged neutron capture cross-section, and t0 is the average neutron exposure (21). The branching decay of 186Re

West, Stuart

291

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOE Patents [OSTI]

An improved method for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue.

Peurrung, Anthony J. (Richland, WA)

1997-01-01T23:59:59.000Z

292

Calculation of sensitivity coefficients for a neutron well logging tool  

E-Print Network [OSTI]

(Lsmsrsh, 1966; Bartine et al. , 1974; Duderstadt et al. , 1976). The straightforward (direct) calculation requires knowledge of the forward neutron flux, neutron cross section data, and detector responses (such as reaction rates) for each situation, i.... e. , the detector's responses are repeatedly com- puted for each change in the formation's composition. The perturbation (indirect) method requires knowledge of the forward neutron flux, detector response, and sd- joint neutron flux for a base...

Chen, Chien-Hsiang

2012-06-07T23:59:59.000Z

293

High Thermal Conductivity UO2-BeO Nulcear Fuel: Neutronic Performance Assessments and Overview of Fabrication  

E-Print Network [OSTI]

The objective of this work was to evaluate a new high conductivity nuclear fuel form. Uranium dioxide (UO2) is a very effective nuclear fuel, but it’s performance is limited by its low thermal conductivity. The fuel concept considered here is a...

Naramore, Michael J

2010-08-03T23:59:59.000Z

294

New neutron physics using spallation sources  

SciTech Connect (OSTI)

The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. The energy range of neutron research which is being explored with these sources extends from thermal energies to almost 800 MeV. The emphasis here is on prospective experiments below 100 keV neutron energy using the intense neutron bursts produced by the Proton Storage Ring (PSR) at Los Alamos. 30 refs., 10 figs.

Bowman, C.D.

1988-01-01T23:59:59.000Z

295

Comparison of MCNP6 and experimental results for neutron counts, Rossi-{alpha}, and Feynman-{alpha} distributions  

SciTech Connect (OSTI)

MCNP6, the general-purpose Monte Carlo N-Particle code, has the capability to perform time-dependent calculations by tracking the time interval between successive events of the neutron random walk. In fixed-source calculations for a subcritical assembly, the zero time value is assigned at the moment the neutron is emitted by the external neutron source. The PTRAC and F8 cards of MCNP allow to tally the time when a neutron is captured by {sup 3}He(n, p) reactions in the neutron detector. From this information, it is possible to build three different time distributions: neutron counts, Rossi-{alpha}, and Feynman-{alpha}. The neutron counts time distribution represents the number of neutrons captured as a function of time. The Rossi-a distribution represents the number of neutron pairs captured as a function of the time interval between two capture events. The Feynman-a distribution represents the variance-to-mean ratio, minus one, of the neutron counts array as a function of a fixed time interval. The MCNP6 results for these three time distributions have been compared with the experimental data of the YALINA Thermal facility and have been found to be in quite good agreement. (authors)

Talamo, A.; Gohar, Y. [Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL 60439 (United States); Sadovich, S.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C. [Joint Institute for Power and Nuclear Research-Sosny, 99 Academician A.K. Krasin Str., Minsk 220109 (Belarus)

2013-07-01T23:59:59.000Z

296

Determination of cross section for production of low energy gamma-rays by thermal neutron capture in silver and antimony  

E-Print Network [OSTI]

~ -', : - - . , 40-, :. . . =-;=. a =-'Sped%'ea. QM@&e8 fn. AgiegiP4 4O gbetryi:Niyz&eh = C@A&4 6@CNfLvl'S@S lg Nlv1klCk5g s s e e 0 ~ ~ ~ -a a a a'? a a e ~ s s, e ~ i' g~+ @@~cob, in. Attiny~e=4ba~. X~~-. -~=-~ ? ':":;, =::? , . g@P'fQg 5 QEC~~Q~ l. @ Qi, l~l" e...'praises ' The a'esrags'neutron energy ie about four'xdevx These nsutxone' ars 'eaei~l $l". erma1iged '@ paraffin~ . , jeti~ation ewperlments sith indium foils. using the oadm'Lum 1 I therma%tee plant)Gully apl Qf ths xerutrene from 'the plutonium beryllium...

Edens, Donald Lee

1959-01-01T23:59:59.000Z

297

array detector systems: Topics by E-print Network  

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

System for a Neutron Detector Array Physics Websites Summary: a stable light emitting diode (LED) light source and a fiber optic network distributing the light to the...

298

Wolter mirror microscope : novel neutron focussing and imaging optic  

E-Print Network [OSTI]

In this thesis, I investigated the effectiveness of a Wolter Type I neutron microscope as a focusing and imaging device for thermal and cold neutrons sources by simulating the performance of the optics in a standard neutron ...

Bagdasarova, Yelena S. (Yelena Sergeyevna)

2010-01-01T23:59:59.000Z

299

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U  

E-Print Network [OSTI]

The Coulomb effects hypothesis is used to interpret even-odd effects of maximum total kinetic energy as a function of mass and charge of fragments from thermal neutron induced fission of 235U. Assuming spherical fragments at scission, the Coulomb interaction energy between fragments (C_sph) is higher than the Q-value, the available energy. Therefore at scission the fragments must be deformed, so that the Coulomb interaction energy does not exceed the Q-value. The fact that the even-odd effects in the maximum total kinetic energy as a function of the charge and mass, respectively, are lower than the even-odd effects of Q is consistent with the assumption that odd mass fragments are softer than the even-even fragments. Even-odd effects of charge distribution in super asymmetric fragmentation also are interpreted with the Coulomb effect hypothesis. Because the difference between C_sph and Q increases with asymmetry, fragmentations require higher total deformation energy to occur. Higher deformation energy of the...

Montoya, Modesto

2015-01-01T23:59:59.000Z

300

Micro-Pocket Fission Detectors (MPFD) For Fuel Assembly Analysis  

SciTech Connect (OSTI)

Neutron sensors capable of real-time measurement of thermal flux, fast flux, and temperature in a single miniaturized probe are needed in irradiation tests required to demonstrate the performance of candidate new fuels, and cladding materials. In-core ceramic-based miniature neutron detectors or “Micro-Pocket Fission Detectors” (MPFDs) have been studied at Kansas State University (KSU). The first MPFD prototypes were tested in various neutron fields at the KSU TRIGA research reactor with successful results. Currently, a United States Department of Energy-sponsored joint KSU/Idaho National Laboratory (INL) effort is underway to develop a high-temperature, high-pressure version of the MPFD using radiation-resistant, high temperature materials, which would be capable of withstanding irradiation test conditions in high performance material and test reactors (MTRs). Ultimately, this more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, existing and advanced reactor designs, high performance MTRs, and transient test reactors has the potential to lead to higher accuracy and resolution data from irradiation testing, more detailed core flux measurements and enhanced fuel assembly processing. Prior evaluations by KSU indicate that these sensors could also be used to monitor burn-up of nuclear fuel. If integrated into nuclear fuel assemblies, MPFDs offer several advantages to current spent fuel management systems.

Troy Unruh; Michael Reichenberger; Phillip Ugorowski

2013-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

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

E-Print Network [OSTI]

Theory of Thermal Neutron Scattering. (Dover Publications,S. W. Lovesey, Theory of Neutron Scattering from Condensedwith the inelastic neutron scattering experiment results.

Liu, Jian

2008-01-01T23:59:59.000Z

302

Comparison of different experimental and analytical measures of the thermal annealing response of neutron-irradiated RPV steels  

SciTech Connect (OSTI)

The thermal annealing response of several materials as indicated by Charpy transition temperature (TT) and upper-shelf energy (USE), crack initiation toughness, K{sub Jc}, predictive models, and automated-ball indentation (ABI) testing are compared. The materials investigated are representative reactor pressure vessel (RPV) steels (several welds and a plate) that were irradiated for other tasks of the Heavy-Section Steel Irradiation (HSSI) Program and are relatively well characterized in the unirradiated and irradiated conditions. They have been annealed at two temperatures, 343 and 454 C (650 and 850 F) for varying lengths of time. The correlation of the Charpy response and the fracture toughness, ABI, and the response predicted by the annealing model of Eason et al. for these conditions and materials appears to be reasonable. The USE after annealing at the temperature of 454 C appears to recover at a faster rate than the TT, and even over-recovers (i.e., the recovered USE exceeds that of the unirradiated material).

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-05-01T23:59:59.000Z

303

Comparison of different experimental and analytical measures of the thermal annealing response of neutron-irradiated RPV steels  

SciTech Connect (OSTI)

The thermal annealing response of several materials as indicated by Charpy transition temperature (TT) and upper-shelf energy (USE), crack initiation toughness, K{sub Jc}, predictive models, and automated-ball indentation (ABI) testing are compared. The materials investigated are representative reactor pressure vessel (RPV) steels (several welds and a plate) that were irradiated for other tasks of the Heavy-Section Steel Irradiation (HSSI) Program and are relatively well characterized in the unirradiated and irradiated conditions. They have been annealed at two temperatures, 343 and 454 C (650 and 850 F) for varying lengths of time. The correlation of the Charpy response and the fracture toughness, ABI, and the response predicted by the annealing model of Eason et al. for these conditions and materials appears to be reasonable. The USE after annealing at the temperature of 454 C appears to recover at a faster rate than the TT, and even over-recovers (i.e., the recovered USE exceeds that of the unirradiated material).

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1999-10-01T23:59:59.000Z

304

Electron-neutron scattering and transport properties of neutron stars  

E-Print Network [OSTI]

We show that electrons can couple to the neutron excitations in neutron stars and find that this can limit their contribution to the transport properties of dense matter, especially the shear viscosity. The coupling between electrons and neutrons is induced by protons in the core, and by ions in the crust. We calculate the effective electron-neutron interaction for the kinematics of relevance to the scattering of degenerate electrons at high density. We use this interaction to calculate the electron thermal conductivity, electrical conductivity, and shear viscosity in the neutron star inner crust, and in the core where we consider both normal and superfluid phases of neutron-rich matter. In some cases, particularly when protons are superconducting and neutrons are in their normal phase, we find that electron-neutron scattering can be more important than the other scattering mechanisms considered previously.

Bertoni, Bridget; Rrapaj, Ermal

2014-01-01T23:59:59.000Z

305

Handheld CZT radiation detector  

DOE Patents [OSTI]

A handheld CZT radiation detector having a CZT gamma-ray sensor, a multichannel analyzer, a fuzzy-logic component, and a display component is disclosed. The CZT gamma-ray sensor may be a coplanar grid CZT gamma-ray sensor, which provides high-quality gamma-ray analysis at a wide range of operating temperatures. The multichannel analyzer categorizes pulses produce by the CZT gamma-ray sensor into channels (discrete energy levels), resulting in pulse height data. The fuzzy-logic component analyzes the pulse height data and produces a ranked listing of radioisotopes. The fuzzy-logic component is flexible and well-suited to in-field analysis of radioisotopes. The display component may be a personal data assistant, which provides a user-friendly method of interacting with the detector. In addition, the radiation detector may be equipped with a neutron sensor to provide an enhanced mechanism of sensing radioactive materials.

Murray, William S.; Butterfield, Kenneth B.; Baird, William

2004-08-24T23:59:59.000Z

306

Compact neutron generator  

DOE Patents [OSTI]

A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

Leung, Ka-Ngo; Lou, Tak Pui

2005-03-22T23:59:59.000Z

307

The NIF 4.5-m nTOF Detectors  

SciTech Connect (OSTI)

The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator/photodetector neutron-time-of-flight (nTOF) detectors for measuring DD and DT neutron yields. The detectors provided consistent neutron yield benchmarks from below 1E9 (DD) to nearly 1E15 (DT). The detectors demonstrated DT yield measurement precisions better than 5%, but the absolute accuracy relies on cross calibration with independent measurements of absolute neutron yield. The 4.5-m nTOF data have provided a useful testbed for testing improvements in nTOF data processing, especially with respect to improving the accuracies of the detector impulse response functions. The resulting improvements in data analysis methods have produced more accurate results. In summary, results from the NIF 4.5-m nTOF detectors have provided consistent measurements of DD and DT neutron yields from laser-fusion implosions.

Moran, M J; Bond, E J; Clancy, T J; Eckart, M J; Khater, H Y; Glebov, V Y

2012-05-07T23:59:59.000Z

308

Verification of plutonium content in spent fuel assemblies using neutron self-interrogation  

SciTech Connect (OSTI)

The large amounts of plutonium in reactor spent fuel assemblies has led to increased research directed toward the measurement of the plutonium for safeguards verification. The high levels of fission product gamma-ray activity and curium neutron backgrounds have made the plutonium measurement difficult. We have developed a new technique that can directly measure both the {sup 235}U concentration and the plutonium fissile concentration using the intrinsic neutron emission fronl the curium in the fuel assembly. The passive neutron albedo reactivity (PNAR) method has been described previously where the curium neutrons are moderated in the surrounding water and reflect back into the fuel assembly to induce fissions in the fissile material in the assembly. The cadmium (Cd) ratio is used to separate the spontaneous fission source neutrons from the reflected thermal neutron fission reactions. This method can measure the sum of the {sup 235}U and the plutonium fissile mass, but not the separate components. Our new differential die-away self-interrogation method (DDSI) can be used to separate the {sup 235}U from the {sup 239}Pu. The method has been applied to both fuel rods and full assemblies. For fuel rods the epi-thermal neutron reflection method filters the reflected neutrons through thin Cd filters so that the reflected neutrons are from the epi-cadmium energy region. The neutron fission energy response in the epi-cadmium region is distinctly different for {sup 235}U and {sup 239}Pu. We are able to measure the difference between {sup 235}U and {sup 239}Pu by sampling the neutron induced fission rate as a function of time and multiplicity after the initial fission neutron is detected. We measure the neutron fission rate using list-mode data collection that stores the time correlations between all of the counts. The computer software can select from the data base the time correlations that include singles, doubles, and triples. The die-away time for the doubles distribution is distinctly different for {sup 235}U and {sup 239}Pu. The {sup 239}Pu has a higher fission cross-section in the epi-cadmium neutron region and larger induced fission moments than {sup 235}U, so the measured die-away time can provide the relative amounts of {sup 239}Pu and {sup 235}U. This paper will present the Monte Carlo simulations for the detector and sample configurations for both fuel pins and full fuel assemblies.

Menlove, Howard O [Los Alamos National Laboratory; Menlove, Apencer H [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

309

E-Print Network 3.0 - accelerator driven neutron Sample Search...  

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

Summary: - so called Accelerator-Driven System (ADS). An external neutron source and subcritical operation open... about 3 times a year. An alternative, thermal neutron...

310

E-Print Network 3.0 - accelerator-driven neutron source Sample...  

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

Summary: - so called Accelerator-Driven System (ADS). An external neutron source and subcritical operation open... about 3 times a year. An alternative, thermal neutron...

311

Neutronic reactor  

DOE Patents [OSTI]

A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

Wende, Charles W. J. (Augusta, GA); Babcock, Dale F. (Wilmington, DE); Menegus, Robert L. (Wilmington, DE)

1983-01-01T23:59:59.000Z

312

Report on Advanced Detector Development  

SciTech Connect (OSTI)

Neutron, gamma and charged particle detection improvements are key to supporting many of the foreseen measurements and systems envisioned in the R&D programs and the future fuel cycle requirements, such as basic nuclear physics and data, modeling and simulation, reactor instrumentation, criticality safety, materials management and safeguards. This task will focus on the developmental needs of the FCR&D experimental programs, such as elastic/inelastic scattering, total cross sections and fission neutron spectra measurements, and will leverage a number of existing neutron detector development efforts and programs, such as those at LANL, PNNL, INL, and IAC as well as those at many universities, some of whom are funded under NE grants and contracts. Novel materials and fabrication processes combined with state-of-the-art electronics and computing provide new opportunities for revolutionary detector systems that will be able to meet the high precision needs of the program. This work will be closely coordinated with the Nuclear Data Crosscut. The Advanced Detector Development effort is a broadly-focused activity that supports the development of improved nuclear data measurements and improved detection of nuclear reactions and reactor conditions. This work supports the design and construction of large-scale, multiple component detectors to provide nuclear reaction data of unprecedented quality and precision. Examples include the Time Projection Chamber (TPC) and the DANCE detector at LANL. This work also supports the fabrication and end-user application of novel scintillator materials detection and monitoring.

James K. Jewell

2012-09-01T23:59:59.000Z

313

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOE Patents [OSTI]

An improved method is disclosed for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue. 1 fig.

Peurrung, A.J.

1997-08-19T23:59:59.000Z

314

Neutron capture therapies  

DOE Patents [OSTI]

In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

Yanch, Jacquelyn C. (Cambridge, MA); Shefer, Ruth E. (Newton, MA); Klinkowstein, Robert E. (Winchester, MA)

1999-01-01T23:59:59.000Z

315

Niobium superconducting nanowire single-photon detectors  

E-Print Network [OSTI]

We investigate the performance of superconducting nanowire photon detectors fabricated from ultra-thin Nb. A direct comparison is made between these detectors and similar nanowire detectors fabricated from NbN. We find that Nb detectors are significantly more susceptible than NbN to thermal instability (latching) at high bias. We show that the devices can be stabilized by reducing the input resistance of the readout. Nb detectors optimized in this way are shown to have approximately 2/3 the reset time of similar large-active-area NbN detectors of the same geometry, with approximately 6% detection efficiency for single photons at 470 nm.

Annunziata, Anthony J; Chudow, Joel D; Frunzio, Luigi; Rooks, Michael J; Frydman, Aviad; Prober, Daniel E

2009-01-01T23:59:59.000Z

316

High-efficiency He-3 proportional counter for the detection of delayed neutrons  

SciTech Connect (OSTI)

The present work examines a high-neutron efficiency detector used to measure delayed neutron techniques. The measurement of delayed neutrons requires a detector system that has high neutron efficiency and a low dead- time. The detection system must also have low gamma-ray sensitivity, and in addition must be insensitive to small sample displacement. The operating characteristics of the high-efficiency He-3 proportional counter used for the measurement of {beta}{sub i}-delayed neutrons is reported here.

Loaiza, D.J.

1998-03-01T23:59:59.000Z

317

Delayed neutrons from the neutron irradiation of ²³?U  

E-Print Network [OSTI]

&M University Nuclear Science Center Reactor (NSCR) to verify 235U delayed neutron emission rates. A custom device was created to accurately measure a sample’s pneumatic flight time and the Nuclear Science Center’s (NSC’s) pneumatic transfer system (PTS... parameter measurements, including two 235U samples, an array of three 3He cylindrical neutron detectors, signal processing circuitry, the PTS, a reactor core sensor and a computerized control system. A. Fissile Material Isotope Products Laboratories...

Heinrich, Aaron David

2008-10-10T23:59:59.000Z

318

Ground water and snow sensor based on directional detection of cosmogenic neutrons.  

SciTech Connect (OSTI)

A fast neutron detector is being developed to measure the cosmic ray neutron flux in order to measure soil moisture. Soil that is saturated with water has an enhanced ability to moderate fast neutrons, removing them from the backscatter spectrum. The detector is a two-element, liquid scintillator detector. The choice of liquid scintillator allows rejection of gamma background contamination from the desired neutron signal. This enhances the ability to reconstruct the energy and direction of a coincident neutron event. The ability to image on an event-by-event basis allows the detector to selectively scan the neutron flux as a function of distance from the detector. Calibrations, simulations, and optimization have been completed to understand the detector response to neutron sources at variable distances and directions. This has been applied to laboratory background measurements in preparation for outdoor field tests.

Cooper, Robert Lee; Marleau, Peter; Griffin, Patrick J.

2011-06-01T23:59:59.000Z

319

Alternative Neutron Detection Testing Summary  

SciTech Connect (OSTI)

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. Most currently deployed radiation portal monitors (RPMs) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large area neutron detector. This type of neutron detector is used in the TSA and other RPMs installed in international locations and in the Ludlum and Science Applications International Corporation RPMs deployed primarily for domestic applications. There is a declining supply of 3He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated wavelength-shifting plastic fibers. Reported here is a summary of the testing carried out at Pacific Northwest National Laboratory on these technologies to date, as well as measurements on 3He tubes at various pressures. Details on these measurements are available in the referenced reports. Sponsors of these tests include the Department of Energy (DOE), Department of Homeland Security (DHS), and the Department of Defense (DoD), as well as internal Pacific Northwest National Laboratory funds.

Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Lintereur, Azaree T.; Siciliano, Edward R.; Stromswold, David C.; Woodring, Mitchell L.

2010-04-08T23:59:59.000Z

320

RCPO1 - A Monte Carlo program for solving neutron and photon transport problems in three dimensional geometry with detailed energy description and depletion capability  

SciTech Connect (OSTI)

The RCP01 Monte Carlo program is used to analyze many geometries of interest in nuclear design and analysis of light water moderated reactors such as the core in its pressure vessel with complex piping arrangement, fuel storage arrays, shipping and container arrangements, and neutron detector configurations. Written in FORTRAN and in use on a variety of computers, it is capable of estimating steady state neutron or photon reaction rates and neutron multiplication factors. The energy range covered in neutron calculations is that relevant to the fission process and subsequent slowing-down and thermalization, i.e., 20 MeV to 0 eV. The same energy range is covered for photon calculations.

Ondis, L.A., II; Tyburski, L.J.; Moskowitz, B.S.

2000-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Study of thermal neutron capture gamma rays using a lithium-drifted germanium spectrometer / [by] Victor John Orphan [and] Norman C. Rasmussen  

E-Print Network [OSTI]

A gamma-ray spectrometer, using a 30 cc coaxial Ge(Li) detector, which can be operated as a pair spectrometer at high energies and in the Compton suppression mode at low energies provides an effective means of obtaining ...

Orphan, V. J.

1967-01-01T23:59:59.000Z

322

Polymer-Ceramic MEMS Bimorphs as Thermal Infrared Sensors.  

E-Print Network [OSTI]

??Thermal infrared detectors based on MEMS bimorph beams have the potential to exceed the performance of current uncooled thermal infrared cameras both in terms of… (more)

Warren, Clinton Gregory

2010-01-01T23:59:59.000Z

323

29. Detectors for non-accelerator physics 1 Written 2009 (see the various sections for authors).  

E-Print Network [OSTI]

. PARTICLE DETECTORS FOR NON-ACCEL. PHYSICS . . . . . . . . . 1 29.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 30 29.6.6. Neutrons . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 29. PARTICLE DETECTORS important in particle physics. These include classical cosmic ray experiments, neutrino oscillation

324

E-Print Network 3.0 - absorption bgo detector Sample Search Results  

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

Dept. of Physics, KTH, Stockholm, Sweden Summary: 54 BGO) Yellow: Neutron Shield (polyethylene) Phoswich Detector Cell 140 cm Valid event See: C... undergo Compton scattering in...

325

Study of the neutron and proton capture reactions 10,11b(n, g), 11b(p, g), 14c(p, g), and 15n(p, g) at thermal and astrophysical energies  

E-Print Network [OSTI]

We have studied the neutron-capture reactions 10,11B(n, g) and the role of the 11B(n, g) reaction in seeding r-process nucleosynthesis. The possibility of the description of the available experimental data for cross sections of the neutron capture reaction on 10B at thermal and astrophysical energies, taking into account the resonance at 475 keV, was considered within the framework of the modified potential cluster model (MPCM) with forbidden states and accounting for the resonance behavior of the scattering phase shifts. In the framework of the same model the possibility of describing the available experimental data for the total cross sections of the neutron radiative capture on 11B at thermal and astrophysical energies were considered with taking into account the 21 and 430 keV resonances. Description of the available experimental data on the total cross sections and astrophysical S-factor of the radiative proton capture on 11B to the ground state of 12C was treated at astrophysical energies. The possibility of description of the experimental data for the astrophysical S-factor of the radiative proton capture on 14C to the ground state of 15N at astrophysical energies, and the radiative proton capture on 15N at the energies from 50 to 1500 keV was considered in the framework of the MPCM with the classification of the orbital states according to Young tableaux. It was shown that, on the basis of the M1 and the E1 transitions from different states of the p15N scattering to the ground state of 16O in the p15N channel, it is quite succeed to explain general behavior of the S-factor in the considered energy range in the presence of two resonances.

Sergey Dubovichenko; Albert Dzhazairov-Kakhramanov

2014-05-24T23:59:59.000Z

326

Post irradiation experiment analysis using the APOLLO2 deterministic tool. Validation of JEFF-3.1.1 thermal and epithermal actinides neutron induced cross sections through MELUSINE experiments  

SciTech Connect (OSTI)

Two different experiments performed in the 8 MWth MELUSINE experimental power pool reactor aimed at analyzing 1 GWd/t spent fuel pellets doped with several actinides. The goal was to measure the averaged neutron induced capture cross section in two very different neutron spectra (a PWR-like and an under-moderated one). This paper summarizes the combined deterministic APOLLO2-stochastic TRIPOLI4 analysis using the JEFF-3.1.1 European nuclear data library. A very good agreement is observed for most of neutron induced capture cross section of actinides and a clear underestimation for the {sup 241}Am(n,{gamma}) as an accurate validation of its associated isomeric ratio are emphasized. Finally, a possible huge resonant fluctuation (factor of 2.7 regarding to the 1=0 resonance total orbital momenta) is suggested for isomeric ratio. (authors)

Bernard, D.; Fabbris, O. [CEA, DEN, SPRC, Laboratoire d'Etudes de Physique, F-13108 Saint Paul Lez Durance (France)

2012-07-01T23:59:59.000Z

327

NEUTRON SPECTROSCOPY BY DOUBLE SCATTER AND ASSOCIATED PARTICLE TECHNIQUES.  

SciTech Connect (OSTI)

Multiple detectors can provide [1,2] both directional and spectroscopic information. Neutron spectra may be obtained by neutron double scatter (DSNS), or the spontaneous fission associated particle (AP) technique. Spontaneous fission results in the creation of fission fragments and the release of gamma rays and neutrons. As these occur at the same instant, they are correlated in time. Thus gamma ray detection can start a timing sequence relative to a neutron detector where the time difference is dominated by neutron time-of-flight. In this paper we describe these techniques and compare experimental results with Monte Carlo calculations.

DIOSZEGI,I.

2007-10-28T23:59:59.000Z

328

Actively driven thermal radiation shield  

DOE Patents [OSTI]

A thermal radiation shield for cooled portable gamma-ray spectrometers. The thermal radiation shield is located intermediate the vacuum enclosure and detector enclosure, is actively driven, and is useful in reducing the heat load to mechanical cooler and additionally extends the lifetime of the mechanical cooler. The thermal shield is electrically-powered and is particularly useful for portable solid-state gamma-ray detectors or spectrometers that dramatically reduces the cooling power requirements. For example, the operating shield at 260K (40K below room temperature) will decrease the thermal radiation load to the detector by 50%, which makes possible portable battery operation for a mechanically cooled Ge spectrometer.

Madden, Norman W. (Livermore, CA); Cork, Christopher P. (Pleasant Hill, CA); Becker, John A. (Alameda, CA); Knapp, David A. (Livermore, CA)

2002-01-01T23:59:59.000Z

329
330

MS Detectors  

SciTech Connect (OSTI)

Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

2005-11-01T23:59:59.000Z

331

Neutron skins and neutron stars  

SciTech Connect (OSTI)

The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ('PREX') at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in {sup 208}Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.

Piekarewicz, J. [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States)

2013-11-07T23:59:59.000Z

332

Neutron spectrometer for improved SNM search.  

SciTech Connect (OSTI)

With the exception of large laboratory devices with very low sensitivities, a neutron spectrometer have not been built for fission neutrons such as those emitted by special nuclear materials (SNM). The goal of this work was to use a technique known as Capture Gated Neutron Spectrometry to develop a solid-state device with this functionality. This required modifications to trans-stilbene, a known solid-state scintillator. To provide a neutron capture signal we added lithium to this material. This unique triggering signal allowed identification of neutrons that lose all of their energy in the detector, eliminating uncertainties that arise due to partial energy depositions. We successfully implemented a capture gated neutron spectrometer and were able to distinguish an SNM like fission spectrum from a spectrum stemming from a benign neutron source.

Vance, Andrew L.; Aigeldinger, Georg

2007-03-01T23:59:59.000Z

333

Infra-red signature neutron detector  

DOE Patents [OSTI]

A method of detecting an activator, the method including impinging with an activator a receptor material that includes a photoluminescent material that generates infrared radiation and generation a by-product of a nuclear reaction due to the activator impinging the receptor material. The method further includes generating light from the by-product via the Cherenkov effect, wherein the light activates the photoluminescent material so as to generate the infrared radiation. Identifying a characteristic of the activator based on the infrared radiation.

Bell, Zane William (Oak Ridge, TN) [Oak Ridge, TN; Boatner, Lynn Allen (Oak Ridge, TN) [Oak Ridge, TN

2009-10-13T23:59:59.000Z

334

Neutron guide  

DOE Patents [OSTI]

A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Greene, Geoffrey L. (Los Alamos, NM)

1999-01-01T23:59:59.000Z

335

Microwave detector  

DOE Patents [OSTI]

A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Meldner, Heiner W. (Moss Beach, CA); Cusson, Ronald Y. (Chapel Hill, NC); Johnson, Ray M. (San Ramon, CA)

1986-01-01T23:59:59.000Z

336

Microwave detector  

DOE Patents [OSTI]

A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

1985-02-08T23:59:59.000Z

337

GEANIE at WNR/LANSCE -- A new instrument for neutron science  

SciTech Connect (OSTI)

GEANIE, an array of escape-suppressed high-resolution Ge detectors now installed at the white-neutron source at the Los Alamos Neutron Science Center, is the first large Ge detector array to be used at a high-energy spallation neutron source. GEANIE consists of 20 Ge detectors including both coaxial Ge detectors and planar Ge detectors to enhance capabilities for low-energy {gamma}-ray spectroscopy. The array is located on a 20 m flight path with a neutron flux spanning the energy range from 1 to over 200 MeV. Installation of the first phase of GEANIE was recently completed and data were acquired on a number of samples, including actinides. The unique combination of GEANIE with the neutron source at LANSCE provides new capabilities for neutron science. The status of the array and recent results are presented, and new opportunities for physics and nuclear data are discussed.

Nelson, R.O.; Becker, J.A.; Archer, D.E. [and others

1997-09-01T23:59:59.000Z

338

Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture  

SciTech Connect (OSTI)

The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

Scott Wilde, Raymond Keegan

2008-07-01T23:59:59.000Z

339

Radiation detector system having heat pipe based cooling  

DOE Patents [OSTI]

A radiation detector system having a heat pipe based cooling. The radiation detector system includes a radiation detector thermally coupled to a thermo electric cooler (TEC). The TEC cools down the radiation detector, whereby heat is generated by the TEC. A heat removal device dissipates the heat generated by the TEC to surrounding environment. A heat pipe has a first end thermally coupled to the TEC to receive the heat generated by the TEC, and a second end thermally coupled to the heat removal device. The heat pipe transfers the heat generated by the TEC from the first end to the second end to be removed by the heat removal device.

Iwanczyk, Jan S.; Saveliev, Valeri D.; Barkan, Shaul

2006-10-31T23:59:59.000Z

340

A Direction-Sensitive Detector for Electron Antineutrinos  

SciTech Connect (OSTI)

A modular design is proposed for an electron antineutrino detector based on boron-doped liquid scintillator. Tests have been carried out on small detector systems using neutrons to simulate the antineutrino detection signature. Results from these tests are reported, and the possibility of using a larger system of similar design to detect reactor antineutrinos is discussed.

Brooks, F. D. [Physics Department, University of Cape Town, Rondebosch 7700 (South Africa); Drosg, M. [Faculty of Physics, University of Vienna, Wien A-1090 (Austria); Smit, F. D. [iThemba Laboratory for Accelerator-Based Sciences, Somerset West 7129 (South Africa)

2011-12-13T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Uncertainty evaluation of delayed neutron decay parameters  

E-Print Network [OSTI]

parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical...

Wang, Jinkai

2009-05-15T23:59:59.000Z

342

Cosmic ray neutron background reduction using localized coincidence veto neutron counting  

DOE Patents [OSTI]

This invention relates to both the apparatus and method for increasing the sensitivity of measuring the amount of radioactive material in waste by reducing the interference caused by cosmic ray generated neutrons. The apparatus includes: (a) a plurality of neutron detectors, each of the detectors including means for generating a pulse in response to the detection of a neutron; and (b) means, coupled to each of the neutrons detectors, for counting only some of the pulses from each of the detectors, whether cosmic ray or fission generated. The means for counting includes a means that, after counting one of the pulses, vetos the counting of additional pulses for a prescribed period of time. The prescribed period of time is between 50 and 200 .mu.s. In the preferred embodiment the prescribed period of time is 128 .mu.s. The veto means can be an electronic circuit which includes a leading edge pulse generator which passes a pulse but blocks any subsequent pulse for a period of between 50 and 200 .mu.s. Alternately, the veto means is a software program which includes means for tagging each of the pulses from each of the detectors for both time and position, means for counting one of the pulses from a particular position, and means for rejecting those of the pulses which originate from the particular position and in a time interval on the order of the neutron die-away time in polyethylene or other shield material. The neutron detectors are grouped in pods, preferably at least 10. The apparatus also includes means for vetoing the counting of coincidence pulses from all of the detectors included in each of the pods which are adjacent to the pod which includes the detector which produced the pulse which was counted.

Menlove, Howard O. (Los Alamos, NM); Bourret, Steven C. (Los Alamos, NM); Krick, Merlyn S. (Los Alamos, NM)

2002-01-01T23:59:59.000Z

343

Investigation of Large LGB Detectors for Antineutrino Detection  

E-Print Network [OSTI]

A detector material or configuration that can provide an unambiguous indication of neutron capture can substantially reduce random coincidence backgrounds in antineutrino detection and capture-gated neutron spectrometry applications. Here we investigate the performance of such a material, a composite of plastic scintillator and $^6$Li$_6^{nat}$Gd$(^{10}$BO$_{3})_{3}$:Ce (LGB) crystal shards of ~1 mm dimension and comprising 1% of the detector by mass. While it is found that the optical propagation properties of this material as currently fabricated are only marginally acceptable for antineutrino detection, its neutron capture identification ability is encouraging.

Nelson, P

2011-01-01T23:59:59.000Z

344

Protein crystallography with spallation neutrons  

SciTech Connect (OSTI)

proteins and oriented molecular complexes. With spallation neutrons and their time dependent wavelength structure, one can select data with an optimal wavelength bandwidth and cover the whole Laue spectrum as time (wavelength) resolved diffraction data. This optimizes data quality with best peak to background ratios and provides spatial and energy resolution to eliminate peak overlaps. Such a Protein Crystallography Station (PCS) has been built and tested at Los Alamos Neutron Science Center. A partially coupled moderator is used to increase flux and data are collected by a Cylindrical He3 detector covering 120' with 200mm height. The PCS is described along with examples of data collected from a number of proteins.

Langan, P. (Paul); Schoenborn, Benno P.

2003-01-01T23:59:59.000Z

345

Neutron sources: Present practice and future potential  

SciTech Connect (OSTI)

The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500 MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs.

Cierjacks, S.; Smith, A.B.

1988-01-01T23:59:59.000Z

346

The neutron-gamma Feynman variance to mean approach: gamma detection and total neutron-gamma detection (theory and practice)  

E-Print Network [OSTI]

Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have a particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with inclusion of general reactions and passage intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source enclosed in a steel container. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma, are evaluated experimentally for a weak 252Cf neutron-gamma source in a steel container, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-Y formulas.

Dina Chernikova; Kåre Axell; Senada Avdic; Imre Pázsit; Anders Nordlund

2015-01-23T23:59:59.000Z

347

NEET Micro-Pocket Fission Detector -- FY 2012 Status Report  

SciTech Connect (OSTI)

A research program has been initiated by the NEET program for developing and testing compact miniature fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When implemented, these sensors will significantly advance flux detection capabilities for irradiation tests in US Materials Test Reactors (MTRs).Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, high performance reactors and commercial nuclear power plants. Deployment of Micro-Pocket Fission Detectors (MPFDs) in US DOE-NE program irradiation tests will address several challenges: Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe, MPFDs offer this option. MPFD construction is very different then current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions in typical high performance MTR irradiation tests. New high-fidelity reactor physics codes will need a small, accurate, multipurpose in-core sensor to validate the codes without perturbing the validation experiment; MPFDs fill this requirement. MPFDs can be built with variable sensitivities to survive the lifetime of an experiment or fuel assembly in some MTRs; allowing for more efficient and cost effective power monitoring. The small size of the MPFDs allows multiple sensors to be simultaneously deployed; obtaining data required to visualize the reactor flux and temperature profiles. This report summarizes the research progress for year 1 of this 3 year project. An updated design of the MPFD has been developed, materials and tools to support the new design have been procured, construction methods to support the new design have been initiated at INL’s HTTL and KSU’s SMART Laboratory, plating methods are being updated at KSU, new detector electronics have been designed, built and tested at KSU. In addition, a project meeting was held at KSU and a detector evaluation plan has been initiated between INL and KSU. Once NEET program evaluations are completed, the final MPFD will be deployed in MTR irradiations, enabling DOE-NE programs evaluating the performance of candidate new fuels and materials to better characterize irradiation test conditions.

Troy Unruh; Joy Rempe; Douglas McGregor; Philip Ugorowski; Michael Reichenberger

2012-09-01T23:59:59.000Z

348

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

E-Print Network [OSTI]

the time-of-flight technique. Lithium-6 glass scintillation detectors were used for transmission for natural hafnium, it did affect the way the hafnium interactions would change with exposure to a neutron

Danon, Yaron

349

Delayed neutron energy spectrum measurements of actinide waste isotopes  

E-Print Network [OSTI]

was irradiated using the Texas A&M Nuclear Science Center Reactor (NSCR). Three proton recoil detectors, operating individually, in conjunction with MCNP calculated response functions, were used to measure the delayed neutron energy spectra of each isotope...

Comfort, Christopher M.

2012-06-07T23:59:59.000Z

350

active neutron detection: Topics by E-print Network  

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

the device ("skyshine"). Taylor, David; Turner, Andrew; Davis, Andrew 2014-01-01 48 An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons...

351

Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)  

E-Print Network [OSTI]

Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors.

I. Anghel; J. F. Beacom; M. Bergevin; G. Davies; F. Di Lodovico; A. Elagin; H. Frisch; R. Hill; G. Jocher; T. Katori; J. Learned; R. Northrop; C. Pilcher; E. Ramberg; M. C. Sanchez; M. Smy; H. Sobel; R. Svoboda; S. Usman; M. Vagins; G. Varner; R. Wagner; M. Wetstein; L. Winslow; M. Yeh

2014-02-26T23:59:59.000Z

352

Neutron tubes  

DOE Patents [OSTI]

A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

Leung, Ka-Ngo (Hercules, CA); Lou, Tak Pui (Berkeley, CA); Reijonen, Jani (Oakland, CA)

2008-03-11T23:59:59.000Z

353

Directional measurements for sources of fission neutrons  

SciTech Connect (OSTI)

Although penetrating neutron and gamma-ray emissions arguably provide the most effective signals for locating sources of nuclear radiation, their relatively low fluxes make searching for radioactive materials a tedious process. Even assuming lightly shielded sources and detectors with large areas and high efficiencies, estimated counting times can exceed several minutes for source separations greater than ten meters. Because determining the source position requires measurements at several locations, each with its own background, the search procedure can be lengthy and difficult to automate. Although directional measurements can be helpful, conventional collimation reduces count rates and increases the detector size and weight prohibitively, especially for neutron instruments. We describe an alternative approach for locating radiation sources that is based on the concept of a polarized radiation field. In this model, the presence of a source adds a directional component to the randomly oriented background radiation. The net direction of the local field indicates the source angle, and the magnitude provides an estimate of the distance to the source. The search detector is therefore seen as a device that responds to this polarized radiation field. Our proposed instrument simply substitutes segmented detectors for conventional single-element ones, so it requires little or no collimating material or additional weight. Attenuation across the detector creates differences in the count rates for opposite segments, whose ratios can be used to calculate the orthogonal components of the polarization vector. Although this approach is applicable to different types of radiation and detectors, in this report we demonstrate its use for sources of fission neutrons by using a prototype fast-neutron detector, which also provides background-corrected energy spectra for the incident neutrons.

Byrd, R.C.; Auchampaugh, G.F.; Feldman, W.C.

1993-11-01T23:59:59.000Z

354

Analytical Calculation of the Neutrons Spectrum for Direct Measurement of N-N Scattering at Pulsed Reactor Yaguar  

E-Print Network [OSTI]

Analytical calculation of a single neutron detector counts per YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.

Ignatovich, V K

2008-01-01T23:59:59.000Z

355

Analytical Calculation of the Neutrons Spectrum for Direct Measurement of N-N Scattering at Pulsed Reactor Yaguar  

E-Print Network [OSTI]

Analytical calculation of a single neutron detector counts per YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.

V. K. Ignatovich

2008-06-23T23:59:59.000Z

356

Method and apparatus for detecting neutrons  

DOE Patents [OSTI]

The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO.sub.2 with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation.

Perkins, Richard W. (Richland, WA); Reeder, Paul L. (Richland, WA); Wogman, Ned A. (Richland, WA); Warner, Ray A. (Benton City, WA); Brite, Daniel W. (Richland, WA); Richey, Wayne C. (Richland, WA); Goldman, Don S. (Orangevale, CA)

1997-01-01T23:59:59.000Z

357

Instrumentation for Neutron Scattering at the Missouri University Research Reactor Paul F. Miceli  

E-Print Network [OSTI]

Instrumentation for Neutron Scattering at the Missouri University Research Reactor Paul F. Miceli Research Reactor (MURR) provides significant thermal neutron flux, which enables neutron scattering]. There are presently 5 instruments located on the beam port floor that are dedicated to neutron scattering: (1) TRIAX

Montfrooij, Wouter

358

Neutron counter based on beryllium activation  

SciTech Connect (OSTI)

The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction {sup 9}Be(n, ?){sup 6}He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, {sup 6}He, decays with half-life T{sub 1/2} = 0.807 s emitting ?{sup ?} particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of ?–particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known ?–source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5–the Monte Carlo transport code. It allowed proper application of the results of transport calculations of ?{sup ?} particles emitted from radioactive {sup 6}He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

Bienkowska, B.; Prokopowicz, R.; Kaczmarczyk, J.; Paducha, M. [Institute of Plasma Physics and Laser Microfusion (IPPLM), Hery 23, 01-497 Warsaw (Poland); Scholz, M.; Igielski, A. [Institute of Nuclear Physics PAS (IFJPAN), Radzikowskiego 152, 31-342 Krakow (Poland); Karpinski, L. [Faculty of Electrical Engineering, Rzeszow University of Technology, Pola 2, 35-959 Rzeszow (Poland); Pytel, K. [National Centre for Nuclear Research (NCBJ), Soltana 7, 05-400 Otwock - Swierk (Poland)

2014-08-21T23:59:59.000Z

359

The neutron long counter NERO for studies of beta-delayed neutron emission in the r-process  

E-Print Network [OSTI]

The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring beta-delayed neutron-emission probabilities. The detector was designed to work in conjunction with a beta-decay implantation station, so that beta decays and beta-delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring beta-delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.

Pereira, J; Lorusso, G; Santi, P; Couture, A; Daly, J; Del Santo, M; Elliot, T; Goerres, J; Herlitzius, C; Kratz, K -L; Lamm, L O; Lee, H Y; Montes, F; Ouellette, M; Pellegrini, E; Reeder, P; Schatz, H; Schertz, F; Schnorrenberger, L; Smith, K; Stech, E; Strandberg, E; Ugalde, C; Wiescher, M; Woehr, A; 10.1016/j.nima.2010.02.262

2010-01-01T23:59:59.000Z

360

The neutron long counter NERO for studies of beta-delayed neutron emission in the r-process  

E-Print Network [OSTI]

The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring beta-delayed neutron-emission probabilities. The detector was designed to work in conjunction with a beta-decay implantation station, so that beta decays and beta-delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring beta-delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.

J. Pereira; P. Hosmer; G. Lorusso; P. Santi; A. Couture; J. Daly; M. Del Santo; T. Elliot; J. Goerres; C. Herlitzius; K. -L. Kratz; L. O. Lamm; H. Y. Lee; F. Montes; M. Ouellette; E. Pellegrini; P. Reeder; H. Schatz; F. Schertz; L. Schnorrenberger; K. Smith; E. Stech; E. Strandberg; C. Ugalde; M. Wiescher; A. Woehr

2010-07-28T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Delayed neutrons as a probe of nuclear charge distribution in fission of heavy nuclei by neutrons  

E-Print Network [OSTI]

A method of the determination of cumulative yields of delayed neutron precursors is developed. This method is based on the iterative least-square procedure applied to delayed neutron decay curves measured after irradiation of sup 2 sup 3 sup 5 U sample by thermal neutrons. Obtained cumulative yields in turns were used for deriving the values of the most probable charge in low-energy fission of the above-mentioned nucleus.

Isaev, S G; Piksaikin, V M; Roshchenko, V A

2001-01-01T23:59:59.000Z

362

Neutron spectrometry using LNL bonner spheres and FLUKA  

SciTech Connect (OSTI)

The characterization of neutron fields has been made with a system based on a scintillation detector and multiple moderating spheres. The system, together with the unfolding procedure, have been tested in quasi-monochromatic neutron energy fields and in complex, mixed, cyclotron based environments. FLUKA simulations have been used to produce response functions and reference energy spectra.

Sarchiapone, L.; Zafiropoulos, D. [INFN, Laboratori Nazionali di Legnaro (Italy)

2013-07-18T23:59:59.000Z

363

Study of Fuel Cell Water Transport With Neutron Imaging  

E-Print Network [OSTI]

detector system, constructing computer controlled fuel cell handling mechanism and optimizing dataStudy of Fuel Cell Water Transport With Neutron Imaging David Jacobson (NIST) Paul Huffman (NIST in fully assembled operating fuel cells. Develop a nuclear reactor based state of the art neutron imaging

364

Effect of temperature on performance of {sup 3}He filled neutron proportional counters  

SciTech Connect (OSTI)

Neutron detectors used for cosmic neutron monitoring and various other applications are mounted in hostile environment. It is essential for detectors to sustain extreme climatic conditions, such as extreme temperature and humidity. Effort is made to evaluate the performance of detectors in extreme temperature in terms of pulse height distribution and avalanche formation. Neutron detectors filled with {sup 3}He incorporate an additive gas with quantity optimized for a particular application. Measurements are performed on neutron detectors filled with {sup 3}He and stopping gases Kr and CF{sub 4}. Detector performance for these fill gas combinations in terms of pulse height distribution is evaluated. Gas gain and Diethorn gas constants measured and analyzed for the microscopic effect on pulse formation. Results from these investigations are presented.

Desai, Shraddha S., E-mail: ssdesai@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2014-04-24T23:59:59.000Z

365

Active neutron multiplicity counting of bulk uranium  

SciTech Connect (OSTI)

This paper describes a new nondestructive assay technique being developed to assay bulk uranium containing kilogram quantities of {sup 235}U. The new technique uses neutron multiplicity analysis of data collected with a coincidence counter outfitted with AmLi neutron sources. We have calculated the expected neutron multiplicity count rate and assay precision for this technique and will report on its expected performance as a function of detector design characteristics, {sup 235 }U sample mass, AmLi source strength, and source-to-sample coupling. 11 refs., 2 figs., 2 tabs.

Ensslin, N.; Krick, M.S.; Langner, D.G.; Miller, M.C.

1991-01-01T23:59:59.000Z

366

Measurement of the Neutron Lifetime by Counting Trapped Protons in a Cold Neutron Beam  

E-Print Network [OSTI]

A measurement of the neutron lifetime $\\tau_{n}$ performed by the absolute counting of in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto a silicon detector held at a high potential and counted with nearly unit efficiency. The neutrons were counted by a device with an efficiency inversely proportional to neutron velocity, which cancels the dwell time of the neutron beam in the trap. The result is $\\tau_{n} = (886.6\\pm1.2{\\rm [stat]}\\pm3.2{\\rm [sys]})$ s, which is the most precise measurement of the lifetime using an in-beam method. The systematic uncertainty is dominated by neutron counting, in particular the mass of the deposit and the $^{6}$Li({\\it{n,t}}) cross section. The measurement technique and apparatus, data analysis, and investigation of systematic uncertainties are discussed in detail.

J. S. Nico; M. S. Dewey; D. M. Gilliam; F. E. Wietfeldt; X. Fei; W. M. Snow; G. L. Greene; J. Pauwels; R. Eykens; A. Lamberty; J. Van Gestel; R. D. Scott

2004-11-19T23:59:59.000Z

367

Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons  

E-Print Network [OSTI]

Composite detectors made of stainless steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment.

M. Röder; Z. Elekes; T. Aumann; D. Bemmerer; K. Boretzky; C. Caesar; T. E. Cowan; J. Hehner; M. Heil; M. Kempe; V. Maroussov; O. Nusair; A. V. Prokofiev; R. Reifarth; M. Sobiella; D. Stach; A. Wagner; D. Yakorev; A. Zilges; K. Zuber

2014-07-10T23:59:59.000Z

368

Capacitance measurements on silicon microstrip detectors  

SciTech Connect (OSTI)

Load capacitance is the most significant parameter determining the noise level of charge-sensitive readout electronics. This is the capacitance between the detecting electrode and all other conductors in the system. For the case of silicon microstrip detectors, the significant contributions are those from the other strips on the detector surface and also from the backplane. This article presents the results of capacitance measurements on both the junction and ohmic sides of detectors, and with various geometries. Double-sided detectors with a second metal layer and different readout patterns were also studied. In addition, the authors present measurements of microstrip capacitance after irradiation with both neutrons and photons made as part of the research by the RD20 collaboration into all aspects of the use of silicon microstrips at the Large Hadron Collider at CERN.

Masciocchi, S. (INFN, Milano (Italy) CERN, Geneva (Switzerland)); Peisert, A. (INFN, Padova (Italy)); Roenqvist, C. (SEFT, Helsinki (Finland)); Vite, D.; Wheadon, R. (Imperial Coll., London (United Kingdom))

1993-08-01T23:59:59.000Z

369

Neutron Tomography and Space  

E-Print Network [OSTI]

Kevin Shields, “Optimization of neutron tomography for rapidNEUTRON TOMOGRAPHY AND SPACE Hal Egbert, Ronald Walker, R.industrial applications[1]. Neutron Computed Tomography was

Egbert, Hal; Walker, Ronald; Flocchini, R.

2007-01-01T23:59:59.000Z

370

Neutron range spectrometer  

DOE Patents [OSTI]

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

Manglos, S.H.

1988-03-10T23:59:59.000Z

371

Oscillator detector  

SciTech Connect (OSTI)

An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

Potter, B.M.

1980-05-13T23:59:59.000Z

372

A coupled neutronics/thermalhydraulics tool for calculating fluctuations in Pressurized Water Reactors  

E-Print Network [OSTI]

Water Reactors or Heavy Water Reactors (LarssoA coupled neutronics/thermal­hydraulics tool for calculating fluctuations in Pressurized Water in neutron flux, fuel temperature, moderator den- sity and flow velocity in Pressurized Water Reactors

Demazière, Christophe

373

Delayed neutron measurements for Th-232, Np-237, Pu-239, Pu-241 and depleted uranium  

E-Print Network [OSTI]

The neutron emission rates from five very pure actinide samples (Th-232, Np-237, Pu-239, Pu-241 and depleted uranium) were measured following equilibrium irradiation in fast and thermal neutron fluxes. The relative abundances (alphas) for the first...

Stone, Joseph C.

2001-01-01T23:59:59.000Z

374

Lithium-6 filter for a fission converter-based Boron Neutron Capture Therapy irradiation facility beam  

E-Print Network [OSTI]

(cont.) A storage system was designed to contain the lithium-6 filter safely when it is not in use. A mixed field dosimetry method was used to measure the photon, thermal neutron and fast neutron dose. The measured advantage ...

Gao, Wei, Ph. D.

2005-01-01T23:59:59.000Z

375

The Neutron Imaging Diagnostic at NIF  

SciTech Connect (OSTI)

A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of ICF implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

Merrill, F E; Buckles, R; Clark, D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherly, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H

2012-10-01T23:59:59.000Z

376

The neutron imaging diagnostic at NIF (invited)  

SciTech Connect (OSTI)

A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

Merrill, F. E.; Clark, D. D.; Danly, C. R.; Drury, O. B.; Fatherley, V. E.; Gallegos, R.; Grim, G. P.; Guler, N.; Loomis, E. N.; Martinson, D. D.; Mares, D.; Morley, D. J.; Morgan, G. L.; Oertel, J. A.; Tregillis, I. L.; Volegov, P. L.; Wilde, C. H.; Wilson, D. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Bower, D.; Dzenitis, J. M. [Livermore National Laboratory, Livermore, California 94550 (United States); and others

2012-10-15T23:59:59.000Z

377

Development of multichannel low-energy neutron spectrometer  

SciTech Connect (OSTI)

A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments.

Arikawa, Y., E-mail: arikawa-y@ile.osaka-u.ac.jp; Nagai, T.; Abe, Y.; Kojima, S.; Sakata, S.; Inoue, H.; Utsugi, M.; Iwasa, Y.; Sarukura, N.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka (Japan); Murata, T. [Kumamoto University, 2-40-1 Kurokami, Kumamoto 860-8555 (Japan)

2014-11-15T23:59:59.000Z

378

Neutron irradiation effects on gallium nitride-based Schottky diodes  

SciTech Connect (OSTI)

Depth-resolved cathodoluminescence spectroscopy (DRCLS), time-resolved surface photovoltage spectroscopy, X-ray photoemission spectroscopy (XPS), and current-voltage measurements together show that fast versus thermal neutrons differ strongly in their electronic and morphological effects on metal-GaN Schottky diodes. Fast and thermal neutrons introduce GaN displacement damage and native point defects, while thermal neutrons also drive metallurgical reactions at metal/GaN interfaces. Defect densities exhibit a threshold neutron fluence below which thermal neutrons preferentially heal versus create new native point defects. Scanning XPS and DRCLS reveal strong fluence- and metal-dependent electronic and chemical changes near the free surface and metal interfaces that impact diode properties.

Lin, Chung-Han; Katz, Evan J.; Zhang, Zhichun [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States)] [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Qiu, Jie; Cao, Lei [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)] [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Mishra, Umesh K. [Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of California, Santa Barbara, California 93106 (United States)] [Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of California, Santa Barbara, California 93106 (United States); Brillson, Leonard J. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States) [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

2013-10-14T23:59:59.000Z

379

A solenoidal electron spectrometer for a precision measurement of the neutron $?$-asymmetry with ultracold neutrons  

E-Print Network [OSTI]

We describe an electron spectrometer designed for a precision measurement of the neutron $\\beta$-asymmetry with spin-polarized ultracold neutrons. The spectrometer consists of a 1.0-Tesla solenoidal field with two identical multiwire proportional chamber and plastic scintillator electron detector packages situated within 0.6-Tesla field-expansion regions. Select results from performance studies of the spectrometer with calibration sources are reported.

B. Plaster; R. Carr; B. W. Filippone; D. Harrison; J. Hsiao; T. M. Ito; J. Liu; J. W. Martin; B. Tipton; J. Yuan

2008-06-12T23:59:59.000Z

380

Microscopic description of neutron emission rates in compound nuclei  

E-Print Network [OSTI]

The neutron emission rates in thermal excited nuclei are conventionally described by statistical models with a phenomenological level density parameter that depends on excitation energies, deformations and mass regions. In the microscopic view of hot nuclei, the neutron emission rates can be determined by the external neutron gas densities without any free parameters. Therefore the microscopic description of thermal neutron emissions is desirable that can impact several understandings such as survival probabilities of superheavy compound nuclei and neutron emissivity in reactors. To describe the neutron emission rates microscopically, the external thermal neutron gases are self-consistently obtained based on the Finite-Temperature Hartree-Fock-Bogoliubov (FT-HFB) approach. The results are compared with the statistical model to explore the connections between the FT-HFB approach and the statistical model. The Skyrme FT-HFB equation is solved by HFB-AX in deformed coordinate spaces. Based on the FT-HFB approach, the thermal properties and external neutron gas are properly described with the self-consistent gas substraction procedure. Then neutron emission rates can be obtained based on the densities of external neutron gases. The thermal statistical properties of $^{238}$U and $^{258}$U are studied in detail in terms of excitation energies. The thermal neutron emission rates in $^{238, 258}$U and superheavy compound nuclei $_{112}^{278}$Cn and $_{114}^{292}$Fl are calculated, which agree well with the statistical model by adopting an excitation-energy-dependent level density parameter. The coordinate-space FT-HFB approach can provide reliable microscopic descriptions of neutron emission rates in hot nuclei, as well as microscopic constraints on the excitation energy dependence of level density parameters for statistical models.

Yi Zhu; Junchen Pei

2014-11-02T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Improved Fission Neutron Data Base for Active Interrogation of Actinides  

SciTech Connect (OSTI)

This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

2013-11-06T23:59:59.000Z

382

Gaseous Detectors: recent developments and applications  

E-Print Network [OSTI]

Since long time, the compelling scientific goals of future high energy physics experiments were a driving factor in the development of advanced detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements - the Multiwire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel prize in physics in 1992. Since that time radiation detection and imaging with fast gaseous detectors, capable of economically covering large detection volume with low mass budget, have been playing an important role in many fields of physics. Advances in photo-lithography and micro-processing techniques in the chip industry during the past decade triggered a major transition in the field of gas detectors from wire structures to Micro-Pattern Gas Detector (MPGD) concepts, revolutionizing cell size limitations for many gas detector applications. The high radiation resistance and excellent spatial and time resolution make them an invaluable tool to confront future detector challenges at the next generation of colliders. The design of the new micro-pattern devices appears suitable for industrial production. Novel structures where MPGDs are directly coupled to the CMOS pixel readout represent an exciting field allowing timing and charge measurements as well as precise spatial information in 3D. Originally developed for the high energy physics, MPGD applications has expanded to nuclear physics, UV and visible photon detection, astroparticle and neutrino physics, neutron detection and medical physics.

Maxim Titov

2010-08-24T23:59:59.000Z

383

Modeling gated neutron images of THD capsules  

SciTech Connect (OSTI)

Time gating a neutron detector 28m from a NIF implosion can produce images at different energies. The brighter image near 14 MeV reflects the size and symmetry of the capsule 'hot spot'. Scattered neutrons, {approx}9.5-13 MeV, reflect the size and symmetry of colder, denser fuel, but with only {approx}1-7% of the neutrons. The gated detector records both the scattered neutron image, and, to a good approximation, an attenuated copy of the primary image left by scintillator decay. By modeling the imaging system the energy band for the scattered neutron image (10-12 MeV) can be chosen, trading off the decayed primary image and the decrease of scattered image brightness with energy. Modeling light decay from EJ399, BC422, BCF99-55, Xylene, DPAC-30, and Liquid A leads to a preference from BCF99-55 for the first NIF detector, but DPAC 30 and Liquid A would be preferred if incorporated into a system. Measurement of the delayed light from the NIF scintillator using implosions at the Omega laser shows BCF99-55 to be a good choice for down-scattered imaging at 28m.

Wilson, Douglas Carl [Los Alamos National Laboratory; Grim, Gary P [Los Alamos National Laboratory; Tregillis, Ian L [Los Alamos National Laboratory; Wilke, Mark D [Los Alamos National Laboratory; Morgan, George L [Los Alamos National Laboratory; Loomis, Eric N [Los Alamos National Laboratory; Wilde, Carl H [Los Alamos National Laboratory; Oertel, John A [Los Alamos National Laboratory; Fatherley, Valerie E [Los Alamos National Laboratory; Clark, David D [Los Alamos National Laboratory; Schmitt, Mark J [Los Alamos National Laboratory; Merrill, Frank E [Los Alamos National Laboratory; Wang, Tai - Sen F [Los Alamos National Laboratory; Danly, Christopher R [Los Alamos National Laboratory; Batha, Steven H [Los Alamos National Laboratory; Patel, M [LLNL; Sepke, S [LLNL; Hatarik, R [LLNL; Fittinghoff, D [LLNL; Bower, D [LLNL; Marinak, M [LLNL; Munro, D [LLNL; Moran, M [LLNL; Hilko, R [NSTEC; Frank, M [LLNL; Buckles, R [NSTEC

2010-01-01T23:59:59.000Z

384

Neutron Repulsion  

E-Print Network [OSTI]

Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding how: a.) The Sun generates and releases neutrinos, energy and solar-wind hydrogen and helium; b.) An inhabitable planet formed and life evolved around an ordinary-looking star; c.) Continuous climate change - induced by cyclic changes in gravitational interactions of the Sun's energetic core with planets - has favored survival by adaptation.

Oliver K. Manuel

2011-02-08T23:59:59.000Z

385

Static detectors and circular-geodesic detectors on the Schwarzschild black hole  

E-Print Network [OSTI]

We examine the response of an Unruh-DeWitt particle detector coupled to a massless scalar field on the (3+1)-dimensional Schwarzschild spacetime, in the Boulware, Hartle-Hawking and Unruh states, for static detectors and detectors on circular geodesics, by primarily numerical methods. For the static detector, the response in the Hartle-Hawking state exhibits the known thermality at the local Hawking temperature, and the response in the Unruh state is thermal at the local Hawking temperature in the limit of a large detector energy gap. For the circular-geodesic detector, we find evidence of thermality in the limit of a large energy gap for the Hartle-Hawking and Unruh states, at a temperature that exceeds the Doppler-shifted local Hawing temperature. Detailed quantitative comparisons between the three states are given. The response in the Hartle-Hawking state is compared with the response in the Minkowski vacuum and in the Minkowski thermal state for the corresponding Rindler, drifted Rindler, and circularly accelerated trajectories. The analysis takes place within first-order perturbation theory and relies in an essential way on stationarity.

Lee Hodgkinson; Jorma Louko; Adrian C. Ottewill

2014-05-05T23:59:59.000Z

386

Neutron Interactions: Q-Equation, Elastic Scattering  

E-Print Network [OSTI]

Since a neutron has no charge it can easily enter into a nucleus and cause a reaction. Neutrons interact primarily with the nucleus of an atom, except in the special case of magnetic scattering where the interaction involves the neutron spin and the magnetic moment of the atom. Because magnetic scattering is of no interest in this class, we can neglect the interaction between neutrons and electrons and think of atoms and nuclei interchangeably. Neutron reactions can take place at any energy, so one has to pay particular attention to the energy variation of the interaction cross section. In a nuclear reactor neutrons can have energies ranging from 10-3 ev (1 mev) to 10 7 ev (10 Mev). This means our study of neutron interactions, in principle, will have to cover an energy range of 10 ten orders of magnitude. In practice we will limit ourselves to two energy ranges, the slowing down region (ev to Kev) and the thermal region (around 0.025 ev). For a given energy region – thermal, epithermal, resonance, fast – not all the possible reactions are equally important. Which reaction is important depends on the target nucleus and the neutron energy. Generally speaking the important types of interactions, in the order of increasing complexity from the standpoint of theoretical

unknown authors

387

Noble Travails: Noble Liquid Dark Matter Detectors  

E-Print Network [OSTI]

, or water, 0.1x flux per 10 cm Cosmic Ray Muons generate high energy neutrons 50 MeV - 3 GeV which are toughGaitskell Noble Travails: Noble Liquid Dark Matter Detectors Rick Gaitskell Particle Astrophysics://particleastro.brown.edu/ http://gaitskell.brown.edu v1 #12;LUX Dark Matter Collaboration 2007 v01_7mm Dark Matter Theory

Golwala, Sunil

388

Preliminary measurements of neutrons from the D-D reaction in the COMPASS tokamak  

SciTech Connect (OSTI)

Recent results of measured fast neutrons created in the D-D reaction on the COMPASS tokamak during ohmic discharges are presented in this paper. Two different type detectors were used during experiment. He-3 detectors and bubble detectors as a support. The measurements are an introduction for neutron diagnostic on tokamak COMPASS and monitoring neutrons during discharges with Neutral Beam Injection (NBI). The He-3 counters and bubble detectors were located in two positions near tokamak vacuum chamber at a distance less than 40 cm to the centre of plasma. The neutrons flux was observed in ohmic discharges. However, analysis of our results does not indicate any clear source of neutrons production during ohmic discharges.

Dankowski, J., E-mail: jan.dankowski@ifj.edu.pl; Kurowski, A.; Twarog, D. [The Henryk Niewodnicza?ski Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152 Str., PL-31-342 Kraków (Poland); Janky, F.; Stockel, J. [Institute of Plasma Physics AS CR, v.v.i. Za Slovankou 1782/3, 182 00 Prague 8 (Czech Republic)

2014-08-21T23:59:59.000Z

389

Letter of Intent: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)  

E-Print Network [OSTI]

Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Wate...

Anghel, I; Bergevin, M; Blanco, C; Catano-Mur, E; Di Lodovico, F; Elagin, A; Frisch, H; Griskevich, J; Hill, R; Jocher, G; Katori, T; Krennrich, F; Learned, J; Malek, M; Northrop, R; Pilcher, C; Ramberg, E; Repond, J; Sacco, R; Sanchez, M C; Smy, M; Sobel, H; Svoboda, R; Usman, S M; Vagins, M; Varner, G; Wagner, R; Weinstein, A; Wetstein, M; Winslow, L; Xia, L; Yeh, M

2015-01-01T23:59:59.000Z

390

Coated semiconductor devices for neutron detection  

DOE Patents [OSTI]

A device for detecting neutrons includes a semi-insulated bulk semiconductor substrate having opposed polished surfaces. A blocking Schottky contact comprised of a series of metals such as Ti, Pt, Au, Ge, Pd, and Ni is formed on a first polished surface of the semiconductor substrate, while a low resistivity ("ohmic") contact comprised of metals such as Au, Ge, and Ni is formed on a second, opposed polished surface of the substrate. In one embodiment, n-type low resistivity pinout contacts comprised of an Au/Ge based eutectic alloy or multi-layered Pd/Ge/Ti/Au are also formed on the opposed polished surfaces and in contact with the Schottky and ohmic contacts. Disposed on the Schottky contact is a neutron reactive film, or coating, for detecting neutrons. The coating is comprised of a hydrogen rich polymer, such as a polyolefin or paraffin; lithium or lithium fluoride; or a heavy metal fissionable material. By varying the coating thickness and electrical settings, neutrons at specific energies can be detected. The coated neutron detector is capable of performing real-time neutron radiography in high gamma fields, digital fast neutron radiography, fissile material identification, and basic neutron detection particularly in high radiation fields.

Klann, Raymond T. (Bolingbrook, IL); McGregor, Douglas S. (Whitmore Lake, MI)

2002-01-01T23:59:59.000Z

391

Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE  

SciTech Connect (OSTI)

A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

Ullmann, John L [Los Alamos National Laboratory; Couture, A J [Los Alamos National Laboratory; Keksis, A L [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; O' Donnell, J M [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Haight, R C [Los Alamos National Laboratory; Rundberg, R S [Los Alamos National Laboratory; Kawano, T [Los Alamos National Laboratory; Chyzh, A [NORTH CAROLINA STATE UNIV; Baramsai, B [NORTH CAROLINA STATE UNIV; Wu, C Y [LLNL; Mitchell, G E [NORTH CAROLINA STATE UNIV; Becker, J A [LLNL; Krticka, M [CHARLES UNIV

2010-01-01T23:59:59.000Z

392

Recent Results and Fabrication of Micro-Pocket Fission Detectors (MPFD)  

E-Print Network [OSTI]

environments found in a reactor core. Self-powered neutron detectors (SPND) have the advantages of no voltage to noise ratio of the fission and ionization chambers, the low voltage requirements and small size of SPND

Shultis, J. Kenneth

393

Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network  

E-Print Network [OSTI]

Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus ...

Barsotti, Lisa

394

Neutron Scattering Experiment Automation with Python  

SciTech Connect (OSTI)

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.

Zolnierczuk, Piotr A [ORNL] [ORNL; Riedel, Richard A [ORNL] [ORNL

2010-01-01T23:59:59.000Z

395

2002 REVIEW OF NEUTRON AND NON NEUTRON NUCLEAR DATA.  

SciTech Connect (OSTI)

Review articles are in preparation for the 2003 edition of the CRC's Handbook of Chemistry and Physics dealing with both non-neutron and neutron nuclear data. Highlights include: withdrawal of the claim for discovery of element 118; new measurements of isotopic abundances have led to changes for many elements; a new set of recommended standards for calibration of {gamma}-ray energies have been published for many nuclides; new half-life measurements reported for very short lived isotopes, many long-lived nuclides and {beta}{beta} decay measurements for quasi-stable nuclides; a new reassessment of spontaneous fission (sf) half-lives for ground state nuclides, distinguishing half-lives from sf decay and cluster decay half-lives and the new cluster-fission decay; charged particle cross sections, (n,p) and (n,{alpha}) measurements for thermal neutrons incident on light nuclides; new thermal (n,{gamma}) cross sections and neutron resonance integrals measured. Details are presented.

HOLDEN,N.E.

2002-08-18T23:59:59.000Z

396

A compact stilbene crystal neutron spectrometer for EAST D-D plasma neutron diagnostics  

SciTech Connect (OSTI)

A new compact stilbene crystal neutron spectrometer has been investigated and applied in the neutron emission spectroscopy on the EAST tokamak. A new components analysis method is presented to study the anisotropic light output in the stilbene crystal detector. A Geant4 code was developed to simulate the neutron responses in the spectrometer. Based on both the optimal light output function and the fitted pulse height resolution function, a reliable neutron response matrix was obtained by Geant4 simulations and validated by 2.5 MeV and 14 MeV neutron measurements at a 4.5 MV Van de Graaff accelerator. The spectrometer was used to diagnose the ion temperature in plasma discharges with lower hybrid wave injection and ion cyclotron resonance heating on the EAST tokamak.

Zhang Xing; Yuan Xi; Xie Xufei; Chen Zhongjing; Peng Xingyu; Chen Jinxiang; Zhang Guohui; Li Xiangqing; Fan Tieshuan [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Chengfu Road 201, 100871 Beijing (China); Zhong Guoqiang; Hu Liqun; Wan Baonian [Institute of Plasma Physics, Chinese Academy of Sciences, PO Box 1126, 230031 Hefei, Anhui (China)

2013-03-15T23:59:59.000Z

397

Identification and rejection of scattered neutrons in AGATA  

E-Print Network [OSTI]

Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were measured in an AGATA experiment performed at INFN Laboratori Nazionali di Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors (12 36-fold segmented high-purity germanium crystals), placed at a distance of 50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment was to study the interaction of neutrons in the segmented high-purity germanium detectors of AGATA and to investigate the possibility to discriminate neutrons and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were used for a time-of-flight measurement, which gave an independent discrimination of neutrons and gamma rays and which was used to optimise the gamma-ray tracking-based neutron rejection methods. It was found that standard gamma-ray tracking, without any additional neutron rejection features, eliminates effectively most of the interaction points due to recoiling Ge nuclei after elastic scattering of neutrons. Standard tracking rejects also a significant amount of the events due to inelastic scattering of neutrons in the germanium crystals. Further enhancements of the neutron rejection was obtained by setting conditions on the following quantities, which were evaluated for each event by the tracking algorithm: energy of the first and second interaction point, difference in the calculated incoming direction of the gamma ray, figure-of-merit value. The experimental results of tracking with neutron rejection agree rather well with Geant4 simulations.

M. ?enyi?it; A. Ataç; S. Akkoyun; A. Ka?ka?; D. Bazzacco; J. Nyberg; F. Recchia; S. Brambilla; F. Camera; F. C. L. Crespi; E. Farnea; A. Giaz; A. Gottardo; R. Kempley; J. Ljungvall; D. Mengoni; C. Michelagnoli; B. Million; M. Palacz; L. Pellegri; S. Riboldi; E. ?ahin; P. A. Söderström; J. J. Valiente Dobon; the AGATA collaboration

2013-06-12T23:59:59.000Z

398

Fission meter and neutron detection using poisson distribution comparison  

DOE Patents [OSTI]

A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

Rowland, Mark S; Snyderman, Neal J

2014-11-18T23:59:59.000Z

399

Thermal Fluids  

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

Thermal Fluids The Thermal Fluids and Heat Transfer program works on thermal hydraulic reactor safety code development and experimental heat transferthermal hydraulics. The...

400

Application of Pd silicide in the process of silicon detectors  

SciTech Connect (OSTI)

A new technology called a self-aligned metal-silicide process is described in the fabrication of silicon detectors. It has been found that this technology improves both detector yield and leakage current. The use of a metal silicide also gives a lower contact resistance and, depending on the thermal process, a controllable junction depth, which may be essential in the integration of detectors and their electronics. 15 refs., 6 figs., 7 tabs.

Li, Zheng; Chen, Wei; Kraner, H.W.

1989-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Application of Pd silicide in the process of silicon detectors  

SciTech Connect (OSTI)

A new technology called a self-aligned metal-silicide process is described in the fabrication of silicon detectors. It has been found that this technology improves both detector yield and leakage current. The use of a metal silicide also gives a lower contact resistance and, depending on the thermal process, a controllable junction depth, which may be essential in the integration of detectors and their electronics.

Li, Z.; Chen, W.; Kraner, H.W. (Brookhaven National Lab., Upton, NY (USA))

1990-04-01T23:59:59.000Z

402

Particle Identification in the NIMROD-ISiS Detector Array  

E-Print Network [OSTI]

Interest in the influence of the neutron-to-proton (N/Z) ratio on multifragmenting nuclei has demanded an improvement in the capabilities of multi-detector arrays as well as the companion analysis methods. The particle identification method used in the NIMROD-ISiS 4 $\\pi$ array is described. Performance of the detectors and the analysis method are presented for the reaction of 86Kr+64Ni at 35MeV/u.

S. Wuenschel; K. Hagel; L. W. May; R. Wada; S. J. Yennello

2009-03-04T23:59:59.000Z

403

Particle Identification in the NIMROD-ISiS Detector Array  

SciTech Connect (OSTI)

Interest in the influence of the neutron-to-proton (N/Z) ratio on multifragmenting nuclei has demanded an improvement in the capabilities of multi-detector arrays as well as the companion analysis methods. The particle identification method used in the NIMROD-ISiS 4{pi} array is described. Performance of the detectors and the analysis method are presented for the reaction of {sup 86}Kr+{sup 64}Ni at 35 MeV/u.

Wuenschel, S.; Hagel, K.; May, L. W.; Wada, R.; Yennello, S. J. [Texas A and M University Cyclotron Institute College Station TX 77843 (United States)

2009-03-10T23:59:59.000Z

404

Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source  

SciTech Connect (OSTI)

A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using {sup 3}He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations.

Hollas, C.L.; Goulding, C.A.; Myers, W.L.

1999-09-20T23:59:59.000Z

405

NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS  

E-Print Network [OSTI]

NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS AND POLARIZED 3He R. GOLUB~and Steve K REPORTS (Review Section of Physics Letters) 237, No. 1(1994)1--62. PHYSICS REPORTS North-Holland Neutron electric-dipole moment, ultracold neutrons and polarized 3He R. Goluba and Steve K. Lamoreauxb a

406

Safety control circuit for a neutronic reactor  

DOE Patents [OSTI]

A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Ellsworth, Howard C. (Richland, WA)

2004-04-27T23:59:59.000Z

407

Neutron reflecting supermirror structure  

DOE Patents [OSTI]

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

408

Neutron reflecting supermirror structure  

DOE Patents [OSTI]

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

Wood, J.L.

1992-12-01T23:59:59.000Z

409

Neutron irradiation effects on metal-gallium nitride contacts  

SciTech Connect (OSTI)

We have measured the effect of fast and thermal neutrons on GaN Schottky barriers and ohmic contacts using current–voltage and transmission line method electrical techniques, optical, atomic force and scanning electron microscopy morphological techniques, and X-ray photoemission spectroscopy chemical techniques. These studies reveal a 10{sup 15}?n/cm{sup 2} neutron threshold for Schottky barrier ideality factor increases, a 10{sup 15}?n/cm{sup 2} fast plus thermal neutron threshold for ohmic contact sheet and contact resistance increases, and 10{sup 16}?n/cm{sup 2} neutron fluence threshold for major device degradation identified with thermally driven diffusion of Ga and N into the metal contacts and surface phase changes. These results demonstrate the need for protecting metal-GaN contacts in device applications subject to neutron radiation.

Katz, Evan J.; Lin, Chung-Han; Zhang, Zhichun [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Qiu, Jie; Cao, Lei [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Mishra, Umesh K. [Departments of Electrical and Computer Engineering and Materials Science and Engineering University of California, Santa Barbara, California 93106 (United States); Brillson, Leonard J., E-mail: brillson.1@osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

2014-03-28T23:59:59.000Z

410

Solar Neutron Events of October-November 2003  

E-Print Network [OSTI]

During the period when the Sun was intensely active on October-November 2003, two remarkable solar neutron events were observed by the ground-based neutron monitors. On October 28, 2003, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 sigma) by the neutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with an X28 class flare, relativistic solar neutrons were observed by the neutron monitors at Haleakala in Hawaii and Mexico City, and by the solar neutron telescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observed at the same time by these detectors, with the significance calculated as 7.5 sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard the INTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at the same time in these events. By using the time profiles of the gamma-ray lines, we can explain the time profile of the neutron monitor. It appears that neutrons were produced at the same time as the gamma-ray emission.

K. Watanabe; M. Gros; P. H. Stoker; K. Kudela; C. Lopate; J. F. Valdes-Galicia; A. Hurtado; O. Musalem; R. Ogasawara; Y. Mizumoto; M. Nakagiri; A. Miyashita; Y. Matsubara; T. Sako; Y. Muraki; T. Sakai; S. Shibata

2005-09-19T23:59:59.000Z

411

Enhanced reaction rates in NDP analysis with neutron scattering  

SciTech Connect (OSTI)

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.

Downing, R. Gregory, E-mail: gregory.downing@nist.gov [National Institute of Standards and Technology, Chemical Sciences Division, Gaithersburg, Maryland 20899 (United States)

2014-04-15T23:59:59.000Z

412

Construction and testing of the instrument for neutron holographic study at the Budapest Research Reactor  

SciTech Connect (OSTI)

Neutron scattering device dedicated to neutron holography experiments is described. The device is operating at a constant wavelength prepared by a double focusing monochromator. It is equipped by highly efficient shielding, proper collimator, Eulerian cradle, monitor detector, gamma-ray, and neutron detectors as well. Relevant software serves as control for the measurement and data collection. The harmonized application of the components enumerated above makes our device extremely efficient and unparalleled. Two atomic resolution neutron holographic experiments carried out illustrate the efficiency and power of the instrument.

Marko, Marton; Toeroek, Gyula; Cser, Laszlo [Department of Neutron Spectroscopy, Research Institute for Solid State Physics and Optics, P.O.B. 49, H-1525 Budapest (Hungary); Szakal, Alex [Department of Neutron Spectroscopy, Research Institute for Solid State Physics and Optics, P.O.B. 49, H-1525 Budapest (Hungary); Budapest University of Technology and Economics, Muegyetem rakpart 1-3, H-1113 Budapest (Hungary)

2010-10-15T23:59:59.000Z

413

Nuclear structure through moment measurements: Exploiting ?-ray detector arrays with ancillary detectors  

SciTech Connect (OSTI)

Experimental methods to measure the magnetic moments of short-lived excited states in beams of rare isotopes are outlined. The emphasis is on the so-called High-Velocity Transient-Field (HVTF) and the Recoil in Vacuum (RIV) methods, and the role of ?-ray detector arrays with ancillary detectors. Insights into the structure of neutron-rich nuclei through such measurements on radioactive beams are discussed. Opportunities for the future development of these techniques, for applications to both stable and radioactive beams, are explored.

Stuchbery, Andrew E. [Department of Nuclear Physics, The Australian National University, Canberra, ACT 0200 (Australia)

2014-08-14T23:59:59.000Z

414

Development of a three-dimensional two-fluid code with transient neutronic feedback for LWR applications  

E-Print Network [OSTI]

The development of a three-dimensional coupled neutronics/thermalhydraulics code for LWR safety analysis has been initiated. The transient neutronics code QUANDRY has been joined to the two-fluid thermal-hydraulics code ...

Griggs, D. P.

1981-01-01T23:59:59.000Z

415

Status Summary of 3He and Neutron Detection Alternatives for Homeland Security  

SciTech Connect (OSTI)

This is a short summary whitepaper on results of our alternatives work: Neutron detection is an important aspect of interdiction of radiological threats for homeland security purposes since plutonium, a material used for nuclear weapons, is a significant source of fission neutrons [Kouzes 2005]. Because of the imminent shortage of 3He, which is used in the most commonly deployed neutron detectors, a replacement technology for neutron detection is required for most detection systems in the very near future [Kouzes 2009a]. For homeland security applications, neutron false alarms from a detector can result in significant impact. This puts a strong requirement on any neutron detection technology not to generate false neutron counts in the presence of a large gamma ray-only source [Kouzes et al. 2008].

Kouzes, Richard T.; Ely, James H.

2010-04-28T23:59:59.000Z

416

Methodology for the use of proportional counters in pulsed fast neutron yield measurements  

E-Print Network [OSTI]

This paper introduces in full detail a methodology for the measurement of neutron yield and the necessary efficiency calibration, to be applied to the intensity measurement of neutron bursts where individual neutrons are not resolved in time, for any given moderated neutron proportional counter array. The method allows efficiency calibration employing the detection neutrons arising from an isotopic neutron source. Full statistical study of the procedure is descripted, taking into account contributions arising from counting statistics, piling-up statistics of real detector pulse-height spectra and background fluctuations. The useful information is extracted from the net waveform area of the signal arising from the electric charge accumulated inside the detector tube. Improvement of detection limit is gained, therefore this detection system can be used in detection of low emission neutron pulsed sources with pulses of duration from nanoseconds to up. The application of the methodology to detection systems to be...

Tarifeño-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo

2011-01-01T23:59:59.000Z

417

22.54 Neutron Interactions and Applications, Spring 2002  

E-Print Network [OSTI]

Comprehensive treatment of neutron interactions in condensed matter at energies from thermal to MeV, focusing on aspects most relevant to radiation therapy, industrial imaging, and materials research applications. Comparative ...

Yip, Sidney

418

Detection of concealed mercury with thermal neutrons  

SciTech Connect (OSTI)

In the United States today, governments at all levels and the citizenry are paying increasing attention to the effects, both real and hypothetical, of industrial activity on the environment. Responsible modem industries, reflecting this heightened public and regulatory awareness, are either substituting benign materials for hazardous ones, or using hazardous materials only under carefully controlled conditions. In addition, present-day environmental consciousness dictates that we deal responsibly with legacy wastes. The decontamination and decommissioning (D&D) of facilities at which mercury was used or processed presents a variety of challenges. Elemental mercury is a liquid at room temperature and readily evaporates in air. In large mercury-laden buildings, droplets may evaporate from one area only to recondense in other cooler areas. The rate of evaporation is a function of humidity and temperature; consequently, different parts of a building may be sources or sinks of mercury at different times of the day or even the year. Additionally, although mercury oxidizes in air, the oxides decompose upon heating. Hence, oxides contained within pipes or equipment, may be decomposed when those pipes and equipment are cut with saws or torches. Furthermore, mercury seeps through the pores and cracks in concrete blocks and pads, and collects as puddles and blobs in void spaces within and under them.

Bell, Z.W.

1994-08-18T23:59:59.000Z

419

An advanced model for the prediction of the total burnup-dependent self-powered rhodium detector response  

SciTech Connect (OSTI)

This paper presents an advanced method to generate the burnup dependent total response of a rhodium self-powered detector operating in a pressurized water reactor environment. Full use is made of advanced nodal neutronic and coupled electron-photon transport techniques. The method accounts for (1) the detailed energy and spatial dependence of the neutron activation of each detector segment in a three-dimensional representation, (2) the generation of electrons caused by both neutron and gamma interactions in all the geometrical regions of the detector, and (3) the transport of the electrons within the detector to provide an observable current. All components of the detector signal are directly calculated - the method does not require the use of any empirical data, such as detector sensitivities. Intermediate results, such as beta escape fractions, were compared to measured data, and the overall technique was extensively benchmarked against operating data from three reactors.

Ober, T.G. [Entergy Operations, Inc., Jackson, MS (United States); Malloy, J.W. [Tetra Engineering Group, Simsbury, CT (United States)

1995-12-31T23:59:59.000Z

420

High spatial resolution particle detectors  

DOE Patents [OSTI]

Disclosed below are representative embodiments of methods, apparatus, and systems for detecting particles, such as radiation or charged particles. One exemplary embodiment disclosed herein is particle detector comprising an optical fiber with a first end and second end opposite the first end. The optical fiber of this embodiment further comprises a doped region at the first end and a non-doped region adjacent to the doped region. The doped region of the optical fiber is configured to scintillate upon interaction with a target particle, thereby generating one or more photons that propagate through the optical fiber and to the second end. Embodiments of the disclosed technology can be used in a variety of applications, including associated particle imaging and cold neutron scattering.

Boatner, Lynn A.; Mihalczo, John T.

2012-09-04T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Neutron Interferometry: Lessons in Experimental Quantum Mechanics Helmut Rauch and Samuel A. Werner  

E-Print Network [OSTI]

Neutron Interferometry: Lessons in Experimental Quantum Mechanics Helmut Rauch and Samuel A. Werner Today, 55, 52 (2002). The copious availability of thermalized neutrons makes them an ideal probe of choice for many fundamental physics investigations. A prime example is the field of neutron

Lynn, Jeffrey W.

422

Gamma ray detector shield  

DOE Patents [OSTI]

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

Ohlinger, R.D.; Humphrey, H.W.

1985-08-26T23:59:59.000Z

423

Tevatron detector upgrades  

SciTech Connect (OSTI)

The D0 and CDF experiments are in the process of upgrading their detectors to cope with the high luminosities projected for the remainder of Tevatron Run II. They discuss the expected Tevatron environment through 2009, the detector challenges due to increasing luminosity in this period, and the solutions undertaken by the two experiments to mitigate detector problems and maximize physics results.

Lipton, R.; /Fermilab

2005-01-01T23:59:59.000Z

424

High Brightness Neutron Source for Radiography  

SciTech Connect (OSTI)

This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases of yield of two orders of magnitude. The first fast neutron radiographic images were obtained using neutron cameras and a new fast neutron generator. These early images demonstrated the feasibility of using fast neutrons for imaging and penetrating thick objects of high density and imaging. Fast neutrons can be used to image low atomic number materials (e.g. plastics, explosives, lubricants and ceramics) that are shielded by high density materials (e.g. lead, tungsten and uranium). Fast neutron radiography could be used as a means to screen weapons for flaws and chemical stability. X-ray radiography can not easily do this. Fast neutron imaging is technically difficult and, consequently, a completely undeveloped market. Two of the generators were designed to have small source size and high brightness, ideal for fast-neutron imaging. With these generators we successfully used two fast neutron cameras: one developed by us, and another developed by a collaborator, Commonwealth Scientific and Industrial Research Organization, CSIRO. We have successfully used these cameras to obtain low resolution images of various objects such as pipe fittings filled with water and other mechanical objects. Higher resolution and contrast images are expected by decreasing the source size and increasing generator yield.

Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

2008-12-08T23:59:59.000Z

425

Neutron Transmission, Capture, and Scattering Measurements at the Gaerttner LINAC Center Y. Danon, L. Liu, E.J. Blain, A.M. Daskalakis, B.J. McDermott, K. Ramic, C.R. Wendorff  

E-Print Network [OSTI]

Neutron Transmission, Capture, and Scattering Measurements at the Gaerttner LINAC Center Y. Danon . As the energy of the neutrons increases to the keV region neutron resonance scattering becomes dominant compared to capture, and scattered neutrons can penetrate the 10 B4C liner of the NaI capture detector and get

Danon, Yaron

426

Publications | Neutron Science | ORNL  

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

Publications SHARE Publications The Neutron Science publications system contains peer-reviewed publications based on research conducted at ORNL's Neutron Science facilities or...

427

SHARP Neutronics Expanded  

Broader source: Energy.gov [DOE]

The SHARP neutronics module, PROTEUS, includes neutron and gamma transport solvers and cross-section processing tools as well as the capability for depletion and fuel cycle analysis.

428

Foil cycling technique for the VESUVIO spectrometer operating in the resonance detector configuration  

SciTech Connect (OSTI)

This article reports a novel experimental technique, namely, the foil cycling technique, developed on the VESUVIO spectrometer (ISIS spallation source) operating in the resonance detector configuration. It is shown that with a proper use of two foils of the same neutron absorbing material it is possible, in a double energy analysis process, to narrow the width of the instrumental resolution of a spectrometer operating in the resonance detector configuration and to achieve an effective subtraction of the neutron and gamma backgrounds. Preliminary experimental results, obtained from deep inelastic neutron scattering measurements on lead, zirconium hydride, and deuterium chloride samples, are presented.

Schooneveld, E. M.; Mayers, J.; Rhodes, N. J.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Gorini, G.; Perelli-Cippo, E.; Tardocchi, M. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Universita degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Rome (Italy); Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano Bicocca, Piazza della Scienza 2, I-20126 Milan (Italy) and CNR-INFM, Universita degli Studi di Milano Bicocca, Piazza della Scienza 2, I-20126 Milan (Italy)

2006-09-15T23:59:59.000Z

429

Detecting sub-MeV neutrons in solid plastic scintillator with gamma-ray discrimination  

E-Print Network [OSTI]

We report on recent efforts to design a solid plastic scintillation hodoscope to measure neutron production cross sections at low energies. Our program includes not only the development of the detector itself, but also a ...

Kovash, Michael A.

430

Exploration of ion temperature profile measurements at JET using the upgraded neutron profile monitor  

SciTech Connect (OSTI)

The neutron profile monitor (NPM), routinely used at the Joint European Torus for neutron emissivity profile measurements, consists of two fan-shaped arrays of collimators and each line of sight (LOS) is equipped with a NE213 liquid organic scintillator for simultaneous measurements of the 2.5 MeV and 14 MeV neutrons. A digital system developed in ENEA has replaced the analog acquisition electronics and now enables the NPM to perform spatially resolved neutron spectrometry by providing neutron pulse height spectra (PHS) for each LOS. However, the NPM was not originally designed as a spectrometer and, therefore, lacks several key features, such as detailed measurements of the detector response functions and the presence of detector stability monitors. We present a proof of principle of ion temperature profile measurements derived from the NPM PHS in high plasma current discharges using simulated detector response functions.

Marocco, D.; Esposito, B.; Riva, M. [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, Frascati I-00044, Roma (Italy); Collaboration: JET-EFDA Contributors

2012-10-15T23:59:59.000Z

431

On the neutron noise diagnostics of pressurized water reactor control rod vibrations II. Stochastic vibrations  

SciTech Connect (OSTI)

In an earlier publication, using the theory of neutron fluctuations induced by a vibrating control rod, a complete formal solution of rod vibration diagnostics based on neutron noise measurements was given in terms of Fourier-transformed neutron detector time signals. The suggested procedure was checked in numerical simulation tests where only periodic vibrations could be considered. The procedure and its numerical testing are elaborated for stochastic two-dimensional vibrations. A simple stochastic theory of two-dimensional flow-induced vibrations is given; then the diagnostic method is formulated in the stochastic case, that is, in terms of neutron detector auto- and crosspower spectra. A previously suggested approximate rod localization technique is also formulated in the stochastic case. Applicability of the methods is then investigated in numerical simulation tests, using the proposed model of stochastic two-dimensional vibrations when generating neutron detector spectra that simulate measured data.

Pazsit, I.; Glockler, O.

1984-09-01T23:59:59.000Z

432

The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance  

SciTech Connect (OSTI)

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B. [Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Sokol, P. E. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

2011-08-15T23:59:59.000Z

433

The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source -- Design and Performance  

SciTech Connect (OSTI)

The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

Ehlers, Georg [ORNL; Podlesnyak, Andrey A [ORNL; Niedziela, Jennifer L [ORNL; Iverson, Erik B [ORNL; Sokol, Paul E [ORNL

2011-01-01T23:59:59.000Z

434

A Neutron Multiplicity Meter for Deep Underground Muon-Induced High Energy Neutron Measurements  

E-Print Network [OSTI]

We present the design of an instrument capable of measuring the high energy ($>$60 MeV) muon-induced neutron flux deep underground. The instrument is based on applying the Gd-loaded liquid-scintillator technique to measure the rate of high-energy neutrons underground based on the neutron multiplicity induced in a Pb target. We present design studies based on Monte Carlo simulations that show that an apparatus consisting of a Pb target of 200 cm by 200 cm area by 60 cm thickness covered by a 60 cm thick Gd-loaded liquid scintillator (0.5% Gd content) detector could measure, at a depth of 2000 meters of water equivalent, a rate of $70\\pm8$ (stat) events/year. Based on these studies, we also discuss the benefits of using a neutron multiplicity meter as a component of active shielding in such experiments.

R. Hennings-Yeomans; D. S. Akerib

2007-01-24T23:59:59.000Z

435

Deuterium density profile determination at JET using a neutron camera and a neutron spectrometer  

SciTech Connect (OSTI)

In this work we estimate the fuel ion density profile in deuterium plasmas at JET, usi