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1

Experimental research on the THGEM-based thermal neutron detector  

E-Print Network (OSTI)

A new thermal neutron detector with the domestically produced THGEM (THick Gas Electron Multiplier) was developed as an alternative to 3He to meet the needs of the next generation of neutron facilities. One type of Au-coated THGEM was designed specifically for the neutron detection. A detector prototype had been developed and the preliminary experimental tests were presented, including the performance of the Au-coated THGEM working in the Ar/CO2 gas mixtures and the neutron imaging test with 252CF source, which would provide the reference of experimental data for the research in future.

Lei, Yang; Zhi-Jia, Sun; Ying, Zhang; Chao-Qiang, Huang; Guang-Ai, Sun; Yan-Feng, Wang; Gui-An, Yang; Hong, Xu; Yu-Guang, Xie; Yuan-Bo, Chen

2014-01-01T23:59:59.000Z

2

Fabrication of Pillar-Structured Thermal Neutron Detectors  

SciTech Connect

Pillar detector is an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce a device for thermal neutron detection. State-of-the-art thermal neutron detectors have shortcomings in achieving simultaneously high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a 3-dimensional silicon PIN diode pillar array filled with isotopic boron 10, ({sup 10}B) a high efficiency device is theoretically possible. The fabricated pillar structures reported in this work are composed of 2 {micro}m diameter silicon pillars with a 4 {micro}m pitch and pillar heights of 6 and 12 {micro}m. The pillar detector with a 12 {micro}m height achieved a thermal neutron detection efficiency of 7.3% at 2V.

Nikolic, R J; Conway, A M; Reinhardt, C E; Graff, R T; Wang, T F; Deo, N; Cheung, C L

2007-11-19T23:59:59.000Z

3

Gamma discrimination in pillar structured thermal neutron detectors  

SciTech Connect

Solid-state thermal neutron detectors are desired to replace {sup 3}He tube based technology for the detection of special nuclear materials. {sup 3}He tubes have some issues with stability, sensitivity to microphonics and very recently, a shortage of {sup 3}He. There are numerous solid-state approaches being investigated that utilize various architectures and material combinations. By using the combination of high-aspect-ratio silicon PIN pillars, which are 2 {micro}m wide with a 2 {micro}m separation, arranged in a square matrix, and surrounded by {sup 10}B, the neutron converter material, a high efficiency thermal neutron detector is possible. Besides intrinsic neutron detection efficiency, neutron to gamma discrimination is an important figure of merit for unambiguous signal identification. In this work, theoretical calculations and experimental measurements are conducted to determine the effect of structure design of pillar structured thermal neutron detectors including: intrinsic layer thickness, pillar height, substrate doping and incident gamma energy on neutron to gamma discrimination.

Shao, Q; Radev, R P; Conway, A M; Voss, L F; Wang, T F; Nikolic, R J; Deo, N; Cheung, C L

2012-03-26T23:59:59.000Z

4

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

5

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

6

Thermal neutron response of a boron-coated GEM detector via GEANT4 Monte Carlo code  

Science Journals Connector (OSTI)

Abstract In this work, we report the design configuration and the performance of the hybrid Gas Electron Multiplier (GEM) detector. In order to make the detector sensitive to thermal neutrons, the forward electrode of the GEM has been coated with the enriched boron-10 material, which works as a neutron converter. A total of 5×5 cm2 configuration of GEM has been used for thermal neutron studies. The response of the detector has been estimated via using GEANT4 MC code with two different physics lists. Using the QGSP_BIC_HP physics list, the neutron detection efficiency was determined to be about 3%, while with QGSP_BERT_HP physics list the efficiency was around 2.5%, at the incident thermal neutron energies of 25 meV. The higher response of the detector proves that GEM-coated with boron converter improves the efficiency for thermal neutrons detection.

M. Jamil; J.T. Rhee; H.G. Kim; Farzana Ahmad; Y.J. Jeon

2015-01-01T23:59:59.000Z

7

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

8

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

SciTech Connect

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

9

Thermal neutron detection using a silicon pad detector and {sup 6}LiF removable converters  

SciTech Connect

A semiconductor detector coupled with a neutron converter is a good candidate for neutron detection, especially for its compactness and reliability if compared with other devices, such as {sup 3}He tubes, even though its intrinsic efficiency is rather lower. In this paper we show a neutron detector design consisting of a 3 cm Multiplication-Sign 3 cm silicon pad detector coupled with one or two external {sup 6}LiF layers, enriched in {sup 6}Li at 95%, placed in contact with the Si active surfaces. This prototype, first characterized and tested at INFN Laboratori Nazionali del Sud and then at JRC Ispra, was successfully shown to detect thermal neutrons with the expected efficiency and an outstanding gamma rejection capability.

Barbagallo, Massimo [Istituto Nazionale di Fisica Nucleare, Sezione di Bari (Italy); Cosentino, Luigi; Marchetta, Carmelo; Pappalardo, Alfio; Scire, Carlotta; Scire, Sergio; Schillaci, Maria; Vecchio, Gianfranco; Finocchiaro, Paolo [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania (Italy); Forcina, Vittorio; Peerani, Paolo [European Commission, Joint Research Centre, Institute of Transuranium Elements, Ispra (Italy); Vaccaro, Stefano [European Commission, Directorate-General for Energy (Luxembourg)

2013-03-15T23:59:59.000Z

10

6:1 aspect ratio silicon pillar based thermal neutron detector filled with B 10  

Science Journals Connector (OSTI)

Current helium-3 tube based thermal neutrondetectors have shortcomings in achieving simultaneously high efficiency and low voltage while maintaining adequate fieldability performance. By using a three-dimensional silicon p - i - n diode pillar array filled with boron-10 these constraints can be overcome. The fabricated pillar structured detector reported here is composed of 2 ? m diameter silicon pillars with a 4 ? m pitch and height of 12 ? m . A thermal neutrondetection efficiency of 7.3 + ? ? 0.6 % and a neutron-to-gamma discrimination of 10 5 at 2 V reverse bias were measured for this detector. When scaled to larger aspect ratio a high efficiency device is possible.

R. J. Nikoli?; A. M. Conway; C. E. Reinhardt; R. T. Graff; T. F. Wang; N. Deo; C. L. Cheung

2008-01-01T23:59:59.000Z

11

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

SciTech Connect

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

12

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

E-Print Network (OSTI)

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.... Randall and Jack V. Walker for their invaluable guidance and assistance during the course of this research, and to Dr. Robert G. Cochran for his suggestions and encouragement. Thanks is also extended to Mr, Floy W. Smith and the staff of the Nuclear...

Feltz, Donald Everett

2012-06-07T23:59:59.000Z

13

First Measurements of the Inclined Boron Layer Thermal-Neutron Detector for Reflectometry  

SciTech Connect

A prototype detector based on the inclined boron layer principle is introduced. For typical measurement conditions at the Liquids Reflectometer at the Spallation Neutron Source, its count rate capability is shown to be superior to that of the current detector by nearly two orders of magnitude.

Clonts, Lloyd G [ORNL; Crow, Lowell [ORNL; Van Vuure, Thorwald L [ORNL; Robertson, Lee [ORNL; Riedel, Richard A [ORNL; Richards, John D [ORNL; Cooper, Ronald G [ORNL; Remec, Igor [ORNL; Ankner, John Francis [ORNL; Browning, Jim [ORNL

2010-01-01T23:59:59.000Z

14

First Measurements of the Inclined Boron Layer Thermal-Neutron Detector for Reflectometry  

SciTech Connect

A prototype detector based on the inclined absorber layer principle is introduced. For the Liquids Reflectometer at the Spallation Neutron Source, it is shown to be a significant improvement over its current detector, which imposes an instantaneous count rate limitation of 50 kcps.

Van Vuure, Thorwald L [ORNL] [ORNL; Clonts, Lloyd G [ORNL] [ORNL; Crow, Lowell [ORNL] [ORNL; Cooper, Ronald G [ORNL] [ORNL; Richards, John D [ORNL] [ORNL; Riedel, Richard A [ORNL] [ORNL; Robertson, Lee [ORNL] [ORNL

2008-01-01T23:59:59.000Z

15

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

16

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

17

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

18

THERMAL NEUTRON BACKSCATTER IMAGING.  

SciTech Connect

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

19

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

20

Ultrafast neutron detector  

DOE Patents (OSTI)

The invention comprises a neutron detector (50) of very high temporal resolution that is particularly well suited for measuring the fusion reaction neutrons produced by laser-driven inertial confinement fusion targets. The detector comprises a biased two-conductor traveling-wave transmission line (54, 56, 58, 68) having a uranium cathode (60) and a phosphor anode (62) as respective parts of the two conductors. A charge line and Auston switch assembly (70, 72, 74) launch an electric field pulse along the transmission line. Neutrons striking the uranium cathode at a location where the field pulse is passing, are enabled to strike the phosphor anode and produce light that is recorded on photographic film (64). The transmission line may be variously configured to achieve specific experimental goals.

Wang, Ching L. (Livermore, CA)

1987-01-01T23:59:59.000Z

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.


21

Thermal Neutron Scattering  

Science Journals Connector (OSTI)

... of its title. It is not for the nuclear physicist, nor even for the neutron physicist, but for the student of solids and liquids. "Thermal ... physicist, but for the student of solids and liquids. "Thermal neutron ...

G. E. BACON

1968-11-09T23:59:59.000Z

22

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

23

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

24

Sandia Neutron Detector Is Based on Polyacetylene  

Science Journals Connector (OSTI)

Sandia Neutron Detector Is Based on Polyacetylene ... It also might form the basis of an electrically readable dosimeter that records neutron flux (measured as neutrons per square centimeter) as well as a detector that could provide a cross-sectional image of neutron flux with high spatial resolution. ... Hence, most neutron detectors use a converter material that converts the neutrons to charged particles. ...

RUDY BAUM

1987-02-09T23:59:59.000Z

25

Neutron detectors comprising boron powder  

SciTech Connect

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

26

Neutron stars - thermal emitters  

E-Print Network (OSTI)

Confronting theoretical models with observations of thermal radiation emitted by neutron stars is one of the most important ways to understand the properties of both, superdense matter in the interiors of the neutron stars and dense magnetized plasmas in their outer layers. Here we review the theory of thermal emission from the surface layers of strongly magnetized neutron stars, and the main properties of the observational data. In particular, we focus on the nearby sources for which a clear thermal component has been detected, without being contaminated by other emission processes (magnetosphere, accretion, nebulae). We also discuss the applications of the modern theoretical models of the formation of spectra of strongly magnetized neutron stars to the observed thermally emitting objects.

Potekhin, A Y; Pons, J A

2014-01-01T23:59:59.000Z

27

Dual Gamma Neutron Directional Elpasolite Detector  

SciTech Connect

Some applications, particularly in homeland security, require detection of both neutron and gamma radiation. Typically, this is accomplished with a combination of two detectors registering neutrons and gammas separately. We have investigated a new type of neutron/gamma (n/?) directional detection capability. We explored a new class of scintillator, cerium (Ce)-doped Elpasolites such as Cs2LiYCl6:Ce (CLYC), Cs2LiLaCl6 (CLLC), Cs2LiLaBr6:Ce (CLLB), or Cs2LiYBr6:Ce (CLYB). These materials are capable of providing energy resolution as good as 2.9% at 662 keV (FWHM), which is better than that of NaI:Tl. Because they contain 6Li, Elpasolites can also detect thermal neutrons. In the energy spectra, the full energy thermal neutron peak appears near or above 3 GEEn MeV. Thus, very effective pulse height discrimination is possible. In addition, the core-to-valence luminescence (CVL) provides Elpasolites with different temporal responses under gamma and neutron excitation, and, therefore, may be exploited for effective pulse shape discrimination. For instance, the CLLC emission consists of two main components: (1) CVL spanning from 220 nm to 320 nm and (2) Ce emission found in the range of 350 to 500 nm. The former emission is of particular interest because it appears only under gamma excitation. It is also very fast, decaying with a 2 ns time constant. The n/? discrimination capability of Elpasolite detectors may be optimized by tuning the cerium doping content for maximum effect on n/? pulse shape differences. The resulting Elpasolite detectors have the ability to collect neutron and gamma data simultaneously, with excellent discrimination. Further, an array of four of these Elpasolites detectors will perform directional detection in both the neutron and gamma channels simultaneously.

Guss, P. P.; Mukhopadhyay, S.

2013-09-01T23:59:59.000Z

28

Amorphous Silicon Based Neutron Detector  

SciTech Connect

Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · Various single-junction and double junction detector devices have been fabricated; · The detector devices fabricated have been systematically tested and analyzed. · Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies developed here could be used to develop X-ray and neutron monitors that could be used in the future for security checks at the airports and other critical facilities. The project would lead to devices that could significantly enhance the performance of multi-billion dollar neutron source facilities in the US and bring our nation to the forefront of neutron beam sciences and technologies which have enormous impact to materials, life science and military research and applications.

Xu, Liwei

2004-12-12T23:59:59.000Z

29

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

30

A final report for Gallium arsenide P-I-N detectors for high-sensitivity imaging of thermal neutrons  

E-Print Network (OSTI)

This SBIR Phase I developed neutron detectors made FR-om gallium arsenide (GaAs) p-type/ intrinsic/n-type (P-I-N) diodes grown by metalorganic chemical vapor deposition (MOCVD) onto semi-insulating (S1) bulk GaAs wafers. A layer of isotonically enriched boron-10 evaporated onto the FR-ont surface serves to convert incoming neutrons into lithium ions and a 1.47 MeV alpha particle which creates electron-hole pairs that are detected by the GaAs diode. Various thicknesses of ''intrinsic'' (I) undoped GaAs were tested, as was use of a back-surface field (BSF) formed FR-om a layer of Al sub x Ga sub 1 sub - sub x As. Schottky-barrier diodes formed FR-om the same structures without the p+ GaAs top layer were tested as a comparison. After mesa etching and application of contacts, devices were tested in visible light before application of the boron coating. Internal quantum efficiency (IQE) of the best diode near the GaAs bandedge is over 90%. The lowest dark current measured is 1 x 10 sup - sup 1 sup 2 amps at -1 V o...

Vernon, S M

1999-01-01T23:59:59.000Z

31

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, T.W.

1983-12-21T23:59:59.000Z

32

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

33

Neutron And Gamma Detector Using An Ionization Chamber With An...  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron And Gamma Detector Using An Ionization Chamber Neutron And Gamma Detector Using An Ionization Chamber With An Integrated Body And Moderator A detector for detecting...

34

Detectors - Instrument Support | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Detectors Detectors Detectors The detector design group, led by Yacouba Diawara is responsible for supporting the design of HFIR and SNS instruments by developing the necessary infrastructure and acquiring detector components that will be used to complete the functionality of the instruments. The group's mission also includes supporting detector research and development (R&D) for the various instruments and their different needs. The support effort for instrument design entails monitoring detector development worldwide as neutron facilities around the globe are getting upgraded and adopting the newest technologies. Detector group technician Ted Visscher inspects a parahedreal lens on an Anger camera Detector group technician Ted Visscher inspects a parahedreal lens on an

35

Neutron-chamber detectors and applications  

SciTech Connect

Detector applications in Nuclear Safeguards and Waste Management have included measuring neutrons from fission and (alpha,n) reactions with well-moderated neutron proportional counters, often embedded in a slab of polyethylene. Other less-moderated geometries are useful for detecting both bare and moderated fission-source neutrons with good efficiency. The neutron chamber is an undermoderated detector design comprising a large, hollow, polyethylene-walled chamber containing one or more proportional counters. Neutron-chamber detectors are relatively inexpensive; can have large apertures, usually through a thin chamber wall; and offer very good detection efficiency per dollar. Neutron-chamber detectors have also been used for monitoring vehicles and for assaying large crates of transuranic waste. Our Monte Carlo calculations for a new application (monitoring low-density waste for concealed plutonium) illustrate the advantages of the hollow-chamber design for detecting moderated fission sources. 9 refs., 6 figs., 2 tabs.

Fehlau, P.E.; Atwater, H.F.; Coop, K.L.

1990-01-01T23:59:59.000Z

36

Detectors - Instrument Support | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Detectors › R & D 100 Award Detectors › R & D 100 Award ORNL team wins R&D 100 award for wavelength-shifting scintillator detector Neutron facilities, national security monitoring will benefit from high-accuracy detector June 2012, Written by Agatha Bardoel A team of eight scientists and technicians in the Neutron Sciences Directorate has won a prestigious R&D 100 Award from R&D Magazine for developing a highly efficient new detector system that helps take pressure off dwindling worldwide supplies of 3He as an active neutron converter. Members of the team receiving an R&D 100 Award for the wavelength-shifting scintillator detector Members of the team receiving an R&D 100 Award for the wavelength-shifting scintillator detector are shown with their invention. They are (from left)

37

High efficiency neutron sensitive amorphous silicon pixel detectors  

SciTech Connect

A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

1993-11-01T23:59:59.000Z

38

IMPROVEMENTS IN CODED APERTURE THERMAL NEUTRON IMAGING.  

SciTech Connect

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

39

Boron-Lined Neutron Detector Measurements  

SciTech Connect

PNNL-18938 Revision 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 a newly designed boron-lined proportional counter option. This testing measured the neutron detection efficiency and gamma ray rejection capabilities of two successive prototypes of a system manufactured by GE Reuter Stokes.

Lintereur, Azaree T.; Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Siciliano, Edward R.; Woodring, Mitchell L.

2010-03-07T23:59:59.000Z

40

Boron-Lined Neutron Detector Measurements  

SciTech Connect

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 a newly designed boron-lined proportional counter option. This testing measured the neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Reuter Stokes.

Lintereur, Azaree T.; Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Siciliano, Edward R.

2009-11-02T23:59:59.000Z

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.


41

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

42

Measurements of fast neutrons by bubble detectors  

SciTech Connect

Neutron bubble detectors have been studied using Am-Be and D-D neuron sources, which give limited energy information. The Bubble Detector Spectrometer (BDS) have six different energy thresholds ranging from 10 KeV to 10 Mev. The number of bubbles obtained in each measurement is related to the dose (standardized response R) equivalent neutrons through sensitivity (b / {mu}Sv) and also with the neutron flux (neutrons per unit area) through a relationship that provided by the manufacturer. Bubble detectors were used with six different answers (0.11 b/ {mu}Sv, 0093 b/{mu}Sv, 0.14 b/{mu}Sv, 0.17 b/{mu}Sv, 0051 b/{mu}Sv). To test the response of the detectors (BDS) radiate a set of six of them with different energy threshold, with a source of Am-Be, placing them at a distance of one meter from it for a few minutes. Also, exposed to dense plasma focus Fuego Nuevo II (FN-II FPD) of ICN-UNAM, apparatus which produces fusion plasma, generating neutrons by nuclear reactions of neutrons whose energy emitting is 2.45 MeV. In this case the detectors were placed at a distance of 50 cm from the pinch at 90 Degree-Sign this was done for a certain number of shots. In both cases, the standard response is reported (Dose in {mu}Sv) for each of the six detectors representing an energy range, this response is given by the expression R{sub i}= B{sub i} / S{sub i} where B{sub i} is the number of bubbles formed in each and the detector sensitivity (S{sub i}) is given for each detector in (b / {mu}Sv). Also, reported for both cases, the detected neutron flux (n cm{sup -2}), by a given ratio and the response involves both standardized R, as the average cross section sigma. The results obtained have been compared with the spectrum of Am-Be source. From these measurements it can be concluded that with a combination of bubble detectors, with different responses is possible to measure the equivalent dose in a range of 10 to 100 {mu}Sv fields mixed neutron and gamma, and pulsed generated fusion devices.

Castillo, F.; Martinez, H. [Laboratorio de Espectroscopia, Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251, Cuernavaca Morelos (Mexico); Leal, B. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F. (Mexico); Rangel, J. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Ciudad Universitaria, Mexico D. F (Mexico); Reyes, P. G. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario 100, Col. Centro, 50000, Toluca Estado de Mexico (Mexico)

2013-07-03T23:59:59.000Z

43

Thermal neutron flux contours from criticality event  

SciTech Connect

The generation of thermal neutron flux contours from a criticality event is demonstrated for an idealized building with a criticality event in one of the rooms. The MCNP Monte Carlo computer code is used to calculate the thermal neutron flux.

Carter, L.L., Westinghouse Hanford

1996-08-01T23:59:59.000Z

44

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

45

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

46

Novel Neutron Detector for n-n Scattering Length Measurement.  

E-Print Network (OSTI)

??The neutron-neutron (n-n) scattering length is a fundamental parameter in nuclear physics; however, measurements are plagued with large uncertainties caused by neutron detector cross talk.… (more)

Wilcox, Eva

2005-01-01T23:59:59.000Z

47

Geant4 based simulations for novel neutron detector development  

E-Print Network (OSTI)

A Geant4-based Python/C++ simulation and coding framework, which has been developed and used in order to aid the R&D efforts for thermal neutron detectors at neutron scattering facilities, is described. Built upon configurable geometry and generator modules, it integrates a general purpose object oriented output file format with meta-data, developed in order to facilitate a faster turn-around time when setting up and analysing simulations. Also discussed are the extensions to Geant4 which have been implemented in order to include the effects of low-energy phenomena such as Bragg diffraction in the polycrystalline support materials of the detector. Finally, an example application of the framework is briefly shown.

Thomas Kittelmann; Irina Stefanescu; Kalliopi Kanaki; Mirko Boin; Richard Hall-Wilton; Karl Zeitelhack

2013-11-05T23:59:59.000Z

48

Geant4 based simulations for novel neutron detector development  

E-Print Network (OSTI)

A Geant4-based Python/C++ simulation and coding framework, which has been developed and used in order to aid the R&D efforts for thermal neutron detectors at neutron scattering facilities, is described. Built upon configurable geometry and generator modules, it integrates a general purpose object oriented output file format with meta-data, developed in order to facilitate a faster turn-around time when setting up and analysing simulations. Also discussed are the extensions to Geant4 which have been implemented in order to include the effects of low-energy phenomena such as Bragg diffraction in the polycrystalline support materials of the detector. Finally, an example application of the framework is briefly shown.

Kittelmann, Thomas; Kanaki, Kalliopi; Boin, Mirko; Hall-Wilton, Richard; Zeitelhack, Karl

2013-01-01T23:59:59.000Z

49

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

50

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

SciTech Connect

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

51

Thermal Neutron Imaging in an Active Interrogation Environment  

SciTech Connect

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

52

Thermal neutron imaging in an active interrogation environment  

SciTech Connect

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

53

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

54

Hand Held Neutron Detector Development for Physics and Security Applications  

E-Print Network (OSTI)

energy neutrons may penetrate through the shielding and cause nuclear recoils on the detector that may be mistaken for a WIMP interaction event. The purpose of this project was to create a detector that shields as well as tags incoming neutrons to measure...

Campbell, Caitlin E

2013-10-04T23:59:59.000Z

55

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

SciTech Connect

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

56

Compound Refractive Lenses for Thermal Neutron Applications  

SciTech Connect

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

57

Elimination of ghosting artifacts from wavelength-shifting fiber neutron detectors  

SciTech Connect

Misassignment of neutron position (ghosting) produces artifacts which have been observed in wavelength-shifting (WLS) fiber detectors developed for time-of-flight (TOF) neutron powder diffraction. In position-sensitive detectors (PSDs) with WLS fiber encoding, thermal and cold neutrons interact with a monolithic {sup 6}LiF/ZnS:Ag scintillator screen, and scintillation photons are generated and transported through the crossed fibers to photomultipliers (PMTs). The neutron position is determined by photon counts in the PMTs within a preset time window. Ghosting occurs when neutrons hit the group boundaries of two neighboring PMTs for x-position multiplexing, which is modeled as resulting from a long travel length (about 3-5 mm) of a small number of scintillation photons. This model is supported by the change observed in aperture images when the threshold number for photon-pulses was adjusted for neutron event determination. When the threshold number of photon-pulses was set above 10 for each PMT, the ghost peaks in the aperture images and TOF spectra of powder diffraction were strongly suppressed or completely eliminated, and the intrinsic background levels of the WLS detectors were significantly reduced. Our result indicates that WLS fiber detector is a promising alternative for {sup 3}He PSDs for neutron scattering.

Wang, C. L.; Diawara, Y.; Hannan, B. W.; Hodges, J. P. [Instrument and Source Design Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Clonts, L. G. [Research Accelerator Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2013-01-15T23:59:59.000Z

58

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

SciTech Connect

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

59

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

60

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.

Polosatkin, Sergey; Dolgov, Alexander

2014-01-01T23:59:59.000Z

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.


61

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

62

Diagnostics and performance evaluation of neutron monitoring system detectors  

SciTech Connect

Neutron monitoring detectors used in Boiling Water Reactor (BWR) power range monitoring control systems are typically miniature fission chambers that remain in the core for many years. Pressurized Water Reactors (PWR) also utilize movable miniature fission chambers for neutron flux mapping during power operations. The baseline performance of the detectors must be established at the time of installation and retested periodically during the life of the detector to evaluate its suitability for continued use. This paper reports on the characteristics that the power range detectors typically exhibit at the beginning of life and describes the normal changes in characteristics that are expected to occur as the detector ages in the in-core environment. Deviations from the normal aging effects that may be revealed through periodic testing are described. Possible root causes for some deviations from the expected performance are discussed. In addition to the power range monitoring detectors, the neutron monitoring system also utilizes other fission chambers for source range or intermediate range neutron monitoring during startup, and neutron or gamma detectors for periodic sensitivity re-calibration of the power range monitoring detectors. Each of the detectors has function specific requirements that call for additional diagnostic testing methods to evaluate performance. Diagnostic tests such as Time Domain Reflectometry and Current vs. Voltage (IV) characterization provide useful information about the condition of the detector and the signal path that links the detector to the reactor monitoring and control system. Typical test results of properly functioning detectors are described and the significance of deviations from a normal result is discussed. (authors)

Kniss, T.; Doyle, J. [GE Energy, 8499 Darrow Rd., Twinsburg, OH 44087 (United States)

2006-07-01T23:59:59.000Z

63

Neutron detectors comprising ultra-thin layers of boron powder  

SciTech Connect

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

64

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

65

Neutron counting and gamma spectroscopy with PVT detectors.  

SciTech Connect

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

66

A High-Efficiency Neutron Detector  

Science Journals Connector (OSTI)

... for neutrons with energies lying between 100 and 100,000 eV. A practicable thickness of boron-10 (2-2J cm.) is effectively 'black' to neutrons of up to 10, ...

J. C. DUCKWORTH; A. W. MERRISON; A. WHITTAKER

1950-01-14T23:59:59.000Z

67

Ship Effect Measurements With Fiber Optic Neutron Detector  

SciTech Connect

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

68

New PTB thermal neutron calibration facility: first results  

Science Journals Connector (OSTI)

......physikalisch-technische bundesanstalt (PTB) operated for almost 10 y an installation at the research reactor of the GKSS in Geesthacht/Germany for irradiations with thermal neutrons. After its shutdown in 2008, no thermal neutron calibration facility was......

M. Luszik-Bhadra; M. Reginatto; H. Wershofen; B. Wiegel; A. Zimbal

2014-10-01T23:59:59.000Z

69

Profile NeutronDetector 9-16-04..pmd  

NLE Websites -- All DOE Office Websites (Extended Search)

GALLIUM ARSENIDE SEMICONDUCTOR-BASED GALLIUM ARSENIDE SEMICONDUCTOR-BASED NEUTRON DETECTOR B E N E F I T S Portable, Accurate Device Detects and Monitors Neutrons and Nuclear Materials * More accurate and sensitive than other technologies * Performance won't degrade over time * Easy implementation and deployment * Rugged, lightweight, and portable for field use * Reduces false readings * Requires less power * Low mass-production cost (about $1 per chip) * Neutron detection * Detecting and monitoring nuclear materials and weapons * Permanent installations and portable field operation * High-vacuum environments (e.g., physics labs and space platforms) An advanced neutron detector developed by Argonne National Laboratory and Kansas State University accurately detects neutrons and finds concealed nuclear weapons and materials, even in harsh or challenging environments. The key

70

Boron-Lined Straw-Tube Neutron Detector Test  

SciTech Connect

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 a boron-lined proportional counter design variation. In the testing described here, the neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Proportional Technologies, Inc, was tested.

Kouzes, Richard T.; Ely, James H.; Stromswold, David C.

2010-08-07T23:59:59.000Z

71

Scalable large-area solid-state neutron detector with continuous p–n junction and extremely low leakage current  

Science Journals Connector (OSTI)

Abstract We report on the fabrication and characterization of solid-state thermal neutron detectors with detection areas up to 16 cm2 that require only a single preamplifier for data acquisition. These detectors consist of a honeycomb-like micro-structured Si diode with boron-10 filled deep holes. A continuous p–n junction formed over the entire surface of the microstructure helps to achieve a low leakage current density of ~6.1×10?9 A/cm2 at ?1 V for a 2.5×2.5 mm2 detector. This low leakage current results in low electronic noise, which enables the fabrication of large-area detectors. An intrinsic thermal neutron detection efficiency of up to 26% was measured for a 2.5×2.5 mm2 detector module and up to 24% was measured for a 1 cm2 detector module. These measurements were obtained under zero bias voltage using a moderated californium-252 source. The relative efficiency remains almost the same when scaling the detector area up to 8 cm2 by connecting 1 cm2 detector modules in series. However, it decreases to 0.89 and 0.82, respectively, for 12 and 16 cm2. Nevertheless, these results demonstrate the promise of using boron filled micro-structured Si diodes as a cost effective alternative to the helium-3 based neutron detection technology and the potential of fabricating scalable large-area solid-state neutron detectors that are desirable for many applications.

Kuan-Chih Huang; Rajendra Dahal; James J.-Q. Lu; Adam Weltz; Yaron Danon; Ishwara B. Bhat

2014-01-01T23:59:59.000Z

72

Thermal radiation from magnetic neutron star surfaces  

E-Print Network (OSTI)

We investigate the thermal emission from magnetic neutron star surfaces in which the cohesive effects of the magnetic field have produced the condensation of the atmosphere and the external layers. This may happen for sufficiently cool atmospheres with moderately intense magnetic fields. The thermal emission from an isothermal bare surface of a neutron star shows no remarkable spectral features, but it is significantly depressed at energies below some threshold energy. However, since the thermal conductivity is very different in the normal and parallel directions to the magnetic field lines, the presence of the magnetic field is expected to produce a highly anisotropic temperature distribution, depending on the magnetic field geometry. In this case, the observed flux of such an object looks very similar to a BB spectrum, but depressed in a nearly constant factor at all energies. This results in a systematic underestimation of the area of the emitter (and therefore its size) by a factor 5-10 (2-3).

J. F. Perez--Azorin; J. A. Miralles; J. A. Pons

2004-10-27T23:59:59.000Z

73

The Thermal Mass limit of Neutron Cores  

E-Print Network (OSTI)

Static thermal equilibrium of a quantum self-gravitating ideal gas in General Relativity is studied at any temperature, taking into account the Tolman-Ehrenfest effect. Thermal contribution to the gravitational stability of static neutron cores is quantified. The curve of maximum mass with respect to temperature is reported. At low temperatures is recovered the Oppenheimer-Volkoff calculation, while at high temperatures is recovered the, recently reported, classical gas calculation. An ultimate upper mass limit $M = 2.43M_\\odot$ of all maximum values is found to occur at Tolman temperature $ T = 1.27mc^2$ with radius $R = 15.2km$.

Roupas, Zacharias

2014-01-01T23:59:59.000Z

74

Anisotropic thermal emission from magnetized neutron stars  

E-Print Network (OSTI)

The thermal emission from isolated neutron stars is not well understood. The X-ray spectrum is very close to a blackbody but there is a systematic optical excess flux with respect to the extrapolation to low energy of the best blackbody fit. This fact, in combination with the observed pulsations in the X-ray flux, can be explained by anisotropies in the surface temperature distribution.We study the thermal emission from neutron stars with strong magnetic fields in order to explain the origin of the anisotropy. We find (numerically) stationary solutions in axial symmetry of the heat transportequations in the neutron star crust and the condensed envelope. The anisotropy in the conductivity tensor is included consistently. The presence of magnetic fields of the expected strength leads to anisotropy in the surface temperature. Models with toroidal components similar to or larger than the poloidal field reproduce qualitatively the observed spectral properties and variability of isolated neutron stars. Our models also predict spectral features at energies between 0.2 and 0.6 keV.

J. F. Perez-Azorin; J. A. Miralles; J. A. Pons

2005-10-24T23:59:59.000Z

75

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

NLE Websites -- All DOE Office Websites (Extended Search)

neutron detector wins ... Y-12 neutron detector wins prestigious R&D 100 Award Posted: July 9, 2013 - 4:11pm Ashley Stowe, Y 12 senior development chemist, working with Fisk...

76

280 TECIINICAL NOTES Statistical Estimates of Thermal Neutron  

E-Print Network (OSTI)

280 TECIINICAL NOTES Statistical Estimates of Thermal Neutron Capture Cross Sections Yu. V. PetrovDecember9, I983 AcceptedJune 13, 1984 Abstract-Fluctuations of neutron resonance param- eters result in the observed distribution of the thermal neutron capture crosssections. The statistical approach allowing

Shlyakhter, Ilya

77

280 TECHNICAL NOTES Statistical Estimates of Thermal Neutron  

E-Print Network (OSTI)

280 TECHNICAL NOTES Statistical Estimates of Thermal Neutron Capture Cross Sections Yu. V. Petrov December 9, 1983 Accepted June 13, 1984 Abstract-Fluctuations of neutron resonance param- eters result in the observed distribution of the thermal neutron capture cross sections. Thestatistical approach allowingfor

Shlyakhter, Ilya

78

Physics of neutron star surface layers and their thermal radiation  

E-Print Network (OSTI)

Physics of neutron star surface layers and their thermal radiation Alexander Y. Potekhin Ioffe review the physical properties of neutron star surface layers, important for the stellar thermal radiation, taking into consideration the effects of strong magnetic fields. Keywords: Neutron stars

79

A fast response and -insensitive neutron detector based on parallel-plate avalanche counter  

Science Journals Connector (OSTI)

......scattering in the detector gas is negligible. However...conditions in terms of gas pressure and applied voltages...compared with the other gas-filled neutron detectors...thin structure and low production cost of this detector, it is......

M. Nakhostin; M. Baba; T. Itoga; T. Oishi; Y. Unno; S. Kamada; T. Okuji

2008-05-01T23:59:59.000Z

80

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

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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81

Thermal neutron capture gamma-rays  

SciTech Connect

The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,..cap alpha..), E = thermal, reactions for which the residual nucleus mass number is greater than or equal to 45 are included. These correspond to evaluations published in Nuclear Data Sheets. The publication source data are contained in the Evaluated Nuclear Structure Data File (ENSDF). The data presented here do not involve any additional evaluation. Appendix I lists all the residual nuclides for which the data are included here. Appendix II gives a cumulated index to A-chain evaluations including the year of publication. The capture gamma ray data are given in two tables - the Table 1 is the list of all gamma rays seen in (n,..gamma..) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide.

Tuli, J.K.

1983-01-01T23:59:59.000Z

82

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

83

Measurement of Thermal Neutron Flux in Photo-Neutron Source  

Science Journals Connector (OSTI)

The Photo-Neutron Source (PNS) project is a study ... design, simulation and construction an accelerator based neutron source for Boron Neutron Capture Therapy (BNCT). The system uses ... medical linear accelerat...

A. Taheri; A. Torkamani; A. Pazirandeh…

2013-01-01T23:59:59.000Z

84

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser  

SciTech Connect

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10{sup 8} DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10{sup 4} per shot and up to 10{sup 11} neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields ({approx}10{sup 11}). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6 Multiplication-Sign 10{sup -4} was used. The combined use of all three detectors allowed for a detection range of 10{sup 4} to 10{sup 11} neutrons per shot.

Bang, W.; Quevedo, H. J.; Dyer, G.; Rougk, J.; Kim, I.; McCormick, M.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

2012-06-15T23:59:59.000Z

85

Neutron detector for fusion reaction-rate measurements  

SciTech Connect

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

86

Neutron And Gamma Detector Using An Ionization Chamber With An Integrated  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron And Gamma Detector Using An Ionization Chamber Neutron And Gamma Detector Using An Ionization Chamber Neutron And Gamma Detector Using An Ionization Chamber With An Integrated Body And Moderator A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. Available for thumbnail of Feynman Center (505) 665-9090 Email Neutron And Gamma Detector Using An Ionization Chamber With An Integrated Body And Moderator 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

87

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

88

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

SciTech Connect

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

89

Use of gamma-ray spectroscopy for direct detection of thermal neutrons  

Science Journals Connector (OSTI)

A neutron detector based on detection of the prompt gamma-radiation emitted as a result of neutron interaction with a suitable neutron absorber is described. Boron-10 loaded polyethylene is used as the neutron...

F. Ghanbari; A. H. Mohagheghi

2001-05-01T23:59:59.000Z

90

Thermal Neutron Capture y's (CapGam)  

DOE Data Explorer (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)

91

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

SciTech Connect

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

92

Numerical techniques for coupled neutronic/thermal-hydraulic reactor calculations  

SciTech Connect

The solution of coupled neutronic/thermal-hydraulic nuclear reactor calculations is achieved through an iterative procedure that treats the components of the calculations in a relatively decoupled fashion. This entails an alternation between the neutronic and thermal-hydraulic components of the calculation while using the most recent estimates of the neutron cross sections, as determined by the thermal-hydraulic feedback relationships. Although this decoupled approach is typically convergent, it has been demonstrated that the rate of convergence is quite inconsistent. As a result of these limitations, an effort has been directed toward the development of numerical techniques that more closely approximate a truly coupled solution.

Betts, C.M.; Kulas, M.M.; Klein, A.C. [Oregon State Univ., Corvallis, OR (United States)] [and others

1995-12-31T23:59:59.000Z

93

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

SciTech Connect

We report on the design, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon micro-structures. The fabricated detectors use boron filled deep holes with aspect ratio of over 12 and showed a very low leakage current density of {approx}7 Multiplication-Sign 10{sup -7} A/cm{sup 2} at -1 V for device sizes varying from 2 Multiplication-Sign 2 to 5 Multiplication-Sign 5 mm{sup 2}. A thermal neutron detection efficiency of 4.5% {+-} 0.5% with discrimination setting of 500 keV and gamma to neutron sensitivity of (1.1 {+-} 0.1) Multiplication-Sign 10{sup -5} for single layer was measured without external bias for these devices. Monte-Carlo simulation predicts a maximum efficiency of 45% for such devices filled with 95% enriched {sup 10}boron.

Dahal, R. [Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Huang, K. C.; LiCausi, N.; Lu, J.-Q.; Bhat, I. [Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Clinton, J.; Danon, Y. [Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2012-06-11T23:59:59.000Z

94

Thermal detector model for cryogenic composite detectors for the dark matter experiments CRESST and EURECA  

E-Print Network (OSTI)

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) and the EURECA (European Underground Rare Event Calorimeter Array) experiments are direct dark matter search experiments where cryogenic detectors are used to detect spin-independent, coherent WIMP (Weakly Interacting Massive Particle)-nucleon scattering events by means of the recoil energy. The cryogenic detectors use a massive single crystal as absorber which is equipped with a TES (transition edge sensor) for signal read-out. They are operated at mK-temperatures. In order to enable a mass production of these detectors, as needed for the EURECA experiment, a so-called composite detector design (CDD) that allows decoupling of the TES fabrication from the optimization procedure of the absorber single-crystal was developed and studied. To further investigate, understand and optimize the performance of composite detectors a detailed thermal detector model which takes into account the CDD has been developed.

S. Roth; C. Ciemniak; C. Coppi; F. v. Feilitzsch; A. Guetlein; C. Isaila; J. -C. Lanfranchi; S. Pfister; W. Potzel; W. Westphal

2008-09-30T23:59:59.000Z

95

Detection of thermal neutrons with a CMOS pixel sensor for a future dosemeter  

SciTech Connect

The RaMsEs group (Radioprotection et Mesures Environnementales) is developing a new compact device for operational neutron dosimetry. The electronic part of the detector is made of an integrated active pixel sensor, originally designed for tracking in particle physics. This device has useful features for neutrons, such as high detection efficiency for charged particles, good radiation resistance, high readout speed, low power consumption and high rejection of photon background. A good response of the device to fast neutrons has already been demonstrated [1]. In order to test the sensibility of the detector to thermal neutrons, experiments have been carried out with a 512 x 512 pixel CMOS sensor on a californium source moderated with heavy water (Cf.D{sub 2}O) on the Van Gogh irradiator at the LMDN, IRSN, Cadarache (France)). A thin boron converter is used to benefit from the significant cross section of the {sup 10}B (n,{alpha}) {sup 7}Li reaction. Results show a high detection efficiency (around 10{sup -3}) of the device to thermal neutrons. Our measurements are in good agreement with GEANT4 Monte Carlo simulations. (authors)

Vanstalle, M.; Husson, D.; Higueret, S.; Le, T. D.; Nourreddine, A. M. [Institut Pluridisciplinaire Hubert Curien, Univ. of Strasbourg, CNRS, 67037 Strasbourg (France)

2011-07-01T23:59:59.000Z

96

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

97

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

98

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

SciTech Connect

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

99

Neutron Detectors for Detection of Nuclear Materials at LANL| U.S. DOE  

Office of Science (SC) Website

Neutron Detectors for Detection of Neutron Detectors for Detection of Nuclear Materials at LANL Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Spinoff Applications Spinoff Archives SBIR/STTR Applications of Nuclear Science and Technology Funding Opportunities Nuclear Science Advisory Committee (NSAC) News & Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3613 F: (301) 903-3833 E: sc.np@science.doe.gov More Information » Spinoff Archives Neutron Detectors for Detection of Nuclear Materials at LANL Print Text Size: A A A RSS Feeds FeedbackShare Page Application/instrumentation: Very Large Array Neutron Detector (VLAND); Development of large volume efficient neutron detectors for use in detection of small amounts (~ 1 gm)

100

Polarization Analysis of Thermal-Neutron Scattering  

Science Journals Connector (OSTI)

A triple-axis neutron spectrometer with polarization-sensitive crystals on both the first and third axes is described. The calculation of polarized-neutron scattering cross sections is presented in a form particularly suited to apply to this instrument. Experimental results on nuclear incoherent scattering, paramagnetic scattering, Bragg scattering, and spin-wave scattering are presented to illustrate the possible applications of neutron-polarization analysis.

R. M. Moon; T. Riste; W. C. Koehler

1969-05-10T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


101

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

E-Print Network (OSTI)

Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors M OF SCIENTIFIC INSTRUMENTS 83, 10E124 (2012) Neutron field parameter measurements on the JET tokamak by means 2 August 2012) The neutron field parameters (fluence and energy distribution) at a specific location

102

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

103

Thermal-Neutron-Capture Gamma Rays in Yb170, Yb172, and Yb174  

Science Journals Connector (OSTI)

A Ge(Li) detector was used to investigate the ? spectra following thermal neutron capture in enriched isotope targets of Yb170, Yb172, and Yb174. In addition to capture in these isotopes, ? lines were identified as resulting from thermal capture in Yb171 and Yb173. The neutron separation energies of Yb171, Yb172, Yb173, Yb174, and Yb175 were found to be 6616, 8023, 6365, 7465, and 5819 keV, respectively. The experimental error is ±3 keV in all cases. For capture by the even-even isotopes, the energies and intensities of ? transitions originating from the capture state are presented together with the spins and Nilsson assignments of the low-lying rotational bands which they populate. Our measurements are compared with those in other experiments, and the results of our measurements are discussed. Regularities in the decay of the capture state to low-lying Nilsson levels have now been observed in comparing thermal neutron capture by different even-even nuclei in the region A=176. The regularities include relatively strong population of Nilsson bands with ? equal to zero or 1 as compared to population of bands with ? greater than 1. In addition, there seems to be a preference for the capture state decaying to particle rather than hole bands. A purely statistical version of thermal neutron capture would not seem to hold in this mass region.

A. I. Namenson and J. C. Ritter

1969-07-20T23:59:59.000Z

104

Estimation of Performance of an Active Well Coincidence Counter Equipped with Boron-Coated Straw Neutron Detectors - 13401  

SciTech Connect

He-3, a very rare isotope of natural helium gas, has ideal properties for the detection of thermal neutrons. As such it has become the standard material for neutron detectors and sees ubiquitous use within many radiometric applications that require neutron sensitivity. Until recently, there has been a fairly abundant supply of He-3. However, with the reduction in nuclear weapons, production of tritium ceased decades ago and the stockpile has largely decayed away, reducing the available He-3 supply to a small fraction of that needed for neutron detection. A suitable and rapidly-deployable replacement technology for neutron detectors must be found. Many potential replacement technologies are under active investigation and development. One broad class of technologies utilizes B-10 as a neutron capture medium in coatings on the internal surfaces of proportional detectors. A particular implementation of this sort of technology is the boron-coated 'straw' (BCS) detectors under development by Proportional Technologies, Inc. (PTi). This technology employs a coating of B-10 enriched boron carbide (B{sub 4}C) on the inside of narrow tubes, roughly 4 mm in diameter. A neutron counter (e.g. a slab, a well counter, or a large assay counter designed to accommodate 200 liter drums) could be constructed by distributing these narrow tubes throughout the polyethylene body of the counter. One type of neutron counter that is of particular importance to safeguards applications is the Active Well Coincidence Counter (AWCC), which is a Los Alamos design that traditionally employs 42 He-3 detectors. This is a very flexible design which can accurately assay small samples of uranium- and plutonium-bearing materials. Utilizing the MCNPX code and benchmarking against measurements where possible, the standard AWCC has been redesigned to utilize the BCS technology. Particular aspects of the counter performance include the single-neutron ('singles') detection efficiency and the time constant for the decrease in neutron population in the counter following a fission event (a.k.a. the die-away time). Results of the modeling and optimization are presented. (authors)

Young, B.M. [Canberra Industries, Inc., 800 Research Parkway, Meriden, CT 06450 (United States)] [Canberra Industries, Inc., 800 Research Parkway, Meriden, CT 06450 (United States); Lacy, J.L.; Athanasiades, A. [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States)] [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States)

2013-07-01T23:59:59.000Z

105

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

106

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

SciTech Connect

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

107

High detection efficiency micro-structured solid-state neutron detector with extremely low leakage current fabricated with continuous p-n junction  

SciTech Connect

We report the continuous p-n junction formation in honeycomb structured Si diode by in situ boron deposition and diffusion process using low pressure chemical vapor deposition for solid-state thermal neutron detection applications. Optimized diffusion temperature of 800 Degree-Sign C was obtained by current density-voltage characteristics for fabricated p{sup +}-n diodes. A very low leakage current density of {approx}2 Multiplication-Sign 10{sup -8} A/cm{sup 2} at -1 V was measured for enriched boron filled honeycomb structured neutron detector with a continuous p{sup +}-n junction. The neutron detection efficiency for a Maxwellian spectrum incident on the face of the detector was measured under zero bias voltage to be {approx}26%. These results are very encouraging for fabrication of large area solid-state neutron detector that could be a viable alternative to {sup 3}He tube based technology.

Huang, Kuan-Chih; Lu, James J.-Q.; Bhat, Ishwara B. [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)] [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Dahal, Rajendra [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States) [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States); Danon, Yaron [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)] [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3522 (United States)

2013-04-15T23:59:59.000Z

108

Estimation of neutron-equivalent dose in organs of patients undergoing radiotherapy by the use of a novel online digital detector  

Science Journals Connector (OSTI)

Neutron peripheral contamination in patients undergoing high-energy photon radiotherapy is considered as a risk factor for secondary cancer induction. Organ-specific neutron-equivalent dose estimation is therefore essential for a reasonable assessment of these associated risks. This work aimed to develop a method to estimate neutron-equivalent doses in multiple organs of radiotherapy patients. The method involved the convolution, at 16 reference points in an anthropomorphic phantom, of the normalized Monte Carlo neutron fluence energy spectra with the kerma and energy-dependent radiation weighting factor. This was then scaled with the total neutron fluence measured with passive detectors, at the same reference points, in order to obtain the equivalent doses in organs. The latter were correlated with the readings of a neutron digital detector located inside the treatment room during phantom irradiation. This digital detector, designed and developed by our group, integrates the thermal neutron fluence. The correlation model, applied to the digital detector readings during patient irradiation, enables the online estimation of neutron-equivalent doses in organs. The model takes into account the specific irradiation site, the field parameters (energy, field size, angle incidence, etc) and the installation (linac and bunker geometry). This method, which is suitable for routine clinical use, will help to systematically generate the dosimetric data essential for the improvement of current risk-estimation models.

F Sánchez-Doblado; C Domingo; F Gómez; B Sánchez-Nieto; J L Muñiz; M J García-Fusté; M R Expósito; R Barquero; G Hartmann; J A Terrón; J Pena; R Méndez; F Gutiérrez; F X Guerre; J Roselló; L Núñez; L Brualla-González; F Manchado; A Lorente; E Gallego; R Capote; D Planes; J I Lagares; X González-Soto; F Sansaloni; R Colmenares; K Amgarou; E Morales; R Bedogni; J P Cano; F Fernández

2012-01-01T23:59:59.000Z

109

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

SciTech Connect

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

110

Modern Techniques for Inelastic Thermal Neutron Scattering Analysis  

Science Journals Connector (OSTI)

Abstract A predictive approach based on ab initio quantum mechanics and/or classical molecular dynamics simulations has been formulated to calculate the scattering law, S ( ? ? , ? ) , and the thermal neutron scattering cross sections of materials. In principle, these atomistic methods make it possible to generate the inelastic thermal neutron scattering cross sections of any material and to accurately reflect the physical conditions of the medium (i.e, temperature, pressure, etc.). In addition, the generated cross sections are free from assumptions such as the incoherent approximation of scattering theory and, in the case of solids, crystalline perfection. As a result, new and improved thermal neutron scattering data libraries have been generated for a variety of materials. Among these are materials used for reactor moderators and reflectors such as reactor-grade graphite and beryllium (including the coherent inelastic scattering component), silicon carbide, cold neutron media such as solid methane, and neutron beam filters such as sapphire and bismuth. Consequently, it is anticipated that the above approach will play a major role in providing the nuclear science and engineering community with its needs of thermal neutron scattering data especially when considering new materials where experimental information may be scarce or nonexistent.

A.I. Hawari

2014-01-01T23:59:59.000Z

111

Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors  

SciTech Connect

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

112

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

SciTech Connect

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

113

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

SciTech Connect

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

114

Tests and Calibration of the NIF Neutron Time of Flight Detectors  

SciTech Connect

The National Ignition Facility (NIF) Neutron Time of Flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD* implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 109 to 2 x 1019. The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 m and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory (LLNL). Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detectors tests and calibration will be presented. *(D = deuterium, T = tritium, H = hydrogen)

Ali, Z.A.; Glebov, V.Yu.; Cruz, M.; Duffy, T.; Stoeckl, C.; Roberts, S.; Sangster, T.C.; Tommasini, R.; Throop, A; Moran, M.; Dauffy, L.; Horsefield, C.

2008-05-15T23:59:59.000Z

115

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

116

A large 2D PSD for thermal neutron detection  

SciTech Connect

A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 x 640 mm{sup 2}. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimize parallax, the gas mixture was 190 kPa {sup 3}He plus 100 kPa CF{sub 4} and the active volume had a thickness of 30 mm. The design maximum neutron count-rate of the detector was 10{sup 5} events per second. The (calculated) neutron detection efficiency was 60% for 2{angstrom} neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 x 5 mm{sup 2}) was thereby defined by the wire geometry. A 16 channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise linewidth of 0.4 fC (fwhm) and channel-to-channel cross-talk of less than 5%. The Proportional Counter Operating System (PCOS III) (LeCroy Corp USA) was used for event encoding. The ECL signals produced by the 16 channel modules were latched in PCOS III by a trigger pulse from the anode and the fast encoders produce a position and width for each event. The information was transferred to a UNIX workstation for accumulation and online display.

Knott, R.B.; Watt, G.; Boldeman, J.W. [Australian Nuclear Science and Technology Organization, Menai, New South Wales (Australia). Physics Div.; Smith, G.C. [Brookhaven National Lab., Upton, NY (United States). Instrumentation Div.

1996-12-31T23:59:59.000Z

117

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

118

Thermal Neutron Capture for Nuclei A = 3 - 20  

NLE Websites -- All DOE Office Websites (Extended Search)

Thermal Neutron Capture Evaluated Data for Nuclei A 3 - 20 Go to the Text Only below if you prefer to view the nuclides in a text list. 19Ne 20Ne 18F 19F 20F 15O 16O 17O 18O 19O...

119

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

120

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

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

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

SciTech Connect

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

122

The Scattering of Thermal Neutrons by Deuterons  

Science Journals Connector (OSTI)

The cross section for the scattering of very slow neutrons by deuterons is calculated by numerical methods. Polarization is completely neglected and the wave equation for the process is set up in such a form as to take correctly into account exchange effects between the incident neutron and the neutron initially in the deuteron. This wave equation is then replaced by an integral equation the solution of which is correctly symmetrized and has the right asymptotic value to describe the scattering process. The numerical integration is performed by replacing the integral equation by a finite set of simultaneous linear algebraic equations. The work is greatly simplified by the use of a sum of two Gauss functions to approximate the ground state deuteron wave function. It is assumed throughout this paper that the interactions between like and unlike particles are equal and are of the general form Vij=-[(1-g-g1-g2)Pij+gPijQij+g1+g2Qij]J(rij), where the symbols have their usual meanings and where J(rij) is a Gauss function. The calculation is carried out for two sets of g's. For the first set, g1=g2=0, g=0.2, the cross section is found to be equal to 4.57×10-24 cm2, and for the second set of g's, g2=2, g=0.22-g2, g1=0.25-0.8g2, the value of the cross section is found to be equal to 6.91×10-24 cm2. The experimental value is at least 20 percent smaller than the first of these values.

Lloyd Motz and Julian Schwinger

1940-07-01T23:59:59.000Z

123

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

SciTech Connect

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

124

Boron thermal/epithermal neutron capture therapy  

SciTech Connect

The development of various particle beams for radiotherapy represents an attempt to improve dose distribution, and to provide high LET radiations which are less sensitive to ambient physical and radiobiological factors such as oxygen tension, cell cycle, and dose rate. In general, a compromise is necessary as effective RBE is reduced in order to spread the dose distribution over the anticipated tumor volume. The approach of delivering stable non-toxic isotopes to tumor, and then activating these atoms subsequently via an external radiation beam has mator advantages; problems associated with high uptake of these isotopes in competing cell pools are obviated, and the general tumor volume can be included in the treatment field of the activating beam. As long as the normal tissues supporting tumor show a low uptake of the isotope to be activated, and as long as the range of the reaction products is short, dose will be restricted to tumor, with a consequent high therapeutic ratio. Neutron Capture Therapy (NCT) is generally carried out by activating boron-10 with low energy neutrons. The range of the high LET, low OER particles from the /sup 10/B(n, ..cap alpha..)/sup 7/Li reaction is approx. 10..mu.., or one cell diameter, a situation that is optimal for cell killing. Significant advantages may be gained by using the NCT procedure in conjunction with improved tissue penetration provided with epithermal or filtered beams, and new compounds showing physiological binding to tumor.

Fairchild, R.G.

1982-01-01T23:59:59.000Z

125

An imaging-plate detector for small-angle neutron scattering  

Science Journals Connector (OSTI)

Small-angle neutron scattering (SANS) measurements have been performed on long-flight-path pinhole-collimation SANS instruments using, as a two-dimensional position-sensitive detector, both a neutron imaging plate, incorporating gadolinium, and a two-step transfer method, with dysprosium foil as the image transfer medium. The reduced pixel size of the imaging plates provides definite advantages over a conventional position-sensitive gas proportional counter in certain specific situations, namely when limited space necessitates a short sample-to-detector distance, when only small samples (comparable in size to the detector pixels) are available, or when used in conjunction with focusing beam optics.

Cheng, Y.T.

2000-10-01T23:59:59.000Z

126

New detector array improves neutron count capability at HFIR's Bio-SANS |  

NLE Websites -- All DOE Office Websites (Extended Search)

Bio-SANS neutron count capability improves Bio-SANS neutron count capability improves New detector array improves neutron count capability at HFIR's Bio-SANS Agatha Bardoel - June 29, 2012 Bio-SANS team that worked on installation of the new detector system. Front row, left to right: Doug Selby, Steve Hicks, Shuo Qian, Sai Venkatesh Pingali, Kathy Bailey, Amy Black Jones, and Derrick Williams. Back row, left to right: Ed Blackburn, John Palatinus, William Brad O'Dell, Mike Humphreys, Justin Beal, Ken Littrell, Greg Jones, Kevin Berry, Volker Urban, Randy Summers, and Ron Maples. Bio-SANS, the Biological Small-Angle Neutron Scattering Instrument at HFIR recently had a detector upgrade that will provide significantly improved performance that is more in line with the instrument's capability. Shorter experiment times are expected, which means more experiments can be

127

Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?  

SciTech Connect

This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.

Robert Hayes

2008-04-18T23:59:59.000Z

128

Ortho- and para-hydrogen in neutron thermalization  

SciTech Connect

The large difference in neutron scattering cross-section at low neutron energies between ortho- and para-hydrogen was recognized early on. In view of this difference (more than an order of magnitude), one might legitimately ask whether the ortho/para ratio has a significant effect on the neutron thermalization properties of a cold hydrogen moderator. Several experiments performed in the 60`s and early 70`s with a variety of source and (liquid hydrogen) moderator configurations attempted to investigate this. The results tend to show that the ortho/para ratio does indeed have an effect on the energy spectrum of the neutron beam produced. Unfortunately, the results are not always consistent with each other and much unknown territory remains to be explored. The problem has been approached from a computational standpoint, but these isolated efforts are far from having examined the ortho/para-hydrogen problem in neutron moderation in all its complexity. Because of space limitations, the authors cannot cover, even briefly, all the aspects of the ortho/para question here. This paper will summarize experiments meant to investigate the effect of the ortho/para ratio on the neutron energy spectrum produced by liquid hydrogen moderators.

Daemen, L. L.; Brun, T. O.

1998-01-01T23:59:59.000Z

129

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

SciTech Connect

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

130

Thermal evolution of neutron stars with global and local neutrality  

E-Print Network (OSTI)

Globally neutral neutron stars, obtained from the solution of the called Einstein-Maxwell-Thomas-Fermi equations that account for all the fundamental interactions, have been recently introduced. These configurations have a more general character than the ones obtained with the traditional Tolman-Oppenheimer-Volkoff, which impose the condition of local charge neutrality. The resulting configurations have a less massive and thinner crust, leading to a new mass-radius relation. Signatures of this new structure of the neutron star on the thermal evolution might be a potential test for this theory. We compute the cooling curves by integrating numerically the energy balance and transport equations in general relativity, for globally neutral neutron stars with crusts of different masses and sizes, according to this theory for different core-crust transition interfaces. We compare and contrast our study with known results for local charge neutrality. We found a new behavior for the relaxation time, depending upon the...

de Carvalho, S M; Rueda, Jorge A; Ruffini, Remo

2014-01-01T23:59:59.000Z

131

Development of a cold-neutron imaging detector based on thick gaseous electron multiplier  

SciTech Connect

We present the results of our recent studies on a cold-neutron imaging detector prototype based on THick Gaseous Electron Multiplier (THGEM). The detector consists of a thin Boron layer, for neutron-to-charged particle conversion, coupled to two THGEM electrodes in cascade for charge amplification and a position-sensitive charge-readout anode. The detector operates in Ne/(5%)CF{sub 4}, at atmospheric pressure, in a stable condition at a gain of around 10{sup 4}. Due to the geometrical structure of the detector elements (THGEM geometry and charge read-out anode), the image of detector active area shows a large inhomogeneity, corrected using a dedicated flat-filed correction algorithm. The prototype provides a detection efficiency of 5% and an effective spatial resolution of the order of 1.3 mm.

Cortesi, M. [Paul Scherrer Institut (PSI), Villigen PSI CH-5234 (Switzerland); Swiss Federal Institute of Technology (ETH), Zurich CH-8092 (Switzerland); Zboray, R.; Kaestner, A. [Paul Scherrer Institut (PSI), Villigen PSI CH-5234 (Switzerland); Prasser, H.-M. [Swiss Federal Institute of Technology (ETH), Zurich CH-8092 (Switzerland)

2013-02-15T23:59:59.000Z

132

Accurate Development of Thermal Neutron Scattering Cross Section Libraries  

SciTech Connect

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

133

Comparison of thermal neutron distributions within shield materials obtained by experiments, SN and monte carlo code calculations  

Science Journals Connector (OSTI)

......The TLDs for thermal neutrons, which consist...measurements of induced activity of gold...measurement of thermal neutron fluence was...region of the energy range 5.04...Watt neutron fission spectrum of 252Cf and......

Yoshihiro Asano; Takeshi Sugita; Takenori Suzaki; Hideyuki Hirose

2005-12-20T23:59:59.000Z

134

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

135

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

136

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

SciTech Connect

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

137

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

SciTech Connect

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

138

Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction  

Science Journals Connector (OSTI)

Two-dimensional position-sensitive gaseous detectors have been developed at the Geesthacht Neutron Facility (GeNF) for high-resolution...2, 3He/CF4 and Xe/CO2, respectively. One neutron detector is used at the AR...

M. Marmotti; M. Haese-Seiller; R. Kampmann

2002-12-01T23:59:59.000Z

139

Directionally Sensitive Neutron Detector For Homeland Security Applications  

E-Print Network (OSTI)

Radiation Portal Monitor SNM Special Nuclear Material US United States vii TABLE OF CONTENTS Page ABSTRACT ................................................................................................................. iii ACKNOWLEDGEMENTS... of Existing Radiation Portal Monitors............................ 7 II.B. Previous Work in the Field of Directionally Sensitive Detectors ...... 11 III THEORY...

Spence, Grant

2012-02-14T23:59:59.000Z

140

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 pres...

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

2012-01-01T23:59:59.000Z

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141

Thermal Design of the Mu2e Detector Solenoid  

SciTech Connect

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

142

Advanced Neutron Source Reactor thermal analysis of fuel plate defects  

SciTech Connect

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

143

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

144

Superheated drop neutron detectors used at the ESRF  

Science Journals Connector (OSTI)

......spectrum. The fluence response of the SDD-100...increasing under-response for energies above 10 MeV...area around the storage ring will be due...The detector response to pulsed radiation...with a repetition frequency of 1 or 10 Hz......

P. Berkvens; P. Colomp

2006-09-01T23:59:59.000Z

145

Early detection of deteriorations affecting neutrons boron detectors  

SciTech Connect

The objective of these studies is to design and to industrialize a new device taking back the features of the actual system of control of boron detectors and updating them by adding some analysis of the pulses shapes for predictive maintenance. (authors)

Domenech, T.; Hamrita, H.; Normand, S. [CEA, LIST, Laboratoire Capteur et Architectures Electroniques, F-91191 Gif/Yvette (France); Daviaud, J. P. [EDF, DPN, 1 place Pleyel, 93 282 Saint Denis Cedex (France); Laroche, M. [EDF, SEPTEN, 12-14 rue Dutrievoz, 69628 Villeurbanne Cedex (France)

2011-07-01T23:59:59.000Z

146

3D neutronic/thermal-hydraulic coupled analysis of MYRRHA  

SciTech Connect

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

147

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

148

The thermal denaturation of DNA studied with neutron scattering Andrew Wildes,1  

E-Print Network (OSTI)

The thermal denaturation of DNA studied with neutron scattering Andrew Wildes,1 Nikos characterized using neutron scattering. A Bragg peak from B-form fibre DNA has been measured as a function techniques have proved to be excellent probes8 . We have used neutron scattering to measure the tem- perature

Boyer, Edmond

149

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

150

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

SciTech Connect

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

151

A scintillating-fiber 14-MeV neutron detector on TFTR during DT operation  

SciTech Connect

A compact 14-MeV neutron detector using an array of scintillating fibers has been tested on the TFTR tokamak under conditions of a high gamma background. This detector uses a fiber-matrix geometry, a magnetic field-insensitive phototube with an active HV base and pulse-height discrimination to reject low-level pulses from 2.5 MeV neutron and intense gammas. Laboratory calibrations have been performed at EG&G Las Vegas using a pulsed DT neutron generator and a 30 kCi {sup 60}Co source as background, at PPPL using DT neutron sources, and at LANL using an energetic deuterium beam and target at a tandem Van de Graaff accelerator. During the first high power DT shots on TFTR in December 1993, the detector was 15.5 meters from the torus in a large collimator. For a rate of 1 {times} 10{sup 18} n/sec from the tokamak, it operated in an equivalent background of 1 {times} 10{sup 10} gammas/cm{sup 2}/sec ({approximately}4 mA current drain) at a DT count rate of 200 kHz.

Wurden, G.A.; Chrien, R.E.; Barnes, C.W.; Sailor, W.C. [Los Alamos National Lab., NM (United States); Roquemore, A.L. [Princeton Plasma Physics Lab., NJ (United States); Lavelle, M.J.; O`Gara, P.M.; Jordan, R.J. [EG& G Energy Measurements, Las Vegas, NV (United States)

1994-07-01T23:59:59.000Z

152

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

SciTech Connect

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

153

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

154

Neutron Energy Response and Background of Electrochemically Etched Nuclear Track Detectors: Study of Various CR-39 Materials  

Science Journals Connector (OSTI)

......Radiation Protection Dosimetry Article Neutron Energy Response and Background of Electrochemically Etched Nuclear Track Detectors: Study of Various CR-39...experiments. Results are presented for the energy dependence of the response of the various......

M. Luszik-Bhadra; W.G. Alberts; E. Piesch

1990-08-01T23:59:59.000Z

155

Investigation of the MTC noise estimation with a coupled neutronic/thermal-hydraulic dedicated model - 'Closing the loop'  

SciTech Connect

This paper investigates the reliability of different noise estimators aimed at determining the Moderator Temperature Coefficient (MTC) of reactivity in Pressurized Water Reactors. By monitoring the inherent fluctuations in the neutron flux and moderator temperature, an on-line monitoring of the MTC without perturbing reactor operation is possible. In order to get an accurate estimation of the MTC by noise analysis, the point-kinetic component of the neutron noise and the core-averaged moderator temperature noise have to be used. Because of the scarcity of the in-core instrumentation, the determination of these quantities is difficult, and several possibilities thus exist for estimating the MTC by noise analysis. Furthermore, the effect of feedback has to be negligible at the frequency chosen for estimating the MTC in order to get a proper determination of the MTC. By using an integrated neutronic/thermal- hydraulic model specifically developed for estimating the three-dimensional distributions of the fluctuations in neutron flux, moderator properties, and fuel temperature, different approaches for estimating the MTC by noise analysis can be tested individually. It is demonstrated that a reliable MTC estimation can only be provided if the core is equipped with a sufficient number of both neutron detectors and temperature sensors, i.e. if the core contain in-core detectors monitoring both the axial and radial distributions of the fluctuations in neutron flux and moderator temperature. It is further proven that the effect of feedback is negligible for frequencies higher than 0.1 Hz, and thus the MTC noise estimations have to be performed at higher frequencies. (authors)

Demaziere, C.; Larsson, V. [Div. of Nuclear Engineering, Dept. of Applied Physics, Chalmers Univ. of Technology, SE-41296 Gothenburg (Sweden)

2012-07-01T23:59:59.000Z

156

CVD Diamond Detectors for Current Mode Neutron Time-of-Flight Spectroscopy at OMEGA/NIF  

SciTech Connect

We have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.4 mA/W at 500 V/mm and 4.0 mA/W at 1000 V/mm. These values are approximately 2 to 5x times higher than those reported for natural Type IIa diamond at similar E-field and thickness (1mm). These characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to target chamber center (TCC), and would record neutron spectra fast enough such that backscattered neutrons and x-rays from the target chamber wall would not be a concern. The acquired neutron spectra could then be used to extract DD fuel areal density from the downscattered secondary to secondary ratio.

G. J. Schmid; V. Yu. Glebov; A. V. Friensehner; D. R. Hargrove; S. P. Hatchett; N. Izumi; R. A. Lerche; T. W. Phillips; T. C. Sangster; C. Silbernagel; C. Stoecki

2001-07-01T23:59:59.000Z

157

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

SciTech Connect

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

158

A water-based neutron detector as a well multiplicity counter  

Science Journals Connector (OSTI)

Abstract We report the performance characteristics of a water-based neutron detecting multiplicity counter for the non-destructive assay of fissile sources. This technique could replace or supplement existing 3He-based multiplicity counters. The counter is a 1.02 m3 tank containing pure deionized water doped with 0.5% GdCl3. It has highly reflective walls and eight 10-in. \\{PMTs\\} mounted at the top. An unshielded source well of 19 cm diameter, mounted at the top and center, extends 73 cm down into the detector. The counter was evaluated using low intensity 252Cf and 60Co sources, and a fast pulsing LED to simulate higher intensity backgrounds. At low gamma ray intensities (~200 kBq or less) we report an absolute neutron detection efficiency of 28% and a 60Co rejection/suppression factor of ~108 to 1. For sources with high gamma ray intensities, the neutron efficiency was 22%±1% up to a 60Co equivalent activity of 4 MBq. The detector background event rate, primarily due to muons and other cosmogenic particles, was found to be stable over a period of almost three months. The minimum detectable neutron source intensity above background was 3.1 n/s, assuming a one-hour data acquisition.

S. Dazeley; A. Asghari; A. Bernstein; N.S. Bowden; V. Mozin

2015-01-01T23:59:59.000Z

159

Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT)  

Science Journals Connector (OSTI)

......the gamma rays in the reactor is different from that...Sesonske, A. Nuclear Reactor Engineering (Van Nostrand...column of the Tapiro reactor (ENEA-Casaccia RC...hence the precision and reliability of the fast neutron...Design Equipment Failure Analysis Gamma Rays therapeutic......

A. Cecilia; S. Baccaro; A. Cemmi; V. Colli; G. Gambarini; G. Rosi; L. Scolari

2004-08-01T23:59:59.000Z

160

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

SciTech Connect

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

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

Background and radiation resistance tests of neutral particle analyzer detectors for ITER by using a fast neutron beam  

SciTech Connect

The radiation resistance and background sensitivity of scintillation (Hamamatsu H8500D photo-multiplier) and semiconductor (ORTEC BF-018-100-60 and BU-012-050-100) detectors to neutron and gamma radiation were investigated. Conclusions are drawn concerning the possibility of using such detectors in neutral particle analyzers that are being developed for ITER at the Ioffe Institute.

Afanasyev, V. I. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kozlovskii, S. S.; Makar'in, D. V. [St. Petersburg State Polytechnical University (Russian Federation); Mel'nik, A. D.; Mironov, M. I.; Nesenevich, V. G.; Petrov, M. P.; Petrov, S. Ya.; Chernyshev, F. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2010-05-15T23:59:59.000Z

162

Mirror thermal noise in laser interferometer gravitational wave detectors operating at room and cryogenic temperature  

E-Print Network (OSTI)

Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.

Janyce Franc; Nazario Morgado; Raffaele Flaminio; Ronny Nawrodt; Iain Martin; Liam Cunningham; Alan Cumming; Sheila Rowan; James Hough

2009-12-01T23:59:59.000Z

163

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

164

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

SciTech Connect

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

165

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

166

Characterization of a thermal neutron beam monitor based on gas electron multiplier technology  

Science Journals Connector (OSTI)

......from gadolinium isotopes (which adsorb neutrons...about 3980b and boron and thermal neutrons...Experimental details Boron carbide (B C...view allows the determination of the coating thickness...Simulation of different isotopes is obtained with...High-voltage scan and determination of working point......

Gabriele Croci; Carlo Cazzaniga; Gerardo Claps; Marco Tardocchi; Marica Rebai; Fabrizio Murtas; Espedito Vassallo; Roberto Caniello; Enrico Perelli Cippo; Giovanni Grosso; Valentino Rigato; Giuseppe Gorini

2014-08-01T23:59:59.000Z

167

Quasi-monoenergetic neutron reference fields in the energy range from thermal to 200 MeV  

Science Journals Connector (OSTI)

......NEUTRON BEAM The thermal reference beam(5) is installed at the research reactor FRG-1 of the GKSS research centre at Geesthacht, Germany. A bent neutron guide is used to transport thermal neutrons from the reactor to the experimental station. The......

R. Nolte; M. S. Allie; R. Böttger; F. D. Brooks; A. Buffler; V. Dangendorf; H. Friedrich; S. Guldbakke; H. Klein; J. P. Meulders; D. Schlegel; H. Schuhmacher; F. D. Smit

2004-08-01T23:59:59.000Z

168

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

2014-10-10T23:59:59.000Z

169

Thermal emission of neutron stars with internal heaters  

Science Journals Connector (OSTI)

......our consideration of thermal coupling/decoupling...dependence of redshifted thermal heat-conduction flux...star (in units of solar luminosity Lo) for...sufficiently long time to overheat the crust and violate the thermal balance of the crust......

A. D. Kaminker; A. A. Kaurov; A. Y. Potekhin; D. G. Yakovlev

2014-01-01T23:59:59.000Z

170

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

171

Defects in {sup 6}LiInSe{sub 2} neutron detector investigated by photo-induced current transient spectroscopy and photoluminescence  

SciTech Connect

{sup 6}LiInSe{sub 2} is a promising thermal neutron semiconductor detector material. The performance of the detector is affected by the carrier mobility-lifetime products. Therefore, defects that function as carrier recombination centers need to be identified. In this letter, characterization of defect levels in {sup 6}LiInSe{sub 2} by photo-induced current transient spectroscopy (PICTS) and photoluminescence is reported. PICTS measurements revealed electron-related defects located at 0.22, 0.36, and 0.55 eV and hole-related defects at 0.19, 0.30, and 0.73 eV. Free exciton and donor-acceptor pairs (DAP) emissions were observed. The PICTS defect level values are consistent with those extracted from DAP transitions.

Cui, Yunlong; Bhattacharya, Pijush; Buliga, Vladimir; Tupitsyn, Eugene; Rowe, Emmanuel; Wiggins, Brenden [Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee 37208 (United States)] [Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee 37208 (United States); Johnstone, Daniel [SEMETROL, 13312 Shore Lake Turn, Chesterfield, Virginia 23838 (United States)] [SEMETROL, 13312 Shore Lake Turn, Chesterfield, Virginia 23838 (United States); Stowe, Ashley [Y-12 National Security Complex, Oak Ridge, Tennessee 37830 (United States)] [Y-12 National Security Complex, Oak Ridge, Tennessee 37830 (United States); Burger, Arnold [Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee 37208 (United States) [Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee 37208 (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2013-08-26T23:59:59.000Z

172

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

SciTech Connect

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

173

Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced fission reactions on Pu239  

Science Journals Connector (OSTI)

Prompt fission neutrons following the thermal and 0.5 MeV neutron-induced fission reaction of Pu239 are calculated using a Monte Carlo approach to the evaporation of the excited fission fragments. Exclusive data such as the multiplicity distribution P(?), the average multiplicity as a function of fragment mass ??(A), and many others are inferred in addition to the most used average prompt fission neutron spectrum ?(Ein,Eout), as well as average neutron multiplicity ??. Experimental information on these more exclusive data help constrain the Monte Carlo model parameters. The calculated average total neutron multiplicity is ??c=2.871 in very close agreement with the evaluated value ??e=2.8725 present in the ENDF/B-VII.0 library. The neutron multiplicity distribution P(?) is in very good agreement with the evaluation by Holden and Zucker. The calculated average spectrum differs in shape from the ENDF/B-VII.0 spectrum, evaluated with the Madland-Nix model. In particular, we predict more neutrons in the low-energy tail of the spectrum (below about 300 keV) than the Madland-Nix calculations, casting some doubts on how much scission neutrons contribute to the shape of the low-energy tail of the spectrum. The spectrum high-energy tail is very sensitive to the total kinetic energy distribution of the fragments as well as to the total excitation energy sharing at scission. Present experimental uncertainties on measured spectra above 6 MeV are too large to distinguish between various theoretical hypotheses. Finally, comparisons of the Monte Carlo results with experimental data on ??(A) indicate that more neutrons are emitted from the light fragments than the heavy ones, in agreement with previous works.

P. Talou; B. Becker; T. Kawano; M. B. Chadwick; Y. Danon

2011-06-23T23:59:59.000Z

174

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

175

Uniformity measurements and new positioning algorithms for wavelength-shifting fiber neutron detectors  

SciTech Connect

Wavelength-shifting (WLS) fiber scintillator detectors were successfully installed at two neutron powder diffractometers at the Spallation Neutron Source (SNS). However, they have the following second-order disadvantages: i). they cannot have both high efficiency and images free of ghosting (position misassignment) concomitantly; ii). the apparent detection efficiency and spatial resolution are not uniform. These issues are related to the diffusion of scintillation photons and the fluctuation in the number of photons (quantum noise) collected by photo-multiplier tubes (PMTs). To mitigate these two issues, we developed two statistics-based positioning algorithms, i.e., a centroid algorithm (CEA) and a correlation algorithm (CA). Compared with the generally used maximum-photon algorithm (MPA), CEA eliminates the ghosting with only about a 10% loss in detection efficiency, and provides better uniformity in detection efficiency and intrinsic background. CA can effectively eliminate ghosting too, but the loss of efficiency at the group boundaries of PMTs is large. The results indicate that both algorithms can reduce the influence of quantum noise on the neutron positioning.

Wang, Cai-Lin [ORNL] [ORNL; Riedel, Richard A [ORNL] [ORNL

2014-01-01T23:59:59.000Z

176

Surface physics with cold and thermal neutron reflectometry. Progress report, April 1, 1991--September 30, 1993  

SciTech Connect

Within the past two and one half years of the project ``Surface Physics With Cold and Thermal Neutron Reflectometry`` a new thermal neutron reflectometer was constructed at the Rhode Island Nuclear Science Center (RINSC). It was used to study various liquid and solid surfaces. Furthermore, neutron reflection experiments were be un at different laboratories in collaboration with Dr. G.P. Fetcher (at Argonne National Laboratory), Dr. T. Russell (IBM Almaden) and Drs. S.K. Satija and A. Karim (at the National Institute for Standards and Technology). The available resources allowed partial construction of an imaging system for ultracold neutrons. It is expected to provide an extremely high resolution in momentum and energy transfer in surface studies using neutron reflectometry. Much of the work reported here was motivated by the possibility of later implementation at the planned Advanced Neutron Source at Oak Ridge. In a separate project the first concrete plans for an intense source of ultracold neutrons for the Advanced Neutron Source were developed.

Steyerl, A.

1993-09-01T23:59:59.000Z

177

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

SciTech Connect

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

178

Thermal conductivity of diamond-loaded glues for the ATLAS particle physics detector  

E-Print Network (OSTI)

The ATLAS experiment is one of two large general-purpose particle detectors at the Large Hadron Collider (LHC) at the CERN laboratory in Geneva, Switzerland. ATLAS has been collecting data from the collisions of protons since December 2009, in order to investigate the conditions that existed during the early Universe and the origins of mass, and other topics in fundamental particle physics. The innermost layers of the ATLAS detector will be exposed to the most radiation over the first few years of operation at the LHC. In particular, the layer closest to the beam pipe, the B-layer, will degrade over time due to the added radiation. To compensate for its degradation, it will be replaced with an Insertable B-Layer (IBL) around 2016. The design of and R&D for the IBL is ongoing, as the hope is to use the most current technologies in the building of this new sub-detector layer. One topic of interest is the use of more thermally conductive glues in the construction of the IBL, in order to facilitate in the dissipation of heat from the detector. In this paper the measurement and use of highly thermally conductive glues, in particular those that are diamond-loaded, will be discussed. The modified transient plane source technique for thermal conductivity is applied in characterizing the glues across a wide temperature range.

E. A. Ouellette; A. Harris

2010-08-04T23:59:59.000Z

179

Neutron Production from Feedback Controlled Thermal Cycling of a Pyroelectric Crystal Stack  

SciTech Connect

The LLNL Crystal Driven Neutron Source is operational and has produced record ion currents of {approx}10 nA and neutron output of 1.9 ({+-}0.3) x 10{sup 5} per thermal cycle using a crystal heating rate of 0.2 C/s from 10 C to 110 C. A 3 cm diameter by 1 cm thick LiTaO{sub 3} crystal with a socket secured field emitter tip is thermally cycled with feedback control for ionization and acceleration of deuterons onto a deuterated target to produce D-D fusion neutrons. The entire crystal and temperature system is mounted on a bellows which allows movement of the crystal along the beam axis and is completely contained on a single small vacuum flange. The modular crystal assembly permitted experimental flexibility. Operationally, flashover breakdowns along the side of the crystal and poor emitter tip characteristics can limit the neutron source. The experimental neutron results extend earlier published work by increasing the ion current and pulse length significantly to achieve a factor-of-two higher neutron output per thermal cycle. These findings are reviewed along with details of the instrument.

Tang, V; Meyer, G; Schmid, G; Spadaccini, C; Kerr, P; Rusnak, B; Sampayan, S; Naranjo, B; Putterman, S

2007-08-09T23:59:59.000Z

180

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

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.


181

Elemental composition of nickel silicide layers using thermal and fast neutrons  

SciTech Connect

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

182

Energy Spectrum of Neutrons from Thermal Fission of U235  

Science Journals Connector (OSTI)

A proton recoil counter has been used to determine the neutron spectrum, in the energy range 3.3-17 Mev, of a beam produced by irradiating 95 percent U235 (metal) in the central experimental hole of the Los Alamos Homogeneous Reactor. Most of the fissions were induced by slow neutrons. The data are combined with those obtained by D. Hill and by T. W. Bonner, R. A. Ferrell and M. C. Rinehart; the composite spectrum so obtained extends from 0.075 to 17 Mev. Fits with two general formulas are discussed.

B. E. Watt

1952-09-15T23:59:59.000Z

183

Measurements of gamma dose and thermal neutron fluence in phantoms exposed to a BNCT epithermal beam with TLD-700  

Science Journals Connector (OSTI)

......epithermal neutron beam for boron neutron capture therapy...separation. INTRODUCTION Boron neutron capture therapy...accumulation of the isotope 10B in tumour tissue...necessary and that for the determination of the ratio R n, a...Carrara M., Borroni M. Determination of gamma dose and thermal......

G. Gambarini; D. Magni; V. Regazzoni; M. Borroni; M. Carrara; E. Pignoli; J. Burian; M. Marek; V. Klupak; L. Viererbl

2014-10-01T23:59:59.000Z

184

Study on generating of thermal neutron scattering cross sections for LiH  

SciTech Connect

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

185

detectors  

NLE Websites -- All DOE Office Websites (Extended Search)

Detectors are made of many layers specialized to identify and record Detectors are made of many layers specialized to identify and record information about the many particles that result from a collision of a proton and an antiproton. A sphere would be the best shape to surround the collision point, but it is cheaper to make cylindrical detectors. Because the particles in the Fermilab accelerator have so much energy, detectors may be 3-5 stories high. The layers of a generic detector: (Run the cursor over the names.) Beam Pipe Tracker Electromagnetic Calorimeter Hadron Calorimeter Magnet Muon Detector Anatomy of a Detector - Identifying Particles - CDF Detector - D0 Detector - Links Project Contact: Thomas Jordan - jordant@fnal.gov Web Maintainer: qnet-webmaster@fnal.gov Last Update: April 13, 2001 http://quarknet.fnal.gov/run2/news

186

Direct Measurement of Neutron?Neutron Scattering  

Science Journals Connector (OSTI)

In order to resolve long?standing discrepancies in indirect measurements of the neutron?neutron scattering length ann and contribute to solving the problem of the charge symmetry of the nuclear force the collaboration DIANNA (Direct Investigation of ann Association) plans to measure the neutron?neutron scattering cross section ? nn . The key issue of our approach is the use of the through?channel in the Russia reactor YAGUAR with a peak neutron flux of 1018 /cm2/s. The proposed experimental setup is described. Results of calculations are presented to connect ? nn with the nn?collision detector count rate and the neutron flux density in the reactor channel. Measurements of the thermal neutron fields inside polyethylene converters show excellent prospects for the realization of the direct nn?experiment.

E. I. Sharapov; C. D. Bowman; B. E. Crawford; W. I. Furman; C. R. Howell; B. G. Levakov; V. I. Litvin; W. I. Lychagin; A. E. Lyzhin; E. P. Magda; G. E. Mitchell; G. V. Muzichka; G. V. Nekhaev; Yu. V. Safronov; V. N. Shvetsov; S. L. Stephenson; A. V. Strelkov; W. Tornow

2003-01-01T23:59:59.000Z

187

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

188

Surface physics with cold and thermal neutron reflectometry  

SciTech Connect

Three aspects of the research project Surface physics with cold and ultracold neutron reflectometry'' were stressed during the present first year: (1) Setup of the reflectometer facility at the research reactor of the Rhode Island Nuclear Science Center. The installation provides a narrow pencil beam'' analyzed by time of flight using a chopper system. Following beam characterization and a test measurement of the total cross section of copper single crystal first reflectivity measurements are currently performed using a supermirror. (2) Design stud for the ultracold neutron imaging system, with involvement of the relevant industry. Bids are available for several components indicating that it will be very difficult to build the entire system unless further funds become available. (3) Analysis of features of neutron reflection from surfaces with special emphasis on the effect of surface roughness both on the specular beam and the diffusely reflected and refracted intensity. Previous theoretical studies were supplemented by further numerical calculations of diffuse scattering distributions using different models. Application of ultracold and cold neutron reflectometry to the study of liquid-vapor phase transition were discussed. The theoretical work also includes the development of tentative ideas for novel fundamental physics experiments.

Steyerl, A.

1991-11-01T23:59:59.000Z

189

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

SciTech Connect

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

190

NEUTRON: a program for computing phonon extinction rules of inelastic neutron scattering and thermal diffuse scattering experiments  

Science Journals Connector (OSTI)

NEUTRON is a program for the determination of phonon extinction rules in inelastic neutron scattering experiments.

Kirov, A.K.

2003-07-19T23:59:59.000Z

191

Development of 10B2O3 processing for use as a neutron conversion material  

Science Journals Connector (OSTI)

Development of thermal neutron detectors is critical for a number of homeland security and physics applications. In this work, we describe our efforts towards developing boron-10 oxide (10B2O3) as a thermal neutr...

L. F. Voss; J. Oiler; A. M. Conway…

2012-01-01T23:59:59.000Z

192

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

SciTech Connect

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

193

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

194

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

SciTech Connect

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

195

DIRECTIONAL DETECTION OF A NEUTRON SOURCE.  

SciTech Connect

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

196

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

SciTech Connect

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

197

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

198

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

SciTech Connect

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

199

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

200

On the scintillation efficiency of carborane-loaded liquid scintillators for thermal neutron detection  

Science Journals Connector (OSTI)

Abstract The scintillation efficiency in response to thermal neutrons was studied by loading different concentrations of carborane (0–8.5 wt%) and naphthalene (0 and 100 g/L) in five liquid organic scintillators. The sample was characterized in Pb and Cd shields under the irradiation of the thermal neutrons from a 252Cf source. A method was developed to extract the net neutron response from the pulse-height spectra. It was found that the order of scintillation efficiencies for both ?-rays and thermal neutrons is as follows: diisopropylnaphthalene>toluene (concentrated solutes)>toluene~pseudocumene~m-xylene. The quench constants, obtained by fitting the Stern–Volmer model to the plots of light output versus carborane concentration, are in the range of 0.35–1.4 M?1 for all the scintillators. The Birks factors, estimated using the specific energy loss profiles of the incident particles, are in the range of 9.3–14 mg cm?2 MeV?1 for all the samples. The light outputs are in the range of 63–86 keV electron equivalents (keVee) in response to thermal neutrons. Loading naphthalene generally promotes the scintillation efficiency of the scintillator with a benzene derivative solvent. Among all the scintillators tested, the diisopropylnaphthalene-based scintillator shows the highest scintillation efficiency, lowest Birks factor, and smallest quench constants. These properties are primarily attributed to the double fused benzene-ring structure of the solvent, which is more efficient to populate to the excited singlet state under ionizing radiation and to transfer the excitation energy to the fluorescent solutes.

Zheng Chang; Nkemakonam C. Okoye; Matthew J. Urffer; Alexander D. Green; Kyle E. Childs; Laurence F. Miller

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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201

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

202

Rotational Corrections to Neutron-Star Radius Measurements from Thermal Spectra  

E-Print Network (OSTI)

We calculate the rotational broadening in the observed thermal spectra of neutron stars spinning at moderate rates in the Hartle-Thorne approximation. These calculations accurately account for the effects of the second-order Doppler boosts as well as for the oblate shapes and the quadrupole moments of the neutron stars. We find that fitting the spectra and inferring the bolometric fluxes under the assumption that a star is not rotating causes an underestimate of the inferred fluxes and, thus, radii. The correction depends on the stellar spin, radius, and observer's inclination. For a 10 km neutron star spinning at 600 Hz, the rotational correction to the flux is ~1-4%, while for a 15 km neutron star with the same spin period, the correction ranges from 2% for pole-on sources to 12% for edge-on sources. We calculate the inclination-averaged corrections to inferred radii as a function of the neutron-star radius and mass and provide an empirical formula for the corrections. For realistic neutron star parameters (1.4 M$_\\odot$, 12 km, 600 Hz), the stellar radius is on the order of 4% larger than the radius inferred under the assumption that the star is not spinning.

Michi Baubock; Feryal Ozel; Dimitrios Psaltis; Sharon M. Morsink

2014-07-11T23:59:59.000Z

203

Rotational Corrections to Neutron-Star Radius Measurements from Thermal Spectra  

E-Print Network (OSTI)

We calculate the rotational broadening in the observed thermal spectra of neutron stars spinning at moderate rates in the Hartle-Thorne approximation. These calculations accurately account for the effects of the second-order Doppler boosts as well as for the oblate shapes and the quadrupole moments of the neutron stars. We find that fitting the spectra and inferring the bolometric fluxes under the assumption that a star is not rotating causes an underestimate of the inferred fluxes and, thus, radii. The correction depends on the stellar spin, radius, and observer's inclination. For a 10 km neutron star spinning at 600 Hz, the rotational correction to the flux is ~1-4%, while for a 15 km neutron star with the same spin period, the correction ranges from 2% for pole-on sources to 12% for edge-on sources. We calculate the inclination-averaged corrections to inferred radii as a function of the neutron-star radius and mass and provide an empirical formula for the corrections. For realistic neutron star parameters ...

Baubock, Michi; Psaltis, Dimitrios; Morsink, Sharon M

2014-01-01T23:59:59.000Z

204

Ratio of the ternary-to-binary fission cross sections induced by thermal and resonance neutrons in 241Pu  

Science Journals Connector (OSTI)

The ternary-to-binary fission cross-section ratio (T/B) was determined for 241Pu for neutron induced fission in the energy region from 0.01 eV to 50 eV. The ternary and binary fission time-of-flight spectra were recorded at a 8.1 m flightpath at the CBNM Linac with a bank of four large gold-silicon surface-barrier detectors viewing a 1 mg/cm2 241Pu target. The ternary alpha pulse-height spectrum in the neutron energy region of interest was checked continuously. From the time-of-flight spectra the ratios of the areas of the strongest resonances in ternary and in binary fission were calculated; in the neutron energy region from 0.01 to 0.5 eV ratios were calculated for 18 zones throughout the spectrum. In the energy region from 1 to 50 eV the T/B ratio varies significantly from resonance to resonance, allowing a classification into a “high” and a “low” group. Although the statistical accuracy is poorer in the region below 1 eV we deduce from these T/B data that the 0.260 eV resonance probably belongs to the “high” group and also that there is only a slight difference between the T/B value at 0.260 eV and at thermal energy. We correlate these T/B values with the resonance spin J in terms of the channel theory of fission.

C. Wagemans; A.J. Deruytter

1974-01-01T23:59:59.000Z

205

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

206

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

207

Antineutrino spectra from 241Pu and 239Pu thermal neutron fission products  

Science Journals Connector (OSTI)

The antineutrino spectrum of fission products from thermal neutron induced fission of 241Pu was derived from a measurement of the correlated beta spectrum. The energy range 1.5 MeV to 9 MeV was covered and a precision of 4% was achieved at 4 MeV. A revised version of the antineutrino spectrum from 239Pu fission is also presented.

A.A. Hahn; K. Schreckenbach; W. Gelletly; F. von Feilitzsch; G. Colvin; B. Krusche

1989-01-01T23:59:59.000Z

208

Detectors  

NLE Websites -- All DOE Office Websites (Extended Search)

Detectores Detectores Avanzar Volver Principal ESTOY PERDIDO!!! Rutherford utilizó el sulfuro de zinc para detectar la presencia de partículas alfa invisibles, y mediante este conocimiento pudo determinar las trayectorias de las partículas alfa; del mismo modo los físicos modernos deben observar los productos, resultantes del decaimiento de las partículas, y deducir así la existencia de partículas. Para detectar las distintas partículas y los productos de decaimiento, los físicos han diseñado detectores multicomponentes que examinan diferentes aspectos de un evento. Cada componente de un detector moderno se emplea para medir la energía y el ímpetu de una partícula, y/o para distinguir entre sí partículas de diferentes tipos. Cuando todos los componentes

209

New idea of a small-sized neutron detector with a plastic fibre  

Science Journals Connector (OSTI)

......National Institute of Advanced Industrial Science...Kyoto University Reactor Research Institute...National Institute of Advanced Industrial Science...Kyoto University Reactor (KUR) and the calibration...neutrons from the heavy water neutron irradiation......

Tetsuro Matsumoto; Hideki Harano; Akihiko Masuda; Jun Nishiyama; Yoshinori Sakurai; Akira Uritani

2011-07-01T23:59:59.000Z

210

Inelastic Thermal Neutron Scattering Cross Sections for Reactor-grade Graphite  

Science Journals Connector (OSTI)

Abstract Current calculations of the inelastic thermal neutron scattering cross sections of graphite are based on representing the material using ideal single crystal models. However, the density of reactor-grade graphite is usually in the range of 1.5 g/cm3 to approximately 1.8 g/cm3, while ideal graphite is characterized by a density of nearly 2.25 g/cm3. This difference in density is manifested as a significant fraction of porosity in the structure of reactor-grade graphite. To account for the porosity effect on the cross sections, classical molecular dynamics (MD) techniques were employed to simulate graphite structures with porosity concentrations of 10% and 30%, which are taken to be representative of reactor-grade graphite. The phonon density of states for the porous systems were generated as the power spectrum of the MD velocity autocorrelation functions. The analysis revealed that for porous graphite the phonon density of states exhibit a rise in the lower frequency region that is relevant to neutron thermalization. Using the generated phonon density of states, the inelastic thermal neutron scattering cross sections were calculated using the NJOY code system. While marked discrepancies exist between measurements and calculations based on ideal graphite models, favorable agreement is found between the calculations based on the porous graphite models and measured data.

A.I. Hawari; V.H. Gillete

2014-01-01T23:59:59.000Z

211

Continuous gravitational waves from isolated Galactic neutron stars in the advanced detector era  

Science Journals Connector (OSTI)

We consider a simulated population of isolated Galactic neutron stars. The rotational frequency of each neutron star evolves through a combination of electromagnetic and gravitational-wave emission. The magnetic field strength dictates the dipolar emission, and the ellipticity (a measure of a neutron star’s deformation) dictates the gravitational-wave emission. Through both analytic and numerical means, we assess the detectability of the Galactic neutron star population and bound the magnetic field strength and ellipticity parameter space of Galactic neutron stars with or without a direct gravitational-wave detection. While our simulated population is primitive, this work establishes a framework by which future efforts can be conducted.

Leslie Wade; Xavier Siemens; David L. Kaplan; Benjamin Knispel; Bruce Allen

2012-12-04T23:59:59.000Z

212

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

SciTech Connect

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

213

New thermal neutron scattering files for ENDF/B-VI release 2  

SciTech Connect

At thermal neutron energies, the binding of the scattering nucleus in a solid, liquid, or gas affects the cross section and the distribution of secondary neutrons. These effects are described in the thermal sub-library of Version VI of the Evaluated Nuclear Data Files (ENDF/B-VI) using the File 7 format. In the original release of the ENDF/B-VI library, the data in File 7 were obtained by converting the thermal scattering evaluations of ENDF/B-III to the ENDF-6 format. These original evaluations were prepared at General Atomics (GA) in the late sixties, and they suffer from accuracy limitations imposed by the computers of the day. This report describes new evaluations for six of the thermal moderator materials and six new cold moderator materials. The calculations were made with the LEAPR module of NJOY, which uses methods based on the British code LEAP, together with the original GA physics models, to obtain new ENDF files that are accurate over a wider range of energy and momentum transfer than the existing files. The new materials are H in H{sub 2}O, Be metal, Be in BeO, C in graphite, H in ZrH, Zr in ZrH, liquid ortho-hydrogen, liquid para-hydrogen, liquid ortho-deuterium, liquid para-deuterium liquid methane, and solid methane.

MacFarlane, R.E.

1994-03-01T23:59:59.000Z

214

Measurement of the fluence response of the GSI neutron ball dosemeter in the energy range from thermal to 19 MeV  

Science Journals Connector (OSTI)

......the GKSS research reactor FRG-1 in Geesthacht. For the accelerator measurements...thermal neutrons was performed at the Geesthacht Neutron Facility (GeNF) laboratory...the GKSS research reactor FRG-1 in Geesthacht. For the accelerator measurements......

G. Fehrenbacher; E. Kozlova; F. Gutermuth; T. Radon; R. Schütz; R. Nolte; R. Böttger

2007-08-01T23:59:59.000Z

215

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

SciTech Connect

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

216

Comparison of discrete and continuous thermal neutron scattering treatments in MCNP5  

SciTech Connect

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

217

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

218

Crystal structures and thermal expansion of -MgSO4 and -MgSO4 from 4.2 to 300 K by neutron powder diffraction  

Science Journals Connector (OSTI)

Powder neutron refinements of two MgSO4 polymorphs are presented, and their highly anisotropic thermal expansivity is analysed using a Debye model.

Fortes, A.D.

2007-07-13T23:59:59.000Z

219

A balloon borne detector to determine high energy neutrons in energy and direction  

Science Journals Connector (OSTI)

A balloon borne experiment for the measurement of solar and atmospheric neutrons in energy and direction above 50 MeV is described. The principle of measurement is the double elastic scattering process of the incoming neutrons with hydrogen atoms. For the registration of the recoil protons spark chambers are used. The hydrogen is contained in thin plastic scintillator and polyethylene plates, which are inserted between the spark chambers. The sparks are recorded photographically from two sides. A detailed description of the design of the experiment is given. The properties of the apparatus were determined by atmospheric neutron measurements at ground level.

E. Heidbreder; K. Pinkau; C. Reppin; V. Schönfelder

1970-01-01T23:59:59.000Z

220

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

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.


221

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

222

Dead-time effects of neutron detectors due to pulsed radiation  

Science Journals Connector (OSTI)

......distance from the accelerator. If electrons are lost in the vacuum system, they...neutrons by nuclear reactions...materials used in vacuum systems of accelerators. Because the...at electron accelerators. For both nuclear reactions......

K. Ott; M. Helmecke; M. Luszik-Bhadra; M. Martin; A. Weber

2013-07-01T23:59:59.000Z

223

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 $\\left( 5.82 \\pm 0.02 \\right)\\%$ 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 $\\left( 5.88 \\pm 0.78 \\right)\\times 10^{-3}$ and $\\left( 7.80 \\pm 0.77 \\right)\\times 10^{-5}$ 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 $< 3.70 \\times 10^{-8}$. The neutron/$\\gamma$ discrimination capabilities are improved in circumstances when a neutron capture signal in th...

Rich, G C; Martinez, H P; Gushue, T

2014-01-01T23:59:59.000Z

224

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

SciTech Connect

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

225

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

2013-06-17T23:59:59.000Z

226

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

227

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

SciTech Connect

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

228

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

229

Observations of Solar Neutron Events by Ground Based Detectors, and Their Interpretation  

Science Journals Connector (OSTI)

Chiba et al. (1992a, b...) came to conclusion that the excess signals in the scintillators can be interpreted as muon production by solar neutrons of energies 5–10 GeV and the average flux in this energy interval...

Prof. Lev I. Dorman

2010-01-01T23:59:59.000Z

230

A fast response and -insensitive neutron detector based on parallel-plate avalanche counter  

Science Journals Connector (OSTI)

......limitations in nuclear material handling or to safety...a foil of converter materials such as 6Li or 10B or...multiplied near the cathode, contribute most to...glass-epoxy frame. The cathode was made of 20-microm nickel foil. The active area of the detector......

M. Nakhostin; M. Baba; T. Itoga; T. Oishi; Y. Unno; S. Kamada; T. Okuji

2008-05-01T23:59:59.000Z

231

Investigation of the possibility to use a fine-mesh solver for resolving coupled neutronics and thermal-hydraulics  

SciTech Connect

The development of a fine-mesh coupled neutronic/thermal-hydraulic solver is touched upon in this paper. The reported work investigates the feasibility of using finite volume techniques to discretize a set of conservation equations modeling neutron transport, fluid dynamics, and heat transfer within a single numerical tool. With the long-term objective of developing fine-mesh computing capabilities for a few selected fuel assemblies in a nuclear core, this preliminary study considers an infinite array of a single fuel assembly having a finite height. Thermal-hydraulic conditions close to the ones existing in PWRs are taken as a first test case. The neutronic modeling relies on the diffusion approximation in a multi-energy group formalism, with cross-sections pre-calculated and tabulated at the sub-pin level using a Monte Carlo technique. The thermal-hydraulics is based on the Navier-Stokes equations, complemented by an energy conservation equation. The non-linear coupling terms between the different conservation equations are fully resolved using classical iteration techniques. Early tests demonstrate that the numerical tool provides an unprecedented level of details of the coupled solution estimated within the same numerical tool and thus avoiding any external data transfer, using fully consistent models between the neutronics and the thermal-hydraulics. (authors)

Jareteg, K.; Vinai, P.; Demaziere, C. [Chalmers University of Technology, Department of Applied Physics, Division of Nuclear Engineering, SE-412 96 Gothenburg (Sweden)

2013-07-01T23:59:59.000Z

232

0-600 kev Gamma-Ray Spectra from Thermal Neutron Capture in the Region A=104 to 198  

Science Journals Connector (OSTI)

The energies and absolute intensities of prominent peaks in the 0-600 kev region of the gamma-ray spectrum following thermal neutron capture have been measured with a single NaI(Tl) scintillation spectrometer. The elements investigated were rhodium, silver, cadmium, indium, antimony, tellurium, iodine, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, hafnium, tantalum, rhenium, iridium, platinum, and gold.

James E. Draper

1959-04-01T23:59:59.000Z

233

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

234

Gamma-gamma directional correlation measurements in 84Kr following thermal neutron capture by natural krypton  

Science Journals Connector (OSTI)

Directional correlations of gamma-ray cascades in 84Kr have been measured following thermal neutron capture by a pressurised natural krypton gas target. Gamma-ray singles spectra were measured up to 5.5 MeV and the correlation data were obtained for the energy range 0.2-2.5 MeV. A decay scheme was developed on the basis of coincidence measurements. The data allow spin-parity assignments to be made to most levels lying below 3.5 MeV and multipole mixing ratios to be evaluated for the more intense transitions. The results are fitted to the SU(5) limit of the IBM-1 and to the IBM-2 and are also compared with the predictions of the dynamic deformation model which indicates that 84Kr is the only krypton isotope with a prolate equilibrium shape. A possible mixed symmetry 2+ state at 2.623 MeV is identified.

S A Hamada; W D Hamilton; F Hoyler

1987-01-01T23:59:59.000Z

235

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

236

Prompt fission neutron multiplicity and spectrum calculations for thermal and fast neutron induced reactions on 233,231Pa nuclei  

Science Journals Connector (OSTI)

The prompt fission neutron multiplicity and spectra of 233Pa(n, f) and 231Pa(n, f) were calculated for incident neutron energies up to 50 MeV and 30 MeV, respectively using refined neutron evaporation models. Those models have been already successfully applied to calculate the prompt neutron multiplicities and spectra for many actinides. The unique experimental data concerning the fission fragment mass distribution and total kinetic energy for the 234,233,232Pa fissioning nuclei were exploited in the frame of the Point-by-Point treatment. The total average prompt neutron multiplicity, the fission fragment pair multiplicity and the multiplicity dependence on fragment mass (sawtooth) for the reactions 233,232,231Pa(nth, f) and the average values of the model parameters for 234-232Pa fissioning nuclei were calculated. For the other Pa fissioning nuclei involved in the studied reactions relevant parameters were established following systematic trends. Due to a total lack of experimental prompt fission neutron multiplicity and spectrum data for Pa isotopes, the present results were compared with systematic trends following from neighboring actinides. The calculated prompt fission neutron multiplicity as well as the prompt ?-ray energy of the 233,231Pa(n, f) reactions are obtained in very good agreement with all systematic trends.

Anabella Tudora; G. Vladuca; F.-J. Hambsch; D. Filipescu; S. Oberstedt

2008-01-01T23:59:59.000Z

237

Thermal-hydraulic criteria for the APT tungsten neutron source design  

SciTech Connect

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

238

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

SciTech Connect

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

239

Apparatuses and methods for detecting, identifying and quantitating radioactive nuclei and methods of distinguishing neutron stimulation of a radiation particle detector from gamma-ray stimulation of a detector  

DOE Patents (OSTI)

In one aspect, the invention encompasses a method of detecting radioactive decay, comprising: a) providing a sample comprising a radioactive material, the radioactive material generating decay particles; b)providing a plurality of detectors proximate the sample, the detectors comprising a first set and a second set, the first set of the detectors comprising liquid state detectors utilizing liquid scintillation material coupled with photo tubes to generate a first electrical signal in response to decay particles stimulating the liquid scintillation material, the second set of the detectors comprising solid state detectors utilizing a crystalline solid to generate a second electrical signal in response to decay particles stimulating the crystalline solid; c) stimulating at least one of the detectors to generate at least one of the first and second electrical signals, the at least one of the first and second electrical signals being indicative of radioactive decay in the sample. In another aspect, the invention encompasses an apparatus for identifying and quantitating radioactive nuclei of a sample comprising radioactive material that decays to generate neutrons and high-energy .gamma.-rays.

Cole, Jerald D. (Idaho Falls, ID); Drigert, Mark W. (Idaho Falls, ID); Reber, Edward L. (Idaho Falls, ID); Aryaeinejad, Rahmat (Idaho Falls, ID)

2001-01-01T23:59:59.000Z

240

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

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

Construction of Thermal Neutron Calibration Fields Using a Graphite Pile and Americium-Beryllium Neutron Sources at KAERI  

Science Journals Connector (OSTI)

Neutron Measurements / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Protection

B. H. Kim; S. M. Jun; J. S. Kim; K. S. Lim; J. L. Kim

242

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

243

Systematic and statistical errors in a Bayesian approach to the estimation of the neutron-star equation of state using advanced gravitational wave detectors  

Science Journals Connector (OSTI)

Advanced ground-based gravitational-wave detectors are capable of measuring tidal influences in binary neutron-star systems. In this work, we report on the statistical uncertainties in measuring tidal deformability with a full Bayesian parameter estimation implementation. We show how simultaneous measurements of chirp mass and tidal deformability can be used to constrain the neutron-star equation of state. We also study the effects of waveform modeling bias and individual instances of detector noise on these measurements. We notably find that systematic error between post-Newtonian waveform families can significantly bias the estimation of tidal parameters, thus motivating the continued development of waveform models that are more reliable at high frequencies.

Leslie Wade; Jolien D.?E. Creighton; Evan Ochsner; Benjamin D. Lackey; Benjamin F. Farr; Tyson B. Littenberg; Vivien Raymond

2014-05-23T23:59:59.000Z

244

Systematic and statistical errors in a bayesian approach to the estimation of the neutron-star equation of state using advanced gravitational wave detectors  

E-Print Network (OSTI)

Advanced ground-based gravitational-wave detectors are capable of measuring tidal influences in binary neutron-star systems. In this work, we report on the statistical uncertainties in measuring tidal deformability with a full Bayesian parameter estimation implementation. We show how simultaneous measurements of chirp mass and tidal deformability can be used to constrain the neutron-star equation of state. We also study the effects of waveform modeling bias and individual instances of detector noise on these measurements. We notably find that systematic error between post-Newtonian waveform families can significantly bias the estimation of tidal parameters, thus motivating the continued development of waveform models that are more reliable at high frequencies.

Wade, Leslie; Ochsner, Evan; Lackey, Benjamin D; Farr, Benjamin F; Littenberg, Tyson B; Raymond, Vivien

2014-01-01T23:59:59.000Z

245

Systematic and statistical errors in a bayesian approach to the estimation of the neutron-star equation of state using advanced gravitational wave detectors  

E-Print Network (OSTI)

Advanced ground-based gravitational-wave detectors are capable of measuring tidal influences in binary neutron-star systems. In this work, we report on the statistical uncertainties in measuring tidal deformability with a full Bayesian parameter estimation implementation. We show how simultaneous measurements of chirp mass and tidal deformability can be used to constrain the neutron-star equation of state. We also study the effects of waveform modeling bias and individual instances of detector noise on these measurements. We notably find that systematic error between post-Newtonian waveform families can significantly bias the estimation of tidal parameters, thus motivating the continued development of waveform models that are more reliable at high frequencies.

Leslie Wade; Jolien D. E. Creighton; Evan Ochsner; Benjamin D. Lackey; Benjamin F. Farr; Tyson B. Littenberg; Vivien Raymond

2014-02-20T23:59:59.000Z

246

Neutron Detection with Mercuric Iodide  

SciTech Connect

Mercuric iodide is a high-density, high-Z semiconducting material useful for gamma ray detection. This makes it convertible to a thermal neutron detector by covering it with a boron rich material and detecting the 478 keV gamma rays resulting from the {sup 10}B(n, {alpha}){sup 7}Li* reaction. However, the 374 barn thermal capture cross section of {sup nat}Hg, makes the detector itself an attractive absorber, and this has been exploited previously. Since previous work indicates that there are no low-energy gamma rays emitted in coincidence with the 368 keV capture gamma from the dominant {sup 199}Hg(n, {gamma}){sup 200}Hg reaction, only the 368 keV capture gamma is seen with any efficiency a relatively thin (few mm) detector. In this paper we report preliminary measurements of neutrons via capture reactions in a bare mercuric iodide crystal and a crystal covered in {sup 10}B-loaded epoxy. The covered detector is an improvement over the bare detector because the presence of both the 478 and 368 keV gamma rays removes the ambiguity associated with the observation of only one of them. Pulse height spectra, obtained with and without lead and cadmium absorbers, showed the expected gamma rays and demonstrated that they were caused by neutrons.

Bell, Z.A.

2003-06-17T23:59:59.000Z

247

Characteristics of Some Radionuclides of Tungsten, Rhenium, and Osmium Formed by Second-Order Thermal Neutron Capture  

Science Journals Connector (OSTI)

The identification and characteristics of several beta-emitting nuclides are reported. The half-life of W188 is 65 days, Os194 about 700 days, while Re189 might be either of two isotopes having half-lives of about 150 days or of at least five years. The mass assignment of W181 has been confirmed in view of its presence in thermal-neutron irradiated tungsten. Re188 was found to have a half-life of 16.9 hours. No gamma-radiation could be found by absorption measurements to be associated with the 18-hour Ir194 daughter of Os194. Thermal-neutron activation cross sections are reported for most of the nuclides.

Manfred Lindner

1951-10-15T23:59:59.000Z

248

Thermoluminescence dosimetry of a thermal neutron field and comparison with Monte Carlo calculations  

Science Journals Connector (OSTI)

......dosemeters (TLDs) regarding the determination of photon and neutron absorbed...disks, 8 1 mm2; Institute of Isotope and Surface Chemistry, IKI...thermoluminescence dosemeters for Boron Neutron Capture Therapy...dosemeters (TLDs) regarding the determination of photon and neutron absorbed......

A. C. Fernandes; J. P. Santos; A. Kling; J. G. Marques; I. C. Gonçalves; A. Ferro Carvalho; L. Santos; J. Cardoso; M. Osvay

2004-08-01T23:59:59.000Z

249

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

250

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

251

Thermal Neutron Capture Therapy Using 10B1-Bpa: Inducement of Marked Lethal Effect on Melanoma Cells Irrespective of X-Ray Sensitivity  

Science Journals Connector (OSTI)

The G-361 cell line exposed to thermal neutron radiation after treatment with 10B1-BPA (100 ?g/ml medium), however, showed similar sensitivity to the P-39 cell line.

M. Ichihashi; H. Utsumi; H. Tsukamoto; Y. Mishima…

1993-01-01T23:59:59.000Z

252

A Combined Neutronic-Thermal Hydraulic Model of CERMET NTR Reactor  

SciTech Connect

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

253

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

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

254

SciTech Connect: 2010 Neutron Review: ORNL Neutron Sciences Progress...  

Office of Scientific and Technical Information (OSTI)

117; GREENHOUSE GASES; HEAVY ION ACCELERATORS; HELIUM 3; HFIR REACTOR; IRON; JINR; MAGNETIC FIELDS; NEUTRON DETECTORS; NEUTRON SOURCES; NEUTRONS; ORNL; RELIABILITY;...

255

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

SciTech Connect

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

256

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

SciTech Connect

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

257

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

NLE Websites -- All DOE Office Websites (Extended Search)

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

258

Search for inelastic scattering of thermal neutrons by planar magnetic excitations  

SciTech Connect

The experimental technique of searching for high-frequency ({approx}10{sup 13} Hz) surface magnetic excitations by neutron reflectometry is considered. The first experimental results are reported.

Bodnarchuk, V. I., E-mail: bodnarch@nf.jinr.ru; Yaradaykin, C. P. [Joint Institute for Nuclear Research (Russian Federation)

2007-05-15T23:59:59.000Z

259

Use of Activation Technique and MCNP Calculations for Measurement of Fast Neutron Spatial Distribution at the MJ Plasma Focus Device.  

Science Journals Connector (OSTI)

In this paper Plasma-Focus (PF) neutron emission properties have been studied using Monte Carlo calculations for neutron and photon transport. A Thermal Neutron Scaling Factor as a function of angular position of silver activation detectors placed around MJ Plasma Focus (PF-1000) device has been calculated. Detector responses calculated for 2.5 MeV neutrons and neutrons produced by Am-Be calibration source have been obtained .The results have shown the detector response dependence on the kind of calibration neutron source and on local geometrical/structural characteristics of the PF-1000 devices. Thus the proper calibration procedure ought to be performed for correct measurement of neutron yield within Plasma-Focus devices.

B. Bienkowska; M. Scholz; K. Wincel; B. Zar?ba

2008-01-01T23:59:59.000Z

260

Measurement of the Surface and Underground Neutron Spectra with the UMD/NIST Fast Neutron Spectrometers.  

E-Print Network (OSTI)

?? The typical fast neutron detector falls into one of two categories, Bonner sphere spectrometers and liquid scintillator proton recoil detectors. These two detector types… (more)

Langford, Thomas J.

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal neutron detector" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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261

The Thermal Neutron Capture Cross Sections of Pa231 and Pa232  

Science Journals Connector (OSTI)

The neutron capture cross section of Pa231 has been determined to be 293 barns, the largest uncertainty in this determination being due to the uncertainty in the half-life of U232 and being of the order of 15 percent.The neutron capture cross section of Pa232 was determined to be about 40{+40}{-20} barns.

R. Elson; P. A. Sellers; E. R. John

1953-04-01T23:59:59.000Z

262

Periodic magnetic field as a polarized and focusing thermal neutron spectrometer and monochromator  

SciTech Connect

A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.

Cremer, J. T.; Williams, D. L.; Fuller, M. J.; Gary, C. K.; Piestrup, M. A. [Adelphi Technology, Inc., 2003 East Bayshore Rd., Redwood City, California 94063 (United States); Pantell, R. H.; Feinstein, J. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Flocchini, R. G.; Boussoufi, M.; Egbert, H. P.; Kloh, M. D.; Walker, R. B. [Davis McClellan Nuclear Radiation Center, University of California, McClellan, California 95652 (United States)

2010-01-15T23:59:59.000Z

263

Integrated neutron/gamma-ray portal monitors for nuclear safeguards  

SciTech Connect

Radiation monitoring is one nuclear-safeguards measure used to protect against the theft of special nuclear materials (SNM) by pedestrians departing from SNM access areas. The integrated neutron/gamma-ray portal monitor is an ideal radiation monitor for the task when the SNM is plutonium. It achieves high sensitivity for detecting both bare and shielded plutonium by combining two types of radiation detector. One type is a neutron-chamber detector, comprising a large, hollow, neutron moderator that contains a single thermal-neutron proportional counter. The entrance wall of each chamber is thin to admit slow neutrons from plutonium contained in a moderating shield, while the other walls are thick to moderate fast neutrons from bare or lead-shielded plutonium so that they can be detected. The other type of detector is a plastic scintillator that is primarily for detecting gamma rays from small amounts of unshielded plutonium. The two types of detector are easily integrated by making scintillators part of the thick back wall of each neutron chamber or by inserting them into each chamber void. We compared the influence of the two methods of integration on detecting neutrons and gamma rays, and we examined the effectiveness of other design factors and the methods for signal detection as well.

Fehlau, P.E.

1993-09-01T23:59:59.000Z

264

A microdosimetric approach to the thermal neutron fluence prescription for clinical BNCT  

Science Journals Connector (OSTI)

......Comput. Assist. Tomogr. 4 , 489-491 (1980). 15. Kobayashi, T. and Kanda, K. Analytical calculation of boron-10 dosage in cell nucleus for neutron capture therapy. Radiat. Res. 91 , 77-94 (1982). 16. Coderre, J. A......

E. H. Kim; C. H. Rhee

2004-12-01T23:59:59.000Z

265

About the Neutron and Nuclear Science Research (WNR) facility...  

NLE Websites -- All DOE Office Websites (Extended Search)

About the Neutron and Nuclear Science (WNR) Facility The Neutron and Nuclear Science (WNR) Facility provides neutron and proton beams and detector arrays for basic, applied,...

266

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

267

Dynamically polarized hydrogen target as a broadband, wavelength-independent thermal neutron spin polarizer  

SciTech Connect

A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8 mm thick and consists of 43.4 wt% water, 54.6 wt% glycerol, and 2 wt% of EHBA-Cr(v) complex. The wavelength of the incident neutrons for the transmission experiment was {lambda} = 8.1 {angstrom} with {Delta}{lambda}/{lambda} = 10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission.

Zhao, Jinkui [ORNL; Garamus, VM [GKSS Research Center, Germany; Mueller, W [GKSS Research Center, Germany; Willumeit, R [GKSS Research Center, Germany

2005-01-01T23:59:59.000Z

268

Electrical and thermal properties of neutron-transmutation-doped Ge at 20 mK  

Science Journals Connector (OSTI)

We report on hot-electron effects in neutron-transmutation-doped Ge (NTD Ge) near 20 mK. Both static and dynamic electrical properties were measured and compared with a model including both variable-range-hopping conduction and hot-electron effects.

Ning Wang; F. C. Wellstood; B. Sadoulet; E. E. Haller; J. Beeman

1990-02-15T23:59:59.000Z

269

Surface physics with cold and thermal neutron reflectometry. Progress report, April 1, 1991--March 31, 1992  

SciTech Connect

Three aspects of the research project ``Surface physics with cold and ultracold neutron reflectometry`` were stressed during the present first year: (1) Setup of the reflectometer facility at the research reactor of the Rhode Island Nuclear Science Center. The installation provides a narrow ``pencil beam`` analyzed by time of flight using a chopper system. Following beam characterization and a test measurement of the total cross section of copper single crystal first reflectivity measurements are currently performed using a supermirror. (2) Design stud for the ultracold neutron imaging system, with involvement of the relevant industry. Bids are available for several components indicating that it will be very difficult to build the entire system unless further funds become available. (3) Analysis of features of neutron reflection from surfaces with special emphasis on the effect of surface roughness both on the specular beam and the diffusely reflected and refracted intensity. Previous theoretical studies were supplemented by further numerical calculations of diffuse scattering distributions using different models. Application of ultracold and cold neutron reflectometry to the study of liquid-vapor phase transition were discussed. The theoretical work also includes the development of tentative ideas for novel fundamental physics experiments.

Steyerl, A.

1991-11-01T23:59:59.000Z

270

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

E-Print Network (OSTI)

of the beam port door and exposing detector at low reactor power. In order to permit operation 26 continously with minimal disruption of normal reactor operations and minimal radiation exposure to operating personnel, an object- detector holding apparatus... exposure except from the gamma rays in the beam. Righ quality radiographs were 29 obtained using Type R film with exposures of 20-30 minutes at a reactor power of 1 MW. Type M2/RP and Type AA films were used when speed was desired. Type AA...

Lorenz, Robert Wayne

2012-06-07T23:59:59.000Z

271

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

272

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

273

Neutron scattering: a tool to detect in vivo thermal stress effects at the molecular dynamics level in micro-organisms  

Science Journals Connector (OSTI)

...Research articles 1004 30 31 68 Neutron scattering: a tool to detect in vivo...conditions was measured by neutron scattering experiments coupled with microbiological...experiments indicated that the neutron scattering method provides a promising...

2013-01-01T23:59:59.000Z

274

Theory of coherent neutron scattering by hydrogen-bonded ferroelectrics at low temperatures. I. General expression for inelastic coherent scattering of slow neutrons and effective thermal factors  

Science Journals Connector (OSTI)

The differential cross section for inelastic coherent scattering of slow neutrons scattered by hydrogen-bonded ferroelectrics at low temperatures...

S. Stamenkovi?

1972-12-01T23:59:59.000Z

275

Neutron Scattering Facilities 1982  

NLE Websites -- All DOE Office Websites (Extended Search)

NEUTRON SOURCES NEUTRON SOURCES Types of Sources U.S. Sources Available for Users Plans for the Future The Neutron Scattering Society of America (NSSA) SNS/ANL School on Neutron and x-Ray Scattering, June 2011 Jim Rhyne Lujan Neutron Scattering Center Los Alamos National Lab. What do we need to do neutron scattering? * Neutron Source - produces neutrons * Diffractometer or Spectrometer - Allows neutrons to interact with sample - Sorts out discrete wavelengths by monochromator (reactor) or by time of flight (pulse source) - Detectors pick up neutrons scattered from sample * Analysis methods to determine material properties * Brain power to interpret results Sources of neutrons for scattering * Nuclear Reactor - Neutrons produced from fission of 235 U - Fission spectrum neutrons

276

The thermal-neutron-induced alpha-accompanied fission of235U investigation of the low energy part of the alpha spectrum  

Science Journals Connector (OSTI)

The energy spectrum of the ?-particles emitted in the thermal-neutron induced fission of235U was measured from 11.5 MeV down to 2 MeV using the parabola mass spectrometer Lohengrin at the I.L.L. high flux reactor...

F. Caïtucoli; B. Leroux; G. Barreau; N. Cârjan…

1980-01-01T23:59:59.000Z

277

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

278

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

SciTech Connect

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

279

Measurement of the Neutron Spectrum of a DD Electronic Neutron Generator  

SciTech Connect

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

280

Testing of Liquid Scintillator Materials for Gamma and Neutron Detection  

SciTech Connect

The key fact about fissile material is that a sufficient quantity of the material can produce chains of fissions, including some very long chains. A chain of fissions will give rise to a detected burst of neutrons with longer chains generally producing larger bursts. These bursts produce distinctive time correlations in a detector near the multiplying material. These correlations are measurable and can be analyzed to infer attributes of the fissile material including fissile material mass, assembly neutron multiplication, characteristic fast fission chain evolution time scale, also known as the {alpha} time scale, thermalization time scale. The correlation signal is very robust with respect to background and to neutron absorbing material.

Verbeke, J M; Nakae, L; Kerr, P; Dietrich, D; Dougan, A

2009-06-19T23:59:59.000Z

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

GADRAS Detector Response Function.  

SciTech Connect

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

282

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

SciTech Connect

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

283

Understanding the symmetry energy using data from the ALADIN-2000 Collaboration taken at the GSI Large Neutron Detector  

Science Journals Connector (OSTI)

The present study deals with the extraction of the symmetry energy from heavy-ion collisions at intermediate energies. Using the isospin quantum molecular dynamical (IQMD) model, the dependence of the sum of the charge number for fragments with Z?2(Zbound) on the multiplicity of neutrons (Mn) from the projectile spectator fragmentation of 124Sn and 124La at 600 MeV/nucleon is compared with the experimental results of the ALADIN-2000 Collaboration. The comparison suggests a soft symmetry energy. In addition, the sensitivities of the symmetry energy toward the Zbound dependence on proton multiplicity (Mp), neutron-to-proton single [R(n/p)] and double ratio [RD(n/p)], are also examined. The Zbound dependence of R(n/p) is found to be the most sensitive observable toward the symmetry energy. The ALADIN Collaboration should extend the results for R(n/p) in the near future.

Sanjeev Kumar and Y. G. Ma (???)

2012-11-21T23:59:59.000Z

284

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

SciTech Connect

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

285

Detector response in a CANDU low void reactivity core  

SciTech Connect

The response of the in-core flux detectors to the CANFLEX Low-Void-Reactivity Fuel (LVRF) [1] bundles for use in the CANDU reactor at Bruce nuclear generation station has been studied. The study was based on 2 detector types - platinum (Pt)-clad Inconel and pure Inconel detectors, and 2 fuel types - LVRF bundles and natural-uranium (NU) bundles. Both detectors show a decrease of thermal-neutron-flux to total-photon-flux ratio when NU fuel bundles are replaced by LVRF bundles in the reactor core (7% for Inconel and 9% for Pt-clad detectors). The ratio of the prompt component of the net electron current to the total net electron current (PFe) of the detectors however shows a different response. The use of LVRF bundles in place of NU fuel bundles in the reactor core did not change the PFe of the Pt-clad Inconel detector but increased the PFe of the pure Inconel detector by less than 2%. The study shows that the Inconel detector has a larger prompt-detector response than that of the platinum-clad detector; it reacts to the change of fluxes in the reactor core more readily. On the other hand, the Pt-clad detector is less sensitive to perturbations of the neutron-to-gamma ratio. Nevertheless the changes in an absolute sense are minimal; one does not anticipate a change of the flux-monitoring system if the NU fuel bundles are replaced with the CANFLEX LVRF bundles in the core of the Bruce nuclear generating station. (authors)

Tsang, K. T. [Atomic Energy of Canada Limited, 2251 Speakman Drive, Mississauga, Ont. L5K 1B2 (Canada)

2006-07-01T23:59:59.000Z

286

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

Office of Science (SC) Website

Neutron Scattering Facilities Neutron Scattering Facilities Scientific User Facilities (SUF) Division SUF Home About User Facilities X-Ray Light Sources Neutron Scattering Facilities Nanoscale Science Research Centers Electron-Beam Microcharacterization Centers Accelerator & Detector Research & Development Principal Investigators' Meetings Scientific Highlights Construction Projects BES Home User Facilities Neutron Scattering Facilities Print Text Size: A A A RSS Feeds FeedbackShare Page This activity supports the operation of three DOE neutron scattering facilities, which are unique and effective tools for probing the structure of matter. Neutron scattering is particularly well-suited for determining the atomic positions of both light and heavy atoms in a solid and thermal fluctuations in these positions. In addition the neutron

287

Science | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Science Neutron Science Neutron Scattering Science Neutrons are one of the fundamental particles that make up matter and have properties that make them ideal for certain types of research. In the universe, neutrons are abundant, making up more than half of all visible matter. Neutron scattering provides information about the positions, motions, and magnetic properties of solids. When a beam of neutrons is aimed at a sample, many neutrons will pass through the material. But some will interact directly with atomic nuclei and "bounce" away at an angle, like colliding balls in a game of pool. This behavior is called neutron diffraction, or neutron scattering. Using detectors, scientists can count scattered neutrons, measure their energies and the angles at which they scatter, and map their final position

288

Neutron Scattering in ORNL'S Calibration Facility  

Science Journals Connector (OSTI)

......Dosimetry Article Neutron Scattering in ORNL'S Calibration...C. Francis Room scattering corrections for several common neutron detectors in a new...and enclosed room scattering situations are compared...good. A personnel neutron spectrometer was......

J.C. Liu; C.S. Sims; W.H. Casson; H. Murakami; C. Francis

1991-01-01T23:59:59.000Z

289

Vacuum photodiode detectors for soft x-ray ITER plasma tomography  

SciTech Connect

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

290

Thermal neutron capture cross-section to {sup 113}Cd isomer for the study of s-process origin of {sup 115}Sn  

SciTech Connect

The astrophysical origin of a p-nucleus {sup 115}Sn has remained still an open question. The nucleus {sup 115}Sn may be produced by a weak branch of the s-process through a beta-unstable isomer in {sup 113}Cd. However, a neutron capture cross-section to this isomer has not been measured with high accuracy at any energy. A neutron capture cross-section for the {sup 112}Cd(n,gamma){sup 113}Cd{sup m} reaction has been measured with neutrons provided from a nuclear reactor. The nucleus {sup 115}Sn may be produced by a nucleosynthesis flow through {sup 113}Cd{sup m} in the s-process. We have obtained the thermal neutron capture cross-section of 0.028+-0.009[b] and the resonance integral of 1.1+-0.3[b] using a cadmium difference method. The cross-section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E<100 keV. We have evaluated the s-process contribution to the solar abundance of {sup 115}Sn using the classical steady-flow model. This calculated result has shown that the production through {sup 113}Cd{sup m} may be minor contribution to {sup 115}Sn.

Hayakawa, Takehito; Shizuma, Toshiyuki [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); Chiba, Satoshi; Hatsukawa, Yuichi; Iwamoto, Nobuyuki; Shinohara, Nobuo; Harada, Hideo [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan)

2010-06-01T23:59:59.000Z

291

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

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

292

Passive Neutron Detection at Borders  

SciTech Connect

Radiation portal monitor systems have been deployed to screen for illicit trafficking of radioactive materials at international border crossings. This report reviews some of the neutron detection requirements and capabilities of passive detection systems used for such applications. Simulations show the effects of cargo materials on neutron spectra, different detector geometries, using a large-array of neutron detectors, and the effects of backgrounds including “ship effect” neutrons.

Kouzes, Richard T.; Siciliano, Edward R.; Ely, James H.; Keller, Paul E.; McConn, Ronald J.

2008-03-01T23:59:59.000Z

293

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

294

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

295

Calculations of neutron spectra after neutron–neutron scattering  

Science Journals Connector (OSTI)

A direct neutron–neutron scattering length, ann, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of ann will not only help resolve conflicting results of ann by indirect means, but also in comparison to the proton–proton scattering length, app, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum—Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal–thermal and thermal–epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

B E Crawford; S L Stephenson; C R Howell; G E Mitchell; W Tornow; W I Furman; E V Lychagin; A Yu Muzichka; G V Nekhaev; A V Strelkov; E I Sharapov; V N Shvetsov

2004-01-01T23:59:59.000Z

296

Radiation hardness of cerium-doped gadolinium silicate Gd2SiO5:Ce against high energy protons, fast and thermal neutrons  

Science Journals Connector (OSTI)

Degradation of Gd2SiO5:Ce in optical transmittance due to proton irradiation was negligibly small below 106 rad, smaller than 2%/cm at 107 rad and large at 108 rad. The radiation hardness of 107 rad against protons is by two orders of magnitude smaller than against low energy ?-rays. Long term spontaneous recovery of the proton-induced damage is not large (10–20% of the initial degradation in 84 days). Recovery upon exposure to UV light occurs to some extent. Degradation due to thermal neutrons was negligibly small for a fluence of 1014 n/cm2. No degradation was observed for exposure to fast neutrons of about 1013 n/cm2 during one year in the extracted beam tunnel of proton synchrotron.

Masaaki Kobayashi; Masaharu Ieiri; Kenjiro Kondo; Taichi Miura; Hiroyuki Noumi; Masaharu Numajiri; Yuichi Oki; Takenori Suzuki; Minoru Takasaki; Kazuhiro Tanaka; Yutaka Yamanoi; Mitsuru Ishii

1993-01-01T23:59:59.000Z

297

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

SciTech Connect

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

298

Neutron Capture Therapy  

Science Journals Connector (OSTI)

... . Only those elements which have a high thermal-neutron capture cross-section, such as boron-10, lithium-6, and uranium-235, are useful. This suggestion was first put forward ... was first put forward in 1936 by Locher. The utilization of thermal neutron capture by boron-10 for the treatment of human-brain tumours, chiefly glioblastoma multiforme, has been under investigation ...

1961-09-23T23:59:59.000Z

299

Neutron calibration facilities  

Science Journals Connector (OSTI)

......shut down. A recent development for a thermal neutron calibration field is a neutron guide used at the research reactor GKSS Geesthacht(35). The result is a high-intensity thermal beam providing a flux of up to 106 s1 with a field size of about 2.5 2......

H. Schuhmacher

2004-08-01T23:59:59.000Z

300

Thermal neutron scattering  

Science Journals Connector (OSTI)

... and liquids. They have just the right wavelength for atomic physics; and, as nuclear scattering takes place effectively at a point, one can use the ... takes place effectively at a point, one can use the scattered intensity to disentangle the motion of atoms. The momentum transfer dependence of ithe ...

D. V. Bugg

1979-06-14T23:59:59.000Z

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

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.

302

Neutron-induced Mammary Neoplasms in the Rat  

Science Journals Connector (OSTI)

...Fission neutrons were appropriately...y-rays or thermal neutrons (12). The neutron fission spectrum (mean energy, about 1...changing the neutron energy from the fission spectrum to 540 keV...the types of induced mammary neoplasms...

Howard H. Vogel, Jr. and Robert Zaldívar

1972-05-01T23:59:59.000Z

303

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

304

Predicted performance of neutron spectrometers using scintillating fibers  

SciTech Connect

A variety of needs exists for knowing the energy spectral content of a neutron flux. Among these needs are arms-control and national-security applications, which arise because different neutron sources produce different neutron energy spectra. This work is primarily directed at these applications. The concept described herein is a spectrometer in the same sense as a Bonner sphere. The instrument response reflects a statistical average of the energy spectrum. The Bonner sphere is an early rendition of this class. In this, a neutron detector is placed at the center of a moderating (and absorbing) sphere (of varying thickness and composition). Spectral unfolding is required, and the resolution and efficiency are, typically, poor, although the potential bandwidth is very large. A recent variation on the Bonner-sphere approach uses {sup 3}He gas proportional counters with resistive wires to locate the position of the event (Toyokawa et al 1996). The spectrometer concept investigated here has the potential for better resolution and much improved neutron efficiency compared to Bonner spheres and similar devices. These improvements are possible because of the development of neutron-sensitive, scintillating-glass fibers. These fibers can be precisely located in space, which allows a corresponding precision in energy resolution. Also, they can be fabricated into arrays that intercept a large fraction of incident thermal neutrons, providing the improvement in neutron economy.

RA Craig; M Bliss

2000-02-14T23:59:59.000Z

305

HOTSPUR: gamma ray emission from spheres pulsed with D-T neutrons. I. Calibration of improved NE213 detector assembly. II. Comparison of TART/SANDYL electron recoil spectra to experiment; preliminary results  

SciTech Connect

The NE213 scintillator detector was modified so that the pulse height would be linear with electron energy over the full range of interest - up to 7.1 MeV. Absolute calibration was done with four different calibrated gamma sources. An average correction factor is obtained which normalizes SANDYL calculations with respect to the calibration experiments. The procedure for calculating neutron-induced gamma-ray output and electron recoil spectra is described, and experimental data from a number of spherical assemblies are given and compared to TART/SANDYL calculations. (LEW)

Goldberg, E.; Hansen, L.F.; Komoto, T.T.; Pohl, B.A.

1986-09-01T23:59:59.000Z

306

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

E-Print Network (OSTI)

for the continuous (a) and dispersed (b) types [16]. 2.3 Silicon Carbide as a High Conductivity Additive Solomon et al. explored the feasibility of increasing the thermal conductivity of oxide fuels by the addition of a second, higher thermal conductivity solid... methodology used to restrict the CO or SiO gases. All processing, therefore, must take place below this temperature. Because of ! "# Table 2.3. Samples used in the thermal conductivity measurements $%&'()&*! $(+!%,-.&/! 0...

Naramore, Michael J

2010-08-03T23:59:59.000Z

307

Dynamics and thermal behaviour of films of oriented DNA fibres investigated using neutron scattering and calorimetry techniques.  

E-Print Network (OSTI)

??The majority of structural studies on DNA have been carried out using fibre diffraction, while studies of its dynamics and thermal behaviour have been mainly… (more)

Valle Orero, Jessica

2012-01-01T23:59:59.000Z

308

Prompt Gamma Emission in Resonance Neutron Induced Fission of 239Pu  

Science Journals Connector (OSTI)

The scientific interest in the resonance neutron induced capture and fission reactions on 239Pu is continuously rising during the last decade. From a practical point of view, this is because more precise data on capture and fission cross sections, fission fragment mass and kinetic energy distributions, variation of prompt fission neutron and gamma yields in the resonance neutron region, are needed for the modelling of new generation nuclear power plants and for nuclear spent fuel and waste transmutation. From a heuristic and fundamental point of view, such a research improves our knowledge and understanding of the fission phenomena itself. To achieve these goals more powerful neutron sources and more precise fission product detectors have to be used. At the Joint Institute for Nuclear Research (JINR) Frank Laboratory of Neutron Physics (FLNP), where already half a century the thermal and resonance neutron induced nuclear reactions are studied, a new electron accelerator driven white spectrum pulsed neutron source IREN has been built and successfully tested. The improved characteristics of this facility, in comparison with those of the former pulse neutron fast reactor IBR-30, will allow measuring some of the neutron-nuclear reaction data with better precision and accuracy. A new experimental setup for detecting gamma rays (and neutrons) has been designed and is under construction. It will consist of 2 rings (arrays) of 12 NaI(Tl) detectors each (or 1 array of 24 detectors) with variable ring diameter and distance between both rings. Such a setup will make possible not only to measure the multiplicity, energy and angular anisotropy of prompt fission gammas, but also to separate the contribution of prompt fission neutrons by their longer time-of-flight from the fissile target to the detectors. The signals from all the 24 detectors will be recorded simultaneously in digitized form and will be stored on the hard disk of the personal computer for further off-line analysis. The measurement of the prompt gamma-ray emission from 239Pu resonance neutron induced fission is one of the most probable candidates for the first experiments to be performed at IREN using the newly designed gamma-ray detector.

I. Ruskov; Yu.N. Kopatch; Ts. Panteleev; V.R. Skoy; V.N. Shvetsov; E. Dermendjiev; N. Janeva; L.B. Pikelner; Yu.V. Grigoriev; Zh.V. Mezentseva; I. Ivanov

2012-01-01T23:59:59.000Z

309

Measurements of gamma dose and thermal neutron fluence in phantoms exposed to a BNCT epithermal beam with TLD-700  

Science Journals Connector (OSTI)

......parameters utilised for the analysis of TLD-700 chips...after exposure (a) at reactor and (b) at the 60Co...beam of the LVR-15 reactor, dedicated to BNCT...Pirola L. Study of reliability of TLFs for the photon dose mapping in reactor neutron fields for BNCT......

G. Gambarini; D. Magni; V. Regazzoni; M. Borroni; M. Carrara; E. Pignoli; J. Burian; M. Marek; V. Klupak; L. Viererbl

2014-10-01T23:59:59.000Z

310

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

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

311

Polarized neutron reflectometry at Dhruva reactor  

Science Journals Connector (OSTI)

Polarized neutron reflectometry (PNR) is an ideal non-destructive ... have installed a position sensitive detector-based polarized neutron reflectometer at Dhruva reactor, Trombay. In ... the chemical structure o...

Surendra Singh; Saibal Basu

2004-08-01T23:59:59.000Z

312

Characterisation of radiation field for irradiation of biological samples at nuclear reactor—comparison of twin detector and recombination methods  

Science Journals Connector (OSTI)

......Symposium on Neutron and Ion Dosimetry...radiation and thermal neutrons, has been...overexposure to fission neutrons...on their energy spectrum. So, there...well as its neutron and gamma...radiation-induced damage to...thermalised fission neutrons...the neutron energy does not...activated by thermal neutrons......

N. Golnik; M. A. Gryzi?ski; M. Kowalska; K. Meronka; P. Tulik

2014-10-01T23:59:59.000Z

313

Application of different TL detectors for the photon dosimetry in mixed radiation fields used for BNCT  

Science Journals Connector (OSTI)

......neutrons as used for Boron Neutron Capture...The experimental determination of the thermal neutron...INTRODUCTION In BNCT a boron compound enriched...and 7LiF of such isotope compositions are...neutrons as used for Boron Neutron Capture...The experimental determination of the thermal neutron......

B. Burgkhardt; P. Bilski; M. Budzanowski; R. Böttger; K. Eberhardt; G. Hampel; P. Olko; A. Straubing

2006-09-01T23:59:59.000Z

314

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

315

Portable Neutron Sensors for Emergency Response Operations  

SciTech Connect

This article presents the experimental work performed in the area of neutron detector development at the Remote Sensing Laboratory–Andrews Operations (RSL-AO) sponsored by the U.S. Department of Energy, National Nuclear Security Administration (NNSA) in the last four years. During the 1950s neutron detectors were developed mostly to characterize nuclear reactors where the neutron flux is high. Due to the indirect nature of neutron detection via interaction with other particles, neutron counting and neutron energy measurements have never been as precise as gamma-ray counting measurements and gamma-ray spectroscopy. This indirect nature is intrinsic to all neutron measurement endeavors (except perhaps for neutron spin-related experiments, viz. neutron spin-echo measurements where one obtains ?eV energy resolution). In emergency response situations generally the count rates are low, and neutrons may be scattered around in inhomogeneous intervening materials. It is also true that neutron sensors are most efficient for the lowest energy neutrons, so it is not as easy to detect and count energetic neutrons. Most of the emergency response neutron detectors are offshoots of nuclear device diagnostics tools and special nuclear materials characterization equipment, because that is what is available commercially. These instruments mostly are laboratory equipment, and not field-deployable gear suited for mobile teams. Our goal is to design and prototype field-deployable, ruggedized, lightweight, efficient neutron detectors.

,

2012-06-24T23:59:59.000Z

316

Determination of the thermal neutron induced 41Ca(n,p)41K and 41Ca(n,?)38Ar reaction cross sections  

Science Journals Connector (OSTI)

The 41Ca(n,p)41K and 41Ca(n,?)38Ar reaction cross sections were determined with thermal neutrons at the high flux reactor of the ILL in Grenoble. For the 41Ca(nth,p)41K reaction cross section, a value of (7±2)?mb was obtained. In the case of the 41Ca(nth,?)38Ar reaction, the transition to the ground state in 38Ar has a cross section ?(nth,?0)?=?(42±6)?mb, the most prominent decay going to the first excited state in 38Ar with a cross section ?(nth,?1)?=?(130±25)?mb. This can be explained by the presence of a nearby bound level with J?=4-. Also 41Ca(nth,??)38Ar transitions have been observed with a cross section of (10±2)?mb. The primary ? transitions are shown to have a M1 multipolarity.

C. Wagemans; R. Bieber; H. Weigmann; P. Geltenbort

1998-04-01T23:59:59.000Z

317

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

NLE Websites -- All DOE Office Websites (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...

318

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

NLE Websites -- All DOE Office Websites (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...

319

Pre-Clinical Studies on Boron Neutron Capture Therapy  

Science Journals Connector (OSTI)

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10 is irradiated with thermal neutrons to yield...1

Rolf F. Barth; Albert H. Soloway…

1989-01-01T23:59:59.000Z

320

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

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

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

322

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

323

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, bs� is the maxwellian-averaged neutron capture cross-section, and t0 is the average neutron exposure (21). The branching decay of 186Re

West, Stuart

324

TL detectors for gamma ray dose measurements in criticality accidents  

Science Journals Connector (OSTI)

......both the neutron and the gamma...radiation field induced by criticality...with both neutron and photon...the neutron spectrum can improve...on neutron energy i.e...251017 fissions, t=35s...data about energy spectrum, the choice...shielding from thermal neutrons (containing......

Saveta Miljanic; Benjamin Zorko; Beatriz Gregori; Zeljka Knezevic

2007-07-01T23:59:59.000Z

325

RESULTS OF FIRST EXPERIMENTS ON NEUTRON GENERATION IN THE VITA NEUTRON SOURCE  

E-Print Network (OSTI)

as activation detector due to capture of epithermal neutrons by iodine also. Bubble detectors were used shell and reliably protected from magnetic fields and electromagnetic noises. Stability of the power

Taskaev, Sergey Yur'evich

326

Hardening neutron spectrum for advanced actinide transmutation experiments in the ATR  

Science Journals Connector (OSTI)

......constant neutron-flux field, the fission power is...over the neutron energy range 0...the neutron spectrum such that all the thermal neutrons...Nuclear Energy-Engineering...fraction of neutron induced gamma-heat...Hardening neutron spectrum for advanced...shorter-lived fission products...performed in a thermal test reactor......

G. S. Chang; R. G. Ambrosek

2005-12-20T23:59:59.000Z

327

Towards an optimum design of a P-MOS radiation detector for use in high-energy medical photon beams and neutron facilities: analysis of activation materials  

Science Journals Connector (OSTI)

......phantom surrounded by water-filled containers extending...depth of maximum dose in water for a 10 cm 10 cm square...all irradiations. The atmospheric pressure and internal...acetone and distilled water. They were then transferred...neutrons from a D-T generator. Table 1. Activation......

Robert A. Price

2005-12-20T23:59:59.000Z

328

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

SciTech Connect

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

329

Industry - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

PartTec PartTec ORNL, PartTec Inc. Licensing Agreement ORNL and PartTec sign licensing agreement (Front) ORNL Deputy Director for Science & Technology Thomas Zacharia and PartTec CEO Herschel Workman. (Back) Bruce Hannan (SNS), PartTec production manager Craig Kline, Rick Riedel (SNS), Jason Hodges (SNS) and Ron Cooper (SNS). The SNS guys were on the development team. Representatives from Oak Ridge National Laboratory and PartTec, an Indiana-based firm, formally signed a licensing agreement Thursday, Aug. 12, to market an advanced neutron detector system developed for the Spallation Neutron Source. The Shifting Scintillator Neutron Detector can determine the time and position of captured neutrons, which enables researchers to obtain very accurate time-of-flight measurements.

330

Rotational Correlation Function of Spherical Rotors and Neutron Scattering  

Science Journals Connector (OSTI)

......Function of Spherical Rotors and Neutron Scattering Juichiro Hama Tuto Nakamura...Correlation Effect on the Slow Neutron Scattering by Polyatomic Molecules with...A. , Kowalska A. Thermal Neutron Scattering-Egelstaff P. A., ed......

Juichiro Hama; Tuto Nakamura

1971-12-01T23:59:59.000Z

331

Neutron Polarization  

Science Journals Connector (OSTI)

The neutron polarization cross section of iron has been measured as a function of energy from 0.7 to 3.3A by two methods: using the single transmission effect in a block of polycrystalline iron at energies selected by a quartz crystal monochromator; and using a single crystal of magnetized magnetite to analyze the beam emerging from the iron polarizer, the magnetite crystal itself serving as monochromator. The measured values are compared with those of other observers and the theoretically expected values. These are found to agree fairly well within the limits of accuracy of the measurements and existing knowledge of the wave function of the iron 3d shell. The two techniques were used also to determine the average polarization (32 percent) as seen by a 1v detector in a beam of reactor neutrons emerging from a 4-cm thick polarizing block of iron. Problems and techniques associated with the measurement of the average polarization of a continuous spectrum are discussed. A simplified experimental treatment of the problem of beam "hardening" is described. A description is given of the use of the magnetic resonance method in conjunction with a single-crystal magnetite analyzer for the measurement of neutron polarization.

C. P. Stanford; T. E. Stephenson; L. W. Cochran; S. Bernstein

1954-04-15T23:59:59.000Z

332

Neutron Imaging by Boric Acid  

E-Print Network (OSTI)

In this paper a new type of passive neutron detector based on the already existing one, CR39, is described. Its operation was verified by three different neutron sources: an Americium-Beryllium (Am241-Be) source; a TRIGA type nuclear reactor; and a fast neutron reactor called TAPIRO. The obtained results, reported here, positively confirm its operation and the accountability of the new developed detecting technique.

Fabio Cardone; Giovanni Cherubini; Walter Perconti; Andrea Petrucci; Alberto Rosada

2013-02-22T23:59:59.000Z

333

Applications of Noble Gas Radiation Detectors to Counter?terrorism  

Science Journals Connector (OSTI)

Radiation detectors are essential tools in the detection analysis and disposition of potential terrorist devices containing hazardous radioactive and/or fissionable materials. For applications where stand?off distance and source shielding are limiting factors large detectors have advantages over small ones. The ability to distinguish between Special Nuclear Materials and false?positive signals from natural or man?made benign sources is also important. Ionization chambers containing compressed noble gases notably xenon and helium?3 can be scaled up to very large sizes improving the solid angle for acceptance of radiation from a distant source. Gamma spectrometers using Xe have a factor of three better energy resolution than NaI scintillators allowing better discrimination between radioisotopes. Xenon detectors can be constructed so as to have extremely low leakage currents enabling them to operate for long periods of time on batteries or solar cells. They are not sensitive to fluctuations in ambient temperature and are therefore suitable for deployment in outdoor locations. Position?sensitive 3He chambers have been built as large as 3000 cm2 and with spatial resolution of less than 1 mm. Combined with coded apertures made of cadmium they can be used to create images of thermal neutron sources. The natural background of spallation neutrons from cosmic rays generates a very low count rate so this instrument could be quite effective at identifying a man?made source such as a spontaneous fission source (Pu) in contact with a moderator (high explosive).

Peter E. Vanier; Leon Forman

2002-01-01T23:59:59.000Z

334

Neutron reflectometry  

Science Journals Connector (OSTI)

Neutron reflectivity is a powerful tool for the ... chapter include: the theory of elastic specular neutron diffraction; polarized neutron reflectivity; surface roughness; experimental methodology; resolution in ...

G. S. Smith; C. F. Majkrzak

2004-01-01T23:59:59.000Z

335

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

336

Neutron-Neutron Interaction  

Science Journals Connector (OSTI)

The present status of the problem of charge dependence is discussed. The information about the neutron-neutron interaction derived from the two-neutron system, three-nucleon systems, final-state interactions in multiparticle reactions, and peripheral processes is critically evaluated. The experimental data indicate the breakdown of charge independence by about 3-5%. Evidence concerning the violation of charge symmetry is inconclusive, but it seems that most of the data are consistent with the assumption that charge symmetry is satisfied within 0.5-1%. The most suitable studies which might improve the knowledge of the neutron-neutron forces are indicated.

IVO ŠLAUS

1967-07-01T23:59:59.000Z

337

Time of Neutron Production on Z?Pinch and Plasma Focus Devices  

Science Journals Connector (OSTI)

In this paper we present the results obtained on the plasma focus PF?1000 in IPPLM Warsaw and on the z?pinch S?300 in RRC Kurchatov Institute in Moscow using a deuterium load. On the PF?1000 plasma?focus device with deuterium filling gas the energy of neutrons and time of their generation are determined by time?of?flight method from seven scintillation detectors positioned in the axial direction. The neutron signals (total yield ?1011 neutrons per shot) correlate with hard x?rays and their maximum occur ?150–200 ns after the pinch phase. The initial portion of neutron pulse has beam?target origin with downstream energies up to 2.8–3.2 MeV and the final portion of neutrons has isotropic distribution of energies in the range of 2.2–2.7 MeV. The z?pinch experiments were performed on the S?300 generator with the load formed from a deuterated CD2 fibre in the axis of a tungsten wire array. The energy of neutrons and time of their generation are determined by time?of?flight method from 5 scintillation detectors positioned in the axial and side?on direction. The neutrons with total yield up to 3×109 per shot are produced in the energy range of 1.8–3.2 MeV at 10–30 ns after the pinch phase represented by dip in the current waveform peak of the voltage and minimum of the pinch diameter. The distribution of neutron velocities is random within the total solid angle. The neutrons in both devices are produced by a non?thermal mechanism with deuterons accelerated to the energies above 100 keV partially in anode?cathode direction and partially with almost isotropic distribution of velocities at the time of the plasma expansion i.e. after the pinch phase.

P. Kubes; J. Kravarik; D. Klir; M. Scholz; M. Paduch; K. Tomaszewski; I. Ivanova?Stanik; B. Bienkowska; L. Karpinski; M. Sadowski; H. Schmidt; Y. L. Bakshaev; P. I. Blinov; A. S. Chernenko; M. I. Ivanov; E. D. Kazakov; A. V. Korelsky; E. V. Kravchenko; V. D. Korolev; A. Y. Shashkov; G. I. Ustroev

2006-01-01T23:59:59.000Z

338

Note on accelerated detectors  

Science Journals Connector (OSTI)

The Unruh result, on the thermal-like behavior of particle detectors under a uniformly accelerated state of motion, is found by a different method which does not involve field quantization in a metric with a horizon. The result is extended to other situations.

P. Meyer

1978-07-15T23:59:59.000Z

339

Gamma-gamma directional correlation measurements in 130,132Xe following thermal neutron capture by natural xenon  

Science Journals Connector (OSTI)

Directional correlations of gamma-ray cascades in 130,132Xe have been measured following thermal n capture by a pressurised natural xenon gas target. Gamma-ray singles spectra were measured up to 5.5 MeV and the coincidence correlation data were obtained for the energy range 0.2-2.5 MeV. Decay schemes were developed on the basis of the coincidence measurements. The data spin-parity assignments to be made to most levels lying below 3.5 MeV in the 132Xe and the multiple mixing ratios to be evaluated for the more intense transitions. The results are fitted to IBM-1 and IBM-2 and are also compared with the prediction of the dynamic deformation model of Kumar (1983). The 23+ level at 1985 keV in 132Xe is considered to be a mixed-symmetry state with B(M1; 23+ to 21+)=0.29 mu N2.

S A Hamada; W D Hamilton; B More

1988-01-01T23:59:59.000Z

340

EPR dosimetry in a mixed neutron and gamma radiation field  

Science Journals Connector (OSTI)

......radicals induced by ionizing...of radio-induced free radicals...Mura, the neutron dose component...neutrons of energy comparable to fission spectrum(15...component of thermal neutron in the SILENE...34 for fission neutrons...shape line spectrum modification...SILENE neutron energies. Nevertheless......

F. Trompier; P. Fattibene; D. Tikunov; A. Bartolotta; A. Carosi; M. C. Doca

2004-08-01T23:59:59.000Z

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.


341

Monte Carlo simulation of explosive detection system based on a Deuterium–Deuterium (D–D) neutron generator  

Science Journals Connector (OSTI)

Abstract An explosive detection system based on a Deuterium–Deuterium (D–D) neutron generator has been simulated using the Monte Carlo N-Particle Transport Code (MCNP5). Nuclear-based explosive detection methods can detect explosives by identifying their elemental components, especially nitrogen. Thermal neutron capture reactions have been used for detecting prompt gamma emission (10.82 MeV) following radiative neutron capture by 14N nuclei. The explosive detection system was built based on a fully high-voltage-shielded, axial D–D neutron generator with a radio frequency (RF) driven ion source and nominal yield of about 1010 fast neutrons per second (E=2.5 MeV). Polyethylene and paraffin were used as moderators with borated polyethylene and lead as neutron and gamma ray shielding, respectively. The shape and the thickness of the moderators and shields are optimized to produce the highest thermal neutron flux at the position of the explosive and the minimum total dose at the outer surfaces of the explosive detection system walls. In addition, simulation of the response functions of NaI, BGO, and LaBr3-based ?-ray detectors to different explosives is described.

K. Bergaoui; N. Reguigui; C.K. Gary; C. Brown; J.T. Cremer; J.H. Vainionpaa; M.A. Piestrup

2014-01-01T23:59:59.000Z

342

Neutron beam imaging at neutron spectrometers at Dhruva  

SciTech Connect

A low efficiency, 2-Dimensional Position Sensitive Neutron Detector based on delay line position encoding is developed. It is designed to handle beam flux of 10{sup 6}-10{sup 7} n/cm{sup 2}/s and for monitoring intensity profiles of neutron beams. The present detector can be mounted in transmission mode, as the hardware allows maximum neutron transmission in sensitive region. Position resolution of 1.2 mm in X and Y directions, is obtained. Online monitoring of beam images and intensity profile of various neutron scattering spectrometers at Dhruva are presented. It shows better dynamic range of intensity over commercial neutron camera and is also time effective over the traditionally used photographic method.

Desai, Shraddha S.; Rao, Mala N. [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2012-06-05T23:59:59.000Z

343

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

344

Scission neutron emission and prompt fission neutron spectrum  

E-Print Network (OSTI)

The mass, energy and angular integrated spectra of prompt fission neutrons for sup 2 sup 3 sup 5 U induced fission in the energy range from thermal to 5 MeV were analyzed. It allows assume that about 0.362+-0.025 neutrons per fission are emitted due to another mechanism then neutron emission from excited fragments after full acceleration. The spectrum of scission neutrons consists of two components with average energy 0.98 MeV and 2.74 MeV. The share of scission neutrons and their spectrum shape estimated in this work does not contradict to results of differential experiments analyzed in previous papers.

Kornilov, N V

2001-01-01T23:59:59.000Z

345

Passive Neutron Detection in Ports for Homeland Security Applications  

E-Print Network (OSTI)

with experimental measurements showed that detectors parallel to the surface of water were best at detecting neutron sources below the surface. Additionally, stacking detectors and placing a cadmium sheet between the polyethylene blocks resulted in a greater...

Pedicini, Eowyn E

2013-05-07T23:59:59.000Z

346

The NIF 4.5-m nTOF Detectors  

SciTech Connect

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

347

Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron  

E-Print Network (OSTI)

DESIG: E 263 09 ^TITLE: Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron ^SIGNUSE: Refer to Guide E 844 for guidance on the selection, irradiation, and quality control of neutron dosimeters. Refer to Practice E 261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors. Pure iron in the form of foil or wire is readily available and easily handled. Fig. 1 shows a plot of cross section as a function of neutron energy for the fast-neutron reaction 54Fe(n,p)54Mn (1). This figure is for illustrative purposes only to indicate the range of response of the 54Fe(n,p)54Mn reaction. Refer to Guide E 1018 for descriptions of recommended tabulated dosimetry cross sections. 54Mn has a half-life of 312.13 days (3) (2) and emits a gamma ray with an energy of 834.845 keV (5). (2) Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.57878 (46)-h 56Mn, 44.95-d (8) 59Fe, and 5.27...

American Society for Testing and Materials. Philadelphia

2009-01-01T23:59:59.000Z

348

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

SciTech Connect

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

349

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

NLE Websites -- All DOE Office Websites (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...

350

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

NLE Websites -- All DOE Office Websites (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...

351

Cold neutron facility for prompt gamma-neutron activation analysis  

Science Journals Connector (OSTI)

The restart of the recently upgraded research reactor in Budapest is foreseen at the end of this year. A number of fast, thermal and cold neutron beams will serve for research, industrial and educational activiti...

G. Molnár; ZS. Révay; Á. Veres; A. Simonits…

1993-01-01T23:59:59.000Z

352

Coherence lengths and neutron optics  

Science Journals Connector (OSTI)

The dynamical diffraction of divergent beams and its application to neutron interferometry are considered. The coherence properties of thermal neutrons are studied, and it is shown that the extreme anisotropy of dynamically diffracted wave packets should be included in the discussion of coherence lengths. Finally, the mechanism leading to a nondispersive phase shift is investigated.

D. Petrascheck

1987-05-01T23:59:59.000Z

353

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

354

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

355

Neutron Polarimetry  

Science Journals Connector (OSTI)

8 July 1993 research-article Neutron Polarimetry P. Jane Brown J. Bruce Forsyth Francis Tasset Zero-field neutron polarimetry is a technique which has...polarization analysis to be carried out in a neutron scattering experiment. The incident...

1993-01-01T23:59:59.000Z

356

SIGNIFICANT CHANGE IN THE CONSTRUCTION OF A DOOR TO A ROOM WITH SLOWED DOWN NEUTRON FIELD BY MEANS OF COMMONLY USED INEXPENSIVE PROTECTIVE MATERIALS  

Science Journals Connector (OSTI)

......for neutron energies from thermal to 20 MeV...slowed down neutrons for the considered...kinetic energies of slowed...the energy spectrum of gamma radiation induced by neutrons...cross-section, fission fragments and delayed neutrons. Nucl...the neutron spectra generated by a high-energy clinical...Chen C. Y. Thermal neutron fluence......

Adam Konefal; Marcin Laciak; Anna Dawidowska; Wojciech Osewski

2013-12-01T23:59:59.000Z

357

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

358

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

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

359

Alternative Neutron Detection Testing Summary  

SciTech Connect

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

360

SHARP Neutronics Expanded | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

SHARP Neutronics Expanded SHARP Neutronics Expanded SHARP Neutronics Expanded January 29, 2013 - 1:28pm Addthis Fully heterogeneous predictions of thermal neutron flux in a hypothetical metal-oxide-fueled PWR Fully heterogeneous predictions of thermal neutron flux in a hypothetical metal-oxide-fueled PWR SHARP neutronics Module Development 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. The existing high-fidelity solver package was extended to be independent of reactor technology and demonstrated with 2-D MOC and Sn method simulations of LWR core configurations. Efforts to support verification and validation of the DeCART code, used as one reference solution method by the SHARP code

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

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

362

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

363

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

NLE Websites -- All DOE Office Websites (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...

364

Neutron Production, Neutron Facilities and Neutron Instrumentation  

Science Journals Connector (OSTI)

...Mexico, 87545, U.S.A, e-mail: sven@lanl.gov Hans-Georg Priesmeyer Geesthacht Neutron Scattering Facility, GKSS Research Center, 21502 Geesthacht, Germany, e-mail: hans-georg.priesmeyer@gkss.de NEUTRON GENERATION The...

Sven C. Vogel; Hans-Georg Priesmeyer

365

A new technique for beta attenuation studies in neutron activation foils using 4?- coincidence system  

Science Journals Connector (OSTI)

......low flux neutron measurements...low flux neutron measurements...Characteristics of the neutron activation...Resonance energy (eV) Resonance...46 barn (fission spectrum averaged...dose, the induced activity...irradiated in the thermal column of......

Deepa Sathian; M. P. Chougaonkar; Y. S. Mayya

2010-12-01T23:59:59.000Z

366

Dosimetry of fission neutrons in a 1-W reactor, UTR-Kinki  

Science Journals Connector (OSTI)

......2, the neutron energy spectrum calculated by MCNP4B...technique and the thermal neutron fluence rates from...determining the energy spectrum of the reactor's fission neutrons. It also...value, the activity induced in the In foils......

Satoru Endo; Eiji Yoshida; Yusuke Yoshitake; Tetsuo Horiguchi; Wenyi Zhang; Kazuo Fujikawa; Masaharu Hoshi; Tetsuo Itoh; Masayori Ishikawa; Kiyoshi Shizuma

2002-12-01T23:59:59.000Z

367

Neutron Scattering Investigation on Quantum Spin System SrCu2(BO3)2  

Science Journals Connector (OSTI)

......research-article Articles Neutron Scattering Investigation on Quantum Spin...review the zero field inelastic neutron scattering results obtained by using both the thermal and cold neutron triple axis instrument. The......

Kazuhisa Kakurai; Katsuyuki Nukui; Naofumi Aso; Masakazu Nishi; Hiroaki Kadowaki; Hiroshi Kageyama; Yutaka Ueda; L.-P. Regnault; O. Cépas

2005-05-01T23:59:59.000Z

368

SINGLE CRYSTAL NEUTRON DIFFRACTION.  

SciTech Connect

Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

KOETZLE,T.F.

2001-03-13T23:59:59.000Z

369

Neutron sources and transmutation of nuclear waste  

Science Journals Connector (OSTI)

Intense neutron sources with different energy spectra are of interest for a variety of applications. In my presentation, after briefly touching on the situation of radioactive waste in Italy, I will try to give a broad picture of Italian existing or proposed neutron sources based on accelerators, ranging from thermal to fast neutrons. I will also describe a specific project for a low-power ADS, aimed at studying neutron spectra as well as at demonstrating incineration and transmutation of nuclear waste.

M. Ripani

2013-01-01T23:59:59.000Z

370

Test of time reversal symmetry with resonance neutron scattering  

Science Journals Connector (OSTI)

Discussions for using thermal neutron scattering from nuclei for symmetry measurements stem from past experiments which have observed large parity violating effects in neutron scattering. The proposed LAMPF II proton storage ring spallation neutron source is a vast improvement over the neutron source used in the parity measurements. A proposal for a time reversal symmetry measurement at the LAMPF II facility is presented. (AIP)

J. David Bowman

1986-01-01T23:59:59.000Z

371

Neutron Reflectivity  

Science Journals Connector (OSTI)

Neutron Reflectivity ... This article is part of the Neutron Reflectivity special issue. ... The articles in this special issue on neutron reflectivity cover a broad range of the applications of this technique and the related X-ray and neutron scattering experiments of SAXS, SANS, GISAXS, and GISANS. ...

Jeffrey Penfold

2009-03-31T23:59:59.000Z

372

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

373

About Neutrons  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Basics Neutron Basics A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter. Find Out What a Neutron Is Youtube icon Properties of Neutrons How Can Neutrons Be Used for Research? Image of glucose movement in plants Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel. Neutrons have many properties that make them ideal for certain types of

374

Present status of the personal neutron dosemeter based on direct ion storage  

Science Journals Connector (OSTI)

......simulated workplace field spectra. Irradiations with thermal neutrons were performed at the thermal beam at GKSS(2) (Geesthacht, Germany). Irradiations with monoenergetic neutron energies were performed at the PTB (Braunschweig, Germany). Two......

A. Fiechtner; M. Boschung; C. Wernli

2004-08-01T23:59:59.000Z

375

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

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

376

A sensitive neutron spectrometer for the National Ignition Facility  

SciTech Connect

We are developing a sensitive neutron spectrometer for the National Ignition Facility laser at Livermore. The spectrometer will consist of a 1020 channel single-neutron-interaction time-of-flight detector array fielded 23 m from the neutron-producing target. It will use an existing detector array together with upgraded electronics for improved time resolution. Measurements of neutron yield, ion and electron temperatures, and density-radius product are all possible under certain conditions using one-, two-, or three-step reaction processes. The locations of the most important potential sources of scattered neutron backgrounds are determined as the first step in designing collimation to reduce these backgrounds.

Watt, R. G.; Chrien, R. E.; Klare, K. A.; Murphy, T. J.; Wilson, D. C.; Haan, S.

2001-01-01T23:59:59.000Z

377

MS Detectors  

SciTech Connect

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

378

Aspherical refractive lenses for small-angle neutron scattering  

Science Journals Connector (OSTI)

This paper discusses the testing and simulation of aspherical neutron lenses as focusing elements for small-angle neutron scattering and their transparency with respect to thermal diffuse scattering.

Frielinghaus, H.

2009-06-20T23:59:59.000Z

379

Boron Neutron Capture Therapy for Murine Malignant Gliomas  

Science Journals Connector (OSTI)

...and epithermal neutron component comprised approximately 5% of the total dose; the majority (~80%) came from the boron-10 reaction and the rest from photons and thermal neutrons (data not shown). All subsequently described BNCT doses are...

Stephen C. Saris; Guido R. Solares; David E. Wazer; Guillermo Cano; Sarah E. Kerley; Melita A. Joyce; Lester S. Adelman; Otto K. Harling; Hywel Madoc-Jones; Robert G. Zamenhof

1992-09-01T23:59:59.000Z

380

A More Informative Approach for Characterization of Polymer Monolithic Phases: Small Angle Neutron Scattering/Ultrasmall Angle Neutron Scattering  

Science Journals Connector (OSTI)

A More Informative Approach for Characterization of Polymer Monolithic Phases: Small Angle Neutron Scattering/Ultrasmall Angle Neutron Scattering ... Scattered neutrons were detected with a 64 cm × 64 cm two-dimensional position sensitive detector with 128 × 128 pixels and 0.5 cm resolution per pixel. ...

Kathleen M. Ford; Brian G. Konzman; Judith F. Rubinson

2011-11-08T23:59:59.000Z

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

Asterix is a reflectometer/diffractometer/grazing-incidence-SANS/SESAME-enabled-SANS spectrometer that is primarily used for experiments or neutron scattering  

E-Print Network (OSTI)

that is primarily used for experiments or neutron scattering techniques requiring polarized neutron beams detector arm is readily configurable for polarization or energy analysis of the scattered neutron beam be translated in the horizontal and vertical directions. Neutron detector (Spin Echo Scattering Angle

382

Validation of a method for neutron dosimetry and spectrometry using neutron activation of metal discs  

Science Journals Connector (OSTI)

......Belgium. MOX fuel is a mixture of depleted uranium oxide and plutonium oxide. The...multisphere neutron spectrometer data. Health Phys (1999) 77(5):579-583...the BD-PND bubble detector. Health Phys. Soc (1999) 77(2......

J. S. Elisabeth Wieslander; Göran Lövestam; Mikael Hult; Andreas Fessler; Joël Gasparro; Pierre Kockerols

2010-03-01T23:59:59.000Z

383

Dosimetry and spectrometry at accelerator based neutron source for boron neutron capture therapy  

Science Journals Connector (OSTI)

An innovative accelerator-based neutron source for boron neutron capture therapy has started operation at the Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using 7Li(p,n)7Be threshold reaction. In the article, techniques to detect neutron and gamma-rays at the facility are described. Gamma radiation is measured with NaI and BGO gamma-spectrometers. The total yield of neutrons is determined by measuring the 477 keV ?-quanta from beryllium decay. For the rough analysis of the generated neutron spectrum we used bubble detectors. As the epithermal neutrons are of interest for neutron capture therapy the NaI detector is used as activation detector. We plan to use a time-of-flight technique for neutron spectra measurement. To realize this technique a new solution of short time neutron generation is proposed.

B. Bayanov; A. Burdakov; A. Kuznetsov; A. Makarov; S. Sinitskii; Yu. Sulyaev; S. Taskaev

2010-01-01T23:59:59.000Z

384

Photon detectors  

SciTech Connect

J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

Va`vra, J.

1995-10-01T23:59:59.000Z

385

Neutron-Neutron Scattering Length  

Science Journals Connector (OSTI)

The final-state interaction of the two neutrons from the reaction ?-+d?2n+? has a pronounced and distinctive effect on the momentum spectrum of the outgoing particles. In particular, the neutron spectrum is sharply peaked in the neighborhood of 2 Mev, with a shape that is quite sensitive to the strength of the nn interaction. In the region of this peak, the relative neutron-neutron momentum is so small that the nn interaction is completely characterized by its scattering length. Hence it is proposed that a measurement of the shape of the neutron spectrum from this reaction may provide a convenient means of measuring the neutron-neutron scattering length. Neutron spectra are calculated in an impulse approximation, for several assumed values of the scattering length. It appears from their shapes that, in this way, present neutron-detection techniques should be capable of determining the scattering length to within 25%.

Kirk W. McVoy

1961-03-01T23:59:59.000Z

386

Deployment of a three-dimensional array of micro-pocket fission detector triads (MPFD[superscript]3) for real-time, in-core neutron flux measurements in the Kansas State University TRIGA Mark-II Nuclear Reactor.  

E-Print Network (OSTI)

??A Micro-Pocket Fission Detector (MPFD) is a miniaturized type of fission chamber developed for use inside a nuclear reactor. Their unique design allows them to… (more)

Ohmes, Martin Francis

2012-01-01T23:59:59.000Z

387

Neutron skins and neutron stars  

SciTech Connect

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

388

Neutron scattering  

Science Journals Connector (OSTI)

... likely to be able to contribute to many different branches of chemistry and secondly because neutron ...neutronscattering ...

A. J. Leadbetter

1977-12-01T23:59:59.000Z

389

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

390

Neutron Diffraction  

Science Journals Connector (OSTI)

22 February 1949 research-article Neutron Diffraction G. E. Bacon J. Thewlis The problem of neutron diffraction by crystals is treated by analogy...deals with a comparison between X-ray and neutron diffraction and it is shown that quantitatively...

1949-01-01T23:59:59.000Z

391

Prompt Fission Neutron Spectrum of Pu241  

Science Journals Connector (OSTI)

The energy distribution of prompt neutrons resulting from the thermal-neutron-induced fission of Pu241 is measured. Fast time-of-flight techniques are employed in the neutron energy range 0.3 to 6.0 Mev. Proton recoils in emulsions are utilized for the measurement of neutron energies from 1.6 to 7.0 Mev. The experimentally determined Pu241 fission neutron spectrum is well represented by the Maxwellian distribution, N(E)?E12e-ET, where E is the neutron energy in Mev, N(E) the number of neutrons per unit energy interval, and T=1.335±0.034 Mev. The measured average Pu241 fission neutron energy is 2.002±0.051 Mev.

A. B. Smith; R. K. Sjoblom; J. H. Roberts

1961-09-15T23:59:59.000Z

392

Contacts | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Science Points of Contact Science Points of Contact Name Research Area Doug Abernathy Wide Angular-Range Chopper Spectrometer (ARCS). Atomic-scale dynamics at thermal and epithermal energies Ke An Engineering Materials Diffractometer (VULCAN). Residual stress, deformation mechanism of materials, phase transitions/transformation, and in situ/operando neutron diffraction in material systems (e.g., working batteries). John Ankner Liquids Reflectometer (LR). Density profiles normal to the surface at liquid surfaces and liquid interfaces Bryan Chakoumakos Nuclear and magnetic crystal structure systematics and structure-property relationships among inorganic materials, powder and single-crystal neutron and x-ray diffraction methods Leighton Coates Macromolecular Neutron Diffractometer (MaNDi). Protein crystallography, biological structure and function

393

POWDER: The Neutron Powder Diffractometer at HFIR | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Powder Diffractometer Neutron Powder Diffractometer Neutron Powder Diffractometer. Neutron Powder Diffractometer. The HB-2A diffractometer is a workhorse instrument used to conduct crystal structural and magnetic structural studies of powdered and ceramic samples, particularly as a function of intensive conditions (T, P, H, etc.). Powder diffraction data collected on this instrument are ideally suited for the Rietveld method. A full range of ancillary sample environments can be used, including cryofurnaces (4-800 K), furnaces (to 1800 K), cryostats (to 0.3 K), and cryomagnets (to 7 T). The Powder Diffractometer has a Debye-Scherrer geometry. The detector bank has 44 3He tubes, each with 6' Soller collimators. A germanium wafer-stack monochromator is vertically focusing and provides one of three principal

394

Neutron Log | Open Energy Information  

Open Energy Info (EERE)

Neutron Log Neutron Log Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Neutron Log Details Activities (4) Areas (4) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Downhole Techniques Exploration Sub Group: Well Log Techniques Parent Exploration Technique: Well Log Techniques Information Provided by Technique Lithology: if used in conjunction with other logs, this technique can provide information on the rock type and the porosity Stratigraphic/Structural: Corelation of rock units Hydrological: Estimate of formation porosity Thermal: Dictionary.png Neutron Log: The neutron log responds primarily to the amount of hydrogen in the formation which is contained in oil, natural gas, and water. The amount of hydrogen can be used to identify zones of higher porosity.

395

Scattering of Neutrons by Deuterons  

Science Journals Connector (OSTI)

The elastic scattering of neutrons by deuterons is considered for energies small enough so that only the l=0 part of the incident wave is different from the corresponding part of a plane wave. The Breit-Feenberg Hamiltonian is used, assuming the same potential between all pairs of particles. Any possible polarization of the deuteron by the neutron is neglected, although the individual particles in the deuteron are taken into account by an approximate method. This method is capable of including exchange between the two neutrons. When the exchange term is included, the theory gives a cross section for thermal neutrons two to three times greater than observed; the cross section for 2.5 Mev neutrons is slightly greater than observed.

L. I. Schiff

1937-08-01T23:59:59.000Z

396

Awards 2007 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

7 7 Staff Awards: 2007 Chakoumakos elected MSA Fellow Bryan Chakoumakos Neutron scientist Bryan Chakoumakos was recently elected a fellow of the Mineralogical Society of America. A member of the Neutron Scattering Science Division, Bryan leads the Single-Crystal Diffraction Group. The group has five neutron scattering instruments in various stages of design and construction, located at HFIR and SNS. The MSA was founded in 1919 and, among other goals, encourages fundamental research on natural materials and supports education through its publications, educational grants, and courses. Pharos Neutron Detector System Researchers at the Department of Energy's Oak Ridge National Laboratory have won six R&D 100 Awards, given annually by R&D Magazine to the year's

397

Special Nuclear Material Detection with a Water Cherenkov based Detector  

SciTech Connect

Fission events from Special Nuclear Material (SNM), such as highly enriched uranium or plutonium, produce a number of neutrons and high energy gamma-rays. Assuming the neutron multiplicity is approximately Poissonian with an average of 2 to 3, the observation of time correlations between these particles from a cargo container would constitute a robust signature of the presence of SNM inside. However, in order to be sensitive to the multiplicity, one would require a high total efficiency. There are two approaches to maximize the total efficiency; maximizing the detector efficiency or maximizing the detector solid angle coverage. The advanced detector group at LLNL is investigating one way to maximize the detector size. We are designing and building a water Cerenkov based gamma and neutron detector for the purpose of developing an efficient and cost effective way to deploy a large solid angle car wash style detector. We report on our progress in constructing a larger detector and also present preliminary results from our prototype detector that indicates detection of neutrons.

Sweany, M; Bernstein, A; Bowden, N; Dazeley, S; Svoboda, R

2008-11-10T23:59:59.000Z

398

Atmospheres and radiating surfaces of neutron stars  

E-Print Network (OSTI)

The beginning of the 21st century was marked by a breakthrough in the studies of thermal radiation of neutron stars. Observations with modern space telescopes have provided a wealth of valuable information. Being correctly interpreted, this information can elucidate physics of superdense matter in the interiors of these stars. The theory of formation of thermal spectra of neutron stars is based on the physics of plasmas and radiative processes in stellar photospheres. It provides the framework for interpretation of observational data and for extracting neutron-star parameters from these data. This paper presents a review of the current state of the theory of surface layers of neutron stars and radiative processes in these layers, with the main focus on the neutron stars that possess strong magnetic fields. In addition to the conventional deep (semi-infinite) atmospheres, radiative condensed surfaces of neutron stars and "thin" (finite) atmospheres are also considered.

Potekhin, A Y

2014-01-01T23:59:59.000Z

399

Neutron skins and neutron stars  

Science Journals Connector (OSTI)

Background: The neutron skin of a heavy nucleus as well as many neutron-star properties are highly sensitive to the poorly constrained density dependence of the symmetry energy.Purpose: To provide for the first time meaningful theoretical errors and to assess the degree of correlation between the neutron-skin thickness of 208Pb and several neutron-star properties.Methods: A proper covariance analysis based on the predictions of an accurately calibrated relativistic functional “FSUGold” is used to quantify theoretical errors and correlation coefficients.Results: We find correlation coefficients of nearly 1 (or ?1) between the neutron-skin thickness of 208Pb and a host of observables of relevance to the structure, dynamics, and composition of neutron stars.Conclusions: We suggest that a follow-up Lead Radius Experiment (PREX) measurement, ideally with a 0.5% accuracy, could significantly constrain the equation of state of neutron-star matter.

F. J. Fattoyev and J. Piekarewicz

2012-07-05T23:59:59.000Z

400

Embedded silicon detector to investigate the natural radiative environment  

Science Journals Connector (OSTI)

A detector based on a silicon diode was developed to investigate the natural radiative environment. As the detector is embeddable, it has low power consumption and is lightweight and small. The instrument was tested under different neutron beams and used during stratospheric balloon flights. A comparison of the experimental results with Monte Carlo simulation results shows that the embeddable detector is a promising means of investigating the natural radiative environment.

D Pantel; J R Vaillé; F Wrobel; L Dilillo; J M Gallière; J L Autran; P Cocquerez; P Chadoutaud; F Saigné

2012-01-01T23:59:59.000Z

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.


401

Neutron Scattering Tutorials | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Scattering Tutorials SHARE Neutron Scattering Tutorials The following lectures were presented at the 2011 and 2010 National School on Neutron & X-Ray Scattering. This...

402

Determination of Radionuclides Induced by Fast Neutrons from the JCO Criticality Accident in Tokai-mura, Japan for Estimating Neutron Doses  

Science Journals Connector (OSTI)

......the g-ray spectrum of the mesh...sections14) with fission neutrons or thermal neutrons...threshold energies for all of...60 Co were induced by (n...Non-destructive -ray spectrum for the mesh...thresh- old energy of the 60...half-lives of neutron-induced radionuclides...abundance) / MeV Fission/ m barn Thermal/ barn......

Sadao Kojima; Tetsuji Imanaka; Jitsuya Takada; Toshiaki Mitsugashira; Takashi Nakanishi; Riki Seki; Muneharu Kondo; Ken-Ichi Sasaki; Tadashi Saito; Yoshiaki Yamaguchi; Michiaki Furukawa

2001-09-01T23:59:59.000Z

403

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

404

Boron-Lined Multitube Neutron Proportional Counter Test  

SciTech Connect

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. These technologies are: 1) Boron trifluoride (BF3)-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated non-scintillating plastic fibers. In addition, a few other companies have detector technologies that might be competitive in the near term as an alternative technology. Reported here are the results of tests of a boron-lined, “multitube” proportional counter manufactured by Centronic Ltd. (Surry, U.K. and Houston, TX). This testing measured the required performance for neutron detection efficiency and gamma-ray rejection capabilities of the detector.

Woodring, Mitchell L.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.

2010-09-07T23:59:59.000Z

405

HFIR Experiment Facilities | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Scattering Scattering Neutron Scattering Facilities at HFIR The fully instrumented HFIR will eventually include 15 state-of-the-art neutron scattering instruments, seven of which will be designed exclusively for cold neutron experiments, located in a guide hall south of the reactor building. The currently available instruments and the status of new instruments can be found on the HFIR Instrument Systems pages. Particularly prominent in the cold neutron guide hall are the two small-angle neutron scattering (SANS) instruments, each terminating in a 70-ft-long evacuated cylinder containing a large moveable neutron detector. In addition to the instruments, laboratories are equipped for users to prepare samples. Perhaps the most exciting development at HFIR is the successfully

406

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

407

Neutron Technologies for Bioenergy Research  

SciTech Connect

Neutron scattering is a powerful technique that can be used to probe the structures and dynamics of complex systems. It can provide a fundamental understanding of the processes involved in the production of biofuels from lignocellulosic biomass. A variety of neutron scattering technologies are available to elucidate both the organization and deconstruction of this complex composite material and the associations and morphology of the component polymers and the enzymes acting on them, across multiple length scales ranging from Angstroms to micrometers and time scales from microseconds to picoseconds. Unlike most other experimental techniques, neutron scattering is uniquely sensitive to hydrogen (and its isotope deuterium), an atom abundantly present throughout biomass and a key effector in many biological, chemical, and industrial processes for producing biofuels. Sensitivity to hydrogen, the ability to replace hydrogen with deuterium to alter scattering levels, the fact that neutrons cause little or no direct radiation damage, and the ability of neutrons to exchange thermal energies with materials, provide neutron scattering technologies with unique capabilities for bioenergy research. Further, neutrons are highly penetrating, making it possible to employ sample environments that are not suitable for other techniques. The true power of neutron scattering is realized when it is combined with computer simulation and modeling and contrast variation techniques enabled through selective deuterium labeling.

Langan, Paul [ORNL

2012-01-01T23:59:59.000Z

408

Neutron Scattering  

Science Journals Connector (OSTI)

... Magnetic Neutron Diffraction By Yurii A. Izyumov and Ruslan P. Ozerov. Translated from the Russian. ... York; Heydon: London, June 1970.) 350s; $37.50; 150 DM.

G. L. SQUIRES

1970-12-05T23:59:59.000Z

409

Development of a portable neutron coincidence counter for field measurements of nuclear materials using the advanced multiplicity capabilities of MCNPX 2.5.F and the neutron coincidence point model  

E-Print Network (OSTI)

given material. In an effort to identify unknown nuclear samples in field inspections, the Portable Neutron Coincidence Counter (PNCC) has been developed. This detector makes use of the coincident neutrons being emitted from a bulk sample. An in...

Thornton, Angela Lynn

2009-05-15T23:59:59.000Z

410

Development of a portable neutron coincidence counter for field measurements of nuclear materials using the advanced multiplicity capabilities of MCNPX 2.5.F and the neutron coincidence point model  

E-Print Network (OSTI)

given material. In an effort to identify unknown nuclear samples in field inspections, the Portable Neutron Coincidence Counter (PNCC) has been developed. This detector makes use of the coincident neutrons being emitted from a bulk sample. An in...

Thornton, Angela Lynn

2008-10-10T23:59:59.000Z

411

Protein crystallography with spallation neutrons  

SciTech Connect

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

412

Boron Neutron Capture Therapy of a Murine Melanoma  

Science Journals Connector (OSTI)

...research-article Basic Sciences Boron Neutron Capture Therapy of a Murine Melanoma 1...for reprints should be addressed. Boron neutron capture therapy has been carried out on...Irradiations with a predominantly thermal neutron beam were performed at the Brookhaven...

Jeffrey A. Coderre; John A. Kalef-Ezra; Ralph G. Fairchild; Peggy L. Micca; Lawrence E. Reinstein; John D. Glass

1988-11-15T23:59:59.000Z

413

A toolkit for epithermal neutron beam characterisation in BNCT  

Science Journals Connector (OSTI)

......neutron fluence spectra calculated...function of neutron energy, data from...USA (new fission converter...free-beam spectrum and dose...beam and neutron and gamma...water phantom thermal and epithermal...The MnRR is induced basically......

Iiro Auterinen; Tom Serén; Jouni Uusi-Simola; Antti Kosunen; Sauli Savolainen

2004-08-01T23:59:59.000Z

414

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

415

Neutron activation analysis  

Science Journals Connector (OSTI)

Neutron activation analysis ... Describes the science and techniques of neutron activation analysis. ...

H. R. Lukens

1967-01-01T23:59:59.000Z

416

Capabilities of the ARCS Instrument - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Capabilities of the ARCS Instrument Capabilities of the ARCS Instrument ARCS Overview The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and

417

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

418

Determination of the full response function of personal neutron dosemeters  

Science Journals Connector (OSTI)

......thermal neutrons was available in most cases from measurements made at the thermal neutron field at the GKSS research centre in Geesthacht, Germany or from measurements made at the SIGMA facility at IRSN in Cadarache, France. The data for broad energy distributions......

M. Reginatto; M. Luszik-Bhadra

2007-07-01T23:59:59.000Z

419

Fast neutron background measurements at shallow depths  

SciTech Connect

We report on measurements of the neutron backgrounds for neutrino experiments at shallow depth (such as the proposed San Onofre neutrino oscillation experiment). A detector capable of pulse-shape discrimination measured the flux of fast neutrons at 20 mwe depth in the Stanford Underground Facility to be (1.07 {+-} 0.30) X 10{sup -6} cm{sup -2} s{sup -1}. An experiment, situated in the Tendon Gallery of the San Onofre Unit 2 reactor. studied spallation neutrons from muons traversing Pb and Cu. An underground experiment in the SUF, employing a detector filled with Gd-loaded liquid scintillator, is measuring the neutron production rate and multiplicity for muon spallation in low-A material (hydrocarbon-based liquid scintillator).

Chen, M.; Hertenberger, R.; Novikov, V. [Inst. of Nuclear Research, Moscow (Russian Federation); Dougherty, B.

1993-10-01T23:59:59.000Z

420

Validation of neutron emission profiles in MAST with a collimated neutron S. Sangaroon, M. Cecconello, S. Conroy, M. Weiszflog, M. Turnyanskiy et al.  

E-Print Network (OSTI)

as well as the detector's response function. The contribution of scattered neutrons to the pulse heightValidation of neutron emission profiles in MAST with a collimated neutron monitor S. Sangaroon, M) Prospects for the Thomson scattering system on NSTX-Upgrade Rev. Sci. Instrum. 83, 10D532 (2012) Swinging

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

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

422

Fission neutron spectra measurements at LANSCE - status and plans  

SciTech Connect

A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. The range of outgoing energies measured so far is from 1 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date will be presented and a discussion of uncertainties will be given in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including mea urements of fission neutrons below 1 MeV and improvements in the data above 8 MeV.

Haight, Robert C [Los Alamos National Laboratory; Noda, Shusaku [Los Alamos National Laboratory; Nelson, Ronald O [Los Alamos National Laboratory; O' Donnell, John M [Los Alamos National Laboratory; Devlin, Matt [Los Alamos National Laboratory; Chatillon, Audrey [CEA-FRANCE; Granier, Thierry [CEA-FRANCE; Taieb, Julien [CEA-FRANCE; Laurent, Benoit [CEA-FRANCE; Belier, Gilbert [CEA-FRANCE; Becker, John A [LLNL; Wu, Ching - Yen [LLNL

2009-01-01T23:59:59.000Z

423

Neutron Microscope  

Science Journals Connector (OSTI)

We report successful operation of a neutron microscope using ultracold neutrons at the high-flux reactor at Grenoble. A sharp, achromatic image of an object slit was obtained at a magnification of 50. The measured resolution of 0.1 mm was limited mainly by the available beam intensity, not by aberrations.

P. Herrmann; K. -A. Steinhauser; R. Gähler; A. Steyerl; W. Mampe

1985-05-06T23:59:59.000Z

424

Neutron scattering  

Science Journals Connector (OSTI)

... statements that the EMBL outstation in Grenoble "[has an] uncertain future" and that "neutrons have not turned out to be particularly useful for biologists" in Peter Newmark's ... on the European Molecular Biology Laboratory (Nature 338, 724; 1989) require some comment.Neutron ...

S. CUSACK; B. JACROT; R. LEBERMAN; R. MAY; P. TlMMINS; G. ZACCAI

1989-06-01T23:59:59.000Z

425

Prompt gamma ray neutron activation analysis of cadmium in municipal solid waste  

E-Print Network (OSTI)

EXPERIMENTAL. . 26 PGNAA Assembly. Detection System Background Determination of Detector Shielding. Self-Shielding. Optimal Bag Size and Orientation. . . . . . . . . . . . . . . Detection Limit and Sensitivity. . . . . . . . . . . . . . . . Neutron Flux... solid waste. This study modified a previous setup that was in a shadow- shield arrangement using Pu-Be neutron sources by: more elaborate detector shielding to reduce background levels; and, irradiating the target bilaterally. The system background...

Dendahl, Katherine Hoge

2012-06-07T23:59:59.000Z

426

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

427

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

428

Covariance Evaluation Methodology for Neutron Cross Sections  

SciTech Connect

We present the NNDC-BNL methodology for estimating neutron cross section covariances in thermal, resolved resonance, unresolved resonance and fast neutron regions. The three key elements of the methodology are Atlas of Neutron Resonances, nuclear reaction code EMPIRE, and the Bayesian code implementing Kalman filter concept. The covariance data processing, visualization and distribution capabilities are integral components of the NNDC methodology. We illustrate its application on examples including relatively detailed evaluation of covariances for two individual nuclei and massive production of simple covariance estimates for 307 materials. Certain peculiarities regarding evaluation of covariances for resolved resonances and the consistency between resonance parameter uncertainties and thermal cross section uncertainties are also discussed.

Herman,M.; Arcilla, R.; Mattoon, C.M.; Mughabghab, S.F.; Oblozinsky, P.; Pigni, M.; Pritychenko, b.; Songzoni, A.A.

2008-09-01T23:59:59.000Z

429

Boron neutron capture enhancement of fast neutron radiotherapy  

Science Journals Connector (OSTI)

Clinical trials have revealed a therapeutic advantage for fast neutron radiation over conventional photon radiation for salivary gland cancer prostate cancer sarcoma and a subgroup of lung cancer. Conversely fast neutron treatment of high grade astrocytic brain tumors [glioblastoma multiforme (GBM)] resulted in tumor sterilization but also caused significant brain injury such that no therapeutic gain was attained. This effect was important however in that photon radiation and other conventional treatments have not demonstrated sterilization of GBM at any dose. Recent laboratory studies demonstrated that the hospital-based fast neutron beam from the University of Washington cyclotron has a thermal neutron component that may be used in a boron-10 neutron capture (BNC) reaction to enhance cell kill. The degree of enhancement was approximately 10 fold and was dependent upon the boron-10 concentration the boron-10 carrier agent and the fast neutron dose per fraction. The results of these experiments will be discussed in the context of creating a therapeutic window for treatment of glioblastoma using BNC-enhanced fast neutron radiation in a clinically tolerable regimen.

K. J. Stelzer; G. E. Laramore; R. Risler; L. Wiens; T. W. Griffin

1997-01-01T23:59:59.000Z

430

Decoherence-free neutron interferometry  

SciTech Connect

Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity.

Pushin, D. A.; Cory, D. G. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Arif, M. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2009-05-15T23:59:59.000Z

431

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

432

Investigation of properties of the TIARA neutron beam facility of importance for calibration applications  

Science Journals Connector (OSTI)

......former, the neutron spectra were measured...field of neutrons produced...to 2 MeV energy loss. Protons...and 232Th fission chambers...only to the thermal neutrons...of low-energy neutrons 20 MeV and...well the spectrum at the calibration...calculate induced radioactivity......

Y. Shikaze; Y. Tanimura; J. Saegusa; M. Tsutsumi; Y. Yamaguchi; Y. Uchita

2007-08-01T23:59:59.000Z

433

The 12B Counter: an active dosemeter for high-energy neutrons  

Science Journals Connector (OSTI)

......measures its own induced radioactivity...reaction Product Energy threshold...taken at a neutron energy of...the time spectra of the 12B...for neutron energy spectra, for instance...with other neutron dosemeters...cylinder 15 Th fission radiator...single-shot time spectrum of the 12B...right): Thermal neutrons (T12 0......

A. Leuschner

2005-12-20T23:59:59.000Z

434

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

435

SciTech Connect: Thermal Hydraulic Characteristics of Fuel Defects...  

Office of Scientific and Technical Information (OSTI)

with experimental data from the Advanced Neutron Source Reactor Thermal Hydraulic Test Loop. The computational results for the High Flux Isotope Reactor core system provide a...

436

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

437

Oscillator detector  

SciTech Connect

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

438

Coherent Neutron Scattering Amplitudes of Krypton and Xenon, and the Electron-Neutron Interaction  

Science Journals Connector (OSTI)

The coherent scattering amplitudes of krypton and xenon for thermal neutrons have been measured by a comparison method involving reflection of a neutron beam from liquid mirrors. The results were (7.68±0.19)×10-13 cm for krypton and (5.10±0.17)×10-13 cm for xenon. When these results are used with the scattering measurements of Hamermesh, Ringo, and Wattenberg, one obtains (3900±800) ev for the electron-neutron interaction.

M. F. Crouch; V. E. Krohn; G. R. Ringo

1956-06-01T23:59:59.000Z

439

Capacitance measurements on silicon microstrip detectors  

SciTech Connect

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

440

Transport coefficients in superfluid neutron stars  

E-Print Network (OSTI)

We study the shear and bulk viscosity coefficients as well as the thermal conductivity as arising from the collisions among phonons in superfluid neutron stars. We use effective field theory techniques to extract the allowed phonon collisional processes, written as a function of the equation of state and the gap of the system. The shear viscosity due to phonon scattering is compared to calculations of that coming from electron collisions. We also comment on the possible consequences for r-mode damping in superfluid neutron stars. Moreover, we find that phonon collisions give the leading contribution to the bulk viscosities in the core of the neutron stars. We finally obtain a temperature-independent thermal conductivity from phonon collisions and compare it with the electron-muon thermal conductivity in superfluid neutron stars.

Tolos, Laura; Sarkar, Sreemoyee; Tarrus, Jaume

2014-01-01T23:59:59.000Z

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441

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 ...

Chernikova, Dina; Avdic, Senada; Pázsit, Imre; Nordlund, Anders

2014-01-01T23:59:59.000Z

442

Neutron spectrometry using LNL bonner spheres and FLUKA  

SciTech Connect

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

443

Neutron Polarization  

Science Journals Connector (OSTI)

The production of polarized neutrons in magnetized iron has been studied, using the intense neutron beams available at the Argonne heavy water pile. The theoretical work of Halpern et al., used as a guide in the experiments, has been checked in many respects, with the exception that the polarization cross section p has a measured value of 3.15 barns compared to the theoretical 1 barn. The application of neutron polarization to the measurement of the approach to saturation in ferromagnets is described and preliminary results are reported.

D. J. Hughes; J. R. Wallace; R. H. Holtzman

1948-06-01T23:59:59.000Z

444

Effect of temperature on performance of {sup 3}He filled neutron proportional counters  

SciTech Connect

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

445

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

446

Electronic personal dosemeters: the solution to problems of individual monitoring in mixed neutron/photon fields?  

Science Journals Connector (OSTI)

......detectors with an electronic counting device...However, these calculations are rarely available...SAPHYDOSE-N, GSF electronic neutron dosemeter...neutron dosemeter and does not need to work...Development of electronic personal neutron...In: Technical Handbook (2000). 6......

M. Luszik-Bhadra

2004-08-01T23:59:59.000Z

447

Neutron scattering instrumentation at reactor based installations  

Science Journals Connector (OSTI)

During the past decade neutron scattering techniques have been applied to an increasingly wide range of scientific problems. Concurrently a number of substantial improvements of neutron scattering instrumentation have occurred to stimulate this trend. In this article several such developments which have occurred at reactor?based installations are described. Individual spectrometer components which are discussed in some detail include: neutron?optical devices such as guide tubes supermirrors and multilayer systems; neutronmonochromators with optimum reflectivity mosaic and focusing characteristics; position?sensitive detectors of several types; and equipment required for neutronpolarizationanalysis. Several novel spectrometers which have enhanced the role of neutron scattering during the past ten years are also described. These include spectrometers for small?angle scattering backscattering and neutron spin echo. An extensive bibliography is included which covers both early and more recent developments.

Roger Pynn

1984-01-01T23:59:59.000Z

448

Neutron Checkup  

Science Journals Connector (OSTI)

Neutron activation analysis is yet another technique in the arsenal of diagnostic methods that physicians can draw on to examine the health of their patients. The University of Washington's school of medicine in Seattle is the first facility in the ...

1969-11-10T23:59:59.000Z

449

Neutron Reflectometry  

Science Journals Connector (OSTI)

Neutron reflectometry is a relatively new technique [1,2]. In the last years, it has been extensively used for solving soft matter problems like polymer mixing [3,4] or the structure of liquids at the surface [5,

Claude Fermon; Frédéric Ott; Alain Menelle

1999-01-01T23:59:59.000Z

450

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

451

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

452

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