Calculation of efficiency of high-energy neutron detection by plastic scintillators

International Nuclear Information System (INIS)

Telegin, Yu.N.

1977-01-01

A computer was used to calculate neutron (5-30O MeV) registration effeciencies with plastic scintillators 2,5,10, 20,30,40 and 50 cm thick. The results are shown in the form of tables. The contributions to efficiency of various processes have been analysed. The calculation results may be used in planning experiments with neutron counters

MCNP modelling of a combined neutron/gamma counter

CERN Document Server

Bourva, L C A; Ottmar, H; Weaver, D R

1999-01-01

A series of Monte Carlo neutron calculations for a combined gamma/passive neutron coincidence counter has been performed. This type of device, part of a suite of non-destructive assay instruments utilised for the enforcement of the Euratom nuclear safeguards within the European Union, is to be used for high accuracy measurements of the plutonium content of small samples of nuclear materials. The multi-purpose Monte Carlo N-particle (MCNP) code version 4B has been used to model in detail the neutron coincidence detector and to investigate the leakage self-multiplication of PuO sub 2 and mixed U-Pu oxide (MOX) reference samples used to calibrate the instrument. The MCNP calculations have been used together with a neutron coincidence counting interpretative model to determine characteristic parameters of the detector. A comparative study to both experimental and previous numerical results has been performed. Sensitivity curves of the variation of the detector's efficiency, epsilon, to, alpha, the ratio of (alpha...

Neutron coincidence counter for MOX fuel pins in storage trays: users' manual

International Nuclear Information System (INIS)

Cowder, L.; Menlove, H.

1982-08-01

The neutron coincidence counter for measurement of mixed-oxide fuel pins in storage trays is described. The special detector head has been designed so that the detectors, high-voltage junction boxes, and electronics are interchangeable with those of the high-level neutron coincidence counter system. This manual describes the system components and the operation and maintenance of the counter. The counter was developed at Los Alamos National Laboratory for in-plant inspection applications by the International Atomic Energy Agency

An extended range neutron rem counter

International Nuclear Information System (INIS)

Birattari, C.; Nuccetelli, C.; Pelliccioni, M.; Silari, M.

1990-01-01

Extensive Monte Carlo calculations have been carried out to assess the possibility of extending the sensitivity of a neutron rem counter of the Andersson-Braun type up to several hundred MeV. The validity of the model adopted has first been checked by comparing with experimental data the calculated response curve and the angular dependence of the sensitivity for a well known commercial rem counter. Next, a number of modifications to the configuration of the moderator-attenuator have been investigated. The response functions and angular distributions produced by two simple solutions yielding an instrument with a sensitivity extended up to 400 MeV are presented. The response of the original rem counter and of its two modified versions to nine test spectra has also been calculated. The resulting instrument is transportable rather than portable, but the availability of an extended range neutron survey meter would be of great advantage at medium and high energy particle accelerator facilities. (orig.)

Measurement of highly enriched uranium metal buttons with the high-level neutron coincidence counter operating in the active mode

International Nuclear Information System (INIS)

Foley, J.E.

1980-10-01

The portable High-Level Neutron Coincidence Counter is used in the active mode with the addition of AmLi neutron sources to assay the 235 U content of highly enriched metal pieces or buttons. It is concluded that the portable instrument is a practical instrument for assaying uranium metal buttons with masses in the range 1.5 to 4 kg

The side-on response of a standard long counter to fast neutrons

International Nuclear Information System (INIS)

Johnson, F.A.

1979-01-01

The response of a standard long counter to neutrons incident into its front face relative to its response to those incident into its side was measured for a range of neutron energies, and an increasing sensitivity to high-energy neutrons incident into the side was evident. The effect of a shadow bar in contributing to an initial degradation in energy of neutrons which then scatter from the surroundings into the counter was suggested by the response of the counter in the side-on orientation as a function of the separation distance of the bar from a source. (Auth.)

{sup 10}B multi-grid proportional gas counters for large area thermal neutron detectors

Energy Technology Data Exchange (ETDEWEB)

Andersen, K. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Bigault, T. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Birch, J. [Linköping University, SE-581, 83 Linköping (Sweden); Buffet, J. C.; Correa, J. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Hall-Wilton, R. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Hultman, L. [Linköping University, SE-581, 83 Linköping (Sweden); Höglund, C. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Linköping University, SE-581, 83 Linköping (Sweden); Guérard, B., E-mail: guerard@ill.fr [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Jensen, J. [Linköping University, SE-581, 83 Linköping (Sweden); Khaplanov, A. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Kirstein, O. [Linköping University, SE-581, 83 Linköping (Sweden); Piscitelli, F.; Van Esch, P. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Vettier, C. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden)

2013-08-21

{sup 3}He was a popular material in neutrons detectors until its availability dropped drastically in 2008. The development of techniques based on alternative convertors is now of high priority for neutron research institutes. Thin films of {sup 10}B or {sup 10}B{sub 4}C have been used in gas proportional counters to detect neutrons, but until now, only for small or medium sensitive area. We present here the multi-grid design, introduced at the ILL and developed in collaboration with ESS for LAN (large area neutron) detectors. Typically thirty {sup 10}B{sub 4}C films of 1 μm thickness are used to convert neutrons into ionizing particles which are subsequently detected in a proportional gas counter. The principle and the fabrication of the multi-grid are described and some preliminary results obtained with a prototype of 200 cm×8 cm are reported; a detection efficiency of 48% has been measured at 2.5 Å with a monochromatic neutron beam line, showing the good potential of this new technique.

Study on the neutron dosimetric characteristics of Tissue Equivalent Proportional Counter

Energy Technology Data Exchange (ETDEWEB)

Nunomiya, T.; Kim, E.; Kurosawa, T.; Taniguchi, S.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Tsujimura, N.; Momose, T.; Shinohara, K. [Japan Nuclear Cycle Development Inst., Environment and Safety Division, Tokai Works, Tokai, Ibaraki (Japan)

1999-03-01

The neutron dosimetric characteristics of TEPC (Tissue Equivalent Proportional Counter) has been investigated under a cooperative study between Tohoku University and JNC since 1997. This TEPC is a spherical, large volume, single-wire proportional counter (the model LETSW-5, manufactured by Far West Technology, Inc.) and filled with a tissue equivalent gas in a spherical detector of the A-150 tissue equivalent plastic. The TEPC can measure the spectra of absorbed dose in LET and easily estimate the tissue equivalent dose to neutron. This report summarizes the dosimetric characteristics of TEPC to the monoenergetic neutrons with energy from 8 keV to 15 MeV. It is found that TEPC can estimate the ambient dose equivalent, H*(10), with an accuracy from 0.9 to 2 to the neutron above 0.25 MeV and TEPC has a good counting efficiency enough to measure neutron doses with low dose rate at the stray neutron fields. (author)

The high-level neutron coincidence counter (HLNCC) family of detectors

International Nuclear Information System (INIS)

Ramalho, A.; Dahn, E.; Selleck, E.; Kupryashkin, V.; Dubreuil, A.

1983-01-01

A description of a group of detectors based on The High-Level Neutron Coincidence Counter (HLNCC) concept is presented. Experience in their utilization is summarized and the procedures followed in calibration and data treatment are described. Advantages of the use of this variety of detectors in simplifying the NDA verifications, reducing the interference with facility operators, and increasing the effectiveness of the inspectors' work are stressed. Likewise, remaining problems such as the need for a vigorous programme directed at achieving the best independent calibrations are emphasized. (author)

Manual for the Portable Handheld Neutron Counter (PHNC) for Neutron Survey and the Measurement of Plutonium Samples

International Nuclear Information System (INIS)

Menlove, H.O.

2005-01-01

We have designed a portable neutron detector for passive neutron scanning measurement and coincidence counting of bulk samples of plutonium. The counter will be used for neutron survey applications as well as the measurement of plutonium samples for portable applications. The detector uses advanced design 3 He tubes to increase the efficiency and battery operated shift register electronics. This report describes the hardware, performance, and calibration for the system

Calibration of a large multi-element neutron counter in the energy range 85-430 MeV

CERN Document Server

Strong, J A; Esterling, R J; Garvey, J; Green, M G; Harnew, N; Jane, M R; Jobes, M; Mawson, J; McMahon, T; Robertson, A W; Thomas, D H

1978-01-01

Describes the calibration of a large 60 element neutron counter with a threshold of 2.7 MeV equivalent electron energy. The performance of the counter has been measured in the neutron kinetic energy range 8.5-430 MeV using a neutron beam at the CERN Synchrocyclotron. The results obtained for the efficiency as a function of energy are in reasonable agreement with a Monte Carlo calculation. (7 refs).

Neutron dosimetry using proportional counters with tissue equivalent walls

International Nuclear Information System (INIS)

Kerviller, H. de

1965-01-01

The author reminds the calculation method of the neutron absorbed dose in a material and deduce of it the conditions what this material have to fill to be equivalent to biological tissues. Various proportional counters are mode with walls in new tissue equivalent material and filled with various gases. The multiplication factor and neutron energy response of these counters are investigated and compared with those obtained with ethylene lined polyethylene counters. The conditions of working of such proportional counters for neutron dosimetry in energy range 10 -2 to 15 MeV are specified. (author) [fr

Neutron measurements inside reactors with semiconductor counters; Apsolutno merenje neutronskih flukseva u jezgru reaktora RA visokim snagama

Energy Technology Data Exchange (ETDEWEB)

Ajdacic, V; Lalovic, B; Barucija, M; Petrovic, B [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku i dinamiku reaktora, Vinca, Beograd (Serbia and Montenegro)

1964-06-15

A method of absolute in-core measurement of high neutron fluxes inside reactors operating in the megawatt region is described. In this method a semiconductor counter observes particles coming from neutron induced reactions in a target placed inside the reactor core through a long evacuated aluminum tube. The paper deals with factors which influence the accuracy of the method. Possible use of the long- tube method for neutron flux measurements in advanced reactors with neutron flux of 10{sup 15}-10{sup 16} n/cm{sup 2} sec is also discussed. The possibility of using the Li{sup 6} semiconductor counter spectrometer for measuring fast neutron spectra inside the zero power reactor at Vinca has been investigated. Great difficulties associated with the high interference of thermal neutrons have been encountered. The thermal neutron interference is almost completely suppressed by a new detector-target arrangement, in which only those products of the Li{sup 6} (n,alpha)T reactions whose mutual angle of emission is different from 180 deg are detected in coincidence. Resolution of the spectrometer as a function of the reactor power and correction factors of the spectrometer efficiency for various neutron energies are presented (author)

Channel coincidence counter: version 1

International Nuclear Information System (INIS)

Krick, M.S.; Menlove, H.O.

1980-06-01

A thermal neutron coincidence counter has been designed for the assay of fast critical assembly fuel drawers and plutonium-bearing fuel rods. The principal feature of the detector is a 7-cm by 7-cm by 97-cm detector channel, which provides a uniform neutron detection efficiency of 16% along the central 40 cm of the channel. The electronics system is identical to that used for the High-Level Neutron Coincidence Counter

DEVELOPMENT OF HETEROGENEOUS PROPORTIONAL COUNTERS FOR NEUTRON DOSIMETRY.

Science.gov (United States)

Forouzan, Faezeh; Waker, Anthony J

2018-01-10

The use of a custom-made cylindrical graphite proportional counter (Cy-GPC) along with a cylindrical tissue equivalent proportional counter (TEPC) for neutron-gamma mixed-field dosimetry has been studied in the following steps: first, the consistency of the gamma dose measurement between the Cy-TEPC and the Cy-GPC was investigated over a range of 20 keV (X-ray) to 0.661 MeV (Cs-137 gamma ray). Then, with both the counters used simultaneously, the neutron and gamma ray doses produced by a P385 Neutron Generator (Thermo Fisher Scientific) together with a Cs-137 gamma source were determined. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A semiconductor counter telescope for neutron reaction studies

Energy Technology Data Exchange (ETDEWEB)

Lalovic, B I; Ajdacic, V S [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1963-12-15

A counter telescope consisting of two or three semiconductor counters for {delta}E/{delta}x vs. E analysis was made for studying nuclear reactions induced by 14.4 MeV neutrons. Various factors important for the telescope performance are discussed in details and some solutions for getting an optimum resolution and a low background are given. Protons, deuterons and alpha particles resulting from scattering and reactions of 14.4 MeV neutrons on deuterium, tritium, praseodymium and niobium were detected, and pulses from the counters recorded on a two-dimensional analyzer. These experiments have shown that the telescope compares favorably with other types of telescopes with regards to the upper limit of neutron flux which can be used, (DELTADELTA)x and E resolution, versatility and compactness (author)

Development of a neutron detector with high detection efficiency and high spatial resolution and its applications to reactor physics experiments

International Nuclear Information System (INIS)

Tojo, Takao

1979-09-01

For detection of thermal neutrons in multiplying systems, a scintillator mixture of ZnS(Ag), 6 LiF and polyethylene was prepared, and its characteristics were shown. A sintillation detector using the mixture and a long acrylic-resin light guide was developed for measuring thermal neutrons in an U-H 2 O subcritical assembly(JAERISA). The detector was applied in the following reactor physics measurements with JAERISA: (1) cadmium ratio, (2) infinite multiplication factor, (3) material buckling, and (4) prompt neutron lifetime by pulsed neutron method. These experiments revealed that neutrons in the assembly are successfully detected by the detector owing to its outstanding characteristics of gamma-ray insensitivity, high detection efficiency and high spatial resolution. In the process of activity measurement of a foil activation detector with a GM counter, it was shown that accurate counting loss correction are difficult by usual method, because of the appreciable resolving time dependence on counting rates. In accurate correction, a new method was introduced for precise measurement of the resolving time; the dependence was made clear. A new correction method was developed, which enables direct reading of the corrected counting rates, even at high counting rates. (author)

A gaseous scintillation counter filled with He3 for neutron spectrometry

International Nuclear Information System (INIS)

Baldin, S.A.; Matveev, V.V.

1962-01-01

The paper describes a gas plant and gaseous scintillation counter, and gives the results of experiments on the recording and spectrometry of neutron beams using a gaseous scintillation counter filled with a mixture of 10% xenene and 90% helium-3 at an overall pressure of 20 ata. Data are given on the design of the gas plant, which makes it possible to operate the counter continuously over long periods of time, as well as providing the required gas mixtures at overall pressures of up to 60 atm and ensuring constant freedom of the gas from contamination. In addition, the paper presents the results of research on the counter's energy resolution and linearity at different energy levels and indicates its efficiency in gamma fields of intensity up to 3 r/h; the possibility of extending the working energy-range of gaseous scintillation counters filled with helium-3 is also considered. (author) [fr

Evaluation of in-plant neutron coincidence counters for the measurement of molten salt extraction residues

International Nuclear Information System (INIS)

Langner, D.G.; Russo, P.A.; Wachter, J.R.

1993-01-01

Americium is extracted from plutonium by a molten salt extraction (MSE) process. The residual americium-laden salts are a significant waste stream in this pyrochemical purification process. Rapid assay of MSE residues is desirable to minimize the exposure of personnel to these often high-level emissions. However, the quantitative assay of plutonium in MSE residues is difficult. Variable, unknown (a,n) rates and variable emitted-neutron energy spectra preclude the use of standard neutron coincidence counting techniques with old-generation neutron coincidence counters. Gamma-ray assay methods have not been successful with some residues because of random lumps of plutonium metal. In this paper, we present measurements of MSE residues with two state-of-the-art neutron coincidence counters at the Los Alamos Plutonium Processing Facility: an in-line counter built for the assay of bulk waste material and the pyrochemical multiplicity counter that underwent test and evaluation at that facility. Both of these counters were designed to minimize the effects on measurements of variations in the sample geometry and variable energy spectra of emitted neutrons. These results are compared to measurements made with an HLNCII and with a 20-yr-old in-line well counter. The latter two counters are not optimized in ft sense. We conclude that the newer counters provide significantly improved assay results. The pyrochemical multiplicity counter operated in the conventional coincidence mode provided the best assays overall

Proton-recoil proportional counter tests at TREAT

International Nuclear Information System (INIS)

Fink, C.L.; Eichholz, J.J.; Burrows, D.R.; DeVolpi, A.

1979-01-01

A methane filled proton-recoil proportional counter will be used as a fission neutron detector in the fast-neutron hodoscope. To provide meaningful fuel-motion information the proportional counter should have: a linear response over a wide range of reactor powers background ratio (the number of high energy neutrons detected must be maximized relative to low energy neutrons, and gamma ray sensitivity must be kept small); and a detector efficiency for fission neutrons above 1 MeV of approximately 1%. In addition, it is desirable that the detector and the associated amplifier/discriminator be capable of operating at counting rates in excess of 500 kHz. This paper reports on tests that were conducted on several proportional counters at the TREAT reactor

A suspended boron foil multi-wire proportional counter neutron detector

Energy Technology Data Exchange (ETDEWEB)

Nelson, Kyle A.; Edwards, Nathaniel S.; Hinson, Niklas J.; Wayant, Clayton D.; McGregor, Douglas S.

2014-12-11

Three natural boron foils, approximately 1.0 cm in diameter and 1.0 µm thick, were obtained from The Lebow Company and suspended in a multi-wire proportional counter. Suspending the B foils allowed the alpha particle and Li ion reaction products to escape simultaneously, one on each side of the foil, and be measured concurrently in the gas volume. The thermal neutron response pulse-height spectrum was obtained and two obvious peaks appear from the 94% and 6% branches of the {sup 10}B(n,α){sup 7}Li neutron reaction. Scanning electron microscope images were collected to obtain the exact B foil thicknesses and MCNP6 simulations were completed for those same B thicknesses. Pulse-height spectra obtained from the simulations were compared to experimental data and matched well. The theoretical intrinsic thermal–neutron detection efficiency for enriched {sup 10}B foils was calculated and is presented. Additionally, the intrinsic thermal neutron detection efficiency of the three natural B foils was calculated to be 3.2±0.2%.

A suspended boron foil multi-wire proportional counter neutron detector

Science.gov (United States)

Nelson, Kyle A.; Edwards, Nathaniel S.; Hinson, Niklas J.; Wayant, Clayton D.; McGregor, Douglas S.

2014-12-01

Three natural boron foils, approximately 1.0 cm in diameter and 1.0 μm thick, were obtained from The Lebow Company and suspended in a multi-wire proportional counter. Suspending the B foils allowed the alpha particle and Li ion reaction products to escape simultaneously, one on each side of the foil, and be measured concurrently in the gas volume. The thermal neutron response pulse-height spectrum was obtained and two obvious peaks appear from the 94% and 6% branches of the 10B(n,α)7Li neutron reaction. Scanning electron microscope images were collected to obtain the exact B foil thicknesses and MCNP6 simulations were completed for those same B thicknesses. Pulse-height spectra obtained from the simulations were compared to experimental data and matched well. The theoretical intrinsic thermal-neutron detection efficiency for enriched 10B foils was calculated and is presented. Additionally, the intrinsic thermal neutron detection efficiency of the three natural B foils was calculated to be 3.2±0.2%.

Mathematical model and computer programme for theoretical calculation of calibration curves of neutron soil moisture probes with highly effective counters

International Nuclear Information System (INIS)

Kolev, N.A.

1981-07-01

A mathematical model based on the three group theory for theoretical calculation by means of computer of the calibration curves of neutron soil moisture probes with highly effective counters, is described. Methods for experimental correction of the mathematical model are discussed and proposed. The computer programme described allows the calibration of neutron probes with high or low effective counters, and central or end geometry, with or without linearizing of the calibration curve. The use of two calculation variants and printing of output data gives the possibility not only for calibration, but also for other researches. The separate data inputs for soil and probe temperature allow the temperature influence analysis. The computer programme and calculation examples are given. (author)

A portable neutron coincidence counter

Energy Technology Data Exchange (ETDEWEB)

Peurrung, A.J.; Bowyer, S.M.; Craig, R.A.; Dudder, G.B.; Knopf, M.A.; Panisko, M.E.; Reeder, P.L.; Stromswold, D.C.; Sunberg, D.S.

1996-11-01

Pacific Northwest National Laboratory has designed and constructed a prototype portable neutron coincidence counter intended for use in a variety of applications, such as the verification and inspection of weapons components, safety measurements for novel and challenging situations, portable portal deployment to prevent the transportation of fissile materials, uranium enrichment measurements in hard-to-reach locations, waste assays for objects that cannot be measured by existing measurement systems, and decontamination and decommissioning. The counting system weighs less than 40 kg and is composed of parts each weighing no more than 5 kg. In addition, the counter`s design is sufficiently flexible to allow rapid, reliable assembly around containers of nearly arbitrary size and shape. The counter is able to discern the presence of 1 kg of weapons-grade plutonium within an ALR-8 (30-gal drum) in roughly 100 seconds and 10 g in roughly 1000 seconds. The counter`s electronics are also designed for maximum adaptability, allowing operation under a wide variety of circumstances, including exposure to gamma-ray fields of 1 R/h. This report provides a detailed review of the design and construction process. Finally, preliminary experimental measurements that confirm the performance capabilities of this counter are discussed. 6 refs., 18 figs., 3 tabs.

Orion, a high efficiency 4π neutron detector

International Nuclear Information System (INIS)

Crema, E.; Piasecki, E.; Wang, X.M.; Doubre, H.; Galin, J.; Guerreau, D.; Pouthas, J.; Saint-Laurent, F.

1990-01-01

In intermediate energy heavy ion collisions the multiplicity of emitted neutrons is strongly connected to energy dissipation and to impact parameter. We present the 4π detector ORION, a high efficiency liquid scintillator detector which permits to get information on the multiplicity of neutrons measured event-wise and on the spatial distribution of these neutrons [fr

Advanced Multilayer Composite Heavy-Oxide Scintillator Detectors for High Efficiency Fast Neutron Detection

Science.gov (United States)

Ryzhikov, Vladimir D.; Naydenov, Sergei V.; Pochet, Thierry; Onyshchenko, Gennadiy M.; Piven, Leonid A.; Smith, Craig F.

2018-01-01

We have developed and evaluated a new approach to fast neutron and neutron-gamma detection based on large-area multilayer composite heterogeneous detection media consisting of dispersed granules of small-crystalline scintillators contained in a transparent organic (plastic) matrix. Layers of the composite material are alternated with layers of transparent plastic scintillator material serving as light guides. The resulting detection medium - designated as ZEBRA - serves as both an active neutron converter and a detection scintillator which is designed to detect both neutrons and gamma-quanta. The composite layers of the ZEBRA detector consist of small heavy-oxide scintillators in the form of granules of crystalline BGO, GSO, ZWO, PWO and other materials. We have produced and tested the ZEBRA detector of sizes 100x100x41 mm and greater, and determined that they have very high efficiency of fast neutron detection (up to 49% or greater), comparable to that which can be achieved by large sized heavy-oxide single crystals of about Ø40x80 cm3 volume. We have also studied the sensitivity variation to fast neutron detection by using different types of multilayer ZEBRA detectors of 100 cm2 surface area and 41 mm thickness (with a detector weight of about 1 kg) and found it to be comparable to the sensitivity of a 3He-detector representing a total cross-section of about 2000 cm2 (with a weight of detector, including its plastic moderator, of about 120 kg). The measured count rate in response to a fast neutron source of 252Cf at 2 m for the ZEBRA-GSO detector of size 100x100x41 mm3 was 2.84 cps/ng, and this count rate can be doubled by increasing the detector height (and area) up to 200x100 mm2. In summary, the ZEBRA detectors represent a new type of high efficiency and low cost solid-state neutron detector that can be used for stationary neutron/gamma portals. They may represent an interesting alternative to expensive, bulky gas counters based on 3He or 10B neutron

Detection efficiency of the neutron detector BELEN-48 measured at the PTB Braunschweig

Energy Technology Data Exchange (ETDEWEB)

Marta, Michele [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig Universitaet Giessen (Germany); Agramunt, Jorge; Tain, Jose Luis [IFIC-CSIC University of Valencia, Valencia (Spain); Caballero-Folch, Roger; Cortes, Guillem; Riego, Albert [INTE-DFEN, Universitat Politecnica de Catalunya, Barcelona (Spain); Dillmann, Iris [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig Universitaet Giessen (Germany); TRIUMF, Vancouver (Canada); Erhard, Martin; Giesen, Ulrich; Nolte, Ralf; Roettger, Stefan [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Fraile, Luis M. [Universidad Complutense de Madrid (Spain)

2014-07-01

The BEta-deLayEd Neutron detector BELEN-48 is a highly efficient detector of β-delayed neutrons, for nuclear structure, nuclear astrophysics and reactor studies. It consists of 48 {sup 3}He proportional counters arranged in a polyethylene matrix in a way that the detection efficiency remains constant for neutron energies from thermal up to a few MeV. In order to validate MCNPX simulations, the detection efficiency has been calibrated with well-known (p,n) and (α,n) reactions on {sup 7}Li, {sup 13}C and {sup 51}V producing neutrons with energies between 0.1 and 5 MeV. The experiment has been performed at the neutron metrology facility of PTB, which allowed the measurement of yields and angular distributions with a calibrated monitor. The new results indicate anisotropies, which are not reported in literature and have been taken into account to obtain the experimental efficiencies for BELEN.

Development of a position-sensitive fission counter and measurement of neutron flux distributions

International Nuclear Information System (INIS)

Yamagishi, Hideshi; Soyama, Kazuhiko; Kakuta, Tsunemi

2001-08-01

A position-sensitive fission counter (PSFC) that operates in high neutron flux and high gamma-ray background such as at the side of a power reactor vessel has been developed. Neutron detection using the PSFC with a solenoid electrode is based on a delay-line method. The PSFC that has the outer diameter of 25 mm and the sensitive length of 1000 mm was manufactured for investigation of the performances. The PSFC provided output current pulses that were sufficiently higher than the alpha noise, though the PSFC has a solenoid electrode and large electrode-capacitance. The S/N ratio of PSFC outputs proved to be higher than that of ordinary fission counters with 200 mm sensitive length. A performance test to measure neutron flux distributions by a neutron measuring system with the PSFC was carried out by the side of a graphite pile, W2.4 x H1.4 x L1.2 m, with neutron sources, Am-Be 370 GBq x 2. It was confirmed that the neutron flux distribution was well measured with the system. (author)

Monte carlo calculation of energy-dependent response of high-sensitive neutron monitor, HISENS

International Nuclear Information System (INIS)

Imanaka, Tetsuji; Ebisawa, Tohru; Kobayashi, Keiji; Koide, Hiroaki; Seo, Takeshi; Kawano, Shinji

1988-01-01

A highly sensitive neutron monitor system, HISENS, has been developed to measure leakage neutrons from nuclear facilities. The counter system of HISENS contains a detector bank which consists of ten cylindrical proportional counters filled with 10 atm 3 He gas and a paraffin moderator mounted in an aluminum case. The size of the detector bank is 56 cm high, 66 cm wide and 10 cm thick. It is revealed by a calibration experiment using an 241 Am-Be neutron source that the sensitivity of HISENS is about 2000 times as large as that of a typical commercial rem-counter. Since HISENS is designed to have a high sensitivity in a wide range of neutron energy, the shape of its energy dependent response curve cannot be matched to that of the dose equivalent conversion factor. To estimate dose equivalent values from neutron counts by HISENS, it is necessary to know the energy and angular characteristics of both HISENS and the neutron field. The area of one side of the detector bank is 3700 cm 2 and the detection efficiency in the constant region of the response curve is about 30 %. Thus, the sensitivity of HISENS for this energy range is 740 cps/(n/cm 2 /sec). This value indicates the extremely high sensitivity of HISENS as compared with exsisting highly sensitive neutron monitors. (Nogami, K.)

Monte Carlo simulation of neutron counters for safeguards applications

International Nuclear Information System (INIS)

Looman, Marc; Peerani, Paolo; Tagziria, Hamid

2009-01-01

MCNP-PTA is a new Monte Carlo code for the simulation of neutron counters for nuclear safeguards applications developed at the Joint Research Centre (JRC) in Ispra (Italy). After some preliminary considerations outlining the general aspects involved in the computational modelling of neutron counters, this paper describes the specific details and approximations which make up the basis of the model implemented in the code. One of the major improvements allowed by the use of Monte Carlo simulation is a considerable reduction in both the experimental work and in the reference materials required for the calibration of the instruments. This new approach to the calibration of counters using Monte Carlo simulation techniques is also discussed.

Preliminary calibration of the ACP safeguards neutron counter

Science.gov (United States)

Lee, T. H.; Kim, H. D.; Yoon, J. S.; Lee, S. Y.; Swinhoe, M.; Menlove, H. O.

2007-10-01

The Advanced Spent Fuel Conditioning Process (ACP), a kind of pyroprocess, has been developed at the Korea Atomic Energy Research Institute (KAERI). Since there is no IAEA safeguards criteria for this process, KAERI has developed a neutron coincidence counter to make it possible to perform a material control and accounting (MC&A) for its ACP materials for the purpose of a transparency in the peaceful uses of nuclear materials at KAERI. The test results of the ACP Safeguards Neutron Counter (ASNC) show a satisfactory performance for the Doubles count measurement with a low measurement error for its cylindrical sample cavity. The neutron detection efficiency is about 21% with an error of ±1.32% along the axial direction of the cavity. Using two 252Cf neutron sources, we obtained various parameters for the Singles and Doubles rates for the ASNC. The Singles, Doubles, and Triples rates for a 252Cf point source were obtained by using the MCNPX code and the results for the ft8 cap multiplicity tally option with the values of ɛ, fd, and ft measured with a strong source most closely match the measurement results to within a 1% error. A preliminary calibration curve for the ASNC was generated by using the point model equation relationship between 244Cm and 252Cf and the calibration coefficient for the non-multiplying sample is 2.78×10 5 (Doubles counts/s/g 244Cm). The preliminary calibration curves for the ACP samples were also obtained by using an MCNPX simulation. A neutron multiplication influence on an increase of the Doubles rate for a metal ingot and UO2 powder is clearly observed. These calibration curves will be modified and complemented, when hot calibration samples become available. To verify the validity of this calibration curve, a measurement of spent fuel standards for a known 244Cm mass will be performed in the near future.

Calibration and Monte Carlo modelling of neutron long counters

CERN Document Server

Tagziria, H

2000-01-01

The Monte Carlo technique has become a very powerful tool in radiation transport as full advantage is taken of enhanced cross-section data, more powerful computers and statistical techniques, together with better characterisation of neutron and photon source spectra. At the National Physical Laboratory, calculations using the Monte Carlo radiation transport code MCNP-4B have been combined with accurate measurements to characterise two long counters routinely used to standardise monoenergetic neutron fields. New and more accurate response function curves have been produced for both long counters. A novel approach using Monte Carlo methods has been developed, validated and used to model the response function of the counters and determine more accurately their effective centres, which have always been difficult to establish experimentally. Calculations and measurements agree well, especially for the De Pangher long counter for which details of the design and constructional material are well known. The sensitivit...

Some aspects of the use of proton recoil proportional counters for fast neutron personnel dosimeters

International Nuclear Information System (INIS)

Yule, T.J.; Bennett, E.F.

1984-01-01

Gas-filled proton recoil proportional counters have been used extensively for the measurement of neutron spectra in degraded fission-spectrum environments. Some considerations relating to the use of these counters for personnel dosimetry are here described. High sensitivity and good accuracy in the determination of dose-equivalent can be obtained if relatively high pressure hydrogen-filled proportional counters are used as the active element in a dosimeter system

Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

Energy Technology Data Exchange (ETDEWEB)

Smith, L.; Murphy, J.W. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Kim, J. [Korean Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of); Rozhdestvenskyy, S.; Mejia, I. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Park, H. [Korean Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of); Allee, D.R. [Flexible Display Center, Arizona State University, Phoenix, AZ 85284 (United States); Quevedo-Lopez, M. [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Gnade, B., E-mail: beg031000@utdallas.edu [Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States)

2016-12-01

Solid-state neutron detectors offer an alternative to {sup 3}He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10{sup −6} gamma-ray efficiency.

High energy neutron dosimeter

International Nuclear Information System (INIS)

Rai, K.S.F.

1994-01-01

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures

A compact and high efficiency GAGG well counter for radiocesium concentration measurements

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Ogata, Yoshimune

2014-07-01

After the Fukushima nuclear disaster, social concern about radiocesium ({sup 137}Cs and {sup 134}Cs) contamination in food increased. However, highly efficient instruments that can measure low level radioactivity are quite expensive and heavy. A compact, lightweight, and reliable radiation detector that can inexpensively monitor low level radiocesium is highly desired. We developed a compact and highly efficient radiocesium detector to detect ∼32 keV X-rays from radiocesium instead of high energy gamma photons. A 1-mm thick GAGG scintillator was selected to effectively detect ∼32 keV X-rays from {sup 137}Cs to reduce the influence of ambient radiation. Four sets of 25 mm×25 mm×1 mm GAGG plates, each of which was optically coupled to a triangular-shaped light guide, were optically coupled to a photomultiplier tube (PMT) to form a square-shaped well counter. Another GAGG plate was directly optically coupled to the PMT to form its bottom detector. The energy resolution of the GAGG well counter was 22.3% FWHM for 122 keV gamma rays and 32% FWHM for ∼32 keV X-rays. The counting efficiency for the X-rays from radiocesium (mixture of {sup 137}Cs and {sup 134}Cs) was 4.5%. In measurements of the low level radiocesium mixture, a photo-peak of ∼32 keV X-rays can clearly be distinguished from the background. The minimum detectable activity (MDA) was estimated to be ∼100 Bq/kg for 1000 s measurement. The results show that our developed GAGG well counter is promising for the detection of radiocesium in food.

Calibration methodology for proportional counters applied to yield measurements of a neutron burst

Energy Technology Data Exchange (ETDEWEB)

Tarifeño-Saldivia, Ariel, E-mail: atarifeno@cchen.cl, E-mail: atarisal@gmail.com; Pavez, Cristian; Soto, Leopoldo [Comisión Chilena de Energía Nuclear, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Santiago (Chile); Departamento de Ciencias Fisicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Republica 220, Santiago (Chile); Mayer, Roberto E. [Instituto Balseiro and Centro Atómico Bariloche, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, San Carlos de Bariloche R8402AGP (Argentina)

2014-01-15

This paper introduces a methodology for the yield measurement of a neutron burst using neutron proportional counters. This methodology is to be applied when single neutron events cannot be resolved in time by nuclear standard electronics, or when a continuous current cannot be measured at the output of the counter. The methodology is based on the calibration of the counter in pulse mode, and the use of a statistical model to estimate the number of detected events from the accumulated charge resulting from the detection of the burst of neutrons. The model is developed and presented in full detail. For the measurement of fast neutron yields generated from plasma focus experiments using a moderated proportional counter, the implementation of the methodology is herein discussed. An experimental verification of the accuracy of the methodology is presented. An improvement of more than one order of magnitude in the accuracy of the detection system is obtained by using this methodology with respect to previous calibration methods.

Calibration methodology for proportional counters applied to yield measurements of a neutron burst

International Nuclear Information System (INIS)

Tarifeño-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo; Mayer, Roberto E.

2014-01-01

This paper introduces a methodology for the yield measurement of a neutron burst using neutron proportional counters. This methodology is to be applied when single neutron events cannot be resolved in time by nuclear standard electronics, or when a continuous current cannot be measured at the output of the counter. The methodology is based on the calibration of the counter in pulse mode, and the use of a statistical model to estimate the number of detected events from the accumulated charge resulting from the detection of the burst of neutrons. The model is developed and presented in full detail. For the measurement of fast neutron yields generated from plasma focus experiments using a moderated proportional counter, the implementation of the methodology is herein discussed. An experimental verification of the accuracy of the methodology is presented. An improvement of more than one order of magnitude in the accuracy of the detection system is obtained by using this methodology with respect to previous calibration methods

Introduction to Neutron Coincidence Counter Design Based on Boron-10

Energy Technology Data Exchange (ETDEWEB)

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

2012-01-22

The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

Neutron time-of-flight counters and spectrometers for diagnostics of burning fusion plasmas

International Nuclear Information System (INIS)

Elevant, T.; Olsson, M.

1991-02-01

Experiment with burning fusion plasmas in tokamaks will place particular requirements on neutron measurements from radiation resistance-, physics-, burn control- and reliability considerations. The possibility to meet these needs by measurements of neutron fluxes and energy spectra by means of time-of-flight techniques are described. Reference counters and spectrometers are proposed and characterized with respect to efficiency, count-rate capabilities, energy resolution and tolerable neutron and γ-radiation background levels. The instruments can be used in a neutron camera and are capable to operate in collimated neutron fluxes up to levels corresponding to full nuclear output power in the next generation of experiments. Energy resolutions of the spectrometers enables determination of ion temperatures from 3 (keV) through analysis of the Doppler broadening. Primarily, the instruments are aimed for studies of 14 (MeV) neutrons produced in (d,t)-plasmas but can, after minor modifications, be used for analysis of 2.45 (MeV) neutrons produced in (d,d)-plasma. (au) (33 refs.)

Ideal response function of a 3He proportional counter to thermal neutrons determined by different length counters

International Nuclear Information System (INIS)

Takeda, Naoto; Kudo, Katsuhisa; Kobayashi, Katsuhei; Yoshimoto, Takaaki

2000-01-01

The relative gas multiplication along the cylindrical axis of three 3 He proportional counters with different length were measured by using a thermal neutron beam at the Kyoto University Reactor and an ideal response function by taking into account the difference of pulse height spectra were measured by different length counters. The three 3 He proportional counters (model type of P4-0806, P4-0806 and P4-0808 manufactured by Reuter-Stokes) prepared for relative gas multiplication measurements had identical structure having cylindrical outer shells of 304 stainless steel except for different sensitive lengths of 10 cm, 15 cm and 20 cm, respectively. All counters were filled with 400 kPa of 3 He gas and 200 kPa of Ar gas. The pulse height distributions were measured by moving the counter in the direction of it's cylindrical axis perpendicular to the thermal neutron beam. The measured pulse heights corresponding to the full energy peaks at various entrance points were normalized to that of the whole counter irradiation. The results as a function of the distance from the bottom edge of the stainless steel cylinder are shown. The total transition region of gas gain corresponded to about 23 %, 15 % and 10 % of each nominal sensitive region corresponding to shot, middle and long counters. The ideal pulse height spectrum (dots) obtained by using proportional counters of 10 cm and 20 cm in nominal sensitive length to thermal neutron beam is shown in the paper in comparison to simulated one which was calculated assuming the constant gain within the sensitive region and zero gas gain outside the sensitive regions. The simulation realized the ideal response function fairly well. (S.Y.)

A helium-3 proportional counter technique for estimating fast and intermediate neutrons

International Nuclear Information System (INIS)

Kosako, Toshiso; Nakazawa, Masaharu; Sekiguchi, Akira; Wakabayashi, Hiroaki.

1976-11-01

3 He proportional counter was employed to determine the fast and intermediate neutron spectra of wide energy region. The mixed gas ( 3 He, Kr) type counter response and the spectrum unfolding code were prepared and applied to some neutron fields. The counter response calculation was performed by using the Monte Carlo code, paying regards to dealing of the particle range calculation of the mixed gas. An experiment was carried out by using the van de Graaff accelerator to check the response function. The spectrum unfolding code was prepared so that it may have the function of automatic evaluation of the higher energy spectrum's effect to the pulse hight distribution of the lower energy region. The neutron spectra of the various neutron fields were measured and compared with the calculations such as the discrete ordinate Sn calculations. It became clear that the technique developed here can be applied to the practical use in the neutron energy range from about 150 KeV to 5 MeV. (auth.)

A neutron well counter for plutonium assay in 200 l waste drums

International Nuclear Information System (INIS)

Eyrich, W.; Kuechle, M.; Shafiee, M.

1979-05-01

A neutron well counter is briefly described which will be used for monitoring the plutonium content of 200 l barrels in the waste treatment plant of the Kernforschungszentrum Karlsruhe. Measurements on simulated waste were made to study the influence of matrix material and non-homogeneous plutonium distribution. The variation in detection efficiency could be reduced from 28% to 10% when the signals from inner and outer neutron detectors in the polyethylene annulus are counted separately and a correction is applied, using this information. This method is superior to the source addition technique. Coincidence counting shows a larger variation which could not be reduced to below 18%. (orig.) [de

Proton-recoil proportional-counter array for neutron-image construction

International Nuclear Information System (INIS)

Fink, C.L.; Eichholz, J.J.; DeVolpi, A.

1984-01-01

The fuel-motion measurement capability of the fast-neutron hodoscope has been upgraded by the addition of a 360-detector proton-recoil proportional-counter array, which detects high-energy fission neutrons. The current sensitive amplifier/discriminator module for each detector fits into a 12.7 by 12.7 by 102 mm package and cost less than $100 per module. It has a 50 ns rise time, a noise level of 100 nA, and a deadtime per event of 200 ns. Provision has been provided for the independent adjustment of the input current versus discriminator voltage for each module. The new proportional-counters cost approximately $400 each. Each detector has been tested to have the same gain versus voltage response. A space-charge model relating count-rate changes to space-charge effects has also been developed. The new detector array has been operational for approximately two years and has become the main detector system in fuel-motion analysis. It has significantly improved the linearity, stability, count-rate capability, and setup ease of the hodoscope

Measurement of fast neutron spectra inside reactors with a Li{sup 6} semiconductor counter spectrometer

Energy Technology Data Exchange (ETDEWEB)

Ajdacic, V S; Lalovic, B I; Petrovic, B P [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1963-12-15

The possibility of using the Li{sup 6} semiconductor counter spectrometer for measuring fast neutron spectra inside reactors has been investigated in details and some solutions of the difficulties associated with the high interference of thermal neutrons in well-moderated reactors are suggested and checked experimentally (author)

Hexagonal boron nitride neutron detectors with high detection efficiencies

Science.gov (United States)

Maity, A.; Grenadier, S. J.; Li, J.; Lin, J. Y.; Jiang, H. X.

2018-01-01

Neutron detectors fabricated from 10B enriched hexagonal boron nitride (h-10BN or h-BN) epilayers have demonstrated the highest thermal neutron detection efficiency among solid-state neutron detectors to date at about 53%. In this work, photoconductive-like vertical detectors with a detection area of 1 × 1 mm2 were fabricated from 50 μm thick free-standing h-BN epilayers using Ni/Au and Ti/Al bilayers as ohmic contacts. Leakage currents, mobility-lifetime (μτ) products under UV photoexcitation, and neutron detection efficiencies have been measured for a total of 16 different device configurations. The results have unambiguously identified that detectors incorporating the Ni/Au bilayer on both surfaces as ohmic contacts and using the negatively biased top surface for neutron irradiation are the most desired device configurations. It was noted that high growth temperatures of h-10BN epilayers on sapphire substrates tend to yield a higher concentration of oxygen impurities near the bottom surface, leading to a better device performance by the chosen top surface for irradiation than by the bottom. Preferential scattering of oxygen donors tends to reduce the mobility of holes more than that of electrons, making the biasing scheme with the ability of rapidly extracting holes at the irradiated surface while leaving the electrons to travel a large average distance inside the detector at a preferred choice. When measured against a calibrated 6LiF filled micro-structured semiconductor neutron detector, it was shown that the optimized configuration has pushed the detection efficiency of h-BN neutron detectors to 58%. These detailed studies also provided a better understanding of growth-mediated impurities in h-BN epilayers and their effects on the charge collection and neutron detection efficiencies.

High-efficiency transmision neutron polarizer for high-resolution double crystal diffractometer

International Nuclear Information System (INIS)

Ioffe, A.; Krist, T.; Mezei, F.; Gordeev, G.; Ibrayev, B.

1997-01-01

An efficient transmission geometry neutron polarizer for the high-resolution double crystal diffractometer at HMI (λ=4.8 A) is described. A polarization of about 94% was achieved and the polarized neutron beam intensity amounts to 40% of the nonpolarized beam intensity. This opens up wide possibilities for the study of magnetic small-angle scattering for extremely small momentum transfer (Q∝10 -5 A -1 ). (orig.)

The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

Energy Technology Data Exchange (ETDEWEB)

McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cleveland, Steven L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-03-01

The ²³⁵U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic ²³⁵U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and ²⁵²Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., ²⁵²Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The ²⁵²Cf shuffler systems rely on the use of high-output ²⁵²Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of ²³⁵U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.

Detection of neutrons of intermediate energy using 10B, enclosed in a coaxial Ge(Li) counter

International Nuclear Information System (INIS)

Huck, A.; Klotz, G.; Walter, G.

1976-01-01

A neutron detector operating in the energy range 1keV to roughly 1MeV with a time response that is fast enough to be used in time-of-flight experiments, has been designed and built. The neutron is absorbed in boron-10, placed inside a coaxial Ge(Li) counter. Efficient detection of the 478keV line from 7 Li, resulting from 10 B(n,α) 7 Li*, is realized. At the same time, the measurement of accompanying γ radiations, emitted by the neutron source, can be performed. Examples of results, obtained using (p,nγ) reactions, are given [fr

High efficiency focus neutron generator

Science.gov (United States)

Sadeghi, H.; Amrollahi, R.; Zare, M.; Fazelpour, S.

2017-12-01

In the present paper, the new idea to increase the neutron yield of plasma focus devices is investigated and the results are presented. Based on many studies, more than 90% of neutrons in plasma focus devices were produced by beam target interactions and only 10% of them were due to thermonuclear reactions. While propounding the new idea, the number of collisions between deuteron ions and deuterium gas atoms were increased remarkably well. The COMSOL Multiphysics 5.2 was used to study the given idea in the known 28 plasma focus devices. In this circumstance, the neutron yield of this system was also obtained and reported. Finally, it was found that in the ENEA device with 1 Hz working frequency, 1.1 × 109 and 1.1 × 1011 neutrons per second were produced by D-D and D-T reactions, respectively. In addition, in the NX2 device with 16 Hz working frequency, 1.34 × 1010 and 1.34 × 1012 neutrons per second were produced by D-D and D-T reactions, respectively. The results show that with regards to the sizes and energy of these devices, they can be used as the efficient neutron generators.

A measurement of the efficiency for the detection of neutrons in the momentum range 200 to 3200 MeV/c, in large volume liquid scintillation counters

International Nuclear Information System (INIS)

Brown, R.M.; Clark, A.G.; Duke, P.J.

1976-04-01

A description is given of a system of 194 large volume liquid scintillation counters designed to detect neutrons in an experiment on the reaction π - p → π 0 n in the resonance region. The detection efficiency of the system has been determined, as a function of neutron momentum, in three separate measurements, covering the range 200 to 3200 MeV/c. Below 400 MeV/c the efficiency shows the expected momentum dependence near threshold, rising to a maximum of 50% near 300 MeV/c and then falling to 43% near 400 MeV/c. In the region 400 to 700 MeV/c the efficiency rises to 47% near 600 MeV/c and falls again to 43%, an effect not seen before; the efficiency was expected to be almost momentum independent in this region. Above the threshold for inelastic processes in nucleon-nucleon collision (approximately 800 MeV/c) the efficiency rises significantly reaching a maximum value of 65% above 1700 MeV/c. (author)

Dual-chamber/dual-anode proportional counter incorporating an intervening thin-foil solid neutron converter

International Nuclear Information System (INIS)

Boatner, Lynn A.; Neal, John S.; Blackston, Matthew A.; Kolopus, James A.; Ramey, Joanne O.

2012-01-01

A dual-chamber/dual-anode gas proportional counter utilizing thin solid 6 LiF or 10 B neutron converters coated on a 2-micon-thick Mylar film that is positioned between the two counter chambers and anodes has been designed, fabricated, and tested using a variety of fill gases—including naturally abundant helium. In this device, neutron conversion products emitted from both sides of the coated converter foil are detected—rather than having half of the products absorbed in the wall of a conventional tube-type counter where the solid neutron converter is deposited on the tube wall. Geant4-based radiation transport calculations were used to determine the optimum neutron converter coating thickness for both isotopes. Solution methods for applying these optimized-thickness coatings on a Mylar film were developed that were carried out at room temperature without any specialized equipment and that can be adapted to standard coating methods such as silk screen or ink jet printing. The performance characteristics of the dual-chamber/dual-anode neutron detector were determined for both types of isotopically enriched converters. The experimental performance of the 6 LiF-converter-based detector was described well by modeling results from Geant4. Additional modeling studies of multiple-foil/multiple-chamber/anode configurations addressed the basic issue of the relatively longer absorption range of neutrons versus the shorter range of the conversion products for 6 LiF and 10 B. Combined with the experimental results, these simulations indicate that a high-performance neutron detector can be realized in a single device through the application of these multiple-foil/solid converter, multiple-chamber detector concepts.

Calibration methodology for proportional counters applied to yield measurements of a neutron burst

International Nuclear Information System (INIS)

Tarifeño-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo; Mayer, Roberto E

2015-01-01

This work introduces a methodology for the yield measurement of a neutron burst using neutron proportional counters. The methodology is based on the calibration of the counter in pulse mode, and the use of a statistical model to estimate the number of detected events from the accumulated charge resulting from detection of the burst of neutrons. An improvement of more than one order of magnitude in the accuracy of a paraffin wax moderated 3 He-filled tube is obtained by using this methodology with respect to previous calibration methods. (paper)

Application of Whole Body Counter to Neutron Dose Assessment in Criticality Accidents

Energy Technology Data Exchange (ETDEWEB)

Kurihara, O.; Tsujimura, N.; Takasaki, K.; Momose, T.; Maruo, Y. [Japan Nuclear Cycle Development Institute, Tokai (Japan)

2001-09-15

Neutron dose assessment in criticality accidents using Whole Body Counter (WBC) was proved to be an effective method as rapid neutron dose estimation at the JCO criticality accident in Tokai-mura. The 1.36MeV gamma-ray of {sup 24}Na in a body can be detected easily by a germanium detector. The Minimum Detectable Activity (MDA) of {sup 24}Na is approximately 50Bq for 10minute measurement by the germanium-type whole body counter at JNC Tokai Works. Neutron energy spectra at the typical shielding conditions in criticality accidents were calculated and the conversion factor, whole body activity-to-organ mass weighted neutron absorbed dose, corresponding to each condition were determined. The conversion factor for uncollied fission spectrum is 7.7 [(Bq{sup 24}Na/g{sup 23}Na)/mGy].

Prototype fast neutron counter for the assay of impure plutonium

International Nuclear Information System (INIS)

Wachter, J.R.; Adams, E.L.; Ensslin, N.

1987-01-01

A fast coincident neutron counter using liquid scintillators and gamma-ray/neutron pulse-shape discrimination has been constructed for the analysis of plutonium samples with unknown self-multiplication and (α,n) production. The counter was used to measure plutonium-bearing materials that cover a range of masses and (α,n) reaction rates of importance to the safeguards community. Measured values of the 240 Pu effective mass differed, on average, from their declared values by 0.4% for plutonium oxides and by -2.2% for metal and MgO-loaded samples. Poorer results were obtained for materials with large (α,n) reaction rates and low self-multiplication such as plutonium ash and plutonium fluoride

A neutron detector for measurement of total neutron production cross sections

International Nuclear Information System (INIS)

Sekharan, K.K.; Laumer, H.; Kern, B.D.; Gabbard, F.

1976-01-01

A neutron detector has been constructed and calibrated for the accurate measurement of total neutron production cross sections. The detector consists of a polyethylene sphere of 60 cm diameter in which eight 10 BF 3 counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies from 30 keV to 1.5 MeV by counting neutrons from 7 Li(p, n) 7 Be. By adjusting the radial positions of the BF 3 counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from 51 V(p, n) 51 Cr and 57 Fe(p, n) 57 Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for determination of neutron production cross sections are given. (Auth.)

Efficiency calibration of solid track spark auto counter

International Nuclear Information System (INIS)

Wang Mei; Wen Zhongwei; Lin Jufang; Liu Rong; Jiang Li; Lu Xinxin; Zhu Tonghua

2008-01-01

The factors influencing detection efficiency of solid track spark auto counter were analyzed, and the best etch condition and parameters of charge were also reconfirmed. With small plate fission ionization chamber, the efficiency of solid track spark auto counter at various experiment assemblies was re-calibrated. The efficiency of solid track spark auto counter at various experimental conditions was obtained. (authors)

Measurement and simulation of the neutron detection efficiency with a Pb-scintillating fiber calorimeter

Energy Technology Data Exchange (ETDEWEB)

Anelli, M; Bertolucci, S; Curceanu, C; Giovannella, S; Happacher, F; Iliescu, M; Martini, M; Miscetti, S [Laboratori Nazionali di Frascati, INFN (Italy); Battistoni, G [Sezione INFN di Milano (Italy); Bini, C; Zorzi, G De; Domenico, Adi; Gauzzi, P [Ubiversita degli Studi ' La Sapienza' e Sezine INFN di Roma (Italy); Branchini, P; Micco, B Di; Ngugen, F; Paseri, A [Universita degli di Studi ' Roma Tre' e Sezione INFN di Roma Tre (Italy); Ferrari, A [Fondazione CNAO, Milano (Italy); Prokfiev, A [Svedberg Laboratory, Uppsala University (Sweden); Fiore, S, E-mail: matteo.martino@inf.infn.i

2009-04-01

We have measured the overall detection efficiency of a small prototype of the KLOE PB-scintillation fiber calorimeter to neutrons with kinetic energy range [5,175] MeV. The measurement has been done in a dedicated test beam in the neutron beam facility of the Svedberg Laboratory, TSL Uppsala. The measurements of the neutron detection efficiency of a NE110 scintillator provided a reference calibration. At the lowest trigger threshold, the overall calorimeter efficiency ranges from 28% to 33%. This value largely exceeds the estimated {approx}8% expected if the response were proportional only to the scintillator equivalent thickness. A detailed simulation of the calorimeter and of the TSL beam line has been performed with the FLUKA Monte Carlo code. The simulated response of the detector to neutrons is presented together with the first data to Monte Carlo comparison. The results show an overall neutron efficiency of about 35%. The reasons for such an efficiency enhancement, in comparison with the typical scintillator-based neutron counters, are explained, opening the road to a novel neutron detector.

A New Neutron Multiplicity Counter for the Measurement of Impure Plutonium Metal at Westinghouse Savannah River Site

International Nuclear Information System (INIS)

Baker, L.B.; Faison, D.M.; Langner, D.G.; Sweet, M.R.; Salazar, S.D.; Kroncke, K.E.

1998-07-01

A new neutron multiplicity counter has been designed, fabricated, characterized, and installed for use in the assay of impure plutonium metal buttons from the FB-Line at the Westinghouse Savannah River Site (WSRS). This instrument incorporates the performance characteristics of the Pyrochemical or In-plant Multiplicity Counter with the package size of the Plutonium Scrap Multiplicity Counter. In addition, state-of-the art features such as the de-randomizer circuit and separate ring outputs have been added. The counter consists of 113, 71 cm active length 3He tubes in a polyethylene moderator. Its efficiency for 252Cf is 57.8 percent, the highest of any multiplicity counter to date. Its die-away time is 50.4 ms and its deadtime is 50 ns. In this paper we will present the characterization data for the counter and the results of preliminary metal measurements at WSRS. We will also discuss the new challenges the impure metal buttons from FB-Line are presenting to the multiplicity counting technique

Development of a high-count-rate neutron detector with position sensitivity and high efficiency

International Nuclear Information System (INIS)

Nelson, R.; Sandoval, J.

1996-01-01

While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled 3 He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source

A neutron calibration technique for detectors with low neutron/high photon sensitivity

International Nuclear Information System (INIS)

Jahr, R.; Guldbakke, S.; Cosack, M.; Dietze, G.; Klein, H.

1978-03-01

The neutron response of a detector with low neutron-/high photon sensitivity is given by the difference of two terms: the response to the mixed neutron-photon field, measured directly, and the response to the photons, deduced from additional measurements with a photon spectrometer. The technique is particularly suited for use in connection with targets which consist of a thick backing and thin layer of neutron producing material such as T, D, Li nuclei. Then the photon component of the mixed field is very nearly the same as the pure photon field from a 'phantom target', being identical with the neutron producing target except for the missing neutron producing material. Using this technique in connection with a T target (Ti-T-layer on silver backing) and the corresponding phantom target (Ti-layer on silver backing), a GM counter was calibrated at a neutron energy of 2.5 MeV. Possibilities are discussed to subsequently calibrate the GM counter at other neutron energies without the use of the photon spectrometer. (orig./HP) [de

Development of high efficiency neutron detectors

International Nuclear Information System (INIS)

Pickrell, M.M.; Menlove, H.O.

1993-01-01

The authors have designed a novel neutron detector system using conventional 3 He detector tubes and composites of polyethylene and graphite. At this time the design consists entirely of MCNP simulations of different detector configurations and materials. These detectors are applicable to low-level passive and active neutron assay systems such as the passive add-a-source and the 252 Cf shuffler. Monte Carlo simulations of these neutron detector designs achieved efficiencies of over 35% for assay chambers that can accommodate 55-gal. drums. Only slight increases in the number of detector tubes and helium pressure are required. The detectors also have reduced die-away times. Potential applications are coincident and multiplicity neutron counting for waste disposal and safeguards. The authors will present the general design philosophy, underlying physics, calculation mechanics, and results

Use of the helium-3 proportional counter for neutron spectrometry

International Nuclear Information System (INIS)

Vialettes, H.; Le Thanh, P.

1967-01-01

Up to now, two methods have been mainly used for neutron spectrometry near nuclear installations: - photographic emulsion spectrometry - the so-called, 'multisphere' technique spectrometry. The first method, which is fairly difficult to apply, has a threshold energy of about 500 keV; this is a big disadvantage for an apparatus which has to be used for spectrometry around nuclear installations where the neutron radiation is very much degraded energetically. The second method does not suffer from this disadvantage but the results which it yields are only approximate. In order to extend the energy range of the neutron spectra studied with sufficient accuracy the use of a helium-3 proportional counter has been considered. This report presents the principles of operation of the helium-3 spectrometer, and the calculation methods which make it possible to take into account the two main effects tending to deform the spectra obtained: - energy absorption by the walls of the counter, - energy loss of the incident neutrons due to elastic collisions with helium-3 nuclei. As an example of the application, the shape of the neutron spectrum emitted by a polonium-lithium source is given; the results obtained are in excellent agreement with theoretical predictions. (authors) [fr

Cosmic Ray Background Analysis For A Cargo Container Counter

International Nuclear Information System (INIS)

Ensslin, Norbert; Geist, W.H.; Lestone, J.P.; Mayo, D.R.; Menlove, Howard O.

2001-01-01

We have developed a new model for calculating the expected yield of cosmic-ray spallation neutrons in a Cargo Container Counter, and we have benchmarked the model against measurements made with several existing large neutron counters. We also developed two versions of a new measurement uncertainty prediction code based on Microsoft Excel spreadsheets. The codes calculate the minimum detectability limit for the Cargo Container Counter for either neutron singles or doubles counting, and also propagate the uncertainties associated with efficiency normalization flux monitors and cosmic ray flux monitors. This paper will describe the physics basis for this analysis, and the results obtained for several different counter designs.

Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

Energy Technology Data Exchange (ETDEWEB)

Cowles, Christian C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-10-01

The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

Calibration of the neutron scintillation counter threshold

International Nuclear Information System (INIS)

Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.

1978-01-01

A method for calibrating the threshold of a neutron counter in the form of a 10x10x40 cm plastic scintillator is described. The method is based on the evaluation of the Compton boundary of γ-spectrum from the discrimination curve of counter loading. The results of calibration using 60 Co and 24 Na γ-sources are given. In order to eValuate the Compton edge rapidly, linear extrapolation of the linear part of the discrimination curve towards its intersection with the X axis is recommended. Special measurements have shown that the calibration results do not practically depend on the distance between the cathode of a photomultiplier and the place where collimated γ-radiation of the calibration source reaches the scintillator

A neutron detector for measurement of total neutron production cross sections

Energy Technology Data Exchange (ETDEWEB)

Sekharan, K K; Laumer, H; Kern, B D; Gabbard, F [Kentucky Univ., Lexington (USA). Dept. of Physics and Astronomy

1976-03-01

A neutron detector has been constructed and calibrated for the accurate measurement of total neutron production cross sections. The detector consists of a polyethylene sphere of 60 cm diameter in which eight /sup 10/BF/sub 3/ counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies from 30 keV to 1.5 MeV by counting neutrons from /sup 7/Li(p, n)/sup 7/Be. By adjusting the radial positions of the BF/sub 3/ counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from /sup 51/V(p, n)/sup 51/Cr and /sup 57/Fe(p, n)/sup 57/Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for determination of neutron production cross sections are given.

Manual for the Epithermal Neutron Multiplicity Detector (ENMC) for Measurement of Impure MOX and Plutonium Samples

International Nuclear Information System (INIS)

Menlove, H. O.; Rael, C. D.; Kroncke, K. E.; DeAguero, K. J.

2004-01-01

We have designed a high-efficiency neutron detector for passive neutron coincidence and multiplicity counting of dirty scrap and bulk samples of plutonium. The counter will be used for the measurement of impure plutonium samples at the JNC MOX fabrication facility in Japan. The counter can also be used to create working standards from bulk process MOX. The detector uses advanced design "3He tubes to increase the efficiency and to shorten the neutron die-away time. The efficiency is 64% and the die-away time is 19.1 ?s. The Epithermal Neutron Multiplicity Counter (ENMC) is designed for high-precision measurements of bulk plutonium samples with diameters of less than 200 mm. The average neutron energy from the sample can be measured using the ratio of the inner ring of He-3 tubes to the outer ring. This report describes the hardware, performance, and calibration for the ENMC.

High neutronic efficiency, low current targets for accelerator-based BNCT applications

International Nuclear Information System (INIS)

Powell, J.R.; Ludewig, H.; Todosow, M.

1998-01-01

The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (10 9 n/cm 2 /s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin (∼ 5 cm iron). However, this approach has an extremely low neutron yield (n/p ∼ 1.0(-6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target ∼ 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies (∼ 2.5 MeV) have a much higher yield (n/p ∼ 1.0(-4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV

Response matrix of a multisphere neutron spectrometer with an 3 He proportional counter

International Nuclear Information System (INIS)

Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Mercado S, G.A.

2005-01-01

The response matrix of a Bonner sphere spectrometer was calculated by use of the MCNP code. As thermal neutron counter, the spectrometer has a 3.2 cm-diameter 3 He-filled proportional counter which is located at the center of a set of polyethylene spheres. The response was calculated for 0, 3, 5, 6, 8, 10, 12, and 16 inches-diameter polyethylene spheres for neutrons whose energy goes from 10 -9 to 20 MeV. The response matrix was compared with a set of responses measured with several monoenergetic neutron sources. In this comparison the calculated matrix agrees with the experimental results. The matrix was also compared with the response matrix calculated for the PTB C spectrometer. Even though that calculation was carried out using a detailed model to describe the proportional counter; both matrices do agree, but small differences are observed in the bare case because of the difference in the model used during calculations. Other differences are in some spheres for 14.8 and 20 MeV neutrons, probably due to the differences in the cross sections used during both calculations. (Author) 28 refs., 1 tab., 6 figs

Discrimination of the wall effect in a thin counter with micro-gap structure for neutron position sensing

Energy Technology Data Exchange (ETDEWEB)

Sakae, Takeji; Manabe, Tohru; Kitamura, Yasunori; Nohtomi, Akihiro [Kyushu Univ., Fukuoka (Japan); Sakamoto, Sigeyasu

1996-07-01

Simulation by the Monte Carlo method is applied to estimate the wall effect in a thermal neutron counter having a new function for discriminating the effect. The counter is designed to have paralleled electrodes with micro-gap structure. A resistive anode is used for position sensing on the center of a set of the three electrode. The structure can be made by simple arrangement of anode and cathode wires on an insulator plane. The calculation shows discrimination of the wall effect can be achieved by coincident counting of two or three elements included in the counter. By using the coincident counting, the thickness of the neutron counter can be made into 1 mm with the information of the total energy created in the neutron detection. (author)

Hot nuclei studied with high efficiency neutron detectors

International Nuclear Information System (INIS)

Galin, J.

1990-01-01

We have shown the invaluable benefit that a high efficiency 4π neutron detector can bring to the study of reaction mechanisms following collisions of heavy nuclei at intermediate energy. Analysis requires Monte-Carlo simulations for comparison between experimental data and any emission model. In systematic measurements with projectiles of velocity corresponding to energies between 27 and 77 MeV/u, where both the influence of beam velocity and mass have been investigated separately, it has been shown that the projectile-target mass asymmetry, much more than velocity, has a decisive influence on energy dissipation. The closer the projectile mass to the target mass, the more energy is dissipated per unit mass of the considered projectile plus target system. The latter presents all the characteristics of a thermalized system, evaporating a copious number of light particles: up to about 40 neutrons (after efficiency correction) and 11 light charged particles in the most dissipative collisions between Kr+Au, and 90 neutrons for Pb+U with a yet unknown number of l.c.p. In the Kr experiment, these particles are isotropically emitted in the frame of a fused system, excited with 1.2 GeV. Moreover, l.c.p. exhibit Maxwellian energy distributions as in any standard evaporation process. We are now eager to better characterize the properties of the Pb+Au (U) systems for which about 1/3 of the neutrons are freed in a rather large fraction of all collisions. The thermalized energy should then approach very closely the total binding energy of the two interacting nuclei

A deadtime reduction circuit for thermal neutron coincidence counters with Amptek preamplifiers

International Nuclear Information System (INIS)

Bourret, S.C.; Krick, M.S.

1994-01-01

We have developed a deadtime reduction circuit for thermal neutron coincidence counters using Amptek preamplifier/amplifier/discriminator circuits. The principle is to remove the overlap between the output pulses from the Amptek circuits by adding a derandomizer between the Amptek circuits and the shift-register coincidence electronics. We implemented the derandomizer as an Actel programmable logic array; the derandomizer board is small and can be mounted in the high-voltage junction box with the Amptek circuits, if desired. Up to 32 Amptek circuits can be used with one derandomizer. The derandomizer has seven outputs: four groups of eight inputs, two groups of 16 inputs, and one group of 32 inputs. We selected these groupings to facilitate detector ring-ratio measurements. The circuit was tested with the five-ring research multiplicity counter, which has five output signals-one for each ring. The counter's deadtime was reduced from 70 to 30 ns

Transparent platinum counter electrode for efficient semi-transparent dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Iefanova, Anastasiia; Nepal, Jeevan; Poudel, Prashant; Davoux, Daren; Gautam, Umesh [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States); Mallam, Venkataiah [Chemistry and Biochemistry Department, South Dakota State University, Brookings, SD 57006 (United States); Qiao, Qiquan [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States); Logue, Brian [Chemistry and Biochemistry Department, South Dakota State University, Brookings, SD 57006 (United States); Baroughi, Mahdi Farrokh, E-mail: m.farrokhbaroughi@sdstate.edu [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States)

2014-07-01

A method for fabrication of highly transparent platinum counter electrodes (CEs) has been developed based on spray coating of Pt nanoparticles (NPs) on hot substrates. This method leads to 86% reduction in Pt consumption reducing the Pt cost per peak watt of counter electrode from $0.79/Wp down to $0.11/Wp compared to the conventional Pt counter electrodes made by sputter deposition. The simplicity and low cost of this method provide a basis for an up-scalable fabrication process. The Pt NP layer is over 88% transparent, leading to overall transparency of 80% when incorporated with indium tin oxide/glass substrates for functional counter electrodes. This counter electrode exhibits a large surface area and high catalytic activity, comparable to that of the conventional opaque CEs. Semi-transparent dye-sensitized solar cells fabricated based on this counter electrode showed 6.17% power conversion efficiency. - Highlights: • Counter electrode (CE) prepared by spraying nanoparticle (NP) Pt on hot substrate. • Low cost and scalable fabrication process of CE. • The spray deposited CE uses 10 times less Pt compared to the sputtering method. • The CE is 80% transparent and exhibits a large surface and high catalytic activity. • A semitransparent dye-sensitized solar cell with Pt NP CE was 6.17% efficient.

Non-periodic multi-slit masking for a single counter rotating 2-disc chopper and channeling guides for high resolution and high intensity neutron TOF spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Bartkowiak, M.; Hofmann, T.; Stüßer, N.

2017-02-01

Energy resolution is an important design goal for time-of-flight instruments and neutron spectroscopy. For high-resolution applications, it is required that the burst times of choppers be short, going down to the µs-range. To produce short pulses while maintaining high neutron flux, we propose beam masks with more than two slits on a counter-rotating 2-disc chopper, behind specially adapted focusing multi-channel guides. A novel non-regular arrangement of the slits ensures that the beam opens only once per chopper cycle, when the masks are congruently aligned. Additionally, beam splitting and intensity focusing by guides before and after the chopper position provide high intensities even for small samples. Phase-space analysis and Monte Carlo simulations on examples of four-slit masks with adapted guide geometries show the potential of the proposed setup.

Fast-neutron coincidence-counter manual

International Nuclear Information System (INIS)

Ensslin, N.; Atwell, T.L.; Lee, D.M.; Erkkila, B.; Marshall, R.S.; Morgan, A.; Shonrock, C.; Tippens, B.; Van Lyssel, T.

1982-03-01

The fast neutron counter (FNC) described in this report is a computer-based assay system employing fast-pulse counting instrumentation. It is installed below a glove box in the metal electrorefining area of the Los Alamos National Laboratory Plutonium Processing Facility. The instrument was designed to assay plutonium salts and residues from this process and to verify the mass of electrorefined metal. Los Alamos National Laboratory Groups Q-1, Q-3, and CMB-11 carried out a joint test and evaluation plan of this instrument between May 1978 and May 1979. The results of that evaluation, a description of the FNC, and operating instructions for further use are given in this report

Engineered porous silicon counter electrodes for high efficiency dye-sensitized solar cells.

Science.gov (United States)

Erwin, William R; Oakes, Landon; Chatterjee, Shahana; Zarick, Holly F; Pint, Cary L; Bardhan, Rizia

2014-06-25

In this work, we demonstrate for the first time, the use of porous silicon (P-Si) as counter electrodes in dye-sensitized solar cells (DSSCs) with efficiencies (5.38%) comparable to that achieved with platinum counter electrodes (5.80%). To activate the P-Si for triiodide reduction, few layer carbon passivation is utilized to enable electrochemical stability of the silicon surface. Our results suggest porous silicon as a promising sustainable and manufacturable alternative to rare metals for electrochemical solar cells, following appropriate surface modification.

An annular BF3 counter of large sensitive volume

International Nuclear Information System (INIS)

Janardhanan, S.; Swaminathan, N.

1975-01-01

An annular neutron counter having a large sensitive volume with inner and outer diameter 31 cms with multiple electrode system fabricated especially to measure the neutron output from fissile region of standard fast reactor fuel of length nearly equivalent to 500 cms is described. The counter efficiency is nearly 0.3% for neutron and sensitivity 0.0018 counts/neutron for (alpha, neutron) and spontaneous fission source. Its other potential applications which are indicated are : (1) quality control of fast reactor fuel pins (2) fuel inventory (3) assessing radioactivity of solid waste packets containing PuO 2 (4) uniformity of fuel loading of a reactor and (5) neutron monitoring in a fuel plant. (M.G.B.)

Energy and angular distributions of neutrons from 252Cf spontaneous fission

International Nuclear Information System (INIS)

Vasil'ev, Yu.A.; Sidorov, L.V.; Vasil'eva, N.K.

1982-01-01

Some results from a first series of measurements of energy and angular distributions of neutrons from 252 Cf spontaneous fission using a spectrometer with high neutron detection efficiency, i.e. a 4π neutron time-of-flight spectrometer, were already presented. Subsequently, a second series of measurements was performed using a more sophisticated technique. For this second series, we used a more intense 252 Cf layer (25,000 spontaneous fissions per second). The angular resolution was improved by a factor of 2-3 by combining the hexahedral counter modules, placed at the same angle with respect to the direction of motion of the fragments, in new panoramic counters. The neutron counters were calibrated against the average 252 Cf neutron spectrum at several positions of the axis of the fragment detector with respect to the neutron counters. In the spectrum measurements and calibration work, the scattered neutron background was not determined theoretically, as in the first series of measurements, but experimentally using four extra scintillation counters with scatter cones; the counters were set up at 60 deg., 80 deg., 100 deg., and 120 deg. to the direction of separation of the fragments

Design of an extended range long counter using super Monte Carlo simulation

International Nuclear Information System (INIS)

Mazunga, Mohamed; Li, Taosheng; Li, Yanan; Hong, Bing; Wang, Yongfeng; Ji, Xiang

2017-01-01

We have designed an extended range neutron long counter on the basis of work optimized using SuperMC code. The problem of the existing traditional long counters is that their response function falls rapidly above 5 MeV. We proposed a new designed by adding two layers of converter material inside the polyethylene moderator. The relatively low density chromium and high density lead metals convert high energy neutron by (n, xn) spallation reaction. This produces more neutrons of lower energies, which have higher probability of being detected by thermal 3 He-counter. The response function at lower neutron energies was improved by inserting small polyethylene cylinder in front of 3 He counter. In this design we achieved to extent the flat response function of the long counter from few keV up to 150 MeV. The total fluctuation of response curve is less than ±9% over the entire energy range. The designed long counter is suitable to be used as neutron monitor for monitoring neutron fluence at high-energy neutron source. (authors)

The extended range neutron rem counter LINUS: overview and latest developments

International Nuclear Information System (INIS)

Birattari, C.; Rancati, T.; Esposito, A.; Pelliccioni, M.; Ferrari, A.; Silari, M.

1997-01-01

The 'history' of the extended range neutron rem counter LINUS, since its first conception in 1990 is reviewed, along with the latest developments. These include the calibration of the initially cylindrical version with nearly monoenergetic neutrons in the energy range 34-66 MeV, a detailed evaluation of the anisotropy of its response function, the construction and calibration of an improved spherical version, and recent measurements in reference high energy stray radiation fields. The instrument can now be considered as being fully characterized. Similar monitors built by other laboratories following the present design have confirmed its performances. The instrument is now in semi-routine use at a number of particle accelerator facilities and is one of several devices used on-board of aircrafts for assessing the exposure to cosmic rays at commercial flight altitudes. (author)

Neutron dose equivalent next to the target shield of a neutron therapy facility using an LET counter

International Nuclear Information System (INIS)

Stinchcomb, T.G.; Kuchnir, F.T.

1981-01-01

The use of a spherical tissue-equivalent proportional counter for measurements of the lineal energy (y) and derivations of the linear energy transfer (LET) for fast neutrons has the advantage of giving distributions of dose and dose equivalent as functions of either LET or y. A measurement next to the target shielding of the neutron therapy facility at the University of Chicago Hospitals and Clinics (UCHC) is described, and the data processing is outlined. The distributions are presented and compared to those from measurements in the neutron beam. The average quality factors are presented

Analysis of Cherenkov counter efficiencies for E691

International Nuclear Information System (INIS)

Cremaldi, L.; Elliott, J.; Gibney, M.; Nauenberg, U.

1985-01-01

A program is outlined which simulates Cherenkov counters. The program can compute the effect of the magnetic field on the efficiencies of Cherenkov counters. It also tells what cone to mirror distance gives the highest collection efficiency and at which target position should the laser be placed to represent the direction of the actual Cherenkov light the mirror sees

Neutron spectrometry with proton recoil proportional counters at the research and measurement reactor Braunschweig - status of the technique

International Nuclear Information System (INIS)

Knauf, K.; Wittstock, J.

1987-07-01

This status report is concerned with the facilities set up for neutron spectrometry at the Research and Measurement Reactor Braunschweig, based on proton recoil proportional counters. Cylindrical counters for irradiation by a neutron beam normal to the counter wire and commercial spherical counters are employed. They can be filled with hydrogen or a hydrogeneous gas up to a pressure of 1 MPa depending on their use. The filling method and the electronic pulse processing are described. The pulse analysis system includes a pulse shape discrimination branch in order to separate γ-ray induced pulses. Finally, experimental investigations with spherical counters are discussed regarding the region of proportionality and the influence of the counter voltage on the shape of the response function. (orig./HP) [de

Study of the response of a lithium yttrium borate scintillator based neutron rem counter by Monte Carlo radiation transport simulations

Science.gov (United States)

Sunil, C.; Tyagi, Mohit; Biju, K.; Shanbhag, A. A.; Bandyopadhyay, T.

2015-12-01

The scarcity and the high cost of 3He has spurred the use of various detectors for neutron monitoring. A new lithium yttrium borate scintillator developed in BARC has been studied for its use in a neutron rem counter. The scintillator is made of natural lithium and boron, and the yield of reaction products that will generate a signal in a real time detector has been studied by FLUKA Monte Carlo radiation transport code. A 2 cm lead introduced to enhance the gamma rejection shows no appreciable change in the shape of the fluence response or in the yield of reaction products. The fluence response when normalized at the average energy of an Am-Be neutron source shows promise of being used as rem counter.

Study of the response of a lithium yttrium borate scintillator based neutron rem counter by Monte Carlo radiation transport simulations

Energy Technology Data Exchange (ETDEWEB)

Sunil, C., E-mail: csunil11@gmail.com [Accelerator Radiation Safety Section, Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, Mohit [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Biju, K.; Shanbhag, A.A.; Bandyopadhyay, T. [Accelerator Radiation Safety Section, Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2015-12-11

The scarcity and the high cost of {sup 3}He has spurred the use of various detectors for neutron monitoring. A new lithium yttrium borate scintillator developed in BARC has been studied for its use in a neutron rem counter. The scintillator is made of natural lithium and boron, and the yield of reaction products that will generate a signal in a real time detector has been studied by FLUKA Monte Carlo radiation transport code. A 2 cm lead introduced to enhance the gamma rejection shows no appreciable change in the shape of the fluence response or in the yield of reaction products. The fluence response when normalized at the average energy of an Am–Be neutron source shows promise of being used as rem counter.

Highly efficient and stable dye-sensitized solar cells based on nanographite/polypyrrole counter electrode

International Nuclear Information System (INIS)

Yue, Gentian; Zhang, Xin’an; Wang, Lei; Tan, Furui; Wu, Jihuai; Jiang, Qiwei; Lin, Jianming; Huang, Miaoliang; Lan, Zhang

2014-01-01

Graphical abstract: Much higher photovoltaic performance of dye-sensitized solar cell with nanographite/PPy counter electrode as well as that of Pt configuration device. - Highlights: • Pt-free dye-sensitized solar cells. • The nanographite/PPy composite film showed high catalytic activity as well as Pt electrode. • The enhanced catalytic activity was attributed to increased active sites. • The DSSC based on the nanographite/PPy electrode showed a high photovoltaic performance. - Abstract: Nanographite/polypyrrole (NG/PPy) composite film was successfully prepared via in situ polymerization on rigid fluorine-doped tin oxide substrate and served as counter electrode (CE) for dye-sensitized solar cells (DSSCs). The surface morphology and composition of the composite film were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and Fourier transform infrared spectroscopy (FTIR). The electrochemical performance of the NG/PPy electrode was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results of CV and EIS revealed that the NG/PPy electrode possessed excellent electrocatalytic activity for the reduction reaction of triiodide to iodide and low charge transfer resistance at the interface between electrolyte and CE, respectively. The DSSC assembled with the novel NG/PPy CE exhibited an enhanced power conversion efficiency of 7.40% under full sunlight illumination as comparing to that of the DSSC based on sputtered-Pt electrode. Thus, the NG/PPy CE could be premeditated as a promising alternative CE for low-cost and high- efficient DSSCs

Proceedings of the symposium on measurements of neutron energy spectra using recoil proton proportional counters

International Nuclear Information System (INIS)

Urabe, Itsumasa

1986-01-01

This is a report of the symposium on measurements of neutron energy spectra using recoil proton proportional counters held at the Research Reactor Institute of Kyoto University on January 27 in 1986. An energy resolution, wall effects of response functions, n · γ discrimination methods and other fundamental properties of recoil proton counters are discussed for a new development of an application of this counter. (author)

Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

Science.gov (United States)

Kuroda, Yusuke; Yamamoto, Akiko; Kuwabara, Hajime; Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko

2013-11-01

A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

Directory of Open Access Journals (Sweden)

Kuroda Yusuke

2013-11-01

Full Text Available A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

Response functions of the Andersson-Braun and extended range rem counters for neutron energies from thermal to 10 GeV

CERN Document Server

Mares, V; Schraube, H

2002-01-01

This work is devoted to the calculation of responses as functions of neutron energy for a paired set of Andersson-Braun rem counters, which is commercially available. Different Monte Carlo codes such as MCNP, LAHET, HADRON and MCNPX were applied in the calculations. The study extended to frontal, lateral and isotropic neutron incidence. For an estimation of the contribution of charged high-energy particles to the reading, the responses to protons and pions were also determined. The results obtained give good bases for the practical use of the new instrument in high-energy neutron fields.

filled neutron detectors

Indian Academy of Sciences (India)

Boron trifluoride (BF3) proportional counters are used as detectors for thermal neutrons. They are characterized by high neutron sensitivity and good gamma discriminating properties. Most practical BF3 counters are filled with pure boron trifluoride gas enriched up to 96% 10B. But BF3 is not an ideal proportional counter ...

Variable dead time counters. 1 - theoretical responses and the effects of neutron multiplication

International Nuclear Information System (INIS)

Lees, E.W.; Hooton, B.W.

1978-10-01

A theoretical expression is derived for calculating the response of any variable dead time counter (VDC) used in the passive assay of plutonium by neutron counting of the natural spontaneous fission activity. The effects of neutron multiplication in the sample arising from interactions of the original spontaneous fission neutrons is shown to modify the linear relationship between VDC signal and Pu mass. Numerical examples are shown for the Euratom VDC and a systematic investigation of the various factors affecting neutron multiplication is reported. Limited comparisons between the calculations and experimental data indicate provisional validity of the calculations. (author)

Radiation protection metrology at a high-energy neutron therapy facility

International Nuclear Information System (INIS)

Bonnett, D.E.; Sherwin, A.G.; More, B.R.

1991-01-01

A radiation protection survey has been carried out at a high-energy neutron therapy facility using a combination of different detectors and counters. Included in the survey were measurements with a tissue equivalent proportional counter (TEPC), a rem meter, a large volume ionisation chamber (LVI) and a Geiger counter. Dose equivalent rates, normalised to a proton beam current of 25 μA, of between 1 μSv.h -1 and 0.7 Sv.h -1 were recorded depending on the location. In general the results confirm the tendency of the rem meter to over-read in fields consisting mainly of low energy neutrons and illustrate the advantages of the diagnostic and gamma discriminating properties of the TEPC. The LVI-Geiger system was found to be the least favourable combination of dosemeters, substantially under-reading and being unable to estimate the neutron dose rate at levels below about 32 μGy.h -1 . (author)

Simulations for the neutron detector TETRA with MCNP

International Nuclear Information System (INIS)

Testov, D.; Kuznetsova, E.; Wilson, Jh.

2013-01-01

To study the nuclear structure of β-delayed neutron precursors at ALTO ISOL-facility at IPN (Orsay), the high efficiency 4π neutron detector TETRA with 3 He filled counters built at JINR (Dubna) was modified. The MCNP simulations to optimize the future configuration were necessary. The details of the calculations and the major results obtained are discussed

Neutron measurements in search of cold fusion

International Nuclear Information System (INIS)

Anderson, R.E.; Goulding, C.A.; Johnson, M.W.; Butterfield, K.B.; Gottesfeld, S.; Baker, D.A.; Springer, T.E.; Garzon, F.H.; Bolton, R.D.; Leonard, E.M.; Chancellor, T.

1990-01-01

We have conducted a research for neutron emission from cold fusion systems of the electrochemical type and, to a lesser extent, the high-pressure gas cell type. Using a high-efficiency well counter and an NE 213 scintillator, the experiments were conducted on the earth's surface and in a shielded cave approximately 50 ft underground. After approximately 6500 h of counting time, we have obtained no evidence for cold fusion processes leading to neutron production. However, we have observed all three types of neutron data that have been presented as evidence for cold fusion: large positive fluctuations in the neutron counting rate, weak peaks near 2.5 MeV in the neutron energy spectrum, and bursts of up to 145 neutrons in 500-μs intervals. The data were obtained under circumstances that clearly show our results to be data encountered as a part of naturally occurring neutron background, which is due primarily to cosmic rays. Thus, observing these types of data does not, of itself, provide evidence for the existence of cold fusion processes. Artifacts in the data that were due to counter misbehavior were also to lead to long-term ''neutron bursts'' whose time duration varied from several hours to several days. We conclude that any experiments which attempt to observe neutron emission must include strong steps to ensure that the experiments deal adequately with both cosmic-ray processes and counter misbehavior. 13 refs., 14 figs

High-efficiency resonant rf spin rotator with broad phase space acceptance for pulsed polarized cold neutron beams

Directory of Open Access Journals (Sweden)

P.-N. Seo

2008-08-01

Full Text Available High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating γ-ray asymmetry A_{γ} in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5  cm×9.5  cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized ^{3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8±0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPDGamma experiment are considered.

A transparent nickel selenide counter electrode for high efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Dong, Jia; Wu, Jihuai, E-mail: jhwu@hqu.edu.cn; Jia, Jinbiao; Ge, Jinhua; Bao, Quanlin; Wang, Chaotao; Fan, Leqing

2017-04-15

Highlights: • Ni{sub 0.85}Se was obtained by hydrothermal way and the film was gained by spin-coating. • Ni{sub 0.85}Se film has good conductivity and excellent electrocatalytic activity. • DSSC based on transparent Ni{sub 0.85}Se counter electrode obtains PCE of 8.96%. • The PCE reaches 10.76% when putting a mirror under Ni{sub 0.85}Se counter electrode. - Abstract: Nickel selenide (Ni{sub 0.85}Se) was synthesized by a facile one-step hydrothermal reaction and Ni{sub 0.85}Se film was prepared by spin-coating Ni{sub 0.85}Se ink on FTO and used as counter electrode (CE) in dye-sensitized solar cells (DSSC). The Ni{sub 0.85}Se CEs not only show high transmittance in visible range, but also possess remarkable electrocatalytic activity toward I{sup −}/I{sub 3}{sup −}. The electrocatalytic ability of Ni{sub 0.85}Se films was verified by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves. The DSSC using Ni{sub 0.85}Se CE exhibits a power conversion efficiency (PCE) of 8.96%, while the DSSC consisting of sputtered Pt CE only exhibits a PCE of 8.15%. When adding a mirror under Ni{sub 0.85}Se CE, the resultant DSSC exhibits a PCE of 10.76%, which exceeds that of a DSSC based on sputtered Pt CE (8.44%) by 27.49%.

The Efficiency of the BC-720 Scintillator in a High-Energy (20--800 MeV) Accelerator Neutron Field

Energy Technology Data Exchange (ETDEWEB)

Miles, Leslie H. [Univ. of Missouri, Columbia, MO (United States)

2005-12-01

High-energy neutron doses (>20 MeV) are of little importance to most radiation workers. However, space and flight crews, and people working around medical and scientific accelerators receive over half of their radiation dose from high-energy neutrons. Unfortunately, neutrons are difficult to measure, and no suitable dosimetry has yet been developed to measure this radiation. In this paper, basic high-energy neutron interactions, characteristics of high-energy neutron environments, present neutron dosimetry, and quantities used in neutron dosimetry are discussed before looking into the potential of the BC-720 scintillator to improve dosimetry. This research utilized 800 MeV protons impinging upon the WNR Facility spallation neutron source at Los Alamos National Laboratory. Time-of-flight methods and a U-238 Fission Chamber were used to aid evaluation of the efficiency of the BC-720. Results showed that the efficiency is finite over the 20–650 MeV energy region studied, although it decreases by a factor of ten between 40 and 100 MeV. This limits the use of this dosimeter to measure doses at sitespecific locations. It also encourages modifications to use this dosimeter for any unknown neutron field. As such, this dosimeter has the potential for a small, lightweight, real-time dose measurement, which could impact neutron dosimetry in all high-energy neutron environments.

Report for General Research January 8, to April 30, 1951 (Alpha - Neutron Volume)

Energy Technology Data Exchange (ETDEWEB)

Haring, M.M.

1951-01-04

An experimental, gamma-sensitive, coaxial radioelectric cell has been tested by the Control Section. It was found to be as precise as the rotating sample gamma counter but much faster and simpler to operate. A gamma-sensitive, radioelectric cell of improved design has been constructed for the 'Y' Section. A neutron sensitive radioelectric cell has been tested over a range of pressures with various filling gases and with several combinations of hydrogenous electrode backings. Neutron to gamma discrimination ratios as high as 2,000 to 1 were obtained, A multiple electrode, alpha radiation, radioelectric cell using coated plastic electrodes gave increased current output, but the electrode life was quite short. Preliminary life tests indicated that aluminum electroscope foil would give excellent electrode life and techniques were worked out for making good electrodes of both aluminum and of gold electroscope foil. The vacuum-pressure gas system has been redesigned and completely rebuilt (p. 5) The fast-neutron scintillation counter is much smaller and lighter than a B-wall proportional counter and a large moderator. The former is more efficient for polonium-beryllium neutron sources but is less efficient for radium-beryllium neutron sources or for polonium sources producing lower energy neutrons The fast neutron scintillation counter would thus be very useful if the neutron to gamma discrimination ratio could be markedly improved. Preliminary experiments indicate that this ratio can be improved by carefully tailoring the frequency response characteristics of the amplifier used. Phosphors are also being investigated from the standpoint of improving this ratio. Preliminary attempts to detect neutrons by measuring the neutron-capture gamma of cadmium were unsuccessful. However, the conversion gamma from alpha-beryllium neutron sources can be detected with high efficiency; and this might be used to determine the neutron flux from such sources even in the presence

Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

International Nuclear Information System (INIS)

Dighe, P.M.; Das, D.

2015-01-01

An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×10 4 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors

Data acquisition systems for uses of multi-counter time analyzer and one-dimensional PSD pulse height analyzer to neutron scattering measurements

International Nuclear Information System (INIS)

Ono, Masayoshi; Tasaki, Seiji; Okamoto, Sunao

1989-01-01

A data acquisition system having the various modern electronic devices was designed and tested for practical use of neutron time-of-flight (TOF) measurements with multiple counters. The system is principally composed of TOF logic units (load-able up to 128 units) with a control unit and a conventional micro-computer. The TOF logic unit (main memory, 2048 ch, 24 bits/ch) demonstrates about 1.7 times higher efficiency for neutron counting rate per channel than the one by a conventional TOF logic unit. Meanwhile, some data-access functions of the TOF logic unit were applied to position sensitive analyzer of one-dimensional neutron PSD for small angle scattering. The analyzer was tested with use of pulse generator. The result shows good linearity. (author)

Test of the rem-counter WENDI-II from Eberline in different energy-dispersed neutron fields

International Nuclear Information System (INIS)

Gutermuth, F.; Radon, T.; Fehrenbacher, G.; Siekmann, R.

2004-03-01

The neutron rem-counter WENDI-II from Eberline was tested in high-energy particle accelerator produced neutron fields. A radioactive 241 Am-Be(αn) source was used as a reference. The experimentally determined responses are compared to Monte-Carlo simulations of the response function done by R. H. Olsher et al. (2000). The energy spectra of the accelerator produced neutron fields were determined employing Monte-Carlo simulations, too. According to the simulations done by C. Birattari et al. (1998) and in this work these neutron fields exhibit large contributions to the ambient dose equivalent resulting from neutrons with kinetic energy of more than 20 MeV up to a few 100 MeV. The WENDI-II detector proved to show a response of approximately 3.10 9 pulses per Sievert ambient dose equivalent. Considering the experimental and statistical uncertainties the results are consistent with the assumption that the dose response of the WENDI-II reproduces quite accurately the function for the ambient dose equivalent of the ICRP 74

Secondary standard neutron detector for measuring total reaction cross sections

International Nuclear Information System (INIS)

Sekharan, K.K.; Laumer, H.; Gabbard, F.

1975-01-01

A neutron detector has been constructed and calibrated for the accurate measurement of total neutron-production cross sections. The detector consists of a polyethylene sphere of 24'' diameter in which 8- 10 BF 3 counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies, from 30 keV to 1.5 MeV by counting neutrons from 7 Li(p,n) 7 Be. By adjusting the radial positions of the BF 3 counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from 51 V(p,n) 51 Cr and 57 Fe(p,n) 57 Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for measurement of total neutron yields from neutron producing reactions such as 23 Na(p,n) 23 Mg are given

Realisation and qualification of a tissue equivalent proportional counter with a multi-cellular geometry for the individual neutron dosimetry

International Nuclear Information System (INIS)

Hoflack, Ch.

1999-01-01

The present day dosimetry means for radiations with a strong ionization density cannot fulfill the future radioprotection regulations which will require an individual dosimetry with active dosemeters. The aim of this work is the study and development of an individual dosemeter based on a tissue equivalent proportional counter and with a multi-cellular geometry allowing to reach a sensibility equivalent to environmental dosemeters. A pressure regulation bench has been added to the detector in order to reduce the degassing of the detector parts and to reach a sufficient service life for the implementation of the characterization tests. The hole counter system has been adopted for the first prototypes in order to reduce the sensibility of the wires multiplication system with respect to mechanical vibrations. Tests performed with an internal alpha source have shown that a better electrical efficiency can be reached when more severe mechanical limits are adopted during the construction. The dose equivalent response of the prototype for mono-energy neutrons of 144 keV to 2.5 MeV is analyzed experimentally and by simulation. During experiments with normal incidence neutrons, the prototype fulfills the requirements of the CEI N O 1323 standard for energies comprised between 400 keV and 2.5 MeV, while the simulation indicates a satisfactory response up to 200 keV. A preliminary study of the behaviour of the detector with respect to the neutrons incidence indicates that the multi-cellular geometry is efficient for large angles (the sensibility of the prototype is increased by a factor 3). Finally, simulation studies have to be made to optimize the electrical operation and the geometry of the next prototype. (J.S.)

Ultracold neutron detectors based on {sup 10}B converters used in the qBounce experiments

Energy Technology Data Exchange (ETDEWEB)

Jenke, Tobias, E-mail: tjenke@ati.ac.at [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Cronenberg, Gunther; Filter, Hanno [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Geltenbort, Peter [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Klein, Martin [Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Lauer, Thorsten [FRM II, TU München, Lichtenbergstraße 1, 85748 Garching (Germany); Mitsch, Kevin [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Saul, Heiko [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); FRM II, TU München, Lichtenbergstraße 1, 85748 Garching (Germany); Seiler, Dominik [Physik Department, TU München, James-Franck-Straße, 85748 Garching (Germany); Stadler, David [Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Thalhammer, Martin [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Abele, Hartmut, E-mail: abele@ati.ac.at [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Physik Department, TU München, James-Franck-Straße, 85748 Garching (Germany)

2013-12-21

Gravity experiments with very slow, so-called ultracold neutrons connect quantum mechanics with tests of Newton's inverse square law at short distances. These experiments face a low count rate and hence need highly optimized detector concepts. In the frame of this paper, we present low-background ultracold neutron counters and track detectors with micron resolution based on a {sup 10}B converter. We discuss the optimization of {sup 10}B converter layers, detector design and concepts for read-out electronics focusing on high-efficiency and low-background. We describe modifications of the counters that allow one to detect ultracold neutrons selectively on their spin-orientation. This is required for searches of hypothetical forces with spin–mass couplings. The mentioned experiments utilize a beam-monitoring concept which accounts for variations in the neutron flux that are typical for nuclear research facilities. The converter can also be used for detectors, which feature high efficiencies paired with high spatial resolution of 1–2μm. They allow one to resolve the quantum mechanical wave function of an ultracold neutron bound in the gravity potential above a neutron mirror.

Neutron spectra measuring by magnetless hadron spectrometer

International Nuclear Information System (INIS)

Bayukov, Yu.D.; Buklej, A.E.; Gavrilov, V.B.

1980-01-01

The energy resolution, efficiency and background conditions of neutron recording in inclusive nuclear reactions by a magnetless hadron spectrometer (MHS) in the 8-300 MeV energy range. The scheme of apparatus lay-out for measuring neutron recording efficiency is shown. For recording colliding particles with the 3 GeV/c momentum four beam scintillation counters, the latter of which of 30x40 mm dimensions and 1 mm thickness defines the working beam range in the target centre, are used. Targets of the 80 mm diameter made of C and Pb (2.08 g/cm 2 and 3.04 g/cm 2 thickness, respectively) are located at the 45 deg angle in respect to the beam direction. Secondary particles escaping at the 90 deg angle are recorded by two telescopes of the scintillation counters. For neutron and γ quanta recording the special scintillation detector of the 20 cm thickness encircled by an anticoincidence counter is used. The neutron recording efficiency is determined on the basis of comparison of the neutron production differential cross sections of the π +- 12 C 6 → nX reactions and of proton production in isotopically symmetric reactions π +- 12 C 6 → pX. The experimental data are in good agreement with the calculation data [ru

The calculated neutron response of a sphere with the multi-counters

International Nuclear Information System (INIS)

Li Taosheng; Yang Lianzhen; Li Dongyu

2004-01-01

Based on the difference of the neutron distribution in the moderator, three position sensitive proportional counters which are perpendicular to each other are inserted into the moderator. The energy responses with six spherical moderators and six incidence directions have been calculated by MCNP4A code. The calculated results for two divided region methods in the radial of the spherical moderator have been analyzed and compared. (authors)

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

International Nuclear Information System (INIS)

Trotter, D.E. Gonzalez; Meneses, F. Salinas; Tornow, W.; Crowell, A.S.; Howell, C.R.; Schmidt, D.; Walter, R.L.

2009-01-01

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the 1 S 0 neutron-neutron and neutron-proton scattering lengths a nn and a np , respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E n =13MeV.

Passive neutron design study for 200-L waste drums

International Nuclear Information System (INIS)

Menlove, H.O.; Beddingfield, D.B.; Pickrell, M.M.

1997-09-01

We have developed a passive neutron counter for the measurement of plutonium in 200-L drums of scrap and waste. The counter incorporates high efficiency for the multiplicity counting in addition to the traditional coincidence counting. The 252 Cf add-a-source feature is used to provide an accurate assay over a wide range of waste matrix materials. The room background neutron rate is reduced by using 30 cm of external polyethylene shielding and the cosmic-ray background is reduced by statistical filtering techniques. Monte Carlo Code calculations were used to determine the optimum detector design, including the gas pressure, size, number, and placement of the 3 He tubes in the moderator. Various moderators, including polyethylene, plastics, teflon, and graphite, were evaluated to obtain the maximum efficiency and minimum detectable mass of plutonium

Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polythiophene composite counter electrodes prepared by electrodeposition

Science.gov (United States)

Luo, Jun; Niu, Hai-jun; Wu, Wen-jun; Wang, Cheng; Bai, Xu-duo; Wang, Wen

2012-01-01

For the purpose of increasing the energy conversion efficiency of dye-sensitized solar cells (DSSCs), multi-wall carbon nanotube (MWCNT)/polythiophene (PTh) composite film counter electrode has been fabricated by electrophoresis and cyclic voltammetry (CV) in sequence. The morphology and chemical structure have been characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), and Raman spectroscopy respectively. The overall energy conversion efficiency of the DSSC employing the MWCNT/PTh composite film has reached 4.72%, which is close to that of the DSSC with a platinum (Pt) counter electrode (5.68%). Compared with a standard DSSC with MWCNT counter electrode whose efficiency is 2.68%, the energy conversion efficiency has been increased by 76.12% for the DSSC with MWCNT/PTh counter electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I 3- reduction can potentially be used as the counter electrode in a high-performance DSSC.

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

Energy Technology Data Exchange (ETDEWEB)

Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

2009-02-11

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

Highly efficient solid-state neutron scintillators based on hybrid sol-gel nanocomposite materials

International Nuclear Information System (INIS)

Kesanli, Banu; Hong, Kunlun; Meyer, Kent; Im, Hee-Jung; Dai, Sheng

2006-01-01

This research highlights opportunities in the formulation of neutron scintillators that not only have high scintillation efficiencies but also can be readily cast into two-dimensional detectors. Series of transparent, crack-free monoliths were prepared from hybrid polystyrene-silica nanocomposites in the presence of arene-containing alkoxide precursor through room temperature sol-gel processing. The monoliths also contain lithium-6 salicylate as a target material for neutron-capture reactions and amphiphilic scintillator solution as a fluorescent sensitizer. Polystyrene was functionalized by trimethoxysilyl group in order to enable the covalent incorporation of aromatic functional groups into the inorganic sol-gel matrices for minimizing macroscopic phase segregation and facilitating lithium-6 doping in the sol-gel samples. Neutron and alpha responses of these hybrid polystyrene-silica monoliths were explored

Application of thin-film breakdown counters for characterization of neutron field of the VESUVIO instrument at the ISIS spallation source

Science.gov (United States)

Smirnov, A. N.; Pietropaolo, A.; Prokofiev, A. V.; Rodionova, E. E.; Frost, C. D.; Ansell, S.; Schooneveld, E. M.; Gorini, G.

2012-09-01

The high-energy neutron field of the VESUVIO instrument at the ISIS facility has been characterized using the technique of thin-film breakdown counters (TFBC). The technique utilizes neutron-induced fission reactions of natU and 209Bi with detection of fission fragments by TFBCs. Experimentally determined count rates of the fragments are ≈50% higher than those calculated using spectral neutron flux simulated with the MCNPX code. This work is a part of the project to develop ChipIr, a new dedicated facility for the accelerated testing of electronic components and systems for neutron-induced single event effects in the new Target Station 2 at ISIS. The TFBC technique has shown to be applicable for on-line monitoring of the neutron flux in the neutron energy range 1-800 MeV at the position of the device under test (DUT).

Application of thin-film breakdown counters for characterization of neutron field of the VESUVIO instrument at the ISIS spallation source

International Nuclear Information System (INIS)

Smirnov, A.N.; Pietropaolo, A.; Prokofiev, A.V.; Rodionova, E.E.; Frost, C.D.; Ansell, S.; Schooneveld, E.M.; Gorini, G.

2012-01-01

The high-energy neutron field of the VESUVIO instrument at the ISIS facility has been characterized using the technique of thin-film breakdown counters (TFBC). The technique utilizes neutron-induced fission reactions of nat U and 209 Bi with detection of fission fragments by TFBCs. Experimentally determined count rates of the fragments are ≈50% higher than those calculated using spectral neutron flux simulated with the MCNPX code. This work is a part of the project to develop ChipIr, a new dedicated facility for the accelerated testing of electronic components and systems for neutron-induced single event effects in the new Target Station 2 at ISIS. The TFBC technique has shown to be applicable for on-line monitoring of the neutron flux in the neutron energy range 1–800 MeV at the position of the device under test (DUT).

Simulation and preliminary experimental results for an active neutron counter using a neutron generator for a fissile material accounting

International Nuclear Information System (INIS)

Ahn, Seong-Kyu; Lee, Tae-Hoon; Shin, Hee-Sung; Kim, Ho-Dong

2009-01-01

An active neutron coincidence counter using a neutron generator as an interrogation source has been suggested. Because of the high energy of the interrogation neutron source, 2.5 MeV, the induced fission rate is strongly affected by the moderator design. MCNPX simulation has been performed to evaluate the performance achieved with these moderators. The side- and bottom-moderator are significantly important to thermalize neutrons to induce fission. Based on the simulation results, the moderators are designed to be adapted to the experimental system. Their preliminary performance has been tested by using natural uranium oxide powder samples. For a sample of up to 3.5 kg, which contains 21.7 g of 235 U, 2.64 cps/g- 235 U coincidence events have been measured. Mean background error was 9.57 cps and the resultant coincidence error was 13.8 cps. The experimental result shows the current status of an active counting using a neutron generator which still has some challenges to overcome. However, the controllability of an interrogation source makes this system more applicable for a variety of combinations with other non-destructive methods like a passive coincidence counting especially under a harsh environment such as a hot cell. More precise experimental setup and tests with higher enriched samples will be followed to develop a system to apply it to an active measurement for the safeguards of a spent fuel treatment process.

Development of a high efficient conventional type cold neutron source using a non-explosive material

International Nuclear Information System (INIS)

Kiyanagi, Y.; Satoh, S.

1999-01-01

An efficient cold moderator that can be used easily at a small neutron source would be useful for neutron radiography, prompt gamma ray analysis and so on. Non-explosive materials are chosen for a cold moderator since explosive materials such as hydrogen and methane require a safety system. Neutronic performances of coupled moderators of various non-explosive materials are studied so as to develop such a cold moderator since the coupled moderator system is the best to obtain high intensity of cold neutrons. Effect of premoderator is studied and neutron spectra from methanol, ethanol, benzene, mesitylene and benzene methanol are measured around 20 K. The premoderator increased the cold neutron intensity by about 50∼70%. Methanol and mesitylene gave the highest cold neutron intensity. Effect of Be filter-reflector is also studied and a intensity gain of about 20% was obtained below about 5 MeV. (author)

Design of neutron diagnostic for MTX

International Nuclear Information System (INIS)

Ogawa, Toshihide; Oasa, Kazumi; Hoshino, Katsumichi; Odajima, Kazuo; Maeda, Hikosuke

1990-07-01

A neutron diagnostic system was designed for the Microwave Tokamak Experiment being carried out at the lawrence Livermore National Laboratory. High speed measurements are important to this experiment. Plastic scintillator is used for this fast response detection of neutron. Proportional counters and fission counters are used for the total neutron emission rate measurements. (author)

Passive assay of plutonium metal plates using a fast-neutron multiplicity counter

Energy Technology Data Exchange (ETDEWEB)

Di Fulvio, A., E-mail: difulvio@umich.edu [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Shin, T.H.; Jordan, T.; Sosa, C.; Ruch, M.L.; Clarke, S.D. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Chichester, D.L. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Pozzi, S.A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

2017-05-21

We developed a fast-neutron multiplicity counter based on organic scintillators (EJ-309 liquid and stilbene). The system detects correlated photon and neutron multiplets emitted by fission reactions, within a gate time of tens of nanoseconds. The system was used at Idaho National Laboratory to assay a variety of plutonium metal plates. A coincidence counting strategy was used to quantify the {sup 240}Pu effective mass of the samples. Coincident neutrons, detected within a 40-ns coincidence window, show a monotonic trend, increasing with the {sup 240}Pu-effective mass (in this work, we tested the 0.005–0.5 kg range). After calibration, the system estimated the {sup 240}Pu effective mass of an unknown sample ({sup 240}Pu{sub eff} >50 g) with an uncertainty lower than 1% in a 4-min assay time.

Application of thin-film breakdown counters for characterization of neutron field of the VESUVIO instrument at the ISIS spallation source

Energy Technology Data Exchange (ETDEWEB)

Smirnov, A.N. [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation); Pietropaolo, A., E-mail: antonino.pietropaolo@roma2.infn.it [CNISM UdR Tor Vergata, and Centro NAST Roma, Italy Scientifica 1 I-00133 Roma Italy (Italy); Prokofiev, A.V. [The Svedberg Laboratory, Uppsala University, Uppsala (Sweden); Rodionova, E.E. [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation); Frost, C.D.; Ansell, S.; Schooneveld, E.M. [ISIS Facility, Rutherford Appleton Laboratory, Chilton (United Kingdom); Gorini, G. [Dipartimento di Fisica ' G. Occhialini,' Universita degli Studi di Milano-Bicocca, Milano (Italy)

2012-09-21

The high-energy neutron field of the VESUVIO instrument at the ISIS facility has been characterized using the technique of thin-film breakdown counters (TFBC). The technique utilizes neutron-induced fission reactions of {sup nat}U and {sup 209}Bi with detection of fission fragments by TFBCs. Experimentally determined count rates of the fragments are Almost-Equal-To 50% higher than those calculated using spectral neutron flux simulated with the MCNPX code. This work is a part of the project to develop ChipIr, a new dedicated facility for the accelerated testing of electronic components and systems for neutron-induced single event effects in the new Target Station 2 at ISIS. The TFBC technique has shown to be applicable for on-line monitoring of the neutron flux in the neutron energy range 1-800 MeV at the position of the device under test (DUT).

Study of neutron rich nuclei by delayed neutron decay using the Tonnerre multidetector; Etude de la decroissance par neutrons retardes de noyaux legers riches en neutrons avec le multidetecteur tonnerre

Energy Technology Data Exchange (ETDEWEB)

Timis, C.N

2001-07-01

A new detection array for beta delayed neutrons was built. It includes up to 32 plastic scintillation counters 180 cm long located at 120 cm from the target. Neutron energy spectra are measured by time-of-flight in the 300 keV-15 MeV range with good energy resolution. The device was tested with several known nuclei. Its performances are discussed in comparison with Monte Carlo simulations. They very high overall detection efficiency on the TONNERRE array made it possible to study one and two neutron emission of {sup 11}Li. A complete decay scheme was obtained. The {sup 33}Mg and {sup 35}Al beta decays were investigated for the first time by neutron and gamma spectroscopy. Complete decay schemes were established and compared to large scale shell-model calculations. (authors)

A compact neutron counter telescope with thick radiator (COTETRA) for fusion experiment

International Nuclear Information System (INIS)

Osakabe, M.; Itoh, S.; Gotoh, Y.; Sasao, M.; Fujita, J.

1993-01-01

A new type of neutron spectrometer, based on recoil proton measurement, has been developed for diagnosing a DT fusion plasma. This spectrometer has such advantages as: 1. direct measurement of the neutron energy without the unfolding procedure, 2. relatively high detection efficiency for 14 MeV neutrons, 3. a wide dynamic range of counting rate, and 4. perfect n-γ discrimination. To examine the performance of this spectrometer, we developed a Monte Carlo simulation code. It predicts that we may achieve energy resolution up to 3 % with a detection efficiency of 10 -5 [count cm 2 /n] if we could successfully adjust the condition of the spectrometer. A prototype spectrometer was constructed and was compared with the Monte Carlo prediction. The energy resolution of 5.3 ± 0.7 % for 14 MeV neutron was obtained for the prototype spectrometer and the calculation agrees with the experimental results within its margin of error if we take into account the intrinsic energy resolution of the detector that is used in the prototype. (author)

A single-supply, high rate, small size and cheap electronic chain for 3He neutron counters

International Nuclear Information System (INIS)

Boffa, A.; Fazzi, A.; Pirovano, C.; Varoli, V.

1996-01-01

The paper describes a complete counting chain (charge preamplifier, shaping amplifier and threshold discriminator) devoted to 3 He neutron detectors. Since it is characterized by single supply operation, high counting rate, small size and low cost, it is well suited for high efficiency neutron well detectors where a large number (10 - 100) of counting tubes are used. Such detectors are commonly used for verification of Plutonium stocks. The preamplifier adopts an innovative circuit with the gate of the input JFET floating and a DC feedback loop that stabilizes the output voltage acting on the input cascode second transistor. Static and dynamic analysis, including the effects of the detector bias network, is reported. The shaping amplifier transfer function is a fifth order approximation of the gaussian response. All the complex pole pairs are realized with a single fourth order Voltage Controlled Voltage Source cell thus minimizing component count. Experimental signals and spectra, obtained with shaping time constants in the 1 μs - 100 ns range, are reported and discussed

A neutron survey meter with sensitivity extended up to 400 MeV

International Nuclear Information System (INIS)

Birattari, C.; Silari, M.

1992-01-01

The well-known Andersson-Braun rem counter is widely employed for radiation protection purposes, but its efficiency shows a marked decrease for neutron energies above about 10 MeV. Since the availability of a survey meter with a good sensitivity to higher energies can be very useful, for instance, at many particle accelerator facilities, a neutron monitor with a response function extended up to 400 MeV has been achieved by modifying the structure of the moderator-attenuator of a commercial instrument. The first experimental tests carried out to verify the response of the new monitor both to low and high energy neutrons are reported. A comparison with the response function of three conventional commercial rem counters is presented. (author)

Calibration of Single High Purity Germanium Detector for Whole Body Counter

International Nuclear Information System (INIS)

Taha, T.M.; Morsi, T.M.

2009-01-01

A new Accuscan II single germanium detector for whole body counter was installed in NRC (Egypt). The current paper concerned on calibration of single high purity germanium detector for whole body counter. Physical parameters affecting on performance of whole body counter such as linearity, minimum detectable activity and source detector distance, SDD were investigated. Counting efficiencies for the detector have been investigated in rear wall, fixed diagnostic position in air. Counting efficiencies for organ compartments such as thyroid, lung, upper and lower gastrointestinal tract have been investigated using transfer phantom in fixed diagnostic and screening positions respectively. The organ compartment efficiencies in screening geometry were higher than that value of diagnostic geometry by a factor of three. The committed dose equivalents of I-131 in thyroid were ranged from 0.073 ± 0.004 to 1.73±0.09 mSv and in lung was 0.02±0.001 mSv

Study and building of a detection array for delayed neutrons: TONNERRE

International Nuclear Information System (INIS)

Martin, Thierry

1998-01-01

This work has been undertaken within a French-Romanian collaboration in order to build a high efficiency detector array for delayed neutrons: barrel-shaped TONNERRE. Some neutron-rich nuclei decay through 1, 2 or 3 neutron emission after β - decay. More exotic nuclei will be produced by SPIRAL at GANIL. An array with high efficiency and good resolution is then required. Thirty two BC400 plastic scintillators (160 x 20 x 4 cm 3 ) allow us to get the time of flight neutron spectra. They are bent for uniform flight path and viewed by a photomultiplier tube at both ends. Simulations have allowed to establish scintillator size and to minimize light attenuation. Intrinsic efficiency and crosstalk have been measured with 252 Cf and compared to GEANT. 1 to 5 MeV neutrons are detected with good timing and position properties. Other counters will be built for neutrons from 300 keV to 1 MeV. Planned to run at several particle accelerators (GANIL, CERN, and others), TONNERRE is modular and many geometries are possible. (author)

Highly efficient dye-sensitized solar cell with GNS/MWCNT/PANI as a counter electrode

International Nuclear Information System (INIS)

Al-bahrani, Majid Raissan; Xu, Xiaobao; Ahmad, Waqar; Ren, Xiaoliang; Su, Jun; Cheng, Ze; Gao, Yihua

2014-01-01

Highlights: • High-performance PANI/MWCNT-CE was incorporated in a Pt-CE in DSSCs. • GNS/MWCNT/PANI-CE exhibits a high power conversion efficiency (PCE) of 7.52%. • GNS/MWCNT/PANI composite has a high catalytic activity for the reduction of I 3 − . • GNS/MWCNT/PANI composite has a low R CT on the electrolyte/CE interface. - Abstract: A graphene-based nanosheet composite/multiwalled carbon nanotube/polyaniline (GNS/MWCNT/PANI) was synthesized via an in situ polymerization technique and applied by the spin-coating method as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). The combination of the high catalytic activity of PANI and outstanding conductivity of GNS/MWCNT improved the photovoltaic performance of the hybrid CE. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the GNS/MWCNT/PANI composite has high catalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte/electrode interface. Transmission electron microscopy (TEM) images showed that the GNS/MWCNT/PANI-CE has a rough and porous structure and X-ray diffraction analysis confirmed the formation of PANI coating on the surface of the GNS/CNT. In particular, current–voltage measurements showed the superior power conversion efficiency (PCE) of 7.52% of the DSSC based on GNS/MWCNT/PANI-CE compared to the PCE of 6.69% of the DSSC based on Pt-CE

Highly efficient dye-sensitized solar cell with GNS/MWCNT/PANI as a counter electrode

Energy Technology Data Exchange (ETDEWEB)

Al-bahrani, Majid Raissan [Center for Nanoscale Characterization and Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China); Faculty of Science, Thi-Qar University, Nassiriya (Iraq); Xu, Xiaobao [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, 430074 Wuhan (China); Ahmad, Waqar; Ren, Xiaoliang; Su, Jun [Center for Nanoscale Characterization and Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China); Cheng, Ze [School of Physics, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan 430074 (China); Gao, Yihua, E-mail: gaoyihua@hust.edu.cn [Center for Nanoscale Characterization and Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China)

2014-11-15

Highlights: • High-performance PANI/MWCNT-CE was incorporated in a Pt-CE in DSSCs. • GNS/MWCNT/PANI-CE exhibits a high power conversion efficiency (PCE) of 7.52%. • GNS/MWCNT/PANI composite has a high catalytic activity for the reduction of I{sub 3}{sup −}. • GNS/MWCNT/PANI composite has a low R{sub CT} on the electrolyte/CE interface. - Abstract: A graphene-based nanosheet composite/multiwalled carbon nanotube/polyaniline (GNS/MWCNT/PANI) was synthesized via an in situ polymerization technique and applied by the spin-coating method as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). The combination of the high catalytic activity of PANI and outstanding conductivity of GNS/MWCNT improved the photovoltaic performance of the hybrid CE. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the GNS/MWCNT/PANI composite has high catalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte/electrode interface. Transmission electron microscopy (TEM) images showed that the GNS/MWCNT/PANI-CE has a rough and porous structure and X-ray diffraction analysis confirmed the formation of PANI coating on the surface of the GNS/CNT. In particular, current–voltage measurements showed the superior power conversion efficiency (PCE) of 7.52% of the DSSC based on GNS/MWCNT/PANI-CE compared to the PCE of 6.69% of the DSSC based on Pt-CE.

Study and building of a detection array for delayed neutrons: TONNERRE; Etude et realisation d`un ensemble de detection pour neutrons retardes: TONNERRE

Energy Technology Data Exchange (ETDEWEB)

Martin, Thierry [Lab. de Physique Corpusculaire, Caen Univ., 14 - Caen (France)

1998-11-09

This work has been undertaken within a French-Romanian collaboration in order to build a high efficiency detector array for delayed neutrons: barrel-shaped TONNERRE. Some neutron-rich nuclei decay through 1, 2 or 3 neutron emission after {beta}{sup -} decay. More exotic nuclei will be produced by SPIRAL at GANIL. An array with high efficiency and good resolution is then required. Thirty two BC400 plastic scintillators (160 x 20 x 4 cm{sup 3}) allow us to get the time of flight neutron spectra. They are bent for uniform flight path and viewed by a photomultiplier tube at both ends. Simulations have allowed to establish scintillator size and to minimize light attenuation. Intrinsic efficiency and crosstalk have been measured with {sup 252}Cf and compared to GEANT. 1 to 5 MeV neutrons are detected with good timing and position properties. Other counters will be built for neutrons from 300 keV to 1 MeV. Planned to run at several particle accelerators (GANIL, CERN, and others), TONNERRE is modular and many geometries are possible. (author) 48 refs., 78 figs., 20 tabs.

Errors in estimating neutron quality factor using lineal energy distributions measured in tissue-equivalent proportional counters

International Nuclear Information System (INIS)

Borak, T.B.; Stinchcomb, T.G.

1982-01-01

Neutron dose equivalent is obtained from quality factors which are defined in terms of LET. It is possible to estimate the dose averaged quality factor, antiQ, directly from distributions in lineal energy, y, that are measured in tissue-equivalent proportional counters. This eliminates a mathematical transformation of the absorbed dose from D(y) to D(L). We evaluate the inherent error in computing Q from D(y) rather than D(L) for neutron spectra below 4 MeV. The effects of neutron energy and simulated tissue diameters within a gas cavity are examined in detail. (author)

NiS(NPs)-PEDOT-PSS composite counter electrode for a high efficiency dye sensitized solar cell

Energy Technology Data Exchange (ETDEWEB)

Maiaugree, Wasan [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Center for Alternative Energy Research and Development, Khon Kaen University, Khon Kaen 40002 (Thailand); Pimparue, Pachara; Jarernboon, Wirat [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Pimanpang, Samuk [Department of Physics, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Amornkitbamrung, Vittaya [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Swatsitang, Ekaphan, E-mail: ekaphan@kku.ac.th [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Center for Alternative Energy Research and Development, Khon Kaen University, Khon Kaen 40002 (Thailand)

2017-06-15

Graphical abstract: Figure(a) and (b) represent models depict PEDOT-PSS counter electrodes of DSSC without and with NiS NPs modification, respectively. The active surface area of PEDOT-PSS polymer can be improved by combining with NiS(NPs). The I-V curves in figure (c) show the superior photovoltaic conversion efficiency of 8.18% for NiS(NPs)/PEDOT-PSS DSSC. - Highlights: • Active surface area of PEDOT-PSS CE can be improved by mixing with NiS(NPs). • Electrocatalytic activity of mixed NiS(NPs)/PEDOT-PSS polymer is also improved. • NiS(NPs)/PEDOT-PSS CE shows a very low charge transfer resistance of 0.46 Ω. • In this work, the high photovoltaic conversion efficiency of 8.18% is achieved. - Abstract: Nickel sulfide (NiS) nanoparticles (NPs) (NiS(NPs)) were prepared by the hydrothermal method. X-ray diffraction (XRD) results indicate the hexagonal structure of NiS(NPs). SEM micrographs reveal the agglomeration of irregular hexagonal – shaped NiS(NPs) with estimated particle size in the range of 50–150 nm. Counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) were prepared by coating the composite slurry of different NiS(NPs) loadings and Poly (3, 4-Ethylendioxythiophene) – Poly (Styrene Sulfonate) (PEDOT-PSS) on fluoride-doped tin oxide (FTO) substrates using a doctor blading technique. Cyclic voltammetry (CV) results indicate that the composites of NiS(NPs) and PEDOT-PSS (NiS(NPs)/PEDOT-PSS) films could function as a catalyst for I{sub 3}{sup −} reduction with a maximum cell efficiency of 8.18% for a cell of 0.3 g NiS(NPs) loading.

Development Of A Method For Measurement Of Total Neutron Cross Sections Based On The Neutron Transmission Method Using A He-3 Counter On Filtered Neutron Beams At Dalat Research Reactor

International Nuclear Information System (INIS)

Tran Tuan Anh; Dang Lanh; Nguyen Canh Hai; Nguyen Xuan Hai; Pham Kien; Nguyen Thuy Nham; Pham Ngoc Son; Ho Huu Thang

2007-01-01

Determination of total neutron cross sections and average resonance parameters in the energy range from tens keV to hundreds keV is important for fast reactors calculations and designs because this energy range gives the most output of all neutron induced reactions in the spectrum of fast reactors. Besides, the total neutron cross section measurement is also one of the methods for determination of s, p and d-wave neutron strength functions. The purpose of this project is to develop a method for measurement of total neutron cross sections based on the neutron transmission technique using a He-3 counter. The average total neutron cross sections of 238 U were obtained from neutron transmission measurements on filtered neutron beams of 55 keV and 144 keV at the horizontal channel No.4 of the Dalat research reactor. The present results have been compared with the previous measurements, and the evaluated data from ENDF/B-6.8 library. (author)

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

Science.gov (United States)

McGregor, Douglas S.; Shultis, John K.; Rice, Blake B.; McNeil, Walter J.; Solomon, Clell J.; Patterson, Eric L.; Bellinger, Steven L.

2010-12-21

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.

Dead time of different neutron detectors associated with a pulsed electronics with current collection

International Nuclear Information System (INIS)

Bacconnet, Eugene; Duchene, Jean; Duquesne, Henry; Schmitt, Andre

1968-01-01

After having outlined that the development of fast neutron reactor physics, notably kinetics, requires highly efficient neutron detectors and pulse measurement chains able to cope with high counting rates, the authors report the measurement of dead time of various neutron detectors which are used in the experimental study of fast neutron reactors. They present the SAITB 1 electronic measurement set, its components, its general characteristics, the protected connection between the detector and the electronics. They present and report the experiment: generalities about detector location and measurements, studied detectors (fission chambers, boron counters), and report the exploitation of the obtained results (principle, data, high-threshold counting gain) [fr

Study on the novel neutron-to-proton convertor for improving the detection efficiency of a triple GEM based fast neutron detector

International Nuclear Information System (INIS)

Wang Xiaodong; Yang Lei; Zhang Chunhui; Hu Bitao; Yang Herun; Zhang Junwei; Ren Zhongguo; Ha Ri-Ba-La; An Luxing

2015-01-01

A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier (GEM) detector, which, coupled with a novel multi-layered high-density polyethylene (HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with "5"5Fe X-ray source to ensure that it has a good performance. The effective gain and obtained energy resolution is 5.0 × 10"4 and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38. (authors)

Detection of pulsed fast neutrons by a proportional counter boron-convered and enveloped in paraffin moderators

International Nuclear Information System (INIS)

Goncalez, O.L.; Yanagihara, L.S.; Veissid, V.L.C.P.; Herdade, S.B.

1983-01-01

The response to pulsed fast neutrons by a parafin moderated boron-lined proportional counter is investigated theoretically and experimentally. The neutrons pulses are generated by 60 MeV electrons from a linear accelerator. The calculation of the counting loss based on the detector dead time and on the exponential decresse of the thermal neutron population in the moderator is presented in detail. An analytical relation between the true counting rate and the reduced one, indicated by the detector, is found. In this formula three parameters appear: the decay constant of the thermal neutron population, the detector dead time and the pulse frequency of the neutron source. The decay constant is calculated by diffusion theory. The experimental results for six values of moderator thickness (between 2.5 to 12.5 cm) agree with our theoretical calculation within 20 per cent. (Author) [pt

Development of new type boron-coating proportional counter and its experimental investigation and simulation calculation

International Nuclear Information System (INIS)

Zhang Zixia; Wei Zhiyong; Fang Meihua; Qiang Peng; Zhu Li; Chen Guoyun

2015-01-01

Three materials wherein suitable proportion of isotope enriched 10 B powder, 1, 2-ethylene dichloride and formvar resin were blended to make 10 B neutron sensitive coating by oneself. A new type proportional counter that coated with 10 B neutron sensitive coating was made. Furthermore, in order to increase the character and quality of the neutron detector, a set of 14 annulus epoxy sheets which were sided with 10 B film were placed in the tube. A series performance tests were done by 241 Am-Be neutron source. The tests of 3.7 × 10 9 Bq 211 Am-Be neutron source show that the plateau length of detector is 150 V from 750 V to 900 V, while the plateau slope is 8.2%/100 V. When the working voltage is 800 V, the count rate of new type boron-coating proportional counter is 50 s -1 . The level of sensitivity is 0.71 cm 2 . Compared with the detector only coated with 10 B film in the inner walls of detector, neutron sensitivity area of the new detector increases to 3.15 times. The results show that the plateau length increases from 80 V to 150 V, and the plateau slope is improved from 12.4%/100 V to 7.58%/100 V, while the neutron sensitivity increases to 2.63 times. Using Geant4 software based on Monte Carlo method, this paper presented the response and detection efficiency of new type boron-coating proportional counter, which was covered with φ55 mm × 250 mm cylinder high density polyethylene moderator material. The simulation results of Geant4 are in agreement with the results of 241 Am-Be neutron source experiment. It shows the reliability of simulation application. (authors)

Development of NRESP98 Monte Carlo codes for the calculation of neutron response functions of neutron detectors. Calculation of the response function of spherical BF{sub 3} proportional counter

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, M.; Saito, K.; Ando, H. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1998-05-01

The method to calculate the response function of spherical BF{sub 3} proportional counter, which is commonly used as neutron dose rate meter and neutron spectrometer with multi moderator system, is developed. As the calculation code for evaluating the response function, the existing code series NRESP, the Monte Carlo code for the calculation of response function of neutron detectors, is selected. However, the application scope of the existing NRESP is restricted, the NRESP98 is tuned as generally applicable code, with expansion of the geometrical condition, the applicable element, etc. The NRESP98 is tested with the response function of the spherical BF{sub 3} proportional counter. Including the effect of the distribution of amplification factor, the detailed evaluation of the charged particle transportation and the effect of the statistical distribution, the result of NRESP98 calculation fit the experience within {+-}10%. (author)

Transmission efficiency of neutron guide tube with alignment errors

International Nuclear Information System (INIS)

Kawabata, Yuji; Suzuki, Masatoshi; Sakamoto, Masanobu; Harami, Taikan; Takahashi, Hidetake; Onishi, Nobuaki

1990-01-01

The experimental studies on the neutron transmission efficiencies of neutron guide tubes were carried out by using thermal neutrons from the JAERI electron linac. The neutron guide tube facility on a large scale have been planned on the reconstructed JRR-3 in JAERI. The neutron efficiencies of the 1/10 scale neutron guide tube, which is 2 mm width and 1.8 m length, with and without appreciable alignment errors were studied to evaluate the efficiencies of the planned ones. Calculated results by the Neutron Guide Tube Analysis Code 'NEUGT' were also assessed by these neutron experiments. The experimental results agree well with the calculated results by 'NEUGT' even with alignment errors. From this experimental study, the efficiency of the planned neutron guide tubes is estimated to be good enough for the neutron beam experiments. (author)

Counter-Based Broadcast Scheme Considering Reachability, Network Density, and Energy Efficiency for Wireless Sensor Networks.

Science.gov (United States)

Jung, Ji-Young; Seo, Dong-Yoon; Lee, Jung-Ryun

2018-01-04

A wireless sensor network (WSN) is emerging as an innovative method for gathering information that will significantly improve the reliability and efficiency of infrastructure systems. Broadcast is a common method to disseminate information in WSNs. A variety of counter-based broadcast schemes have been proposed to mitigate the broadcast-storm problems, using the count threshold value and a random access delay. However, because of the limited propagation of the broadcast-message, there exists a trade-off in a sense that redundant retransmissions of the broadcast-message become low and energy efficiency of a node is enhanced, but reachability become low. Therefore, it is necessary to study an efficient counter-based broadcast scheme that can dynamically adjust the random access delay and count threshold value to ensure high reachability, low redundant of broadcast-messages, and low energy consumption of nodes. Thus, in this paper, we first measure the additional coverage provided by a node that receives the same broadcast-message from two neighbor nodes, in order to achieve high reachability with low redundant retransmissions of broadcast-messages. Second, we propose a new counter-based broadcast scheme considering the size of the additional coverage area, distance between the node and the broadcasting node, remaining battery of the node, and variations of the node density. Finally, we evaluate performance of the proposed scheme compared with the existing counter-based broadcast schemes. Simulation results show that the proposed scheme outperforms the existing schemes in terms of saved rebroadcasts, reachability, and total energy consumption.

Performance Evaluation of the Neutron Coincidence Counter for the Advanced Spent Fuel Conditioning Process

International Nuclear Information System (INIS)

Lee, S.Y.; Li, T.K.; Menlove, Howard O.; Kim, H.D.; Ko, W.I.; Park, S.W.

2005-01-01

The Advanced Spent Fuel Conditioning Process (ACP) is a pyrochemical dry reprocessing technique to convert oxide-type spent nuclear fuel into a metallic form. The Korea Atomic Energy Research Institute (KAERI) has been developing this technology for the purpose of spent fuel management and is planning to perform a lab-scale demonstration in 2006. With this technology, a significant reduction of the volume and heat load of spent fuel is expected, which could decrease the burden of safety and economics. In this study, MCNPX code calculations were carried out to estimate the performance of a neutron coincidence counter designed for measruement of the process materials in the pilot-scale ACP facility. To verify the design requirement, the singles and doubles counting rates of the detectors were simulated with the latest coincidence capability of the MCNPX code. Then, the precision of the coincidence measurements were evaluated on various process materials from the ACP. It was verified that the performance of the neutron coincidence counter could meet the design criteria for all samples in the ACP, and the material accounting system for the pilot-scale ACP facility could meet the IAEA safeguards goals.

Directional epithermal neutron detector

International Nuclear Information System (INIS)

Givens, W.W.; Mills, W.R. Jr.

1986-01-01

A borehole tool for epithermal neutron die-away logging of subterranean formations surrounding a borehole is described which consists of: (a) a pulsed source of fast neutrons for irradiating the formations surrounding a borehole, (b) at least one neutron counter for counting epithermal neutrons returning to the borehole from the irradiated formations, (c) a neutron moderating material, (d) an outer thermal neutron shield providing a housing for the counter and the moderating material, (e) an inner thermal neutron shield dividing the housing so as to provide a first compartment bounded by the inner thermal neutron shield and a first portion of the outer thermal neutron shield and a second compartment bounded by the inner thermal neutron shield and a second portion of the outer thermal neutron shield, the counter being positioned within the first compartment and the moderating material being positioned within the second compartment, and (f) means for positioning the borehole tool against one side of the borehole wall and azimuthally orienting the borehole tool such that the first chamber is in juxtaposition with the borehole wall, the formation epithermal neutrons penetrating into the first chamber through the first portion of the outer thermal neutron shield are detected by the neutron counter for die-away measurement, thereby maximizing the directional sensitivty of the neutron counter to formation epithermal neutrons, the borehole fluid epithermal neutrons penetrating into the second chamber through the second chamber through the second portion of the outer thermal neutron shield are largely slowed down and lowered in energy by the moderating material and absorbed by the inner thermal neutron shield before penetrating into the first chamber, thereby minimizing the directional sensitivity of the neutron counter to borehole fluid epithermal neutrons

4π-spectrometer technique for measurements of secondary neutron average number in nuclear fission by 252Cf neutrons

International Nuclear Information System (INIS)

Vasil'ev, Yu.A.; Barashkov, Yu.A.; Golovanov, O.A.; Sidorov, L.V.

1977-01-01

A method for determining the average number of secondary neutrons anti ν produced in nuclear fission by the neutrons of the 252 Cf fission spectra by means of a 4π time-of-flight spectrometer is described. Layers of 252 Cf and an isotope studied are placed close to each other; if the isotope layer density is 1 mg/cm 2 probability of its fission is about 10 -5 per one spontaneous fission of californium. Fission fragments of 252 Cf and the isotope investigated have been detected by two surface-barrier counters with an efficiency close to 100%. The layers and the counters are situated in a measuring chamber placed in the center of the 4π time-of-flight spectrometer. The latter is utilized as a neutron counter because of its fast response. The method has been verified by carrying out measurements for 235 U and 239 Pu. A comparison of the experimental and calculated results shows that the method suggested can apply to determine the number of secondary neutrons in fission of isotopes that have not been investigated yet

Intrinsic neutron source strengths in uranium solutions

International Nuclear Information System (INIS)

Anderson, R.E.; Robba, A.A.; Seale, R.L.; Rutherford, D.A.; Butterfield, K.B.; Brunson, G.S.

1991-01-01

Neutron production rates for 5% enriched uranyl fluoride and 93% uranyl nitrate solutions have been measured using a high-efficiency neutron well counter. Measurements were made for both solution types as a function of sample volume. These results were extrapolated to zero sample volume to eliminate sample size effects, such as multiplication and absorption. For the 5% enriched uranyl fluoride solution, a neutron production rate of 0.0414 ± 0.0041 n/s/ml was measured; for the 93% enriched uranyl nitrate solution, a neutron production rate of 0.0232 ± 0.0023 n/s/ml was measured. The biggest uncertainty is in measuring the detector efficiency, and further work on this aspect of the experiment is planned. Calculations for the neutron production rates based on measured thick-target (alpha, n) production rates and shown alpha stopping powers are in reasonable agreement with the data for the uranyl nitrate solution, but are in poor agreement with the data for the uranyl fluoride solution. 8 refs., 7 figs., 5 tabs

Use of the helium-3 proportional counter for neutron spectrometry; Utilisation du compteur proportionnel a helium 3 pour la spectrometrie des neutrons

Energy Technology Data Exchange (ETDEWEB)

Vialettes, H; Le Thanh, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-07-01

Up to now, two methods have been mainly used for neutron spectrometry near nuclear installations: - photographic emulsion spectrometry - the so-called, 'multisphere' technique spectrometry. The first method, which is fairly difficult to apply, has a threshold energy of about 500 keV; this is a big disadvantage for an apparatus which has to be used for spectrometry around nuclear installations where the neutron radiation is very much degraded energetically. The second method does not suffer from this disadvantage but the results which it yields are only approximate. In order to extend the energy range of the neutron spectra studied with sufficient accuracy the use of a helium-3 proportional counter has been considered. This report presents the principles of operation of the helium-3 spectrometer, and the calculation methods which make it possible to take into account the two main effects tending to deform the spectra obtained: - energy absorption by the walls of the counter, - energy loss of the incident neutrons due to elastic collisions with helium-3 nuclei. As an example of the application, the shape of the neutron spectrum emitted by a polonium-lithium source is given; the results obtained are in excellent agreement with theoretical predictions. (authors) [French] Jusqu'ici deux methodes ont ete utilisees principalement pour la spectrometrie des neutrons autour des installations nucleaires: - la spectrometrie par emulsions photographiques - la spectrometrie par la technique dite des multispheres. La premiere methode, d'un emploi assez delicat presente un seuil en energie d'environ 500 keV qui est un obstacle serieux a la spectrometrie autour des installations nucleaires ou le rayonnement neutronique est tres degrade en energie. La deuxieme methode ne presente pas cet inconvenient mais les resultats qu'elle permet d'obtenir ne sont qu'approches. Pour etendre la gamme d'energie des spectres de neutrons etudies avec une precision suffisante, l'utilisation du

Space and power efficient hybrid counters array

Science.gov (United States)

Gara, Alan G [Mount Kisco, NY; Salapura, Valentina [Chappaqua, NY

2009-05-12

A hybrid counter array device for counting events. The hybrid counter array includes a first counter portion comprising N counter devices, each counter device for receiving signals representing occurrences of events from an event source and providing a first count value corresponding to a lower order bits of the hybrid counter array. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits of the hybrid counter array. A control device monitors each of the N counter devices of the first counter portion and initiates updating a value of a corresponding second count value stored at the corresponding addressable memory location in the second counter portion. Thus, a combination of the first and second count values provide an instantaneous measure of number of events received.

Constant sensitivity circuit for solid state nuclear radiation counters

International Nuclear Information System (INIS)

Kronenberg, S.; Erkkila, B.

1985-01-01

The utilization of solid state counters in tactical radiological instruments for measuring intensities and doses of fallout gamma rays offers advantages over Geiger-Mueller (GM) counters such as a much wider dynamic range and low operating voltages. Their very small size is suitable for use in miniaturized equipment. However, these devices have a serious problem if used in a mixed, fast neutron/gamma environment such as is encountered e.g. in a battlefield where tactical nuclear weapons are used and neutrons, prompt, initial gammas and fallout gammas are killing factors of comparable importance. Exposure to fast neutrons reduces seriously their sensitivity. This makes the solid state counters at this time unacceptable for use in Army tactical surveillance equipment and in other applications where according to requirements the performance must not be impaired by exposure to fast neutrons. It seems to be possible to reduce to some extent this neutron generated damage by improving the crystal counters

An ancient form of position-sensitive detector - the individual counter array

International Nuclear Information System (INIS)

Hewat, A.W.

1983-01-01

Large position sensitive detectors (PSDs) have been very successful as high efficiency neutron powder diffractometers. Complete powder patterns can be obtained within minutes, making possible real-time measurements of structural changes accompanying chemical and electrochemical reactions. The angular resolution of such machines is determined by the diameter of the sample, and not simply by the resolution of the detector itself. It is argued that since sample diameters are usually 5mm to 10mm, it is possible to use an array of individual counters of similar diameter rather than a true PSD. Such a low to medium resolution individual counter array (ICA) can be made more efficient than the true PSD, produces an identical diffraction pattern, and has several practical advantages, including covering a greater solid angle. For high resolution powder diffraction, it has already been demonstrated that an ICA, in this case associated with Soller collimators, is again the most efficient solution. This is because the sample volume (and intensity) of a high resolution PSD decreases quadratically with the diameter of the sample. The only alternative to very small samples would be a large sample-detector distance, and then large vertical divergences cannot be achieved because of mechanical limitations on gas-filled PSD apertures; again intensity is lost. The resolution and efficiency of the ICA are discussed. (author)

EXILL—a high-efficiency, high-resolution setup for γ-spectroscopy at an intense cold neutron beam facility

Science.gov (United States)

Jentschel, M.; Blanc, A.; de France, G.; Köster, U.; Leoni, S.; Mutti, P.; Simpson, G.; Soldner, T.; Ur, C.; Urban, W.; Ahmed, S.; Astier, A.; Augey, L.; Back, T.; Baczyk, P.; Bajoga, A.; Balabanski, D.; Belgya, T.; Benzoni, G.; Bernards, C.; Biswas, D. C.; Bocchi, G.; Bottoni, S.; Britton, R.; Bruyneel, B.; Burnett, J.; Cakirli, R. B.; Carroll, R.; Catford, W.; Cederwall, B.; Celikovic, I.; Cieplicka-Oryńczak, N.; Clement, E.; Cooper, N.; Crespi, F.; Csatlos, M.; Curien, D.; Czerwiński, M.; Danu, L. S.; Davies, A.; Didierjean, F.; Drouet, F.; Duchêne, G.; Ducoin, C.; Eberhardt, K.; Erturk, S.; Fraile, L. M.; Gottardo, A.; Grente, L.; Grocutt, L.; Guerrero, C.; Guinet, D.; Hartig, A.-L.; Henrich, C.; Ignatov, A.; Ilieva, S.; Ivanova, D.; John, B. V.; John, R.; Jolie, J.; Kisyov, S.; Krticka, M.; Konstantinopoulos, T.; Korgul, A.; Krasznahorkay, A.; Kröll, T.; Kurpeta, J.; Kuti, I.; Lalkovski, S.; Larijani, C.; Leguillon, R.; Lica, R.; Litaize, O.; Lozeva, R.; Magron, C.; Mancuso, C.; Ruiz Martinez, E.; Massarczyk, R.; Mazzocchi, C.; Melon, B.; Mengoni, D.; Michelagnoli, C.; Million, B.; Mokry, C.; Mukhopadhyay, S.; Mulholland, K.; Nannini, A.; Napoli, D. R.; Olaizola, B.; Orlandi, R.; Patel, Z.; Paziy, V.; Petrache, C.; Pfeiffer, M.; Pietralla, N.; Podolyak, Z.; Ramdhane, M.; Redon, N.; Regan, P.; Regis, J. M.; Regnier, D.; Oliver, R. J.; Rudigier, M.; Runke, J.; Rzaca-Urban, T.; Saed-Samii, N.; Salsac, M. D.; Scheck, M.; Schwengner, R.; Sengele, L.; Singh, P.; Smith, J.; Stezowski, O.; Szpak, B.; Thomas, T.; Thürauf, M.; Timar, J.; Tom, A.; Tomandl, I.; Tornyi, T.; Townsley, C.; Tuerler, A.; Valenta, S.; Vancraeyenest, A.; Vandone, V.; Vanhoy, J.; Vedia, V.; Warr, N.; Werner, V.; Wilmsen, D.; Wilson, E.; Zerrouki, T.; Zielinska, M.

2017-11-01

In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of γ-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 108 n s-1cm-2 at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM Clover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectors were arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 × 105 Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico- to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of 133Ba, 60Co and 152Eu as well as data from the reactions 27Al(n,γ)28Al and 35Cl(n,γ)36Cl in the energy range from 30 keV up to 10 MeV.

High precision thermal neutron detectors

Energy Technology Data Exchange (ETDEWEB)

Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B. [Brookhaven National Laboratory, Upton, NY (United States)

1994-12-31

Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

High-performance dye-sensitized solar cells with gel-coated binder-free carbon nanotube films as counter electrode

Science.gov (United States)

Mei, Xiaoguang; Cho, Swee Jen; Fan, Benhu; Ouyang, Jianyong

2010-10-01

High-performance dye-sensitized solar cells (DSCs) with binder-free films of carbon nanotubes (CNTs), including single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs), as the counter electrode are reported. The CNT films were fabricated by coating gels, which were prepared by dispersing CNTs in low-molecular-weight poly(ethylene glycol) (PEG) through mechanical grinding and subsequent ultrasonication, on fluorine tin oxide (FTO) glass. PEG was removed from the CNT films through heating. These binder-free CNT films were rough and exhibited good adhesion to substrates. They were used as the counter electrode of DSCs. The DSCs with SWCNT or MWCNT counter electrodes exhibited a light-to-electricity conversion efficiency comparable with that with the conventional platinum (Pt) counter electrode, when the devices were tested immediately after device fabrication. The DSCs with an SWCNT counter electrode exhibited good stability in photovoltaic performance. The efficiency did not decrease after four weeks. On the other hand, DSCs with the MWCNT or Pt counter electrode exhibited a remarkable decrease in the photovoltaic efficiency after four weeks. The high photovoltaic performance of these DSCs is related to the excellent electrochemical catalysis of CNTs on the redox of the iodide/triiodide pair, as revealed by the cyclic voltammetry and ac impedance spectroscopy.

High-performance dye-sensitized solar cells with gel-coated binder-free carbon nanotube films as counter electrode

International Nuclear Information System (INIS)

Mei Xiaoguang; Cho, Swee Jen; Fan Benhu; Ouyang Jianyong

2010-01-01

High-performance dye-sensitized solar cells (DSCs) with binder-free films of carbon nanotubes (CNTs), including single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs), as the counter electrode are reported. The CNT films were fabricated by coating gels, which were prepared by dispersing CNTs in low-molecular-weight poly(ethylene glycol) (PEG) through mechanical grinding and subsequent ultrasonication, on fluorine tin oxide (FTO) glass. PEG was removed from the CNT films through heating. These binder-free CNT films were rough and exhibited good adhesion to substrates. They were used as the counter electrode of DSCs. The DSCs with SWCNT or MWCNT counter electrodes exhibited a light-to-electricity conversion efficiency comparable with that with the conventional platinum (Pt) counter electrode, when the devices were tested immediately after device fabrication. The DSCs with an SWCNT counter electrode exhibited good stability in photovoltaic performance. The efficiency did not decrease after four weeks. On the other hand, DSCs with the MWCNT or Pt counter electrode exhibited a remarkable decrease in the photovoltaic efficiency after four weeks. The high photovoltaic performance of these DSCs is related to the excellent electrochemical catalysis of CNTs on the redox of the iodide/triiodide pair, as revealed by the cyclic voltammetry and ac impedance spectroscopy.

High-speed parallel counter

International Nuclear Information System (INIS)

Gus'kov, B.N.; Kalinnikov, V.A.; Krastev, V.R.; Maksimov, A.N.; Nikityuk, N.M.

1985-01-01

This paper describes a high-speed parallel counter that contains 31 inputs and 15 outputs and is implemented by integrated circuits of series 500. The counter is designed for fast sampling of events according to the number of particles that pass simultaneously through the hodoscopic plane of the detector. The minimum delay of the output signals relative to the input is 43 nsec. The duration of the output signals can be varied from 75 to 120 nsec

Visible light photon counters (VLPCs) for high rate tracking medical imaging and particle astrophysics

International Nuclear Information System (INIS)

Atac, M.

1998-02-01

This paper is on the operation principles of the Visible Light Photon Counters (VLPCs), application to high luminosity-high multiplicity tracking for High Energy Charged Particle Physics, and application to Medical Imaging and Particle Astrophysics. The VLPCs as Solid State Photomultipliers (SSPMS) with high quantum efficiency can detect down to single photons very efficiently with excellent time resolution and high avalanche gains

Miniature proportional counter for compression measurements of laser-fusion targets

International Nuclear Information System (INIS)

Lane, S.M.; Dellis, J.H.; Bennett, C.K.; Campbell, E.M.

1981-10-01

Direct drive laser fusion targets consisting of DT gas encapsulated in glass microshells produce 14.1 MeV neutrons that can interact with silicon-28 nuclei in the glass to produce a 2.2 minute aluminum-28 activity. From the number of 28 Al nuclei created and the neutron yield, the compressed glass areal density can be found. To determine the number of activated atoms created, we collect approximately one-half of the target debris on a thin metal foil which is transferred to our beta-gamma coincidence detector. This detector consists of a 25 cm x 25 cm NaI(Tl) crystal having a 5 cm x 15 cm well. We have recently built a miniature proportional counter that fits into this well and is used to detect beta particles. It is constructed of .025 cm thick copper and has nine separate chambers through which methane flows. The coincidence background is 0.14 cpm and the measured beta efficiency is 45%. We are now building a .0125 cm thick counter made of aluminum having a predicted efficiency of > 90%

Transportable type neutron level indicators

International Nuclear Information System (INIS)

Khatskevich, M.V.; Kalinin, O.V.; Moskovkin, V.N.; Molchanov, A.V.; Bobkov, A.D.; Rabotnov, Yu.A.

1979-01-01

Some peculiarities of designing level neutron converters (LNC) for portable indicators or level neutron relays are considered. The effect of the LNC geometry and other factors on measurement errors has been studied. Calibration results of the LNC with a neutron reflector and without it are presented. It is shown that the problem of level monitoring with the help of portable indicators can be solved practically for any volume, provided two LNC modifications with reflectors are available: the NPU-G modification with horizontal location of a counter for large volumes and the NPU-V with vertical location of a counter for lesser volumes. A possibility of perfecting LNC performances by shielding the counter with thermal neutron absorbers has been studied. The design of the NPU-V modification for the NIUP-2 level indicator is described. It is intended for tubes and cylinders 30-100 mm in diameter. Measurements carried out on different steel and aluminium vessels with a diameter ranging from 300 to 100 mm and a wall thickness of up to 16 mm with the help of the NPU-V and NPU-G modifications proved the efficiency of the LNC to control a variety of products (kerosine, gasoline, oils, acids, alkalis) [ru

Measurement of the detection efficiency of the KLOE calorimeter for neutrons between 22 and 174 MeV

Energy Technology Data Exchange (ETDEWEB)

Anelli, M. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Battistoni, G. [Sezione INFN di Milano (Italy); Bertolucci, S. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Bini, C. [Sapienza Universita di Roma (Italy); Sezione INFN di Roma (Italy); Branchini, P. [Sezione INFN di Roma Tre (Italy); Curceanu, C. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); De Zorzi, G.; Di Domenico, A. [Sapienza Universita di Roma (Italy); Sezione INFN di Roma (Italy); Di Micco, B. [Universita degli di Studi ' Roma Tre' (Italy); Sezione INFN di Roma Tre (Italy); Ferrari, A. [Fondazione CNAO, Milano (Italy); Fiore, S. [Sapienza Universita di Roma (Italy); Sezione INFN di Roma (Italy)], E-mail: salvatore.fiore@roma1.infn.it; Gauzzi, P. [Sapienza Universita di Roma (Italy); Sezione INFN di Roma (Italy); Giovannella, S.; Happacher, F. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Iliescu, M. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); IFIN-HH, Bucharest (Romania); Martini, M.; Miscetti, S. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Nguyen, F. [Universita degli di Studi ' Roma Tre' (Italy); Sezione INFN di Roma Tre (Italy); Passeri, A. [Sezione INFN di Roma Tre (Italy); Prokofiev, A. [Svedberg Laboratory, Uppsala University (Sweden)] (and others)

2009-01-01

A prototype of the high-sampling lead-scintillating fiber KLOE calorimeter has been exposed to neutron beams of 21, 46 and 174 MeV, provided by the The Svedberg Laboratory, Uppsala, to test its neutron detection efficiency. The measurement of the neutron detection efficiency of an NE110 scintillator provided a reference calibration. The measured efficiency is larger than what expected considering the scintillator thickness of the KLOE prototype only. This result proves the existence of a contribution from the passive material to neutron detection efficiency, in a high-sampling calorimeter configuration.

Leakage monitoring equipment of fuel element by delayed neutron method

International Nuclear Information System (INIS)

Ji Changsong; Zhang Shulan; Zhang Shuheng

1999-01-01

Based on monitoring results of delayed neutrons from reactor first circle water, the leakage of reactor fuel elements is monitored. A monitoring equipment consisted of an array of 3 He proportional counter tubes with 75 s delay has been developed. The neutron detection efficiency of 6.1% is obtained

Nitrogen-doped graphene as transparent counter electrode for efficient dye-sensitized solar cells

International Nuclear Information System (INIS)

Wang, Guiqiang; Fang, Yanyan; Lin, Yuan; Xing, Wei; Zhuo, Shuping

2012-01-01

Graphical abstract: Display Omitted Highlights: ► NG sheets are prepared through a hydrothermal reduction of graphite oxide. ► The transparent NG counter electrodes of DSCs are fabricated at room temperature. ► Transparent NG electrode exhibits excellent catalytic activity for the reduction of I 3 − . ► The DSC with NG electrode achieves a comparable efficiency to that of the Pt-based cell. ► The efficiency of rear illumination is about 85% that of front illumination. -- Abstract: Nitrogen-doped graphene sheets are prepared through a hydrothermal reduction of graphite oxide in the presence of ammonia and applied to fabricate the transparent counter electrode of dye-sensitized solar cells. The atomic percentage of nitrogen in doped graphene sample is about 2.5%, and the nitrogen bonds display pyridine and pyrrole-like configurations. Cyclic voltammetry studies demonstrate a much higher electrocatalytic activity toward I − /I 3 − redox reaction for nitrogen-doped graphene, as compared with pristine graphene. The dye-sensitized solar cell with this transparent nitrogen-doped graphene counter electrode shows conversion efficiencies of 6.12% and 5.23% corresponding to front-side and rear-side illumination, respectively. Meanwhile, the cell with a Pt counter electrode shows a conversion efficiency of 6.97% under the same experimental condition. These promising results highlight the potential application of nitrogen-doped graphene in cost-effective, transparent dye-sensitized solar cells.

Calibration of detector efficiency of neutron detector

International Nuclear Information System (INIS)

Guo Hongsheng; He Xijun; Xu Rongkun; Peng Taiping

2001-01-01

BF 3 neutron detector has been set up. Detector efficiency is calibrated by associated particle technique. It is about 3.17 x 10 -4 (1 +- 18%). Neutron yield of neutron generator per pulse (10 7 /pulse) is measured by using the detector

SiC-based neutron detector in quasi-realistic working conditions: efficiency and stability at room and high temperature under fast neutron irradiations

Energy Technology Data Exchange (ETDEWEB)

Ferone, Raffaello; Issa, Fatima; Ottaviani, Laurent; Biondo, Stephane; Vervisch, Vanessa [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231,13397 Marseille Cedex 20, (France); Szalkai, Dora; Klix, Axel [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology Karlsruhe 76344, (Germany); Vermeeren, Ludo [SCK-CEN, Boeretang 200, B-2400 Mol, (Belgium); Saenger, Richard [Schlumberger, Clamart, (France); Lyoussi, Abadallah [CEA, DEN, Departement d' Etudes des Reacteurs, Service de Physique Experimentale, Laboratoire Dosimetrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance, (France)

2015-07-01

In the framework of the European I SMART project, we have designed and made new SiC-based nuclear radiation detectors able to operate in harsh environments and to detect both fast and thermal neutrons. In this paper, we report experimental results of fast neutron irradiation campaign at high temperature (106 deg. C) in quasi-realistic working conditions. Our device does not suffer from high temperature, and spectra do show strong stability, preserving features. These experiments, as well as others in progress, show the I SMART SiC-based device skills to operate in harsh environments, whereas other materials would strongly suffer from degradation. Work is still demanded to test our device at higher temperatures and to enhance efficiency in order to make our device fully exploitable from an industrial point of view. (authors)

Tritium and neutron measurements from deuterated Pd-Si

International Nuclear Information System (INIS)

Claytor, T.N.; Tuggle, D.G.; Menlove, H.O.; Seeger, P.A.; Doty, W.R.; Rohwer, R.K.

1990-01-01

Evidence has been found for tritium and neutron production in palladium and silicon stacks when pulsed with a high electric current. These palladium-silicon stacks consist of alternating layers of pressed palladium and silicon powder. A pulsed high electric current is thought to promote non equilibrium conditions important for tritium and neutron production. More than 2000 hours of neutron counting time has been accumulated in a underground, low background, environment with high efficiency counters (21%). Neutron emission has occurred as infrequent burst or as low level emission lasting for up to 20 hours. In eight of 30 cells, excess tritium greater than 3 sigma has been observed. In each of these measurements, with the powder system, the ratio of tritium detected to total integrated total neutrons inferred has been anomalously high. Recent cells have shown reproducible tritium generation at a level of about 0.5 nCi/hr. Several hydrogen and air control cells have been run with no anomalous excess tritium or neutron emission above background. A significant amount of the total palladium inventory (18%) has been checked for tritium contamination by three independent means. 12 refs., 6 figs., 2 tabs

Low level neutron monitoring using high pressure 3He detectors

International Nuclear Information System (INIS)

Pszona, S.

1995-01-01

Three detectors, two spherical proportional counters and an ionisation chamber, all filled with 3 He to pressures of 160 kPa, 325 kPa and 1 MPa respectively have been experimentally studied with respect to their use for low level neutron monitoring. The ambient dose equivalent responses and the energy resolutions of these detectors have been determined. It is shown that spectral analysis of the signals from these detectors not only gives high sensitivity with regard to ambient dose equivalent but also improves the quality of the measurements. A special instrumentation for low level neutron monitoring is described in which a quality control method has been implemented. (Author)

Thickness optimization of various moderator materials for maximization of thermal neutron fluence

International Nuclear Information System (INIS)

Dhang, Prosenjit; Verma, Rishi; Shyam, Anurag

2015-01-01

Plasma focus device is widely being used as pulsed neutron source for variety of applications. Measurements of neutron yield by largely preferred Helium-3 proportional counter and Silver activation counter are mainly sensitive to thermal neutrons and are typically used with a neutron moderator. Thermalization of neutron is based on scattering reaction and hydrogenous materials are the best thermalizing medium. The efficiency of aforementioned neutron detectors is considerably affected by physical and geometrical properties of thermalizing medium i.e. moderator material, its thickness and shape. In view of the same, simulations have been performed to explore the effective utilization of Polyethylene, Perspex and Light water as moderating mediums for cylindrical and spherical geometry. In this study, estimated thermal fluence value up to 0.5 eV has been considered as the benchmark factor for comparing efficient thermalization by specific material, its thickness and shape. In either of the shapes being cylindrical or spherical, use of Polyethylene as moderating medium has resulted in minimum optimum thickness along with highest thermal fluence. (author)

Binder-Free Graphene Organogels as Cost-Efficient Counter Electrodes for Dye-sensitized Solar Cells

International Nuclear Information System (INIS)

Pan, Dengyu; Feng, Chuanqi; Wang, Liang; Liu, Yuan; Chen, Zhiwen; Shi, Wenyan; Li, Zhen

2016-01-01

Graphene organogels (GOGs) filled with organic electrolytes may function as high-activity, low-cost electrodes for energy conversion and storage devices such as Li ion batteries, supercapacitors, and dye-sensitized solar cells (DSSCs), because of their ideal electron-transport and ion-diffusion pathways through an interconnected 3D porous framework self-assembled from highly conductive and high-specific-area graphene sheets. Here, graphene hydrogels prepared by a modified hydrothermal method are converted into organogels with a specific surface area up to ∼1298 m 2 g −1 by a simple solvent-exchange approach, and pressed onto titanium meshes to form GOG films as economical, wearable counter electrodes for DSSCs. Without optimizing TiO 2 photoanodes, GOG-based DSSCs show a markedly enhanced short-circuit current density (16.34 mA cm −2 ) and thus an impressive power conversion efficiency of 7.2%, higher than those using graphene aerogels (11.6 mA cm −2 , 5.9%) and commercial Pt films (10.2 mA cm −2 , 5.9%) as counter electrodes under otherwise identical conditions. The improved efficiency is ascribed to a substantial reduction in charge-transfer resistance and series resistance, which is correlated with the high conductivity and high specific area of GOGs.

An efficient anticoincidence counter

CERN Multimedia

1977-01-01

This scintillation counter (about 25 cm diameter) was prepared at CERN for an experiment at the Saclay 600 MeV electron linac studying molecular processes originated in liquid hydrogen by muons. The counter is meant to surround the target and detect charged particles emerging from the hydrogen. The experiment was a CERN-Saclay collaboration which used the linac so as to take advantage of the time structure of the electron beam(see CERN Courier Sep 1977 and J. Bardin et al. Phys. Lett. B104 (1981) 320)

Microdosimetry of intermediate energy neutrons in fast neutron fields

International Nuclear Information System (INIS)

Saion, E.B.; Watt, D.E.

1988-01-01

A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

Simulation of neutron fluxes around the W7-X Stellarator

International Nuclear Information System (INIS)

Andersson, Jenny

1999-12-01

A new fusion experiment, the WENDELSTEIN 7-X Stellarator (W7-X), will be undertaken in Greifswald in Germany. Measurements of the neutron flux will provide information on fusion reaction rates and possibly also on ion temperatures as function of time. For this purpose moderating neutron counters will be designed, tested, calibrated and eventually used at W7-X. Extensive Monte-Carlo simulations have been performed in order to select the most suitable detector and moderator combination with a flat response function and highest achievable efficiency. Different detector configurations with different moderating materials have been tried out, showing that a 32 cm thick graphite moderating BF 3 -counter gives the desired flat response and sufficient efficiency. Neutron spectra calculations have been made for different torus models and the influence of floor, walls and ceiling (i.e. reactor hall) have been investigated. Presented results suggest that a more detailed torus model significantly reduces the number of neutron counts at the detector. Calculations including the reactor hall indicate a tendency of shifting the neutron spectra towards the thermal region. The main part of the scattered neutrons are back-scattered from the floor. Finally, calculations on the graphite moderating BF 3 -counter in the detailed torus environment were performed in order to assess the absolute response function under the influence of the reactor hall. The results show that the detector count rate will increase by only 5-7 % when the reactor hall is taken into account. With a stellarator generating 10 12 to 10 16 neutrons per second the detector count rate will be 2x10 5 to 2x10 9 neutrons per second

Simulation of neutron fluxes around the W7-X Stellarator

Energy Technology Data Exchange (ETDEWEB)

Andersson, Jenny

1999-12-01

A new fusion experiment, the WENDELSTEIN 7-X Stellarator (W7-X), will be undertaken in Greifswald in Germany. Measurements of the neutron flux will provide information on fusion reaction rates and possibly also on ion temperatures as function of time. For this purpose moderating neutron counters will be designed, tested, calibrated and eventually used at W7-X. Extensive Monte-Carlo simulations have been performed in order to select the most suitable detector and moderator combination with a flat response function and highest achievable efficiency. Different detector configurations with different moderating materials have been tried out, showing that a 32 cm thick graphite moderating BF{sub 3} -counter gives the desired flat response and sufficient efficiency. Neutron spectra calculations have been made for different torus models and the influence of floor, walls and ceiling (i.e. reactor hall) have been investigated. Presented results suggest that a more detailed torus model significantly reduces the number of neutron counts at the detector. Calculations including the reactor hall indicate a tendency of shifting the neutron spectra towards the thermal region. The main part of the scattered neutrons are back-scattered from the floor. Finally, calculations on the graphite moderating BF{sub 3} -counter in the detailed torus environment were performed in order to assess the absolute response function under the influence of the reactor hall. The results show that the detector count rate will increase by only 5-7 % when the reactor hall is taken into account. With a stellarator generating 10{sup 12} to 10{sup 16} neutrons per second the detector count rate will be 2x10{sup 5} to 2x10{sup 9} neutrons per second.

High energy resolution characteristics on 14MeV neutron spectrometer for fusion experimental reactor

Energy Technology Data Exchange (ETDEWEB)

Iguchi, Tetsuo [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.; Takada, Eiji; Nakazawa, Masaharu

1996-10-01

A 14MeV neutron spectrometer suitable for an ITER-like fusion experimental reactor is now under development on the basis of a recoil proton counter telescope principle in oblique scattering geometry. To verify its high energy resolution characteristics, preliminary experiments are made for a prototypical detector system. The comparison results show reasonably good agreement and demonstrate the possibility of energy resolution of 2.5% in full width at half maximum for 14MeV neutron spectrometry. (author)

Final results for the neutron detector efficiencies

International Nuclear Information System (INIS)

Zhou Zuying; Tang Hongqing; Qi Bujia; Du Yanfeng; Zhou Chenwei; Xia Haihong; Chen Zemin; Chen Zhenpeng; Chen Yingtang

1998-01-01

Final results for neutron detector efficiencies of a liquid organic scintillator are presented. The comparisons of efficiency results to calculations with discrimination against γ-rays and without n-γ discrimination are shown out and discussed. The measured relative neutron detection efficiency of a liquid organic scintillator with the PSD constraint active is in good agreement with SCINFUL calculations from 9 to 40 Mev and NEFF7 calculations from 9 to 20 Mev, the upper limit of the latter code

Neutron activation probe for measuring the presence of uranium in ore bodies

International Nuclear Information System (INIS)

Goldstein, N.P.; Smith, R.C.

1979-01-01

A neutron activation proble comprises a pulsed neutron source in series with a plurality of delayed neutron detectors for measuring radioactivity in a well borehole together with a NaI (Tl) counter for measuring the high energy 2.62 MeV gamma line from thorium. The neutron source emits neutrons which produce fission in uranium and thorium in the ore body and the delayed neutron detectors measure the delayed neutrons produced from such fission while the NaI (Tl) counter measures the 2.62 MeV gamma line from the undisturbed thorium in the ore body. The signal from the NaI (Tl) counter is processed and subtracted from the signal from the delayed neutron detectors with the result being indicative of the amount of uranium present in the ore body

The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual

International Nuclear Information System (INIS)

Eccleston, G.W.; Menlove, H.O.; Abhold, M.; Baker, M.; Pecos, J.

1999-01-01

This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency 3 He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the 240 Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual

Feasibility studies of high-pressure 4π proportional counter for absolute activity measurement

International Nuclear Information System (INIS)

Hino, Y.; Kawada, Y.

1988-01-01

A high-pressure proportional counter system is constructed. The high pressure 4πβ counter system constructed is made of aluminum and is divided into two 2π counters. The gas pressure is controlled with a pressure regulator and very fine leak valves to keep the balance of a stable pressure and constant flow rate. Investigation of characteristics of th counter shows that there is an almost linear relation between voltage and pressure. The linearlity of gas gain of this counter to the electron energies is measured with different gas pressures. Quite good linear gas multiplication is obtained at 0.9 MPa. Another investigation is made of application of to activity measurement of 109 Cd. When the gas pressure is over 0.5 MPa, the proportion of collected conversion electrons to absolute activity comes to a constant value of 96 %. This is quite good agreement with the decay data of 96.4 % conversion electron emission rate. The study indicated many excellent features for activity measurement. Especially the efficiency variation technique is good for automatic data acquisition with a programmable high voltage supplier. Moreover, since it is possible to obtain absolute activity with only one sample, it will be quite useful for limited samples experiments. (N.K.)

Altitude variation of cosmic-ray neutrons

International Nuclear Information System (INIS)

Nakamura, T.; Uwamino, Y.; Ohkubo, T.; Hara, A.

1987-01-01

The altitude variation of the cosmic-ray neutron energy spectrum and the dose equivalent rate was measured at an average geomagnetic latitude of 24 degrees N by using the high-efficiency multi-sphere neutron spectrometer and neutron dose-equivalent counter developed by the authors. The data were obtained from a 2-h flight over Japan on 27 February 1985. The neutron energy spectra measured at sea level and at altitudes of 4880 m and at 11,280 m were compared with the calculated spectra of O'Brien and with other experimental spectra, and they are in moderately good agreement with them. The dose equivalent rate increases according to a quadratic curve up to about 6000 m and then increases linearly between 6000 m and 11,280 m. The dependence of dose equivalent rates at sea level and at an altitude of 12,500 m on geomagnetic latitude also is given by referring to other experimental results

Absolute calibration of the neutron yield measurement on JT-60 Upgrade

International Nuclear Information System (INIS)

Nishitani, Takeo; Takeuchi, Hiroshi; Barnes, C.W.

1991-10-01

Absolutely calibrated measurements of the neutron yield are important for the evaluation of the plasma performance such as the fusion gain Q in DD operating tokamaks. Total neutron yield is measured with 235 U and 238 U fission chambers and 3 He proportional counters in JT-60 Upgrade. The in situ calibration was performed by moving the 252 Cf neutron source toroidally through the JT-60 vacuum vessel. Detection efficiencies of three 235 U and two 3 He detectors were measured for 92 locations of the neutron point source in toroidal scans at two different major radii. The total detection efficiency for the torus neutron source was obtained by averaging the point efficiencies over the whole toroidal angle. The uncertainty of the resulting absolute plasma neutron source calibration is estimated to be ± 10%. (author)

MCNPX Simulation Study of STRAW Neutron Detectors - Summary Paper

International Nuclear Information System (INIS)

Mukhopadhyay, Sanjoy; Maurer, Richard; Mitchell, Stephen

2010-01-01

A novel prototype fission meter is being designed at National Security Technologies, LLC, using a thin uniform coating (only 1 micron thick) of 10 B as a neutron converter inside a large array of thin (4 mm diameter) copper tubes. The copper tubes are only 2 mils thick, and each holds the stretched anode wire under tension and high voltage. The tubes are filled with proportional counter gas (a mixture of 90%/10% of Ar/CO 2 ). The tubes operate in proportional counter mode and attract mobile charged particles (α's) created in the nuclear interaction 10 B(n, 4 He) 7 Li. However, a single tube has about 1/7th the sensitivity of a 3 He tube. Modeling is required to determine if enough such tubes could be placed in a neutron detection assembly of the current size to give comparable sensitivity to 3 He. Detectors lined with 10 B lie between 3 He and 10 BF 3 proportional counters and fission chambers in terms of neutron detection efficiency and gamma ray insensitivity. The mean free path of thermal neutrons in 10 B is about 18 (micro)m. It takes about 60 (micro)m of 10 B layer to completely stop thermal neutrons, but the energetic α-particles generated in the reaction have a range of only 3.3 (micro)m in 10 B environment - hence the thin layer of boron coating on the copper tube. The prototype design is shown in Figure 1. It consists of two panels of three staggered rows of 500-mm-long, 4-mm-diameter straws, with 20 in each row, embedded in 30-mm-thick high density polyethylene (HDPE). The project demonstrates a new application of thin neutron and gamma converter technique (1 micron thin 10 B coated copper tube). It exploits fast timing from multiple straw detectors to count multiplicity of both gamma and neutrons from fissioning materials. The objective is to find a near-term replacement of 3 He gas in neutron detection and measurement (with a very large neutron detection area). All the solid-state detectors developed thus far are small and inefficient. The thin size

Using Backscattering to Enhance Efficiency in Neutron Detectors

DEFF Research Database (Denmark)

Kittelmann, T.; Kanaki, K.; Klinkby, Esben Bryndt

2017-01-01

The principle of using strongly scattering materials to recover efficiency in detectors for neutron instruments, via backscattering of unconverted thermal neutrons, is discussed in general. The feasibility of the method is illustrated through Geant4-based simulations involving thermal neutrons im......, respectively, centimeters and tens of microseconds. Potential mitigation techniques to contain the impact on resolution are investigated and are found to alleviate the issues to some degree, at a cost of reduced gain in efficiency....

Field test and calibration of neutron coincidence counters for high-mass plutonium samples

International Nuclear Information System (INIS)

Menlove, H.O.; Dickinson, R.J.; Douglas, I.

1987-02-01

Five different neutron coincidence systems were evaluated and calibrated for high-mass PuO 2 samples. The samples were from 2 to 7.2 kg of PuO 2 in mass, with a large range of burnup. This report compares the equipment and the results, with an evaluation of deadtime and multiplication corrections

Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

CERN Document Server

Murazaki, M; Uno, Y

2003-01-01

We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of +-13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, alpha, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and sup 3 He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, ...

Little Boy neutron spectrum below 3 MeV

International Nuclear Information System (INIS)

Evans, A.E.; Bennett, E.F.; Yule, T.J.

1984-01-01

The leakage neutron spectrum from the Little Boy replica has been measured from 12 keV to 3 MeV using a high-resolution 3 He ionization chamber, and from 1 keV to 3 MeV using proton-recoil proportional counters. The 3 He-spectrometer measurements were made at distances of 0.75 and 2.0 m from the active center and at angles of 0 0 , 45 0 , and 90 0 with respect to the axis of the assembly. Proton-recoil measurments were made at 90 0 to the assembly axis at distances of 0.75 and 2.0 m, with a shielded measurement made at 2.0 m to estimate background due to scattering. The 3 He spectrometer was calibrated at Los Alamos using monoenergetic 7 Li(p,n) 7 Be neutrons to generate a family of response functions. The proton-recoil counters were calibrated at Argonne by studying the capture of thermal neutrons by nitrogen in the counters, by observation of the 24-keV neutron resonance in iron, and by relating to the known hydrogen content of the counters. The neutron spectrum from Little Boy was found to be highly structured, with peaks corresponding to minima in the iron total neutron cross section. In particular, influence of the 24-keV iron window was evident in both sets of spectra. The measurements provide information for dosimetry calculations and also a valuable intercomparison of neutron spectrometry using the two different detector types. Spectra measured with both detectors are in essential agreement. 8 references, 7 figures, 2 tables

Response of a carbon-walled proportional counter to 14 MeV neutrons

International Nuclear Information System (INIS)

Lewis, K.D.

1982-01-01

The response of a carbon-walled spherical proportional counter filled with a methane-based tissue-equivalent gas mixture at low pressure and irradiated with 14 MeV neutrons is first measured experimentally and is then calculated theoretically by using an analytical model. The model, called the CISS model, is derived from a consideration of four basic modes of interaction of charged particles generated in neutron-nucleus reactions with the spherical cavity of the detector. Since several quantities which have application in neutron dosimetry, radiation protection, and radiation biology make direct use of such spectra, it is desirable to have the ability to theoretically predict what is expected experimentally. Thus, a comparison between the two response curves is made. The discrepancy between them is investigated by considering several physical phenomena occurring within the detector wall which tend to distort the experimental response curve. In particular, the C(n,n',3α) reaction occurring in the detector wall gives rise to multiple events, originating from a single neutron interaction in the wall simultaneously strike the detector cavity, and are recorded as a single larger event in an experimental spectra. In the analytic model, the simultaneous entry of two charged particles into the cavity is scored as two separate smaller events, uncorrelated in their production. In this work, an effort is made to modify the analytic model prediction of the response curve by correcting for the multiple events which occur. Finally, the CISS model is used to compute mass stopping power corrections for this inhomogeneous detector

Neutron multiplicity measurements with ³He alternative: Straw neutron detectors

Energy Technology Data Exchange (ETDEWEB)

Mukhopadhyay, Sanjoy [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Wolff, Ronald [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Detwiler, Ryan [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Maurer, Richard [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Mitchell, Stephen [National Security Technologies, LLC, Las Vegas, NV (United States); Guss, Paul [Remote Sensing Lab. - Nellis, Las Vegas, NV (United States); Lacy, Jeffrey L. [Proportional Technologies, Inc., Houston, TX (United States); Sun, Liang [Proportional Technologies, Inc., Houston, TX (United States); Athanasiades, Athanasios [Proportional Technologies, Inc., Houston, TX (United States)

2015-01-27

Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as ‘‘ship effect ’’) and to the complicated nature of the neutron scattering in that environment. A prototype neutron detector was built using ¹⁰B as the converter in a special form factor called ‘‘straws’’ that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of ³He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used ¹⁰B (in the form of enriched boron carbide: ¹⁰B₄C) for neutron detection instead of ³He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and

Development and Characterization of a High Sensitivity Segmented Fast Neutron Spectrometer (FaNS-2).

Science.gov (United States)

Langford, T J; Beise, E J; Breuer, H; Heimbach, C R; Ji, G; Nico, J S

2016-01-01

We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and 3 He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a 3 He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated 252 Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.

Expected precision of neutron multiplicity measurements of waste drums

International Nuclear Information System (INIS)

Ensslin, N.; Krick, M.S.; Menlove, H.O.

1995-01-01

DOE facilities are beginning to apply passive neutron multiplicity counting techniques to the assay of plutonium scrap and residues. There is also considerable interest in applying this new measurement technique to 208-liter waste drums. The additional information available from multiplicity counting could flag the presence of shielding materials or improve assay accuracy by correcting for matrix effects such as (α,n) induced fission or detector efficiency variations. The potential for multiplicity analysis of waste drums, and the importance of better detector design, can be estimated by calculating the expected assay precision using a Figure of Merit code for assay variance. This paper reports results obtained as a function of waste drum content and detector characteristics. We find that multiplicity analysis of waste drums is feasible if a high-efficiency neutron counter is used. However, results are significantly poorer if the multiplicity analysis must be used to solve for detection efficiency

Measure of the efficiency of a long counter of Hanson's type and use of this counter for the survey of the slow neutrons coming from the reactor of Chatillon; Mesure de l'efficacite d'un long compteur du type Hanson et utilisation de ce compteur a l'etude des neutrons lents sortant de la pile de Chatillon

Energy Technology Data Exchange (ETDEWEB)

Barloutaud, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1953-07-01

A detection device of fast neutrons of efficiency almost independent of the energy of the neutrons has been achieved. It efficiency has been measured in absolute value for groups of neutrons of different energies. This device allowed to get some indications on the energy composition of the neutrons leaving from the reactor of Chatillon. (author) [French] Un dispositif de detection de neutrons rapides d'efficacite pratiquement independante de l'energie des neutrons a ete realise. Son efficacite a ete mesuree en valeur absolue pour des groupes de neutrons de diverses energies. Ce dispositif a permis obtenir quelques indications sur la composition energetique des neutrons sortant de la pile de Chatillon. (auteur)

Neutron detector for detecting rare events of spontaneous fission

International Nuclear Information System (INIS)

Ter-Akop'yan, G.M.; Popeko, A.G.; Sokol, E.A.; Chelnokov, L.P.; Smirnov, V.I.; Gorshkov, V.A.

1981-01-01

The neutron detector for registering rare events of spontaneous fission by detecting multiple neutron emission is described. The detector represents a block of plexiglas of 550 mm diameter and 700 mm height in the centre of which there is a through 160 mm diameter channel for the sample under investigation. The detector comprises 56 3 He filled counters (up to 7 atm pressure) with 1% CO 2 addition. The counters have a 500 mm length and a 32 mm diameter. The sampling of fission events is realized by an electron system which allows determining the number of detected neutrons, numbers of operated counters, signal amplitude and time for fission event detecting. A block diagram of a neutron detector electron system is presented and its operation principle is considered. For protection against cosmic radiation the detector is surronded by a system of plastic scintillators and placed behind the concrete shield of 6 m thickness. The results of measurements of background radiation are given. It has been found that the background radiation of single neutron constitutes about 150 counts per hour, the detecting efficiency of single neutron equals 0.483 +- 0.005, for a 10l detector sensitive volume. By means of the detector described the parameters of multiplicity distribution of prompt neutrons for 256 Fm spontaneous fission are measured. The average multiplicity equals 3.59+-0.06 the dispersion being 2.30+-0.65

Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

International Nuclear Information System (INIS)

Rossa, Riccardo; Borella, Alessandro; Labeau, Pierre-Etienne; Pauly, Nicolas; Meer, Klaas van der

2015-01-01

The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of 239 Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of 239 Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a 239 Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to 239 Pu, in comparison with a 235 U fission chamber, with a 3 He proportional counter, and with a 10 B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the 239 Pu and 235 U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the 3 He and 10 B proportional counters to increase the sensitivity to 239 Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies

Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

Energy Technology Data Exchange (ETDEWEB)

Rossa, Riccardo, E-mail: rrossa@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Borella, Alessandro, E-mail: aborella@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Labeau, Pierre-Etienne, E-mail: pelabeau@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Pauly, Nicolas, E-mail: nipauly@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Meer, Klaas van der, E-mail: kvdmeer@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium)

2015-08-11

The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of {sup 239}Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a {sup 239}Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to {sup 239}Pu, in comparison with a {sup 235}U fission chamber, with a {sup 3}He proportional counter, and with a {sup 10}B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the {sup 239}Pu and {sup 235}U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the {sup 3}He and {sup 10}B proportional counters to increase the sensitivity to {sup 239}Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies.

Transparent nickel selenide used as counter electrode in high efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Jia, Jinbiao; Wu, Jihuai, E-mail: jhwu@hqu.edu.cn; Tu, Yongguang; Huo, Jinghao; Zheng, Min; Lin, Jianming

2015-08-15

Highlights: • A transparent Ni{sub 0.85}Se is prepared by a facile solvothermal reaction. • Ni{sub 0.85}Se electrode has better electrocatalytic activity than Pt electrode. • DSSC with Ni{sub 0.85}Se electrode obtains efficiency of 8.88%, higher than DSSC with Pt. • DSSC with Ni{sub 0.85}Se/mirror electrode achieves an efficiency of 10.19%. - Abstract: A transparent nickel selenide (Ni{sub 0.85}Se) is prepared by a facile solvothermal reaction and used as an efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that the as-prepared Ni{sub 0.85}Se possesses porous structure. Cyclic voltammogram measurement indicates that Ni{sub 0.85}Se electrode has larger current density than Pt electrode. Electrochemical impedance spectroscopy shows that the Ni{sub 0.85}Se electrode has lower charge-transfer resistance than Pt electrode. Under simulated solar light irradiation with intensity of 100 mW cm{sup −2} (AM 1.5), the DSSC based on the Ni{sub 0.85}Se CE achieves a power conversion efficiency (PCE) of 8.88%, which is higher than the solar cell based on Pt CE (8.13%). Based on the transparency of Ni{sub 0.85}Se, the DSSC with Ni{sub 0.85}Se/mirror achieves a PCE of 10.19%.

Development of a Neutron Long Counter Detector for (α, n) Cross Section Measurements at Ohio University

Science.gov (United States)

Brandenburg, Kristyn; Meisel, Zach; Brune, Carl R.; Massey, Thomas; Soltesz, Doug; Subedi, Shiv

2017-01-01

The origin of the elements from roughly zinc-to-tin (30 determined. The neutron-rich neutrino driven wind of core collapse supernova (CCSN) is a proposed site for the nucleosynthesis of these elements. However, a significant source of uncertainty exists in elemental abundance yields from astrophysics model calculations due to the uncertainty for (α , n) reaction rates, as most of the relevant cross sections have yet to be measured. We are developing a neutron long counter tailored to measure neutrons for (α , n) reaction measurements performed at The Ohio University Edwards Accelerator Laboratory. The detector design will be optimized using the Monte-Carlo N-Particle transport code (MCNP6). Details of the optimization process, as well as the present status of the detector design will be provided. The plans for first (α , n) cross section measurements will also be briefly discussed. This work was supported in part by the US Department of Energy under Grant Number DE-FG02-88ER40387.

Universal Fast Breeder Reactor Subassembly Counter manual

International Nuclear Information System (INIS)

Menlove, H.O.; Eccleston, G.W.; Swansen, J.E.; Goris, P.; Abedin-Zadeh, R.; Ramalho, A.

1984-08-01

A neutron coincidence counter has been designed for the measurement of fast breeder reactor fuel assemblies. This assay system can accommodate the full range of geometries and masses found in fast breeder subassemblies under IAEA safeguards. The system's high-performance capability accommodates high plutonium loadings of up to 16 kg. This manual describes the system and its operation and gives performance and calibration parameters for typical applications

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-06-24

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.

Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system

Energy Technology Data Exchange (ETDEWEB)

Verma, Rishi, E-mail: rishiv9@gmail.com, E-mail: rishiv@barc.gov.in; Mishra, Ekansh; Dhang, Prosenjit; Sagar, Karuna; Meena, Manraj; Shyam, Anurag [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre Autonagar, Vishakapatnam 530012 (India)

2016-09-15

The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ∼10 kJ is segregated into four modules of ∼2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA–600 kA (corresponding to charging voltage range of 14 kV–18 kV) in a quarter time period of ∼2 μs. The neutron yield performance of this device has been optimized by discretely varying deuterium filling gas pressure in the range of 6 mbar–11 mbar at ∼17 kV/550 kA discharge. At ∼7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ∼4 × 10{sup 9} neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ∼2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.

Recent improvements to RC-line encoded position-sensitive proportional counters

International Nuclear Information System (INIS)

Borkowski, C.J.; Kopp, M.K.

1977-01-01

Continuing research on the principles of position encoding with RC lines has advanced the design of position-sensitive proportional counters (PSPCs) to meet the requirements for high count rates (>10 5 counts/sec) and good spatial resolution (>10 4 spatial elements) in small-angle scattering experiments with x rays and neutrons. Low-noise preamplifiers were developed with pole-zero cancellation in the feedback circuit and modular linear amplifiers with passive RCL shaping which, compared to previous designs, reduce output saturation at high count rates approx.20 times and shorten the position signal processing time to 2 ) for low-energy ( 800 x 800 mm 2 ) for the measurement of small-angle scattering with neutrons. The method of electronic thickness discrimination was applied to change the effective thickness of an area PSPC from 12 to 2 cm whenever the molybdenum target of an x-ray generator was changed to a copper target. This thickness adjustment increased the signal-to-background ratio by a factor of approx.6 for the 8-keV photons from the copper target, while maintaining a >90% detection efficiency

Use of neutron-capture plastic fibers for nondestructive assay

International Nuclear Information System (INIS)

Heger, A.S.; Grazioso, R.F.; Mayo, D.R.; Ensslin, N.; Miller, M.C.; Huang, H.Y.; Russo, P.A.

1998-01-01

Neutron-capture plastic fibers can be used as a nondestructive assay tool. The detectors consist of an active region assembled from ribbons of boron-( 10 B) loaded optical fibers. The mixture of the moderator and thermal neutron absorber in the fiber yields a detector with high efficiency (var-epsilon) and a short die-away time (τ). The deposited energy of the resultant charged particles is converted to light that is collected by photomultiplier tubes mounted at both ends of the fiber. Thermal neutron coincidence counters (TNCC) made of these fibers can serve to verify fissile materials generated from the nuclear fuel cycle. This type of detector may extend the range of materials now accessible to assay by 3 He detectors. Experiments with single fibers of diameters 0.25, 0.50, and 1.00 mm test their ability to distinguish between the signals generated from neutron interactions and those from gamma rays. These results are compared with those obtained from simulation analyses for the same purpose. Light output and attenuation, neutron detection efficiency, and the signal-to-noise ratios of these fibers have also been investigated. The experimental results for light attenuation and neutron detection efficiency are consistent with the values obtained from simulation studies. A comparison of the performance of various configurations of the plastic scintillating fibers with that of other neutron-capture devices such as 3 He detectors is also discussed

An accurate and portable solid state neutron rem meter

Energy Technology Data Exchange (ETDEWEB)

Oakes, T.M. [Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO (United States); Bellinger, S.L. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS (United States); Miller, W.H. [Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO (United States); Missouri University Research Reactor, Columbia, MO (United States); Myers, E.R. [Department of Physics, University of Missouri, Kansas City, MO (United States); Fronk, R.G.; Cooper, B.W [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS (United States); Sobering, T.J. [Electronics Design Laboratory, Kansas State University, KS (United States); Scott, P.R. [Department of Physics, University of Missouri, Kansas City, MO (United States); Ugorowski, P.; McGregor, D.S; Shultis, J.K. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS (United States); Caruso, A.N., E-mail: carusoan@umkc.edu [Department of Physics, University of Missouri, Kansas City, MO (United States)

2013-08-11

Accurately resolving the ambient neutron dose equivalent spanning the thermal to 15 MeV energy range with a single configuration and lightweight instrument is desirable. This paper presents the design of a portable, high intrinsic efficiency, and accurate neutron rem meter whose energy-dependent response is electronically adjusted to a chosen neutron dose equivalent standard. The instrument may be classified as a moderating type neutron spectrometer, based on an adaptation to the classical Bonner sphere and position sensitive long counter, which, simultaneously counts thermalized neutrons by high thermal efficiency solid state neutron detectors. The use of multiple detectors and moderator arranged along an axis of symmetry (e.g., long axis of a cylinder) with known neutron-slowing properties allows for the construction of a linear combination of responses that approximate the ambient neutron dose equivalent. Variations on the detector configuration are investigated via Monte Carlo N-Particle simulations to minimize the total instrument mass while maintaining acceptable response accuracy—a dose error less than 15% for bare {sup 252}Cf, bare AmBe, an epi-thermal and mixed monoenergetic sources is found at less than 4.5 kg moderator mass in all studied cases. A comparison of the energy dependent dose equivalent response and resultant energy dependent dose equivalent error of the present dosimeter to commercially-available portable rem meters and the prior art are presented. Finally, the present design is assessed by comparison of the simulated output resulting from applications of several known neutron sources and dose rates.

Tests of BF3 counters with getter

International Nuclear Information System (INIS)

Comte, R.; Dauphin, G.

1968-01-01

BF 3 counters with addition of a getter have been developed to improve operation characteristics of these detectors in presence of strong gamma flows. The getter is made of an active coal deposit on the cathode. As noticed by other studies, the degradation of these counters is related to the exposure to strong neutron flows and to gamma radiations. The authors report tests performed on these counters with a brief presentation of the counters, and a presentation of the test installation. A threshold curve and an amplitude spectrum are obtained, and counting is performed for a fixed threshold before and after the exposure of detectors to variable doses of γ radiation. The results after a first 2 hour long irradiation, a 230 hour long second irradiation, and a third irradiation under high voltage (2100 V) are discussed. Thermal tests are then performed and commented

Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

Energy Technology Data Exchange (ETDEWEB)

Murazaki, Minoru; Uno, Yuichi; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of {+-}13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, {alpha}, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and {sup 3}He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, calculated value agreed well with measurement data of PSPC without Cd cover. (author)

A Direction Sensitive Fast Neutron Monitor

Energy Technology Data Exchange (ETDEWEB)

Antolkovic, B; Holmqvist, B; Wiedling, T

1964-06-15

A direction sensitive fast neutron monitor is described and its properties are discussed in some detail. The counter is a modification of the standard long counter of the Hanson and McKibben type. Directional sensitivity is obtained by increasing the shielding of the counter and providing it with a 70 cm long collimator channel. The behaviour of this long counter monitor is compared with that of a standard long counter when both are used in neutron experiments.

Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum.

Science.gov (United States)

Chen, Tao; Liu, Yongling; Zou, Denglang; Chen, Chen; You, Jinmao; Zhou, Guoying; Sun, Jing; Li, Yulin

2014-01-01

This study presents an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid-liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe-emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high-speed counter-current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe-emodin, physcione, and chrysophanol. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive and transportable gadolinium-core plastic scintillator sphere for neutron detection and counting

Energy Technology Data Exchange (ETDEWEB)

Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Méchin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 14050 Caen (France); Hamel, Matthieu [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France)

2016-08-21

Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.

Sensitive and transportable gadolinium-core plastic scintillator sphere for neutron detection and counting

International Nuclear Information System (INIS)

Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane; Méchin, Laurence; Hamel, Matthieu

2016-01-01

Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.

A novel high-performance counter electrode for dye-sensitized solar cells

International Nuclear Information System (INIS)

Wang Guiqiang; Lin Ruifeng; Lin Yuan; Li Xueping; Zhou Xiaowen; Xiao Xurui

2005-01-01

A novel Pt counter electrode for dye-sensitized solar cells (DSC) was prepared by thermal decomposition of H 2 PtCl 6 on NiP-plated glass substrate. The charge-transfer kinetic properties of the platinized NiP-plated glass electrode (Pt/NiP electrode) for triiodide reduction were studied by electrochemical impedance spectroscopy. Pt/NiP electrode has the advantage over the platinized FTO conducting glass electrode (Pt/FTO electrode) in increasing the light reflectance and reducing the sheet resistance leading to improve the light harvest efficiency and the fill factor of the dye-sensitized solar cells effectively. The photon-to-current efficiency and the overall conversion efficiency of DSC using Pt/NiP counter electrode is increased by 20% and 33%, respectively, compared to that of using Pt/FTO counter electrode. Examination of the anodic dissolution and the long-term test on the variation of charge-transfer resistance indicates the good stability of the Pt/NiP electrode in the electrolyte containing iodide/triiodide

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

International Nuclear Information System (INIS)

Miller, M.C.

1998-03-01

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

Vertically aligned single-walled carbon nanotubes as low-cost and high electrocatalytic counter electrode for dye-sensitized solar cells.

Science.gov (United States)

Dong, Pei; Pint, Cary L; Hainey, Mel; Mirri, Francesca; Zhan, Yongjie; Zhang, Jing; Pasquali, Matteo; Hauge, Robert H; Verduzco, Rafael; Jiang, Mian; Lin, Hong; Lou, Jun

2011-08-01

A novel dye-sensitized solar cell (DSSC) structure using vertically aligned single-walled carbon nanotubes (VASWCNTs) as the counter electrode has been developed. In this design, the VASWCNTs serve as a stable high surface area and highly active electrocatalytic counter-electrode that could be a promising alternative to the conventional Pt analogue. Utilizing a scalable dry transfer approach to form a VASWCNTs conductive electrode, the DSSCs with various lengths of VASWCNTs were studied. VASWCNTs-DSSC with 34 μm original length was found to be the optimal choice in the present study. The highest conversion efficiencies of VASWCNTs-DSSC achieved 5.5%, which rivals that of the reference Pt DSSC. From the electrochemical impedance spectroscopy analysis, it shows that the new DSSC offers lower interface resistance between the electrolyte and the counter electrode. This reproducible work emphasizes the promise of VASWCNTs as efficient and stable counter electrode materials in DSSC device design, especially taking into account the low-cost merit of this promising material.

Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device.

Science.gov (United States)

Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A; Garty, Guy; Harken, Andrew; Brenner, David J

2015-09-11

A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n) 3 He and D(d,n) 3 He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9 Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

Evaluation of waste crate counter

International Nuclear Information System (INIS)

Wachter, J.R.; Shaw, S.W.

1994-01-01

A novel nondestructive measurement system has been developed to perform combined gamma-ray, passive neutron, and active neutron analyses of radioactive waste packaged in large crates. The system will be used to examine low level and transuranic waste at the Waste Receiving and Processing facility at Westinghouse-Hanford Corp. Prior to delivery of the system, an extensive evaluation of its performance characteristics will be conducted. The evaluation is to include an assessment of the mechanical properties of the system, gamma-ray attenuation correction algorithms, instrument response as a function of source positions, performance of the high resolution gamma-ray detector for ''hot spot'' and isotopic analyses, active and passive neutron counter response, instrument sensitivity, matrix effects, and packaging effects. This report will discuss the findings of the evaluation program, to date, and indicate future directions for the program

Optimization of a neutron ambient dose equivalent rate meter

International Nuclear Information System (INIS)

Burgkhardt, B.; Fieg, G.; Piesch, E.; Klett, A.; Maushart, R.

1994-01-01

Co-operating in a technology transfer project, the Karlsruhe Nuclear Research Center and EG and G Berthold have developed a neutron equivalent doserate probe with high sensitivity and an energy dependent detection efficiency in accordance with the ICRP60 requirements. The special features of this probe were realized, on the one hand, by optimizing the moderator and absorber geometry through simulation calculations with the neutron transport code MCNP, and, on the other hand, by using a newly designed 3 He-methane proportional counter tube. The measurements were not yet completed when this paper went to press, however, it is to be expected that the response sensitivity will be more than 3 counts/nSv. (orig.) [de

Universal Fast Breeder Reactor Subassembly Counter manual

Energy Technology Data Exchange (ETDEWEB)

Menlove, H.O.; Eccleston, G.W.; Swansen, J.E.; Goris, P.; Abedin-Zadeh, R.; Ramalho, A.

1984-08-01

A neutron coincidence counter has been designed for the measurement of fast breeder reactor fuel assemblies. This assay system can accommodate the full range of geometries and masses found in fast breeder subassemblies under IAEA safeguards. The system's high-performance capability accommodates high plutonium loadings of up to 16 kg. This manual describes the system and its operation and gives performance and calibration parameters for typical applications.

Multiple channel programmable coincidence counter

Science.gov (United States)

Arnone, Gaetano J.

1990-01-01

A programmable digital coincidence counter having multiple channels and featuring minimal dead time. Neutron detectors supply electrical pulses to a synchronizing circuit which in turn inputs derandomized pulses to an adding circuit. A random access memory circuit connected as a programmable length shift register receives and shifts the sum of the pulses, and outputs to a serializer. A counter is input by the adding circuit and downcounted by the seralizer, one pulse at a time. The decoded contents of the counter after each decrement is output to scalers.

Consumer Preferences for High Welfare Meat in Germany: Self-service Counter or Service Counter?

Directory of Open Access Journals (Sweden)

Ramona Weinrich

2015-01-01

Full Text Available Many people view animal welfare standards in the agricultural industry as critical and some consumers would prefer to buy high welfare meat. In order to successfully introduce high welfare meat products onto the market, some important marketing decisions must be made. Due to limited shelf space in retail outlets, niche products like high welfare meat cannot be placed both at the self-service counter and at the service counter. In order to analyze where to place it best an online survey of 642 German consumers was conducted. By means of factor and cluster analyses, consumers’ animal welfare attitudes and their preference for a point of purchase were combined. The different target groups were joint using cross tabulation analysis. The results reveal that consumers in the target group show a more positive attitude to the service counter.

Experimental Assessment of a New Passive Neutron Multiplication Counter for Partial Defect Verification of LWR Fuel Assemblies

International Nuclear Information System (INIS)

LaFleur, A.; Menlove, H.; Park, S.-H.; Lee, S. K.; Oh, J.-M.; Kim, H.-D.

2015-01-01

The development of non-destructive assay (NDA) capabilities to improve partial defect verification of spent fuel assemblies is needed to improve the timely detection of the diversion of significant quantities of fissile material. This NDA capability is important to the implementation of integrated safeguards for spent fuel verification by the International Atomic Energy Agency (IAEA) and would improve deterrence of possible diversions by increasing the risk of early detection. A new NDA technique called Passive Neutron Multiplication Counter (PNMC) is currently being developed at Los Alamos National Laboratory (LANL) to improve safeguards measurements of LightWater Reactor (LWR) fuel assemblies. The PNMC uses the ratio of the fast-neutron emission rate to the thermalneutron emission rate to quantify the neutron multiplication of the item. The fast neutrons versus thermal neutrons are measured using fission chambers (FC) that have differential shielding to isolate fast and thermal energies. The fast-neutron emission rate is directly proportional to the neutron multiplication in the spent fuel assembly; whereas, the thermalneutron leakage is suppressed by the fissile material absorption in the assembly. These FCs are already implemented in the basic Self-Interrogation Neutron Resonance Densitometry (SINRD) detector package. Experimental measurements of fresh and spent PWR fuel assemblies were performed at LANL and the Korea Atomic Energy Research Institute (KAERI), respectively, using a hybrid PNMC and SINRD detector. The results from these measurements provides valuable experimental data that directly supports safeguards research and development (R&D) efforts on the viability of passive neutron NDA techniques and detector designs for partial defect verification of spent fuel assemblies. (author)

Response function measurement of plastic scintillator for high energy neutrons

International Nuclear Information System (INIS)

Sanami, Toshiya; Ban, Syuichi; Takahashi, Kazutoshi; Takada, Masashi

2003-01-01

The response function and detection efficiency of 2''φ x 2''L plastic (PilotU) and NE213 liquid (2''NE213) scintillators, which were used for the measurement of secondary neutrons from high energy electron induced reactions, were measured at Heavy Ion Medical Accelerator in Chiba (HIMAC). High energy neutrons were produced via 400 MeV/n C beam bombardment on a thick graphite target. The detectors were placed at 15 deg with respect to C beam axis, 5 m away from the target. As standard, a 5''φ x 5''L NE213 liquid scintillator (5''NE213) was also placed at same position. Neutron energy was determined by the time-of-flight method with the beam pickup scintillator in front of the target. In front of the detectors, veto scintillators were placed to remove charged particle events. All detector signals were corrected with list mode event by event. We deduce neutron spectrum for each detectors. The efficiency curves for pilotU and 2''NE213 were determined on the bases of 5 N E213 neutron spectrum and its efficiency calculated by CECIL code. (author)

A 4π scintillation counter-optical spark chamber system for neutral particles

International Nuclear Information System (INIS)

Demarzo, C.; Distante, A.; Guerriero, L.; Niccolini, C.; Posa, F.; Walder, F.; Chen, G.T.Y.; Fletcher, C.R.; Lanou, R.E. Jr.; Thornton, R.K.; Barton, D.S.; Lyons, T.; Marx, M.; Rosenson, L.; Thern, R.

1975-01-01

The authors describe a scintillation counter-optical spark chamber system developed for the detection of high energy gamma rays and neutrons. They describe the system components and their use in two completed experiments. (Auth.)

Fusion neutron generation by high-repetitive target injection

International Nuclear Information System (INIS)

Kitagawa, Yoneyoshi

2015-01-01

Pellet injection and repetitive laser illumination are key technologies for realizing inertial fusion energy. The Graduate School for the Creation of New Photonics Industries, Hamamatsu Photonics K. K. and Toyota Motor Corporation demonstrate the pellet injection, counter laser beams' engagement and neutron generation. Deuterated polystyrene (CD) bead pellets, after free-falling for a distance of 18 cm at 1 Hz, are successfully engaged by two counter laser beams from a diode-pumped, ultra-intense laser HAMA. The laser energy, pulse duration, wavelength and the intensity are 0.63 J per beam, 104 fs, 811 nm and 4.7 x 10 18 W/cm 2 , respectively. The irradiated pellets produce D (D, n) 3 He-reacted neutrons with a maximum yield of 9.5 x 10 4 /4π sr/shot. A straight channel with 10 μm-diameter is found through the beads. The pellet size is 1 mm. The results indicate potentially useful technologies for the next step in realizing inertial fusion energy. The results are reviewed as well as some oversea activities. (author)

High energy neutron radiography

International Nuclear Information System (INIS)

Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

1996-01-01

High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos

Passive neutron interrogation in systems with a poorly characterized detection efficiency

International Nuclear Information System (INIS)

Dubi, Chen; Oster, Elad; Ocherashvilli, Aharon; Pedersen, Bent; Hutszy, Janus

2014-01-01

Passive neutron interrogation for fissile mass estimation, relying on neutrons coming from spontaneous fission events, is considered a standard NDT procedure in the nuclear safeguard and safety community. Since most structure materials are (relatively) transparent to neutron radiation, passive neutron interrogation is considered highly effective in the analysis of dirty, poorly characterized samples. On the other hand, since a typical passive interrogation assembly is based on 3He detectors, neutrons from additional neutron sources (mainly (α,n) reactions and induced fissions in the tested sample) cannot be separated from the main spontaneous fission source through energetic spectral analysis. There for, applying the passive interrogation methods the implementation of Neutron Multiplicity Counting (NMC) methods for separation between the main fission source and the additional sources. Applying NMC methods requires a well characterized system, in the sense that both system die away time and detection efficiency must be well known (and in particular, independent of the tested sample)

Neutron microdosimetry at RARAF

International Nuclear Information System (INIS)

Kliauga, P.

1986-01-01

A comprehensive series of measurements of neutron microdosimetry spectra is underway at the RARAF facility. The neutrons generated at RARAF are semi-monoenergetic to monoenergetic, depending on energy. Thus far, measurements have concentrated on 15 MeV, with a few measurements done at 6 MeV. One of the main reasons for undertaking this project is dissatisfaction with the state of accuracy of microdosimetric measurements of neutrons, not only previous measurements done at RARAF, but reports in the literature from all over the world. Only a relatively modest amount of data has been taken for neutrons, as compared to photons, and the survey of dose mean lineal energy values done for the recent ICRU Report No. 36 (December 1983) reveals a spread of values far in excess of accepted estimates of statistical uncertainty (5-10%). One of the major motivations in undertaking this project, therefore, was to elucidate some of the factors, including experimental artifacts, which are important in contributing to systematic errors in measurements. Among the methods being employed are determination of the effect of various counter parameters on neutron spectra, and electronic parameters, also. Another important method of obtaining information is a comparison between different counters. This laboratory has access to perhaps a greater variety of microdosimetric proportional counters than any in the world, from the standard Rossi counter, to various wall-less types of differing geometries. Controlled comparisons of spectra from such differing counters using the same analysis technique can yield much information on the effect of counter geometry on the microdosimetric spectrum

High-pressure 3He gas scintillation neutron spectrometer

International Nuclear Information System (INIS)

Derzon, M.S.; Slaughter, D.R.; Prussin, S.G.

1985-10-01

A high-pressure, 3 He-Xe gas scintillation spectrometer has been developed for neutron spectroscopy on D-D fusion plasmas. The spectrometer exhibits an energy resolution of (121 +- 20 keV) keV (FWHM) at 2.5 MeV and an efficiency of (1.9 +- 0.4) x 10 -3 (n/cm 2 ) -1 . The contribution to the resolution (FWHM) from counting statistics is only (22 +- 3 keV) and the remainder is due predominantly to the variation of light collection efficiency with location of neutron events within the active volume of the detector

The design of the DUPIC spent fuel bundle counter

International Nuclear Information System (INIS)

Menlove, H.O.; Rinard, P.M.; Kroncke, K.E.; Lee, Y.G.

1997-05-01

A neutron coincidence detector had been designed to measure the amount of curium in the fuel bundles and associated process samples used in the direct use of plutonium in Canadian deuterium-uranium (CANDU) fuel cycle. All of the sample categories are highly radioactive from the fission products contained in the pressurized water reactor (PWR) spent fuel feed stock. Substantial shielding is required to protect the He-3 detectors from the intense gamma rays. The Monte Carlo neutron and photon calculational code has been used to design the counter with a uniform response profile along the length of the CANDU-type fuel bundle. Other samples, including cut PWR rods, process powder, waste, and finished rods, can be measured in the system. This report describes the performance characteristics of the counter and support electronics. 3 refs., 23 figs., 6 tabs

Determining {sup 252}Cf source strength by absolute passive neutron correlation counting

Energy Technology Data Exchange (ETDEWEB)

Croft, S. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6166 (United States); Henzlova, D., E-mail: henzlova@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-06-21

Physically small, lightly encapsulated, radionuclide sources containing {sup 252}Cf are widely used for a vast variety of industrial, medical, educational and research applications requiring a convenient source of neutrons. For many quantitative applications, such as detector efficiency calibrations, the absolute strength of the neutron emission is needed. In this work we show how, by using a neutron multiplicity counter the neutron emission rate can be obtained with high accuracy. This provides an independent and alternative way to create reference sources in-house for laboratories such as ours engaged in international safeguards metrology. The method makes use of the unique and well known properties of the {sup 252}Cf spontaneous fission system and applies advanced neutron correlation counting methods. We lay out the foundation of the method and demonstrate it experimentally. We show that accuracy comparable to the best methods currently used by national bodies to certify neutron source strengths is possible.

Note: Fast neutron efficiency in CR-39 nuclear track detectors

Energy Technology Data Exchange (ETDEWEB)

Cavallaro, S. [Dipartimento di Fisica ed Astronomia,Università di Catania, Via S. Sofia 44, 95123 Catania, Italy and INFN-LNS, Via S. Sofia 42, 95123 Catania (Italy)

2015-03-15

CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

Energy Technology Data Exchange (ETDEWEB)

Chen, Yu [Syracuse Univ., NY (United States)

2016-01-01

Direct dark matter detection experiments usually have excellent capability to distinguish nuclear recoils, expected interactions with Weakly Interacting Massive Particle (WIMP) dark matter, and electronic recoils, so that they can efficiently reject background events such as gamma-rays and charged particles. However, both WIMPs and neutrons can induce nuclear recoils. Neutrons are then the most crucial background for direct dark matter detection. It is important to understand and account for all sources of neutron backgrounds when claiming a discovery of dark matter detection or reporting limits on the WIMP-nucleon cross section. One type of neutron background that is not well understood is the cosmogenic neutrons from muons interacting with the underground cavern rock and materials surrounding a dark matter detector. The Neutron Multiplicity Meter (NMM) is a water Cherenkov detector capable of measuring the cosmogenic neutron flux at the Soudan Underground Laboratory, which has an overburden of 2090 meters water equivalent. The NMM consists of two 2.2-tonne gadolinium-doped water tanks situated atop a 20-tonne lead target. It detects a high-energy (>~ 50 MeV) neutron via moderation and capture of the multiple secondary neutrons released when the former interacts in the lead target. The multiplicity of secondary neutrons for the high-energy neutron provides a benchmark for comparison to the current Monte Carlo predictions. Combining with the Monte Carlo simulation, the muon-induced high-energy neutron flux above 50 MeV is measured to be (1.3 ± 0.2) ~ 10-9 cm-2s-1, in reasonable agreement with the model prediction. The measured multiplicity spectrum agrees well with that of Monte Carlo simulation for multiplicity below 10, but shows an excess of approximately a factor of three over Monte Carlo prediction for multiplicities ~ 10 - 20. In an effort to reduce neutron backgrounds for the dark matter experiment SuperCDMS SNO- LAB, an active neutron veto was developed

Photon and neutron dose discrimination using low pressure proportional counters with graphite and A150 walls

International Nuclear Information System (INIS)

Kylloenen, J.; Lindborg, L.

2005-01-01

Full text: The determination of both the low- and high-LET components of ambient dose equivalent in mixed fields is possible with microdosimetric methods. With the multiple-event microdosimetric variance covariance method the sum of those components are directly obtained also in pulsed beams. However, if the value of each dose component is needed a more extended analysis is required. The use of a graphite walled proportional detector in combination with a tissue-equivalent proportional counter in combination with the variance covariance method was here investigated. MCNP simulations were carried out for relevant energies to investigate the photon and neutron responses of the two detectors. The combined graphite and TEPC system, the Sievert instrument, was used for measurements at IRSN, Cadarache, in the workplace calibration fields of CANEL+, SIGMA, a Cf-252 and a moderated Cf(D 2 O,Cd) radiation field. The response of the instrument in various monoenergetic neutron fields is also known from measurements at PTB. The instrument took part in the measurement campaigns in workplace fields in the nuclear industry organized within the EVIDOS contract. The results are analyzed and the method of using a graphite detector compared with alternative methods of analysis is discussed. (author)

Efficiency calibration of a liquid scintillation counter for 90Y Cherenkov counting

International Nuclear Information System (INIS)

Vaca, F.; Garcia-Leon, M.

1998-01-01

In this paper a complete and self-consistent method for 90 Sr determination in environmental samples is presented. It is based on the Cherenkov counting of 90 Y with a conventional liquid scintillation counter. The effects of color quenching on the counting efficiency and background are carefully studied. A working curve is presented which allows to quantify the correction in the counting efficiency depending on the color quenching strength. (orig.)

Characteristics of the NE-213 large-volume neutron counters for muon catalyzed fusion investigation

International Nuclear Information System (INIS)

Bystritsky, V.M.; Wozniak, J.; Zinov, V.G.

1984-01-01

The Monte-Carlo method was used to establish the properties and feasibility of a large-volume NE-213 scin illator as an efficient neutron detector. The recoil proton spectra, calculated efficiencies for different detection thresholds and scintillator sizes are presented for the neutron energy up to 15 MeV. The time characteristics, e. g., time resolution, are discussed. It is also shown that no strong influence of light attenuation by the scintilla or itself on calculated efficiencies is observed, when gamma-calibration technique is used. The detector vol me of approximately 100 l is suggested for application in investigations of μ-atom and μ-molecular processes

Geometry-based multiplication correction for passive neutron coincidence assay of materials with variable and unknown (α,n) neutron rates

International Nuclear Information System (INIS)

Langner, D.G.; Russo, P.A.

1993-02-01

We have studied the problem of assaying impure plutonium-bearing materials using passive neutron coincidence counting. We have developed a technique to analyze neutron coincidence data from impure plutonium samples that uses the bulk geometry of the sample to correct for multiplication in samples for which the (α,n) neutron production rate is unknown. This technique can be applied to any impure plutonium-bearing material whose matrix constituents are approximately constant, whose self-multiplication is low to moderate, whose plutonium isotopic composition is known and not substantially varying, and whose bulk geometry is measurable or can be derived. This technique requires a set of reference materials that have well-characterized plutonium contents. These reference materials are measured once to derive a calibration that is specific to the neutron detector and the material. The technique has been applied to molten salt extraction residues, PuF 4 samples that have a variable salt matrix, and impure plutonium oxide samples. It is also applied to pure plutonium oxide samples for comparison. Assays accurate to 4% (1 σ) were obtained for impure samples measured in a High-Level Neutron Coincidence Counter II. The effects on the technique of variations in neutron detector efficiency with energy and the effects of neutron capture in the sample are discussed

A NRESPG Monte Carlo code for the calculation of neutron response functions for gas counters

Energy Technology Data Exchange (ETDEWEB)

Kudo, K; Takeda, N; Fukuda, A [Electrotechnical Lab., Tsukuba, Ibaraki (Japan); Torii, T; Hashimoto, M; Sugita, T; Yang, X; Dietze, G

1996-07-01

In this paper, we show the outline of the NRESPG and some typical results of the response functions and efficiencies of several kinds of gas counters. The cross section data for the several kinds of filled gases and the wall material of stainless steel or aluminum are taken mainly from ENDF/B-IV. The ENDF/B-V for stainless steel is also used to investigate the influence on pulse height spectra of gas counters due to the difference of nuclear data files. (J.P.N.)

High-efficiency organic glass scintillators

Science.gov (United States)

Feng, Patrick L.; Carlson, Joseph S.

2017-12-19

A new family of neutron/gamma discriminating scintillators is disclosed that comprises stable organic glasses that may be melt-cast into transparent monoliths. These materials have been shown to provide light yields greater than solution-grown trans-stilbene crystals and efficient PSD capabilities when combined with 0.01 to 0.05% by weight of the total composition of a wavelength-shifting fluorophore. Photoluminescence measurements reveal fluorescence quantum yields that are 2 to 5 times greater than conventional plastic or liquid scintillator matrices, which accounts for the superior light yield of these glasses. The unique combination of high scintillation light-yields, efficient neutron/gamma PSD, and straightforward scale-up via melt-casting distinguishes the developed organic glasses from existing scintillators.

Study on the transmission efficiency of curved neutron guide

International Nuclear Information System (INIS)

Wang Hongli; Zhang Li; Guo Liping; Yang Tonghua; Zhao Zhixiang

2004-01-01

Monte-Carlo simulation program NGT2002 is used to study the transmission efficiency of curved neutron guide from character wavelength, film reflectivity, film material, geometry adjustment error, gap between guides and guide fabricate error, the authors get the transmission efficiency curves of the Ni, supper mirror curved neutron guides, also we have a discuss of how to choose the curved neutron guide's character wavelength. By the simulation results, the authors determine the proper film reflectivity value, guide horizontal geometry adjustment error range, optimized gap value between guide elements and guide width fabricate geometry error range. (authors)

Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polypyrrole composite counter electrodes prepared by electrophoresis/electrochemical polymerization

International Nuclear Information System (INIS)

Luo, Jun; Niu, Hai-jun; Wen, Hai-lin; Wu, Wen-jun; Zhao, Ping; Wang, Cheng; Bai, Xu-duo; Wang, Wen

2013-01-01

Graphical abstract: The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. Highlights: ► MWCNT/PPy composite film prepared by electrodeposition layer by layer was used as counter electrode in DSSC. ► The overall energy conversion efficiency of the DSSC was 3.78% by employing the composite film. ► The energy conversion efficiency increased by 41.04% compared with efficiency of 2.68% by using the single MWCNT film. ► We analyzed the mechanism and influence factor of electron transfer in the composite electrode by EIS. - Abstract: For the purpose of replacing the precious Pt counter electrode in dye-sensitized solar cells (DSSCs) with higher energy conversion efficiency, multi-wall carbon nanotube (MWCNT)/polypyrrole (PPy) double layers film counter electrode (CE) was fabricated by electrophoresis and cyclic voltammetry (CV) layer by layer. Atom force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscope (TEM) demonstrated the morphologies of the composite electrode and Raman spectroscopy verified the PPy had come into being. The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. The result of impedance showed that the charge transfer resistance R ct of the MWCNT/PPy CE had the lowest value compared to that of MWCNT or PPy electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I 3 − reduction can potentially be used as the CE in a high-performance DSSC

Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polypyrrole composite counter electrodes prepared by electrophoresis/electrochemical polymerization

Energy Technology Data Exchange (ETDEWEB)

Luo, Jun; Niu, Hai-jun; Wen, Hai-lin [Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Department of Macromolecular Material and Engineering, Heilongjiang University, Harbin 150086 (China); Wu, Wen-jun; Zhao, Ping [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Wang, Cheng; Bai, Xu-duo [Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Department of Macromolecular Material and Engineering, Heilongjiang University, Harbin 150086 (China); Wang, Wen, E-mail: haijunniu@hotmail.com [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150080 (China)

2013-03-15

Graphical abstract: The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. Highlights: ► MWCNT/PPy composite film prepared by electrodeposition layer by layer was used as counter electrode in DSSC. ► The overall energy conversion efficiency of the DSSC was 3.78% by employing the composite film. ► The energy conversion efficiency increased by 41.04% compared with efficiency of 2.68% by using the single MWCNT film. ► We analyzed the mechanism and influence factor of electron transfer in the composite electrode by EIS. - Abstract: For the purpose of replacing the precious Pt counter electrode in dye-sensitized solar cells (DSSCs) with higher energy conversion efficiency, multi-wall carbon nanotube (MWCNT)/polypyrrole (PPy) double layers film counter electrode (CE) was fabricated by electrophoresis and cyclic voltammetry (CV) layer by layer. Atom force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscope (TEM) demonstrated the morphologies of the composite electrode and Raman spectroscopy verified the PPy had come into being. The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. The result of impedance showed that the charge transfer resistance R{sub ct} of the MWCNT/PPy CE had the lowest value compared to that of MWCNT or PPy electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I{sub 3}{sup −} reduction can potentially be used as the CE in a high-performance DSSC.

Evaluation of response function of moderating-type neutron detector and application to environmental neutron measurement

International Nuclear Information System (INIS)

Kosako, Toshiso; Nakamura, Takashi; Iwai, Satoshi; Katsuki, Shinji; Kamata, Masashi.

1983-08-01

The energy-dependent response function of a multi-cylinder moderating-type BF 3 counter, so-called Bonner counter, was calculated by the time-dependent multi-group Monte Carlo code, TMMCR. The calculated response function was evaluated experimentally for neutron energy below about 50 keV down to epithermal energy by the time-of-flight method combining with a large lead pile at the Nuclear Engineering Research Laboratory, University of Tokyo and also above 50 keV by using the monoenergetic neutron standard field a t the Electrotechnical Laboratory. The time delay in the polyethylene moderator of the Bonner counter due to multiple collisions with hydrogen was analyzed by the TMMCR code and used for the time-spectrum analysis of the time-of-flight measurement. The response function obtained by these two experiments showed good agreement with the calculated results. This Bonner counter having a response function evaluated from thermal to MeV energy range was used for spectrometry and dosimetry of environmental neutrons around some nuclear facilities. The neutron spectra and dose measured in the environment around a 252 Cf fission source, fast neutron source reactor and electron synchrotron were all in good agreement with the calculated results and the measured results with other neutron detectors. (author)

High-altitude cosmic ray neutrons: probable source for the high-energy protons of the earth's radiation belts

International Nuclear Information System (INIS)

Hajnal, F.; Wilson, J.

1992-01-01

'Full Text:' Several High-altitude cosmic-ray neutron measurements were performed by the NASA Ames Laboratory in the mid-to late-1970s using airplanes flying at about 13km altitude along constant geomagnetic latitudes of 20, 44 and 51 degrees north. Bonner spheres and manganese, gold and aluminium foils were used in the measurements. In addition, large moderated BF-3 counters served as normalizing instruments. Data analyses performed at that time did not provide complete and unambiguous spectral information and field intensities. Recently, using our new unfolding methods and codes, and Bonner-sphere response function extensions for higher energies, 'new' neutron spectral intensities were obtained, which show progressive hardening of neutron spectra as a function of increasing geomagnetic latitude, with substantial increases in the energy region iron, 1 0 MeV to 10 GeV. For example, we found that the total neutron fluences at 20 and 51 degrees magnetic north are in the ratio of 1 to 5.2 and the 10 MeV to 10 GeV fluence ratio is 1 to 18. The magnitude of these ratios is quite remarkable. From the new results, the derived absolute neutron energy distribution is of the correct strength and shape for the albedo neutrons to be the main source of the high-energy protons trapped in the Earth's inner radiation belt. In addition, the results, depending on the extrapolation scheme used, indicate that the neutron dose equivalent rate may be as high as 0.1 mSv/h near the geomagnetic north pole and thus a significant contributor to the radiation exposures of pilots, flight attendants and the general public. (author)

Production of the $\\Sigma^0_c$ and $\\Sigma^{++}_c$ by High-Energy Neutrons

Energy Technology Data Exchange (ETDEWEB)

Ladbury, Raymond, Jr. [Colorado U.

1988-01-01

We present the first observation of hadroproduction of the $\\Sigma^{++}_C$ and $\\Sigma^0_c$ , decaying into $\\Lambda_{c\\pi}$. The daughter $\\Lambda_c$ is observed in the decay modes $pK \\pi$ and $pK_s\\pi\\pi$. The Experiment was conducted at a broadband neutron beam in the Proton East area of the Fermi National Accelerator Laboratory. A two - magnet multiparticle spectrometer equipped with proportional wire chambers and a high resolution MWPC vertex detector was used to momentum analyze charged particles produced in the interactions of neutrons on targets of beryllium, silicon and tungsten. Particles were identified using three Cerenkov counters. The beam energy for each event was reconstructed using hadronic and electromagnetic calorimetry....

Sealed drift tube cosmic ray veto counters

International Nuclear Information System (INIS)

Rios, R.; Tatar, E.; Bacon, J.D.; Bowles, T.J.; Hill, R.; Green, J.A.; Hogan, G.E.; Ito, T.M.; Makela, M.; Morris, C.L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W.E.; Teasdale, W.; Saltus, M.; Back, H.O.; Cottrell, C.R.

2011-01-01

We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

Effect of different materials in soil on the neutron moisture gauge readings

International Nuclear Information System (INIS)

Abdul-Majid, S.

1991-01-01

Neutron moisture gauges that depend on scattering and thermalization of neutrons have been in use for a long time. The hydrogen in water is the effective element in thermalizing the neutrons coming from a neutron source, where they are detected by neutron detector such as B F 3 counter or boron lined counter. The high cross-section of boron for thermal neutrons makes detectors containing boron ideal for this application. There are always some possibility that some materials exist in soil other than water which can moderate and hence introduce false results in moisture contents measurements. For example, materials such as hydrocarbons, asphalt, wood, etc., contain both hydrogen and carbon. These elements are good neutron moderators. The effects of the existence of such materials in the soil on the gauge readings were examined. Elements of high neutron cross-section such as boron can be a source of large error as well, since they absorb thermal neutrons giving low moisture content value. The effect of such materials as part of the soil constituent on the gauge reading was also examined.3 fig

Evaluation of Neutron shielding efficiency of Metal hydrides

Energy Technology Data Exchange (ETDEWEB)

Jeon, Sang Hwan; Chae, San; Kim, Yong Soo [Hanyang University, Seoul (Korea, Republic of)

2012-05-15

Neutron shielding is achieved of interaction with material by moderation and absorption. Material that contains large amounts hydrogen atoms which are almost same neutron atomic weight is suited for fast neutron shielding material. Therefore, polymers containing high density hydrogen atom are being used for fast neutron shielding. On the other hand, composite materials containing high thermal neutron absorption cross section atom (Li, B, etc) are being used for thermal neutron shielding. However, these materials have low fast neutron absorption cross section. Therefore, these materials are not suited for fast neutron shielding. Hydrogen which has outstanding neutron energy reduction ability has very low thermal neutron absorption cross section, almost cannot be used for thermal neutron shielding. In this case, a large atomic number material (Pb, U, etc.) has been used. Thus, metal hydrides are considered as complement to concrete shielding material. Because metal hydrides contain high hydrogen density and elements with high atomic number. In this research neutron shielding performance and characteristic of nuclear about metal hydrides ((TiH{sub 2}, ZrH{sub 2}, HfH{sub 2}) is evaluated by experiment and MCNPX using {sup 252}Cf neutron source as purpose development shielding material to developed shielding material

Effects of the inversion layer thickness and 10B distribution in it on the characteristics of ion-doped semiconductor neutron counters

International Nuclear Information System (INIS)

Diasamidze, Eh.M.; Solov'ev, Yu.A.; Shmakov, A.N.

1984-01-01

The technique for calculating the dependence of energy spectrum of the 10 B(n, α) 7 Li reaction products in the thickness of the inversion layer in a semiconductor counter fabricated using the diffusion method is proposed. The inversion layer is formed as a result of the 10 B ion implantation into n-type silicon. The cases of uniform and Gaussian distributions of 10 B impurity are considered. Corrections for neutron fluence calculation by α-peak, taking into account α-particle absorption in the inversion layer are obtained. It is concluded that the suggested calculational technique can be used for semiconductor counters fabricated by the diffusion method

NeuLAND MRPC-based detector prototypes tested with fast neutrons

Energy Technology Data Exchange (ETDEWEB)

Caesar, C., E-mail: c.caesar@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Aumann, T. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Bemmerer, D. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Elekes, Z. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); ATOMKI, Debrecen (Hungary); Gonzalez-Diaz, D.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Reifarth, R.; Rossi, D.; Simon, H. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Stach, D.; Wagner, A.; Yakorev, D. [Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [ATOMKI, Debrecen (Hungary)

2012-01-01

Recent results from a first irradiation of multi-gap resistive plate chambers with fast neutrons are presented. The counters have been built at GSI and FZD. The experiment was performed at the 'The Svedberg Laboratory' (TSL) in Uppsala, Sweden, utilizing a quasi-monoenergetic neutron beam with an energy E{sub n}=175 MeV. For a 2 Multiplication-Sign 4 gap prototype operated at E=100 kV/cm, an efficiency of (0.77 {+-}0.33)% was measured.

Scintillating fiber tracking at high luminosities using Visible Light Photon counter readout

International Nuclear Information System (INIS)

Atac, M.

1995-11-01

This paper reviews the research work on the Visible Light Photon Counters (VLPC) that have been developed for the scintillating fiber tracking at high luminosity colliders and high rate fixed target experiments. The devices originated from the joint work between UCLA and Rockwell International Science Center. The VLPCs are capable of counting photons very efficiently down to a single photon level with high avalanche gain, producing pulses at very high rates with very short rise times. Due to small gain dispersions they can be used in counting photons with high quantum efficiencies, therefore they are excellent devices for charged particle tracking using small diameter scintillating plastic fibers. In this paper, fiber tracking for the CDF and D0 upgrades and a possible usage of the VLPC readout for the experiment E803 at Fermilab will be discussed

Neutron detection system for extremely low count rate. Calculation, construction and employment in search for 'cold fusion'

International Nuclear Information System (INIS)

Mayer, R.E.; Patino, N.E.; Florido, P.C.; Gomez, S.E.; Granada, J.R.; Gillette, V.H.

1993-01-01

A 22% efficiency thermal neutron detection system was designed for the investigation of neutron emission from pulsed D 2 O electrolysis. Reasons are discussed for the choice of 10 atm 3 He proportional counters. Optimization calculations carried out through standard reactor code system (AMPX-II) are presented along with construction details and characteristics of the associated electronics. Experimental verification of calculated efficiency and examples of measurements performed with the detector are included. (orig.)

Toward achieving flexible and high sensitivity hexagonal boron nitride neutron detectors

Science.gov (United States)

Maity, A.; Grenadier, S. J.; Li, J.; Lin, J. Y.; Jiang, H. X.

2017-07-01

Hexagonal boron nitride (h-BN) detectors have demonstrated the highest thermal neutron detection efficiency to date among solid-state neutron detectors at about 51%. We report here the realization of h-BN neutron detectors possessing one order of magnitude enhancement in the detection area but maintaining an equal level of detection efficiency of previous achievement. These 3 mm × 3 mm detectors were fabricated from 50 μm thick freestanding and flexible 10B enriched h-BN (h-10BN) films, grown by metal organic chemical vapor deposition followed by mechanical separation from sapphire substrates. Mobility-lifetime results suggested that holes are the majority carriers in unintentionally doped h-BN. The detectors were tested under thermal neutron irradiation from californium-252 (252Cf) moderated by a high density polyethylene moderator. A thermal neutron detection efficiency of ˜53% was achieved at a bias voltage of 200 V. Conforming to traditional solid-state detectors, the realization of h-BN epilayers with enhanced electrical transport properties is the key to enable scaling up the device sizes. More specifically, the present results revealed that achieving an electrical resistivity of greater than 1014 Ωṡcm and a leakage current density of below 3 × 10-10 A/cm2 is needed to fabricate large area h-BN detectors and provided guidance for achieving high sensitivity solid state neutron detectors based on h-BN.

Counter-Stereotypes and Feminism Promote Leadership Aspirations in Highly Identified Women

Science.gov (United States)

Leicht, Carola; Gocłowska, Małgorzata A.; Van Breen, Jolien A.; de Lemus, Soledad; Randsley de Moura, Georgina

2017-01-01

Although women who highly identify with other women are more susceptible to stereotype threat effects, women's identification might associate with greater leadership aspirations contingent on (1) counter-stereotype salience and (2) feminist identification. When gender counter-stereotypes are salient, women's identification should associate with greater leadership aspiration regardless of feminism, while when gender stereotypes are salient, women's identification would predict greater leadership aspirations contingent on a high level of feminist identification. In our study US-based women (N = 208) attended to gender stereotypic (vs. counter-stereotypic) content. We measured identification with women and identification with feminism, and, following the manipulation, leadership aspirations in an imagined work scenario. The interaction between identification with women, identification with feminism, and attention to stereotypes (vs. counter-stereotypes) significantly predicted leadership aspirations. In the counter-stereotypic condition women's identification associated with greater leadership aspirations regardless of feminist identification. In the stereotypic condition women's identification predicted leadership aspirations only at high levels of feminist identification. We conclude that salient counter-stereotypes and a strong identification with feminism may help high women identifiers increase their leadership aspirations. PMID:28626437

Counter-Stereotypes and Feminism Promote Leadership Aspirations in Highly Identified Women.

Science.gov (United States)

Leicht, Carola; Gocłowska, Małgorzata A; Van Breen, Jolien A; de Lemus, Soledad; Randsley de Moura, Georgina

2017-01-01

Although women who highly identify with other women are more susceptible to stereotype threat effects, women's identification might associate with greater leadership aspirations contingent on (1) counter-stereotype salience and (2) feminist identification. When gender counter-stereotypes are salient, women's identification should associate with greater leadership aspiration regardless of feminism, while when gender stereotypes are salient, women's identification would predict greater leadership aspirations contingent on a high level of feminist identification. In our study US-based women ( N = 208) attended to gender stereotypic (vs. counter-stereotypic) content. We measured identification with women and identification with feminism, and, following the manipulation, leadership aspirations in an imagined work scenario. The interaction between identification with women, identification with feminism, and attention to stereotypes (vs. counter-stereotypes) significantly predicted leadership aspirations. In the counter-stereotypic condition women's identification associated with greater leadership aspirations regardless of feminist identification. In the stereotypic condition women's identification predicted leadership aspirations only at high levels of feminist identification. We conclude that salient counter-stereotypes and a strong identification with feminism may help high women identifiers increase their leadership aspirations.

Counter-Stereotypes and Feminism Promote Leadership Aspirations in Highly Identified Women

Directory of Open Access Journals (Sweden)

Carola Leicht

2017-06-01

Full Text Available Although women who highly identify with other women are more susceptible to stereotype threat effects, women's identification might associate with greater leadership aspirations contingent on (1 counter-stereotype salience and (2 feminist identification. When gender counter-stereotypes are salient, women's identification should associate with greater leadership aspiration regardless of feminism, while when gender stereotypes are salient, women's identification would predict greater leadership aspirations contingent on a high level of feminist identification. In our study US-based women (N = 208 attended to gender stereotypic (vs. counter-stereotypic content. We measured identification with women and identification with feminism, and, following the manipulation, leadership aspirations in an imagined work scenario. The interaction between identification with women, identification with feminism, and attention to stereotypes (vs. counter-stereotypes significantly predicted leadership aspirations. In the counter-stereotypic condition women's identification associated with greater leadership aspirations regardless of feminist identification. In the stereotypic condition women's identification predicted leadership aspirations only at high levels of feminist identification. We conclude that salient counter-stereotypes and a strong identification with feminism may help high women identifiers increase their leadership aspirations.

High precision neutron polarization for PERC

International Nuclear Information System (INIS)

Klauser, C.

2013-01-01

The decay of the free neutron into a proton, an electron and an anti-electron neutrino offers a simple system to study the semi-leptonic weak decay. High precision measurements of angular correlation coefficients of this decay provide the opportunity to test the standard model on the low energy frontier. The Proton Electron Radiation Channel PERC is part of a new generation of expriments pushing the accuracy of such an angular correlation coefficient measurement towards 10 -4 . Past experiments have been limited to an accuracy of 10 -3 with uncertainties on the neutron polarization as one of the leading systematic errors. This thesis focuses on the development of a stable, highly precise neutron polarization for a large, divergent cold neutron beam. A diagnostic tool that provides polarization higher than 99.99 % and analyzes with an accuracy of 10 -4 , the Opaque Test Bench, is presented and validated. It consists of two highly opaque polarized helium cells. The Opaque Test Bench reveals depolarizing effects in polarizing supermirrors commonly used for polarization in neutron decay experiments. These effects are investigated in detail. They are due to imperfect lateral magnetization in supermirror layers and can be minimized by significantly increased magnetizing fields and low incidence angle and supermirror factor m. A subsequent test in the crossed (X-SM) geometry demonstrated polarizations up to 99.97% from supermirrors only, improving neutron polarization with supermirrors by an order of magnitude. The thesis also discusses other neutron optical components of the PERC beamline: Monte-Carlo simulations of the beamline under consideration of the primary guide are carried out. In addition, calculation shows that PERC would statistically profit from an installation at the European Spallation source. Furthermore, beamline components were tested. A radio-frequency spin flipper was confirmed to work with an efficiency higher than 0.9999. (author) [de

High yield neutron generators using the DD reaction

Energy Technology Data Exchange (ETDEWEB)

Vainionpaa, J. H.; Harris, J. L.; Piestrup, M. A.; Gary, C. K.; Williams, D. L.; Apodaca, M. D.; Cremer, J. T. [Adelphi technology, 2003 E. Bayshore Rd. 94061, Redwood City, CA (United States); Ji, Qing; Ludewigt, B. A. [Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jones, G. [G and J Enterprise, 1258 Quary Ln, Suite F, Pleasanton California 94566 (United States)

2013-04-19

A product line of high yield neutron generators has been developed at Adelphi technology inc. The generators use the D-D fusion reaction and are driven by an ion beam supplied by a microwave ion source. Yields of up to 5 Multiplication-Sign 10{sup 9} n/s have been achieved, which are comparable to those obtained using the more efficient D-T reaction. The microwave-driven plasma uses the electron cyclotron resonance (ECR) to produce a high plasma density for high current and high atomic ion species. These generators have an actively pumped vacuum system that allows operation at reduced pressure in the target chamber, increasing the overall system reliability. Since no radioactive tritium is used, the generators can be easily serviced, and components can be easily replaced, providing essentially an unlimited lifetime. Fast neutron source size can be adjusted by selecting the aperture and target geometries according to customer specifications. Pulsed and continuous operation has been demonstrated. Minimum pulse lengths of 50 {mu}s have been achieved. Since the generators are easily serviceable, they offer a long lifetime neutron generator for laboratories and commercial systems requiring continuous operation. Several of the generators have been enclosed in radiation shielding/moderator structures designed for customer specifications. These generators have been proven to be useful for prompt gamma neutron activation analysis (PGNAA), neutron activation analysis (NAA) and fast neutron radiography. Thus these generators make excellent fast, epithermal and thermal neutron sources for laboratories and industrial applications that require neutrons with safe operation, small footprint, low cost and small regulatory burden.

Performance of neutron polarimeter SMART-NPOL

International Nuclear Information System (INIS)

Noji, S.; Miki, K.; Yako, K.; Kawabata, T.; Kuboki, H.; Sakai, H.; Sekiguchi, K.; Suda, K.

2007-01-01

The neutron polarimeter SMART-NPOL has been constructed at the RIKEN Accelerator Research Facility for measuring polarization correlations of proton-neutron systems. The SMART-NPOL system consists of 12 parallel neutron counter planes of two dimensionally position-sensitive plastic scintillators with a size of 60x60x3.0cm 3 . Polarimetry measurements were made using the analyzing power of the H1(n-vector,n)H1 reaction occurring in the plastic scintillators. The effective analyzing power of SMART-NPOL was measured with polarized neutrons from the zero-degree Li6(d-vector,n-vector) reaction with an incident deuteron energy of 135MeV/A. The effective analyzing power thus obtained was 0.26±0.01 stat ±0.03 syst and the double scattering efficiency was 1.1x10 -3

Experimental validation of GADRAS's coupled neutron-photon inverse radiation transport solver

International Nuclear Information System (INIS)

Mattingly, John K.; Mitchell, Dean James; Harding, Lee T.

2010-01-01

Sandia National Laboratories has developed an inverse radiation transport solver that applies nonlinear regression to coupled neutron-photon deterministic transport models. The inverse solver uses nonlinear regression to fit a radiation transport model to gamma spectrometry and neutron multiplicity counting measurements. The subject of this paper is the experimental validation of that solver. This paper describes a series of experiments conducted with a 4.5 kg sphere of α-phase, weapons-grade plutonium. The source was measured bare and reflected by high-density polyethylene (HDPE) spherical shells with total thicknesses between 1.27 and 15.24 cm. Neutron and photon emissions from the source were measured using three instruments: a gross neutron counter, a portable neutron multiplicity counter, and a high-resolution gamma spectrometer. These measurements were used as input to the inverse radiation transport solver to evaluate the solver's ability to correctly infer the configuration of the source from its measured radiation signatures.

Dual functional reduced graphene oxide as photoanode and counter electrode in dye-sensitized solar cells and its exceptional efficiency enhancement

Science.gov (United States)

Jumeri, F. A.; Lim, H. N.; Zainal, Z.; Huang, N. M.; Pandikumar, A.; Lim, S. P.

2015-10-01

The dual functionalities of reduced graphene oxide (rGO) as photoanode and counter electrode in dye-sensitized solar cells (DSSCs) is explored. A titanium dioxide (TiO2) film is deposited on an indium tin oxide (ITO) glass using an in-house aerosol-assisted chemical vapor deposition method. Graphene oxide (GO) is then introduced onto the TiO2-ITO substrate, and the GO layer is successively thermally treated to rGO. The TiO2-rGO film is used as a compact layer for the photoanode of the DSSC. A layer of zinc oxide-silver (ZnO-Ag) is introduced on top of the compact layer as an active material. Its highly porous flower-shaped morphology is advantageous for the adsorption of dye. The in-situ electrochemical polymerization method used for the fabrication of polypyrrole incorporated with rGO and p-toluenesulfonate (pTS) (Ppy-rGO-pTS) on an ITO glass is used as a counter electrode for the DSSC. The DSSC assembled with the Ppy-rGO-1.0pTS counter electrode exhibites an enhanced conversion efficiency of 1.99% under solar illumination, which is better than that using conventional Pt as a counter electrode (0.08%). This is attributed to the increased contact area between the Ppy-rGO-pTS counter electrode and electrolyte, which subsequently improves the conductivity and high electrocatalytic activities of the Ppy-rGO-pTS counter electrode.

Development of 2-d position-sensitive neutron detector with individual readout. Operation test and establishment of detection system by means of neutron beam

International Nuclear Information System (INIS)

Tanaka, Hiroki; Yamagishi, Hideshi; Nakamura, Tatsuya; Soyama, Kazuhiko; Aizawa, Kazuya

2005-04-01

We have been developing the 2-d position-sensitive neutron detector with individual readout as next-generation-type detector system for neutron scattering experiments using intense pulsed neutron source. The detection system is designed to fulfill the specifications required for each neutron spectrometer, such as a count rate, efficiency, neutron/gamma-ray ratio, a spatial resolution and a size, by using suitable detector heads. The fundamental and imaging performances of the developed system assembled with a Multi-wire proportional counter head were evaluated using a collimated neutron beam. The system worked stably for long hours at the 4 He gas pressure of 5 atm with a mixture of 30% C 2 H 6 (0.26 atom 3 He) at gas gain of 450. The spatial resolutions were 1.4, 1.6 mm (FWHM) for a cathode- and a back strip- direction, respectively, considering a beam size. It was also confirmed that the spatial uniformity of the detection efficiency over the whole sensitive detection area was rather good, ±8% deviation from the average with the optimum discrimination level. (author)

Two-dimensional position sensitive neutron detector

Indian Academy of Sciences (India)

The detector is a 3He + Kr filled multiwire proportional counter with charge division position readout and has a sensitive area of 345 mm × 345 mm, pixel size 5 mm × 5 mm, active depth 25 mm and is designed for efficiency of 70% for 4 Å neutrons. The detector is tested with 0.5 bar 3He + 1.5 bar krypton gas mixture in active ...

Position sensitive detection of neutrons in high radiation background field.

Science.gov (United States)

Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

2014-01-01

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

First measurements with new high-resolution gadolinium-GEM neutron detectors

CERN Document Server

Pfeiffer, Dorothea; Birch, Jens; Etxegarai, Maddi; Hall-Wilton, Richard; Höglund, Carina; Hultman, Lars; Llamas-Jansa, Isabel; Oliveri, Eraldo; Oksanen, Esko; Robinson, Linda; Ropelewski, Leszek; Schmidt, Susann; Streli, Christina; Thuiner, Patrik

2016-05-17

European Spallation Source instruments like the macromolecular diffractometer, NMX, require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The {\\mu}TPC analysis, proven to improve the spatial resolution in the case of $^{10}$B converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with an estimated efficiency of 10% at a wavelength of 2 {\\AA} and a position resolution better than 350 {\\mu}m.

FLUKA simulations of a moderated reduced weight high energy neutron detection system

Energy Technology Data Exchange (ETDEWEB)

Biju, K., E-mail: bijusivolli@gmail.com [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathy, S.P.; Sunil, C.; Sarkar, P.K. [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2012-08-01

Neutron response of the systems containing high density polyethylene (HDPE) spheres coupled with different external metallic converters has been studied using the FLUKA Monte Carlo simulation code. A diameter of 17.8 cm (7 in.) of the moderating sphere is found to be optimum to obtain the maximum response when used with the neutron converter shells like W, Pb and Zr. Enhancement ratios of the neutron response due to the induced (n, xn) reactions in the outer converters made of W, Pb and Zr are analyzed. It is observed that the enhancement in the response by 1 cm thick Zr shell is comparable to that of 1 cm thick Pb in the energy region of 10-50 MeV. An appreciable enhancement is observed in the case of Zr converter for the higher energy neutrons. Thus, by reducing the dimension of the moderating sphere and using a Zr converter shell, the weight of the system reduces to 10 kg which is less compared to the presently available extended high energy neutron rem meters. The normalized energy dependent ambient dose equivalent response of the zirconium based rem counter (ZReC) at high energies is found to be in good agreement with the energy differential H{sup Low-Asterisk }(10) values suggested by the International Commission on Radiological Protection (ICRP). Based on this study, it is proposed that a rem meter made of 17.8 cm diameter HDPE sphere with 1 cm thick Zr can be used effectively and conveniently for routine monitoring in the accelerator environment.

Variable dead time counters: 2. A computer simulation

International Nuclear Information System (INIS)

Hooton, B.W.; Lees, E.W.

1980-09-01

A computer model has been developed to give a pulse train which simulates that generated by a variable dead time counter (VDC) used in safeguards determination of Pu mass. The model is applied to two algorithms generally used for VDC analysis. It is used to determine their limitations at high counting rates and to investigate the effects of random neutrons from (α,n) reactions. Both algorithms are found to be deficient for use with masses of 240 Pu greater than 100g and one commonly used algorithm is shown, by use of the model and also by theory, to yield a result which is dependent on the random neutron intensity. (author)

Study on calibration of neutron efficiency and relative photo-yield of plastic scintillator

International Nuclear Information System (INIS)

Peng Taiping; Zhang Chuanfei; Li Rurong; Zhang Jianhua; Luo Xiaobing; Xia Yijun; Yang Zhihua

2002-01-01

A method used for the calibration of neutron efficiency and the relative photo yield of plastic scintillator is studied. T(p, n) and D(d, n) reactions are used as neutron resources. The neutron efficiencies and the relative photo yields of plastic scintillators 1421 (40 mm in diameter and 5 mm in thickness) and determined in the neutron energy range of 0.655-5 MeV

Model-based design evaluation of a compact, high-efficiency neutron scatter camera

Science.gov (United States)

Weinfurther, Kyle; Mattingly, John; Brubaker, Erik; Steele, John

2018-03-01

pillar dimensions, scintillator material (EJ-204, EJ-232Q and stilbene), and photodetector (MCP-PM vs. SiPM) response vs. time. We demonstrate that the most precise estimates of incident neutron direction and energy can be obtained using a combination of scintillator material with high luminosity and a photodetector with a narrow impulse response. Specifically, we conclude that an SVSC-PiPS constructed using EJ-204 (a high luminosity plastic scintillator) and an MCP-PM will produce the most precise estimates of incident neutron direction and energy.

Possibility of semiconductor counters application for internal contamination measurement of whole human body

International Nuclear Information System (INIS)

Cunic, O.; Orlic, M.; Bek-Uzarov, Dj.; Pavlovic, S.; Pavlovic, R.

1997-01-01

The possibility of high resolution semiconductor counters application in 'Vinca' Whole Body Counter for direct beta-gamma internal contamination measurement are discussed, assuming the following relevant characteristics: efficiency, resolution and counter price. A comparison with appropriate characteristics of NaI(Tl) crystal used in 'Vinca' WBC is treated. It is evident that the scintillation counters have the higher detection efficiency, but HPGe counters having much better resolution and recently lowest prices are also acceptable to join the existing NaI(Tl) counters with the HPGe counters in the same time, allow better spectral analyses of the human body activity and additionally more precise estimation of the equivalent doses rate which is generally a essential problem in WBC measurements. (author)

Accuracy of neutron dose evaluation in the area monitoring for LHD experiments

CERN Document Server

Yamanishi, H; Uda, T; Tanahashi, S; Saitou, M; Handa, H

2000-01-01

The error in the evaluation of neutron dose during calculation of the neutron field around the large helical device (LHD) in D-D operation is discussed. The expected neutron dose at each monitoring point was derived from the dose conversion factor and neutron fluence data, which was calculated with the radiation transport code DOT-3.5. In contrast, the detected dose at the neutron counter was obtained from the fluence data and the detector response given by calculation with MCNP-4b. The neutron counter used in these calculations consisted of a helium-3 proportional counter with a cylindrical polyethylene moderator. According to the results of the calculations, the ratio of the detected dose to the expected dose was found to lie in the range 1.0-3.0 on the outdoor monitoring points. Since the response of a single neutron counter may lead to inconsistencies in the dose conversion factor, we attempted to minimize these inconsistencies by using a pair of counters with moderators of different thickness. The ratio ...

Evaluation of B10Plus+* proportional detectors for neutron coincidence counting

Energy Technology Data Exchange (ETDEWEB)

Beddingfield, David H.; Yoon, Seokryung [International Atomic Energy Agency, Vienna International Centre, PO Box 100, 1400 Vienna, (Austria)

2015-07-01

GE-Reuter-Stokes (GERS) has developed a new line of neutron proportional counters, the B10Plus+* proportional counter. The detector design is intended to serve as a cost-effective alternative to traditional {sup 3}He proportional counters in a variety of applications. The detector is a hybrid design 10B-lined tube optimized with the addition of a small quantity of 3He gas to improve the detector performance and efficiency. As a demonstration of the B10Plus+* detector, GERS has constructed a Uranium Neutron Collar (UNCL) system consisting of B-10Plus+* proportional counters. GERS has designed and built a demonstration UNCL system intended to match the performance of a Type-I UNCL design in Pressurized Water Reactor (PWR) geometry operating in thermal mode. GERS offered their system on loan to the International Atomic Energy Agency (IAEA) Safeguards Division of Technical and Scientific Services for an assessment of the detector technology and the demonstration system. We have characterized the demonstration UNCL system and compared its performance with a traditional Type-I UNCL design in regular use by the IAEA. This paper summarizes our findings and observations during the characterization and testing activity. (authors)

On efficiently computing multigroup multi-layer neutron reflection and transmission conditions

International Nuclear Information System (INIS)

Abreu, Marcos P. de

2007-01-01

In this article, we present an algorithm for efficient computation of multigroup discrete ordinates neutron reflection and transmission conditions, which replace a multi-layered boundary region in neutron multiplication eigenvalue computations with no spatial truncation error. In contrast to the independent layer-by-layer algorithm considered thus far in our computations, the algorithm here is based on an inductive approach developed by the present author for deriving neutron reflection and transmission conditions for a nonactive boundary region with an arbitrary number of arbitrarily thick layers. With this new algorithm, we were able to increase significantly the computational efficiency of our spectral diamond-spectral Green's function method for solving multigroup neutron multiplication eigenvalue problems with multi-layered boundary regions. We provide comparative results for a two-group reactor core model to illustrate the increased efficiency of our spectral method, and we conclude this article with a number of general remarks. (author)

Fast neutron dosimetry: Progress summary

International Nuclear Information System (INIS)

DeLuca, P.M. Jr.

1988-01-01

The purpose was to investigate the radiological physics and biology of very low energy photons derived from a 1-GeV electron synchrotron storage ring. An extensive beam line and irradiation apparatus was designed, developed, and constructed. Dosimetry measurements required invention and testing of a miniature absolute calorimeter and a cell irradiation fixture suitable for scanning exposures under computer control. Measurements of the kerma factors of oxygen, aluminum and silicon for 14-20 MeV neutrons. Custom designed miniature proportional counters of cylindrical symmetry were employed in these determinations. The oxygen kerma factor was found significantly lower than values calculated from microscopic cross sections. We also tested Mg and Fe walled conventional spherical counters. The direct neutron-counting gas interaction is significant enough for these counters that a correction is needed. We also investigated the application of Nuclear Magnetic Resonance spectroscopy to radiation dosimetry. Our purpose was to take advantage of recent development of very high-field magnets, complex RF-pulse techniques for solvent suppression, and improved spectral analysis techniques

Linear position sensitive neutron detector using fiber optic encoded scintillators

International Nuclear Information System (INIS)

Davidson, P.L.; Wroe, H.

1983-01-01

A linear position sensitive slow neutron detector with 3 mm resolution is described. It uses the fiber optic coding principle in which the resolution elements are separate pieces of lithium loaded glass scintillator each coupled by means of flexible polymer optical fibers to a unique combination of 3 photo multipliers (PM's) out of a bank of 12. A decoder circuit repsponds to a triple coincidence between PM outputs and generates a 12 bit work which identifies the scintillator element which stopped the incident neutron. Some details of the construction and decoding electronics are given together with test results obtained using a laboratory isotope neutron source and a monochomated, collimated neutron beam from a reactor. The count rate in the absence of neutron sources is 2 to 3 c min - 1 per element; the element to element variation in response to a uniform flux is a few percent for 95% of the elements; the resolution as measured by a 1 mm wide prode neutron beam is 3 mm; the relative long term stability is about 0.1% over 3 days and the detection efficiency measured by comparison with an end windowed, high pressure gas counter is about 65% at a neutron wavelength of 0.9A 0

Poly(3,4-ethylenedioxythiophene)/reduced graphene oxide composites as counter electrodes for high efficiency dye-sensitized solar cells

Science.gov (United States)

Ma, Jinfu; Yuan, Shenghua; Yang, Shaolin; Lu, Hui; Li, Yingtao

2018-05-01

A facile, low cost, easy-controllable method to prepare Poly(3,4-ethylenedioxythiophene) (PEDOT)/reduced graphene oxide (rGO) composites by electrochemical deposition onto fluorinated tin oxide (FTO) as counter electrodes (CEs) in high performance dye-sensitized solar cells (DSSCs) is reported. The electro-deposition process was accomplished by electro-polymerization of graphene oxide (GO)/PEDOT composites onto FTO substrates followed by electrochemical reduction of the GO component. Electrochemical measurements show that the I-/I3- catalytic activity of the as-prepared PEDOT/rGO CE is improved compared with that of the pure PEDOT and PEDOT/GO electrode. Through the analysis of photoelectric properties, the performance of the electrodes fabricated with different polymerization times are compared, and the optimal preparation condition is determined. The photoelectric conversion efficiency (PCE) of the DSSC assembled with PEDOT/rGO electrode reaches 7.79%, close to 8.33% of the cell with Platinum (Pt) electrode, and increases by 13.2% compared with 6.88% of the device with the PEDOT electrode.

Passive detectors for neutron fluence measurement

International Nuclear Information System (INIS)

Holt, P.D.

1985-01-01

The use of neutron activation detectors (slow neutron detectors and threshold detectors) and fission track detectors for radiological protection purposes, principally in criticality dosimetry, dosimetry of pulsed accelerators and calibration of neutron fluxes is discussed. References are given to compilations of cross sections. For the determination of the activity induced, either beta ray or gamma ray counting may be used. For beta-ray counting, thin foils are usually necessary which result in low neutron sensitivity. When fission track detectors are used, it is necessary to know the efficiency of track registration. Alternatively, a detector-counter system may be calibrated by exposure to a known flux of monoenergetic neutrons. Usually, the sensitivity of activation detectors is low because small foils are used. For criticality dosimetry, calibration work and shielding studies on accelerators, low sensitivity is acceptable. However, there are some instances where, by the use of long integration times, or very large quantities of detector material with gamma ray detection, neutron fluences in operational areas have been measured. (author)

Activated graphene nanoplatelets as a counter electrode for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Gong, Jiawei [Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, Brookings, South Dakota 57007 (United States); Department of Mechanical Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States); Zhou, Zhengping; Qiao, Qiquan, E-mail: qiquan.qiao@sdstate.edu [Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, Brookings, South Dakota 57007 (United States); Sumathy, K. [Department of Mechanical Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States); Yang, Huojun [Department of Construction Management and Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States)

2016-04-07

Activated graphene nanoplatelets (aGNPs) prepared by a hydrothermal method using KOH as activating agent were used as counter electrode for high efficiency dye-sensitized solar cells (DSSCs). After the KOH activation, the scanning electron microscopy image shows that aGNPs demonstrate a more curled, rough, and porous morphology which could contain both micro- and mesopores. The KOH activation changed the stacked layers of GNPs to a more crumpled and curved morphology. The microstructure of large pores significantly increased the electrode surface area and roughness, leading to the high electrocatalytic activity for triiodide reduction at the counter electrode. The DSSCs fabricated using aGNP as counter electrodes were tested under standard AM 1.5 illumination with an intensity of 91.5 mW/cm{sup 2}. The device achieved an overall power conversion efficiency of 7.7%, which is comparable to the conventional platinum counter electrode (8%). Therefore, the low cost and high performance aGNP based counter electrode is a promising alternative to conventional Pt counter electrode in DSSCs.

Enriched Boron-Doped Amorphous Selenium Based Position-Sensitive Solid-State Thermal Neutron Detector for MPACT Applications

International Nuclear Information System (INIS)

Mandal, Krishna

2017-01-01

High-efficiency thermal neutron detectors with compact size, low power-rating and high spatial, temporal and energy resolution are essential to execute non-proliferation and safeguard protocols. The demands of such detector are not fully covered by the current detection system such as gas proportional counters or scintillator-photomultiplier tube combinations, which are limited by their detection efficiency, stability of response, speed of operation, and physical size. Furthermore, world-wide shortage of 3 He gas, required for widely used gas detection method, has further prompted to design an alternative system. Therefore, a solid-state neutron detection system without the requirement of 3 He will be very desirable. To address the above technology gap, we had proposed to develop new room temperature solidstate thermal neutron detectors based on enriched boron ( 10 B) and enriched lithium ( 6 Li) doped amorphous Se (As- 0.52%, Cl 5 ppm) semiconductor for MPACT applications. The proposed alloy materials have been identified for its many favorable characteristics - a wide bandgap (~2.2 eV at 300 K) for room temperature operation, high glass transition temperature (t g ~ 85°C), a high thermal neutron cross-section (for boron ~ 3840 barns, for lithium ~ 940 barns, 1 barn = 10 -24 cm 2 ), low effective atomic number of Se for small gamma ray sensitivity, and high radiation tolerance due to its amorphous structure.

Fission neutron damage rates and efficiencies in several metals

International Nuclear Information System (INIS)

Klabunde, C.E.; Coltman, R.R. Jr.

1981-11-01

Initial rates of resistivity-measured low-temperature damage production by fission-spectrum fast neutrons have been determined for 14 metals in the same very well characterized irradiation facility. Six of these metals were fcc, 5 bcc, and 3 hcp. Most were of quite high purity. Observed damage rates, after correction for all known extraneous resistivity-producing effects, were compared with rates predicted by the damage calculation code RECOIL, using parameters chosen from the literature. These parameters, effective displacement threshold energy, E/sub d/, and Frenkel-pair resistivity, rho/sub F/, were in many cases only best estimates, the further refinement of which may be aided by the present results. Damage efficiencies (measured/predicted rates) follow the same trends by crystal classes as seen in other fast-neutron studies

An acoustical bubble counter for superheated drop detectors

International Nuclear Information System (INIS)

Taylor, C.; Montvila, D.; Flynn, D.; Brennan, C.; D'Errico, F.

2006-01-01

A new bubble counter has been developed based on the well-established approach of detecting vaporization events acoustically in superheated drop detectors (SDDs). This counter is called the Framework Scientific ABC 1260, and it represents a major improvement over prior versions of this technology. By utilizing advanced acoustic pattern recognition software, the bubble formation event can be differentiated from ambient background noise, as well as from other acoustic signatures. Additional structural design enhancements include a relocation of the electronic components to the bottom of the device; thus allowing for greater stability, easier access to vial SDDs without exposure to system electronics. Upgrades in the electronics permit an increase in the speed of bubble detection by almost 50%, compared with earlier versions of the counters. By positioning the vial on top of the device, temperature and sound insulation can be accommodated for extreme environments. Lead shells can also be utilized for an enhanced response to high-energy neutrons. (authors)

An acoustical bubble counter for superheated drop detectors.

Science.gov (United States)

Taylor, Chris; Montvila, Darius; Flynn, David; Brennan, Christopher; d'Errico, Francesco

2006-01-01

A new bubble counter has been developed based on the well-established approach of detecting vaporization events acoustically in superheated drop detectors (SDDs). This counter is called the Framework Scientific ABC 1260, and it represents a major improvement over prior versions of this technology. By utilizing advanced acoustic pattern recognition software, the bubble formation event can be differentiated from ambient background noise, as well as from other acoustic signatures. Additional structural design enhancements include a relocation of the electronic components to the bottom of the device; thus allowing for greater stability, easier access to vial SDDs without exposure to system electronics. Upgrades in the electronics permit an increase in the speed of bubble detection by almost 50%, compared with earlier versions of the counters. By positioning the vial on top of the device, temperature and sound insulation can be accommodated for extreme environments. Lead shells can also be utilized for an enhanced response to high-energy neutrons.

The High-Energy Polarization-Limiting Radius of Neutron Star Magnetospheres 1, Slowly Rotating Neutron Stars

CERN Document Server

Heyl, J S; Lloyd, D; CERN. Geneva; Heyl, Jeremy S.; Shaviv, Nir J.; Lloyd, Don

2003-01-01

In the presence of strong magnetic fields, the vacuum becomes a birefringent medium. We show that this QED effect decouples the polarization modes of photons leaving the NS surface. Both the total intensity and the intensity in each of the two modes is preserved along a ray's path through the neutron-star magnetosphere. We analyze the consequences that this effect has on aligning the observed polarization vectors across the image of the stellar surface to generate large net polarizations. Counter to previous predictions, we show that the thermal radiation of NSs should be highly polarized even in the optical. When detected, this polarization will be the first demonstration of vacuum birefringence. It could be used as a tool to prove the high magnetic field nature of AXPs and it could also be used to constrain physical NS parameters, such as $R/M$, to which the net polarization is sensitive.

Improved efficiency of CdS quantum dot sensitized solar cell with an organic redox couple and a polymer counter electrode

International Nuclear Information System (INIS)

Shu, Ting; Li, Xiong; Ku, Zhi-Liang; Wang, Shi; Wu, Shi; Jin, Xiao-Hong; Hu, Chun-Di

2014-01-01

Highlights: • The organic AT - /BAT and T - /T 2 redox couples were used in CdS QDSSCs. • The AT - /BAT and PEDOT are better than polysulfide electrolyte and Pt and CoS CEs. • An improved η of 1.53% was obtained with the AT - /BAT electrolyte and the PEDOT CE. • PEDOT CE deposited at high deposition charge has better electrochemical activity. • The AT - /BAT outperformed T - /T 2 electrolyte due to suppressed charge recombination. - Abstract: Quantum dot sensitized solar cells (QDSSCs) based on an organic thiolate/disulfide redox couple (C 7 H 5 N 4 S - /C 14 H 10 N 8 S 2 or C 2 H 3 N 4 S - /C 4 H 6 N 8 S 2 ) and a polymer counter electrode [poly (3, 4-ethylenedioxythiophene), PEDOT] were fabricated and their photovoltaic performance were investigated. In CdS QDSSC, the organic C 7 H 5 N 4 S - /C 14 H 10 N 8 S 2 electrolyte shows better performance than the polysulfide electrolyte, and the PEDOT counter electrode exhibits higher efficiency than that of the Pt counter electrode and the CoS counter electrode. An efficiency of 1.53% was achieved in this QDSSC. The influences of the morphology and the deposition charge of the PEDOT counter electrodes on the cell performance were also studied. Furthermore, it was found that the C 7 H 5 N 4 S - /C 14 H 10 N 8 S 2 redox couple outperformed the C 2 H 3 N 4 S - /C 4 H 6 N 8 S 2 redox couple due to reduced electron recombination

Multi-group transport methods for high-resolution neutron activation analysis

International Nuclear Information System (INIS)

Burns, K. A.; Smith, L. E.; Gesh, C. J.; Shaver, M. W.

2009-01-01

The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples. In these applications, high-resolution gamma-ray spectrometers are used to preserve as much information as possible about the emitted photon flux, which consists of both continuum and characteristic gamma rays with discrete energies. Monte Carlo transport is the most commonly used modeling tool for this type of problem, but computational times for many problems can be prohibitive. This work explores the use of multi-group deterministic methods for the simulation of neutron activation problems. Central to this work is the development of a method for generating multi-group neutron-photon cross-sections in a way that separates the discrete and continuum photon emissions so that the key signatures in neutron activation analysis (i.e., the characteristic line energies) are preserved. The mechanics of the cross-section preparation method are described and contrasted with standard neutron-gamma cross-section sets. These custom cross-sections are then applied to several benchmark problems. Multi-group results for neutron and photon flux are compared to MCNP results. Finally, calculated responses of high-resolution spectrometers are compared. Preliminary findings show promising results when compared to MCNP. A detailed discussion of the potential benefits and shortcomings of the multi-group-based approach, in terms of accuracy, and computational efficiency, is provided. (authors)

Measurement and simulation of neutron detection efficiency in lead-scintillating fiber calorimeters

Energy Technology Data Exchange (ETDEWEB)

Anelli, M.; Bertolucci, S. [Laboratori Nazionali di Frascati, INFN (Italy); Bini, C. [Dipartimento di Fisica dell' Universita ' La Sapienza' , Roma (Italy); INFN Sezione di Roma, Roma (Italy); Branchini, P. [INFN Sezione di Roma Tre, Roma (Italy); Curceanu, C. [Laboratori Nazionali di Frascati, INFN (Italy); De Zorzi, G.; Di Domenico, A. [Dipartimento di Fisica dell' Universita ' La Sapienza' , Roma (Italy); INFN Sezione di Roma, Roma (Italy); Di Micco, B. [Dipartimento di Fisica dell' Universita ' Roma Tre' , Roma (Italy); INFN Sezione di Roma Tre, Roma (Italy); Ferrari, A. [Fondazione CNAO, Milano (Italy); Fiore, S.; Gauzzi, P. [Dipartimento di Fisica dell' Universita ' La Sapienza' , Roma (Italy); INFN Sezione di Roma, Roma (Italy); Giovannella, S., E-mail: simona.giovannella@lnf.infn.i [Laboratori Nazionali di Frascati, INFN (Italy); Happacher, F. [Laboratori Nazionali di Frascati, INFN (Italy); Iliescu, M. [Laboratori Nazionali di Frascati, INFN (Italy); IFIN-HH, Bucharest (Romania); Martini, M. [Laboratori Nazionali di Frascati, INFN (Italy); Dipartimento di Energetica dell' Universita ' La Sapienza' , Roma (Italy); Miscetti, S. [Laboratori Nazionali di Frascati, INFN (Italy); Nguyen, F. [Dipartimento di Fisica dell' Universita ' Roma Tre' , Roma (Italy); INFN Sezione di Roma Tre, Roma (Italy); Passeri, A. [INFN Sezione di Roma Tre, Roma (Italy); Prokofiev, A. [Svedberg Laboratory, Uppsala University (Sweden); Sciascia, B. [Laboratori Nazionali di Frascati, INFN (Italy)

2009-12-15

The overall detection efficiency to neutrons of a small prototype of the KLOE lead-scintillating fiber calorimeter has been measured at the neutron beam facility of The Svedberg Laboratory, TSL, Uppsala, in the kinetic energy range [5-175] MeV. The measurement of the neutron detection efficiency of a NE110 scintillator provided a reference calibration. At the lowest trigger threshold, the overall calorimeter efficiency ranges from 30% to 50%. This value largely exceeds the estimated 8-15% expected if the response were proportional only to the scintillator equivalent thickness. A detailed simulation of the calorimeter and of the TSL beam line has been performed with the FLUKA Monte Carlo code. First data-MC comparisons are encouraging and allow to disentangle a neutron halo component in the beam.

Measurement and simulation of neutron detection efficiency in lead-scintillating fiber calorimeters

International Nuclear Information System (INIS)

Anelli, M.; Bertolucci, S.; Bini, C.; Branchini, P.; Curceanu, C.; De Zorzi, G.; Di Domenico, A.; Di Micco, B.; Ferrari, A.; Fiore, S.; Gauzzi, P.; Giovannella, S.; Happacher, F.; Iliescu, M.; Martini, M.; Miscetti, S.; Nguyen, F.; Passeri, A.; Prokofiev, A.; Sciascia, B.

2009-01-01

The overall detection efficiency to neutrons of a small prototype of the KLOE lead-scintillating fiber calorimeter has been measured at the neutron beam facility of The Svedberg Laboratory, TSL, Uppsala, in the kinetic energy range [5-175] MeV. The measurement of the neutron detection efficiency of a NE110 scintillator provided a reference calibration. At the lowest trigger threshold, the overall calorimeter efficiency ranges from 30% to 50%. This value largely exceeds the estimated 8-15% expected if the response were proportional only to the scintillator equivalent thickness. A detailed simulation of the calorimeter and of the TSL beam line has been performed with the FLUKA Monte Carlo code. First data-MC comparisons are encouraging and allow to disentangle a neutron halo component in the beam.

Design and implementation of the control system for neutron reflectometer

International Nuclear Information System (INIS)

Wu Xuehui; Fu Yongli; Zhou Aiyu; Zhu Kejun; Yuan Guangcui

2011-01-01

The neutron reflectometry is an important technique that has widespread applications as a powerful analytical tool to analyze the surface and interfacial structure and composition of many materials. An efficient and accurate instrument control system is a key component of the system, with software based on LabVIEW and hardware based on PCI-1240 motor control card, TRUMP-PCI-2K multichannel buffer card and 974 counter/timer. It gives an overview of the design and implementation of this control system. The results prove that this system fulfills the needs well with high stability and operability. (authors)

Wind tunnel tests of stratospheric airship counter rotating propellers

Directory of Open Access Journals (Sweden)

Yaxi Chen

2015-01-01

Full Text Available Aerodynamic performance of the high-altitude propeller, especially the counter rotation effects, is experimentally studied. Influences of different configurations on a stratospheric airship, included 2-blade counter-rotating propeller (CRP, dual 2-blade single rotation propellers (SRPs and 4-blade SRP, are also indicated. This research indicates that the effect of counter rotation can greatly improve the efficiency. It shows that the CRP configuration results in a higher efficiency than the dual 2-blade SRPs configuration or 4-blade SRP configuration under the same advance ratio, and the CRP configuration also gains the highest efficiency whether under the situation of providing the same trust or absorbing the same power. It concludes that, for a stratospheric airship, the CRP configuration is better than the multiple SRPs configuration or a multi-blade SRP one.

Facile synthesis of nitrogen-doped reduced graphene oxide as an efficient counter electrode for dye-sensitized solar cells

Science.gov (United States)

Wei, Liguo; Wang, Ping; Yang, Yulin; Luo, Ruidong; Li, Jinqi; Gu, Xiaohu; Zhan, Zhaoshun; Dong, Yongli; Song, Weina; Fan, Ruiqing

2018-04-01

A nitrogen-doped reduced graphene oxide (N-RGO) nanosheet was synthesized by a simple hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electrode microscopy. After being deposited as counter electrode film for dye-sensitized solar cells (DSSCs), it is found that the synthesized N-RGO nanosheet has smaller charge-transfer resistance and better electrocatalytic activity towards reduction of triiodide than the reduced graphene oxide (RGO) nanosheet. Consequently, the DSSCs based on the N-RGO counter electrode achieve an energy conversion efficiency of 4.26%, which is higher than that of the RGO counter electrode (2.85%) prepared under the same conditions, and comparable to the value (5.21%) obtained with the Pt counter electrode as a reference. This N-RGO counter electrode offers the advantages of not only saving the cost of Pt itself but also simplifying the process of counter electrode preparation. Therefore, an inexpensive N-RGO nanosheet is a promising counter electrode material to replace noble metal Pt. [Figure not available: see fulltext.

Analysis of neutron propagation from the skyshine port of a fusion neutron source facility

Energy Technology Data Exchange (ETDEWEB)

Wakisaka, M. [Hokkaido University, Kita-8, Nishi-5, Kita-ku, Sapporo 080-8628 (Japan); Kaneko, J. [Hokkaido University, Kita-8, Nishi-5, Kita-ku, Sapporo 080-8628 (Japan)]. E-mail: kin@qe.eng.hokudai.ac.jp; Fujita, F. [Hokkaido University, Kita-8, Nishi-5, Kita-ku, Sapporo 080-8628 (Japan); Ochiai, K. [Japan Atomic Energy Institute, Tokai-mura, Ibaraki-ken 319-1195 (Japan); Nishitani, T. [Japan Atomic Energy Institute, Tokai-mura, Ibaraki-ken 319-1195 (Japan); Yoshida, S. [Tokai University, 1117 Kitakaname, Hirastuka, Kanagawa-ken 259-1292 (Japan); Sawamura, T. [Hokkaido University, Kita-8, Nishi-5, Kita-ku, Sapporo 080-8628 (Japan)

2005-12-01

The process of neutron leaking from a 14MeV neutron source facility was analyzed by calculations and experiments. The experiments were performed at the Fusion Neutron Source (FNS) facility of the Japan Atomic Energy Institute, Tokai-mura, Japan, which has a port on the roof for skyshine experiments, and a {sup 3}He counter surrounded with a polyethylene moderator of different thicknesses was used to estimate the energy spectra and dose distributions. The {sup 3}He counter with a 3-cm-thick moderator was also used for dose measurements, and the doses evaluated by the counter counts and the calculated count-to-dose conversion factor agreed with the calculations to within {approx}30%. The dose distribution was found to fit a simple analytical expression, D(r)=Q{sub D}exp(-r/{lambda}{sub D})r and the parameters Q{sub D} and {lambda}{sub D} are discussed.

Position-sensitive proportional counters using resistance-capacitance position encoding

International Nuclear Information System (INIS)

Kopp, M.K.; Borkowski, C.J.

1975-12-01

A new method was developed for encoding the position of individual photons, neutrons, or charged particles in proportional counters by using the distributed RC line characteristics of these counters. The signal processing is described and guidelines for the design and operation of these position sensitive proportional counters (PSPCs) are given. Using these guidelines, several prototypic PSPCs were constructed to improve the spatial resolution and shorten the signal processing time; for example, the intrinsic spatial uncertainty was reduced to 28 μ fwhm for alpha particles and 100 μ fwhm for low-energy x rays (2 to 6 keV). Also, the signal processing time was reduced to 0.6 μsec without seriously degrading the spatial resolution. These results have opened new fields of application of the RC position encoding method in imaging distributions of photons, charged particles, or neutrons in nuclear medicine, physics, and radiography

High Brightness Neutron Source for Radiography. Final report

International Nuclear Information System (INIS)

Cremer, J.T.; Piestrup, Melvin A.; Gary, Charles K.; Harris, Jack L.; Williams, David J.; Jones, Glenn E.; Vainionpaa, J.H.; Fuller, Michael J.; Rothbart, George H.; Kwan, J.W.; Ludewigt, B.A.; Gough, R.A.; Reijonen, Jani; Leung, Ka-Ngo

2008-01-01

This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

High-Dose Neutron Detector Development Using ¹⁰B Coated Cells

Energy Technology Data Exchange (ETDEWEB)

Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henzlova, Daniela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-11-08

During FY16 the boron-lined parallel-plate technology was optimized to fully benefit from its fast timing characteristics in order to enhance its high count rate capability. To facilitate high count rate capability, a novel fast amplifier with timing and operating properties matched to the detector characteristics was developed and implemented in the 8” boron plate detector that was purchased from PDT. Each of the 6 sealed-cells was connected to a fast amplifier with corresponding List mode readout from each amplifier. The FY16 work focused on improvements in the boron-10 coating materials and procedures at PDT to significantly improve the neutron detection efficiency. An improvement in the efficiency of a factor of 1.5 was achieved without increasing the metal backing area for the boron coating. This improvement has allowed us to operate the detector in gamma-ray backgrounds that are four orders of magnitude higher than was previously possible while maintaining a relatively high counting efficiency for neutrons. This improvement in the gamma-ray rejection is a key factor in the development of the high dose neutron detector.

Neutron spin echo and high resolution inelastic spectroscopy

International Nuclear Information System (INIS)

Mezei, F.; Hungarian Academy of Sciences, Budapest. Central Research Inst. for Physics)

1982-01-01

The principles of neutrons spin echo (NSE) technique are considered. It is shown that the basis of NSE principle is a single step measurement of the change of the neutron velocity in the scattering process. The backscattering soectroscopy and the NSE techniques are compared. The NSF spectrometer is described. It is shown that 0.5 MeV energy resolution achieved in the NSE experiment is about 40 times superior to those achieved by the other techniques. The NSE technique has the unique feature that provides high resolution in neutron energy change independently of the monochromatization of the beam. The NSE instrument not only covers a wider dynamic range on a pulsed source that on a continuous one, but also collects data more efficiently

Calibration and automatic counting in a neutrons dosimeter

International Nuclear Information System (INIS)

Tavera-Davila, M.L.

1991-01-01

Over the past decade, the majority of improvements in spectrometry have not come from improved detectors but from better computing facilities, in Folding codes, and nuclear data. However several types of passive neutron detectors have the potential for development into crude, low resolution spectrometers, to be worn by individuals, making them attractive to be subject of more time of investigation. This thesis contributes to the understanding of the properties of solid state nuclear tracks (SSNTD) in order to use them in neutron dosimetry and spectrometry. In the first chapter the basic principles on neutron interaction with matter and some relevant considerations about detection and dosimetry are presented. The third chapter deals with detection properties of solid state nuclear track detectors (SSNTD). Calibration methods are presented for three different applications, detection of heavy ions, radon and neutrons. In chapter 4, some equations are derived which predict the whole efficiency formation of thin plastic detectors as a function of range, angle, and type of inciding particle as well as residual thickness. Using experimental data on proton registration properties in thin plastic detectors and the former derived equations, mathematical expressions are developed to predict the sparking counting efficiency for recoll protons and trions produced by neutrons in SSNTD. Chapter five deals with the comparison between experimental results and theoretical results of chapter 4. In chapter 6 experimental optimum parameters for electrochemical etching of thin plastic detectors are presented. The electrochemical etching efficiency is compared with the spark countering efficiency obtained in chapter 5. In chapter 7, general comments on applications to neutron dosimetry are presented. (Author)

Responses of conventional and extended-range neutron detectors in mixed radiation fields around a 150-MeV electron LINAC

International Nuclear Information System (INIS)

Lin, Yu-Chi; Sheu, Rong-Jiun; Chen, Ang-Yu

2015-01-01

This study analyzed the responses of two types of neutron detector in mixed gamma-ray and neutron radiation fields around a 150-MeV electron linear accelerator (LINAC). The detectors were self-assembled, high efficiency, and designed in two configurations: (1) a conventional moderated-type neutron detector based on a large cylindrical He-3 proportional counter; and (2) an extended-range version with an embedded layer of lead in the moderator to increase the detector’s sensitivity to high-energy neutrons. Two sets of the detectors were used to measure neutrons at the downstream and lateral locations simultaneously, where the radiation fields differed considerably in intensities and spectra of gamma rays and neutrons. Analyzing the detector responses through a comparison between calculations and measurements indicated that not only neutrons but also high-energy gamma rays (>5 MeV) triggered the detectors because of photoneutrons produced in the detector materials. In the lateral direction, the contribution of photoneutrons to both detectors was negligible. Downstream of the LINAC, where high-energy photons were abundant, photoneutrons contributed approximately 6% of the response of the conventional neutron detector; however, almost 50% of the registered counts of the extended-range neutron detector were from photoneutrons because of the presence of the detector rather than the effect of the neutron field. Dose readings delivered by extended-range neutron detectors should be interpreted cautiously when used in radiation fields containing a mixture of neutrons and high-energy gamma rays

The Neutron Spectrometry System Using 3He Counter

International Nuclear Information System (INIS)

Dang Lanh; Pham Ngoc Tuan; Tuong Thi Thu Huong; Nguyen Nhi Dien; Nguyen Van Hung

2011-01-01

A spectrometry system was designed for neutron counting at the horizontal channels of Dalat nuclear reactor. The system is able to interface to PC via EZ-USB with full speed. The designed system can be installed for operation not only at the channel No. 4 of the reactor, but also operated with the neutron Howitzer system installed at the Training Center of Nuclear Research Institute for training purposes. Almost results can be achieved effectively while choosing the shaping time of 2 μs of amplifier unit; and an appropriate preamplifier is used to measure neutron spectra. In this work, the multi-channel spectrometer for measuring neutron was designed and tested. (author)

Effect of high gamma background on neutron sensitivity of fission detectors

International Nuclear Information System (INIS)

Balagi, V.; Prasad, K.R.; Kataria, S.K.

2004-01-01

Tests were performed on two parallel plate and two cylindrical fission detectors in pulse and dc mode. The effect of gamma background on neutron sensitivity was studied in thermal neutron flux from 30 nv to 60 nv over which gamma field intensity ranging from 230 kR/h to 3.7 MR/h was superposed. In the case of one of the parallel plate detectors the fall in neutron sensitivity was observed to be 3.7% at 1 MR/h and negligible below 1 MR/h. In the case of one of the cylindrical counters the fall in neutron sensitivity was negligible below 500 kR/h and 37% at 1 MR/h. The data was used to derive the design parameters for a wide range fission detector to be procured for PFBR instrumentation for operation at 600 degC and gamma background of 1 MR/h. (author)

Measurement of radiation skyshine with D-T neutron source

Energy Technology Data Exchange (ETDEWEB)

Yoshida, S.; Nishitani, T. E-mail: nisitani@naka.jaeri.go.jp; Ochiai, K.; Kaneko, J.; Hori, J.; Sato, S.; Yamauchi, M.; Tanaka, R.; Nakao, M.; Wada, M.; Wakisaka, M.; Murata, I.; Kutsukake, C.; Tanaka, S.; Sawamura, T.; Takahashi, A

2003-09-01

The D-T neutron skyshine experiments have been carried out at the Fusion Neutronics Source (FNS) of JAERI with the neutron yield of {approx}1.7x10{sup 11} n/s. The concrete thickness of the roof and the wall of a FNS target room are 1.15 and 2 m, respectively. The FNS skyshine port with a size of 0.9x0.9 m{sup 2} was open during the experimental period. The radiation dose rate outside the target room was measured a maximum distance of 550 m from the D-T target point with a spherical rem-counter. Secondary gamma-rays were measured with high purity Ge detectors and NaI scintillation counters. The highest neutron dose was about 9x10{sup -22} Sv/(source neutron) at a distance of 30 m from the D-T target point and the dose rate was attenuated to 4x10{sup -24} Sv/(source neutron) at a distance of 550 m. The measured neutron dose distribution was analyzed with Monte Carlo code MCNP-4B and a simple line source model. The MCNP calculation overestimates the neutron dose in the distance range larger than 230 m. The line source model agrees well with the experimental results within the distance of 350 m.

Cerenkov counting and Cerenkov-scintillation counting with high refractive index organic liquids using a liquid scintillation counter

International Nuclear Information System (INIS)

Wiebe, L.I.; Helus, F.; Maier-Borst, W.

1978-01-01

18 F and 14 C radioactivity was measured in methyl salicylate (MS), a high refractive index hybrid Cherenkov-scintillation generating medium, using a liquid scintillation counter. At concentrations of up to 21.4%, in MS, dimethyl sulfoxide (DMSO) quenched 14 C fluorescence, and with a 10-fold excess of DMSO over MS, 18 F count rates were reduced below that for DMSO alone, probably as a result of concentration-independent self-quenching due to 'dark-complex' formation. DMSO in lower concentrations did not reduce the counting efficiency of 18 F in MS. Nitrobenzene was a concentration-dependent quencher for both 14 C and 18 F in MS. Chlorobenzene (CB) and DMSO were both found to be weak Cherenkov generators with 18 F. Counting efficiencies for 18 F in MS, CB, and DMSO were 50.3, 7.8 and 4.3% respectively in the coincidence counting mode, and 58.1, 13.0 and 6.8% in the singles mode. 14 C efficiencies were 14.4 and 22.3% for coincidence and singles respectively, and 15.3 and 42.0% using a modern counter designed for coincidence and single photon counting. The high 14 C and 18 F counting efficiency in MS are discussed with respect to excitation mechanism, on the basis of quench and channels ratios changes observed. It is proposed that MS functions as an efficient Cherenkov-scintillation generator for high-energy beta emitters such as 18 F, and as a low-efficiency scintillator for weak beta emitting radionuclides such as 14 C. (author)

Absolute calibration of TFTR helium proportional counters

International Nuclear Information System (INIS)

Strachan, J.D.; Diesso, M.; Jassby, D.; Johnson, L.; McCauley, S.; Munsat, T.; Roquemore, A.L.; Loughlin, M.

1995-06-01

The TFTR helium proportional counters are located in the central five (5) channels of the TFTR multichannel neutron collimator. These detectors were absolutely calibrated using a 14 MeV neutron generator positioned at the horizontal midplane of the TFTR vacuum vessel. The neutron generator position was scanned in centimeter steps to determine the collimator aperture width to 14 MeV neutrons and the absolute sensitivity of each channel. Neutron profiles were measured for TFTR plasmas with time resolution between 5 msec and 50 msec depending upon count rates. The He detectors were used to measure the burnup of 1 MeV tritons in deuterium plasmas, the transport of tritium in trace tritium experiments, and the residual tritium levels in plasmas following 50:50 DT experiments

Scintillation Counters for Neutron Scattering Experiments; Compteurs a scintillations pour les experiences de diffusion neutronique; Stsintillyatsionnye schetchiki dlya ehksperimentov s rasseyaniem nejtronov; Contadores de centelleo para experimentos de dispersion neutronica.

Energy Technology Data Exchange (ETDEWEB)

Harris, D; Duffil, C [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada); Wraight, L A [Aere, Harwell, Didcot, Berks (United Kingdom)

1963-01-15

Scintillation counters discussed in this paper are of two types : (i) UP or B{sub 2}O{sub 3} fixed with zinc sulphide in varving composition, (ii) Li containing glasses of varying composition. The ideal composition of each rype for neutron scattering experiments and their relative sensitivity tae neutrons and {gamma}-rays are considered. The ZnS type can be used with a {gamma}-ray pulse shape discriminator and practical experience of its use in a multi-counter time-of-flight experiment is described. The Li glass has higher {gamma}-background but also higher neutron efficiency. Performance figures of a scintillator containing 25% by wt. Li{sub 2}O and 1 mm thick will be given. (author) [French] Les compteurs a scintillations etudies sont de deux types : i) LiF ou B{sub 2}O{sub 3} fixe par du sulfure de zinc en composition variable, ii) verres contenant du lithium en composition variable. Les auteurs examinent la composition ideale de chaque type de compteur pour les experiences de diffusion de neutrons, ainsi que leur sinsibilite rrelative aux neutrons et aux rayons gamma. On peut utiliser le compteur a ZnS avec un discriminates de forme pour rayons gamma; les auteurs decrivent l'experience qu'ils ont de son emploi dans une experience de temps de vol a plusieurs compteurs. Le compteur verre-Li a un mouvement propre plus eleve pour les rayons gamma mais une meilleure efficacite vis-a-vis des neutrons. Les auteurs donnent quelques chiffres concernant le fonctionnement d'un scintillateur contenant 25% en poids de Li{sub 2}O et ayant une epaisseur de un millimetre. (author) [Spanish] Los contadores de centelleo examinados en esta memoria son de dos tipos : a) de LiF o B{sub 2}O{sub 3} mezclado con sulfuro de cinc en proporciones variables; b) de vidrios litiados de diversas composiciones. Los autores estudian la composicion ideal de cada tipo para experimentos de dispersion neutronica, asi como su sensibilidad relativa a los neutrones y a los rayos gamma. El tio de Zn

A neutron multiplicity analysis method for uranium samples with liquid scintillators

Energy Technology Data Exchange (ETDEWEB)

Zhou, Hao, E-mail: zhouhao_ciae@126.com [China Institute of Atomic Energy, P.O.BOX 275-8, Beijing 102413 (China); Lin, Hongtao [Xi' an Reasearch Institute of High-tech, Xi' an, Shaanxi 710025 (China); Liu, Guorong; Li, Jinghuai; Liang, Qinglei; Zhao, Yonggang [China Institute of Atomic Energy, P.O.BOX 275-8, Beijing 102413 (China)

2015-10-11

A new neutron multiplicity analysis method for uranium samples with liquid scintillators is introduced. An active well-type fast neutron multiplicity counter has been built, which consists of four BC501A liquid scintillators, a n/γdiscrimination module MPD-4, a multi-stop time to digital convertor MCS6A, and two Am–Li sources. A mathematical model is built to symbolize the detection processes of fission neutrons. Based on this model, equations in the form of R=F*P*Q*T could be achieved, where F indicates the induced fission rate by interrogation sources, P indicates the transfer matrix determined by multiplication process, Q indicates the transfer matrix determined by detection efficiency, T indicates the transfer matrix determined by signal recording process and crosstalk in the counter. Unknown parameters about the item are determined by the solutions of the equations. A {sup 252}Cf source and some low enriched uranium items have been measured. The feasibility of the method is proven by its application to the data analysis of the experiments.

A highly efficient parallel algorithm for solving the neutron diffusion nodal equations on shared-memory computers

International Nuclear Information System (INIS)

Azmy, Y.Y.; Kirk, B.L.

1990-01-01

Modern parallel computer architectures offer an enormous potential for reducing CPU and wall-clock execution times of large-scale computations commonly performed in various applications in science and engineering. Recently, several authors have reported their efforts in developing and implementing parallel algorithms for solving the neutron diffusion equation on a variety of shared- and distributed-memory parallel computers. Testing of these algorithms for a variety of two- and three-dimensional meshes showed significant speedup of the computation. Even for very large problems (i.e., three-dimensional fine meshes) executed concurrently on a few nodes in serial (nonvector) mode, however, the measured computational efficiency is very low (40 to 86%). In this paper, the authors present a highly efficient (∼85 to 99.9%) algorithm for solving the two-dimensional nodal diffusion equations on the Sequent Balance 8000 parallel computer. Also presented is a model for the performance, represented by the efficiency, as a function of problem size and the number of participating processors. The model is validated through several tests and then extrapolated to larger problems and more processors to predict the performance of the algorithm in more computationally demanding situations

Fast neutron flux and intracranial dose distribution at a neutron irradiation facility

International Nuclear Information System (INIS)

Matsumoto, Tetsuo; Aizawa, Otohiko; Nozaki, Tetsuya

1981-01-01

A head phantom filled with water was used to measure the fast neutron flux using 115 In(n, n')sup(115m)In and 103 Rh(n, n')sup(103m)Rh reactions. γ-ray from sup(115m)In and x-ray from sup(103m)Rh were detected by a Ge(Li) and a Na(Tl)I counter, respectively. TLD was used to investigate the γ-dose rate distribution inside the phantom. Flux of fast neutron inside the phantom was about 1 x 10 6 n/cm 2 sec, which was 3 order smaller than that of thermal neutron. The fast neutron flux decreased to 1/10 at 15 cm depth, and γ-dose rate was about 200 R/h at 100 kW inside the phantom. Total dose at the surface was 350 rad/h, to which, fast neutrons contributed more than γ-rays. The rate of fast neutron dose was about 10% of thermal neutron's in Kerma dose unit (rad), however, the rate was highly dependent on RBE value. (Nakanishi, T.)

Enriched Boron-Doped Amorphous Selenium Based Position-Sensitive Solid-State Thermal Neutron Detector for MPACT Applications

Energy Technology Data Exchange (ETDEWEB)

Mandal, Krishna [Univ. of South Carolina, Columbia, SC (United States)

2017-09-29

High-efficiency thermal neutron detectors with compact size, low power-rating and high spatial, temporal and energy resolution are essential to execute non-proliferation and safeguard protocols. The demands of such detector are not fully covered by the current detection system such as gas proportional counters or scintillator-photomultiplier tube combinations, which are limited by their detection efficiency, stability of response, speed of operation, and physical size. Furthermore, world-wide shortage of ³He gas, required for widely used gas detection method, has further prompted to design an alternative system. Therefore, a solid-state neutron detection system without the requirement of ³He will be very desirable. To address the above technology gap, we had proposed to develop new room temperature solidstate thermal neutron detectors based on enriched boron (¹⁰B) and enriched lithium (⁶Li) doped amorphous Se (As- 0.52%, Cl 5 ppm) semiconductor for MPACT applications. The proposed alloy materials have been identified for its many favorable characteristics - a wide bandgap (~2.2 eV at 300 K) for room temperature operation, high glass transition temperature (t_g ~ 85°C), a high thermal neutron cross-section (for boron ~ 3840 barns, for lithium ~ 940 barns, 1 barn = 10^-24 cm²), low effective atomic number of Se for small gamma ray sensitivity, and high radiation tolerance due to its amorphous structure.

The n,{gamma} discrimination in recoil-proton proportional counters. Application to the measurement of fast neutron spectra; Discrimination n,{gamma} dans les compteurs proportionnels a protons de recul. Application a la mesure des spectres de neutrons rapides

Energy Technology Data Exchange (ETDEWEB)

Jeandidier, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

A description is given of a spectrometry chain working in the energy range of a few keV to 1 MeV, and designed for measurement of fast neutron spectra. It consists of detectors, recoil proton proportional counters built especially for this work by R. COMTE (DEG/SER) and which make it possible to cover the energy range and also associated electronic equipment. A brief description is first given of the physical processes involved: (n,p) collisions in the gas, influence of {gamma} radiation; the method of discrimination is then presented. It is based on the difference in the rise-times of the pulses. In the experiments described here the use of a bi-parametric system made it possible to employ the most simple discrimination device, based on the fact that the high frequency gamma pulse components are, at a given energy, weaker than those of the neutron pulses. Results are given of measurements carried out on the Van der Graaff (mono-energetic neutrons for testing the linearity of the chain and the resolving power of the counters), and of those made in a sub-critical system Hug at Cadarache. (author) [French] On decrit une chaine de spectrometrie travaillant dans le domaine d'energie de quelques keV a 1 MeV destinee a la mesure des spectres de neutrons rapides. Elle comprend les detecteurs, compteurs proportionnels a protons de recul, realises specialement pour cette etude par M. R. COMTE (DEG/SER), permettant de couvrir la gamme d'energie et l'electronique associee. Apres un rappel des processus physiques mis en jeu: chocs (n,p) dans les gaz, influence des rayonnements {gamma}, on expose la methode de discrimination utilisee. Celle-ci est basee sur la difference des temps de montee des impulsions. Au cours des experiences rapportees ici, la mise en oeuvre d'un ensemble bi-parametrique a permis d'utiliser le dispositif de discrimination le plus simple, base sur la remarque que les composantes a haute frequence des impulsions {gamma} sont, a energie egale, plus faibles

The n,{gamma} discrimination in recoil-proton proportional counters. Application to the measurement of fast neutron spectra; Discrimination n,{gamma} dans les compteurs proportionnels a protons de recul. Application a la mesure des spectres de neutrons rapides

Energy Technology Data Exchange (ETDEWEB)

Jeandidier, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

A description is given of a spectrometry chain working in the energy range of a few keV to 1 MeV, and designed for measurement of fast neutron spectra. It consists of detectors, recoil proton proportional counters built especially for this work by R. COMTE (DEG/SER) and which make it possible to cover the energy range and also associated electronic equipment. A brief description is first given of the physical processes involved: (n,p) collisions in the gas, influence of {gamma} radiation; the method of discrimination is then presented. It is based on the difference in the rise-times of the pulses. In the experiments described here the use of a bi-parametric system made it possible to employ the most simple discrimination device, based on the fact that the high frequency gamma pulse components are, at a given energy, weaker than those of the neutron pulses. Results are given of measurements carried out on the Van der Graaff (mono-energetic neutrons for testing the linearity of the chain and the resolving power of the counters), and of those made in a sub-critical system Hug at Cadarache. (author) [French] On decrit une chaine de spectrometrie travaillant dans le domaine d'energie de quelques keV a 1 MeV destinee a la mesure des spectres de neutrons rapides. Elle comprend les detecteurs, compteurs proportionnels a protons de recul, realises specialement pour cette etude par M. R. COMTE (DEG/SER), permettant de couvrir la gamme d'energie et l'electronique associee. Apres un rappel des processus physiques mis en jeu: chocs (n,p) dans les gaz, influence des rayonnements {gamma}, on expose la methode de discrimination utilisee. Celle-ci est basee sur la difference des temps de montee des impulsions. Au cours des experiences rapportees ici, la mise en oeuvre d'un ensemble bi-parametrique a permis d'utiliser le dispositif de discrimination le plus simple, base sur la remarque que les composantes a haute frequence des impulsions {gamma} sont, a

Commercial bacterial colony counter for semiautomatic track counting

International Nuclear Information System (INIS)

Griffith, R.V.; McMahon, T.A.; Espinosa, G.

1983-01-01

Bacterial colony counters have not been widely used for track counting. However, they do provide an economical alternative to sophisticated optical analyzers for applications that require reproducible track density measurements for large numbers of samples. Simple measurements of size characteristics can be made when there is little need for high resolutions. Such systems are particularly well suited for neutron and alpha dosimetry work, particularly if electrochemical etching or some other track enhancement method has been used. 5 refs., 3 figs

A highly-segmented neutron detector for the A1 experiment at MAMI

Energy Technology Data Exchange (ETDEWEB)

Schoth, Matthias [Institut fuer Kernphysik, Mainz (Germany); Collaboration: A1-Collaboration

2015-07-01

Electric and magnetic form factors of the neutron, are one of the defining properties to characterize its structure quantitatively. A planned physics program to improve the data base significantly requires high performance detection of relativistic neutrons. Exploiting the full potential of the high luminosity supplied by the MAMI accelerator, a novel neutron detector is being developed in the scope of the A1 collaboration. A large active detector volume of 0.96 m{sup 3} is required to achieve a high raw detection efficiency. The detector is subdivided into 2048 plastic scintillators to be able to cope with high background rates. The light is extracted via wavelength shifting fibres and then guided to multi anode photomultiplier. The signal is read out with FPGA based TDCs (TRBv3 developed at GSI). The energy of the signal is obtained via time over threshold information in combination with a suitable shaping and discriminating circuit. Prototype tests have been performed to optimize the choice of materials and geometry. The capability to detect neutrons in the relevant momentum range has been demonstrated using pion production. A Geant4 simulation using tracking algorithms evaluating the deposited energy is able to optimize key detector properties like particle id efficiency, multiplicity or the effective analyzing power for double polarized scattering experiments.

Axle-sleeve Structured MWCNTs/Polyaniline Composite Film as Cost-effective Counter-Electrodes for High Efficient Dye-Sensitized Solar Cells

International Nuclear Information System (INIS)

Niu, Haihong; Qin, Shengxian; Mao, Xiaoli; Zhang, Shouwei; Wang, Renbao; Wan, Lei; Xu, Jinzhang; Miao, Shiding

2014-01-01

Graphical abstract: Axle-sleeve structured composite materials made with carbon nanotubes and polyaniline were prepared via a co-polymerization strategy. The composite materials were employed as cost-effective counter electrode modifier in dye-sensitized solar cells which demonstrate a comparable photo-to-electron conversion efficiency as the Pt catalyst. - Highlights: • Axle-sleeve structured MWCNT/PANI composite was prepared. • The optimum mass ratio of MWCNT/ANIranges between 1:3 and 1:1. • The π-π drive force was confirmed by spectroscopicmeans. • The polymerization time of 12∼24 hrs affords the highest conversion efficiency. • The DSSCs assembled with the MWCNTs/PANI CEs exhibit a comparable η(7.21%) as that with Pt CE (7.59%). - Abstract: Axle-sleeve structured composite materials made with multi-walled carbon nanotubes (MWCNTs) and polyaniline (PANI) were prepared, characterized, and employed as cost-effective counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The composite was synthesized by co-polymerization of aniline with carboxylated MWCNTs by using ammonium persulfate in the acidic medium. Thin films of MWCNTs/PANI were prepared via a spin coating technique followed by thermal treatment in N 2 atmosphere. The micro-structure of the composite was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) linked with energy dispersive spectroscopy (EDS). The coating layer of PANI on the MWCNTs and new-formed chemical bonds between MWCNTs and PANI was studied by UV-Vis absorption, X-ray photoelectron spectroscopy (XPS), Raman and FT-IR spectroscopic means. The effect of the multiple-level porosity or the axle-sleeve structures in the composite of MWCNTs/PANI on the electro-catalytic activity was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopic (EIS) analysis. The DSSCs assembled with MWCNTs/PANI as CEs exhibit a comparable energy conversion efficiency (η) of 7

Aerogel Cherenkov Counters of the KEDR Detector

CERN Document Server

Ovtin, I V; Barnyakov, M Y; Bobrovnikov, V S; Buzykaev, A R; Danilyuk, A F; Katcin, A A; Kononov, S A; Kravchenko, E A; Kuyanov, I A; Onuchin, A P; Rodiakin, V A

2017-01-01

The particle identification system of the KEDR detector is based on aerogel threshold Cherenkov counters called ASHIPH counters. The system consists of 160 counters arranged in two layers. An event reconstruction program for the ASHIPH system was developed. The position of each counter relative to the tracking system was determined using cosmic muons and Bhabha events. The geometric efficiency of the ASHIPH system was verified with Bhabha events. The efficiency of relativistic particle detection was measured with cosmic muons. A π/K separation of 4δ in the momentum range 0.95 −1.45 GeV/c was confirmed. A simulation program for the ASHIPH counters has been developed.

Standardization of portable assay instrumentation: the neutron-coincidence tree

International Nuclear Information System (INIS)

Menlove, H.O.

1983-01-01

Standardization of portable neutron assay instrumentation has been achieved by using the neutron coincidence technique as a common basis for a wide range of instruments and applications. The electronics originally developed for the High-Level Neutron Coincidence Counter has been adapted to both passive- and active-assay instrumentation for field verification of bulk plutonium, inventory samples, pellets, powders, nitrates, high-enriched uranium, and materials-testing-reactor, light-water-reactor, and mixed-oxide fuel assemblies. The family of detectors developed at Los Alamos National Laboratory and their performance under in-field conditions are described. 16 figures, 3 tables

Investigation of the Pulse Height Distribution of Boron Trifluoride Proportional Counters

Energy Technology Data Exchange (ETDEWEB)

Andersson, I Oe; Malmskog, S

1962-08-15

The report describes a theoretical and experimental investigation of the factors that determine the pulse height distribution of BF{sub 3}, proportional counters irradiated by thermal neutrons. The branching ratio of the {sup 10}B (n,{alpha}) {sup 7}Li reaction for thermal neutrons has been measured.

Stabilization of the photomultiplier gain of a liquid scintillation counter

International Nuclear Information System (INIS)

Alkhazov, I.D.; Dmitriev, V.D.; Kuznetsov, A.V.; Malkin, L.Z.; Petrov, B.F.; Sheremet'ev, A.K.; Shpakov, V.I.

1987-01-01

A stabilization system of photomultiplier gain, where light-emitting diode flashes have been used to obtain a reference signal, is described. The diode is placed just in the liquid scintilllator volume. The stabilization system contains several (according to the number of photomultipliers) identical channels, which of them consists of a colorimeter, a control trigger and an integrator with an operational amplifier. Increase of photomultiplier stability is reached by changing voltage of photomultiplier power according to the reference signal amplitude. The level of background and efficiency of neutron detection by a scintillation counter are unchanged when using the stabilization system for 10 days of measurements

Cerenkov counting and Cerenkov-scintillation counting with high refractive index organic liquids using a liquid scintillation counter

Energy Technology Data Exchange (ETDEWEB)

Wiebe, L I; Helus, F; Maier-Borst, W [Deutsches Krebsforschungszentrum, Heidelberg (Germany, F.R.). Inst. fuer Nuklearmedizin

1978-06-01

/sup 18/F and /sup 14/C radioactivity was measured in methyl salicylate (MS), a high refractive index hybrid Cherenkov-scintillation generating medium, using a liquid scintillation counter. At concentrations of up to 21.4%, in MS, dimethyl sulfoxide (DMSO) quenched /sup 14/C fluorescence, and with a 10-fold excess of DMSO over MS, /sup 18/F count rates were reduced below that for DMSO alone, probably as a result of concentration-independent self-quenching due to 'dark-complex' formation. DMSO in lower concentrations did not reduce the counting efficiency of /sup 18/F in MS. Nitrobenzene was a concentration-dependent quencher for both /sup 14/C and /sup 18/F in MS. Chlorobenzene (CB) and DMSO were both found to be weak Cherenkov generators with /sup 18/F. Counting efficiencies for /sup 18/F in MS, CB, and DMSO were 50.3, 7.8 and 4.3% respectively in the coincidence counting mode, and 58.1, 13.0 and 6.8% in the singles mode. /sup 14/C efficiencies were 14.4 and 22.3% for coincidence and singles respectively, and 15.3 and 42.0% using a modern counter designed for coincidence and single photon counting. The high /sup 14/C and /sup 18/F counting efficiency in MS are discussed with respect to excitation mechanism, on the basis of quench and channels ratios changes observed. It is proposed that MS functions as an efficient Cherenkov-scintillation generator for high-energy beta emitters such as /sup 18/F, and as a low-efficiency scintillator for weak beta emitting radionuclides such as /sup 14/C.

NiO-NF/MWCNT nanocomposite catalyst as a counter electrode for high performance dye-sensitized solar cells

International Nuclear Information System (INIS)

Raissan Al-bahrani, Majid; Liu, Linfeng; Ahmad, Waqar; Tao, Jiayou; Tu, Fanfan; Cheng, Ze; Gao, Yihua

2015-01-01

Highlights: • High-performance NiO-NF/MWCNT CE was incorporated in a Pt-CE in DSSCs. • NiO-NF/MWCNT CE exhibits a high power conversion efficiency (PCE) of 7.63%. • NiO-NF/MWCNT composite has a high catalytic activity for the reduction of I 3 − . • NiO-NF/MWCNT composite has a low R ct on the electrolyte/CE interface. - Abstract: In this paper, we fabricated nickel oxide nanofilament/multiwall carbon nanotubes (NiO-NF/MWCNT) nanocomposite by a simple hydrothermal synthesis method as a counter- electrode (CE) in a dye-sensitized solar cell (DSSC). Transmission electron microscopy, scanning electron microscopy images and X-ray diffraction analysis clearly indicated the formation of NiO-NF/MWCNT nanocomposite. The electro-chemical properties of NiO-NF/MWCNT CE are studied by cyclic voltammetry and electrochemical impedance spectroscopy. In particular, current-voltage measurements indicated superior power conversion efficiency (PCE) of 7.63% of the NiO-NF/MWCNT CE compared to 6.72% for the platinum (Pt). The superior photovoltaic performance and low cost of the NiO-NF/MWCNT nanocomposite can be potentially exploited as a new counter-electrode in DSSCs

Absolute efficiency calibration of 6LiF-based solid state thermal neutron detectors

Science.gov (United States)

Finocchiaro, Paolo; Cosentino, Luigi; Lo Meo, Sergio; Nolte, Ralf; Radeck, Desiree

2018-03-01

The demand for new thermal neutron detectors as an alternative to 3He tubes in research, industrial, safety and homeland security applications, is growing. These needs have triggered research and development activities about new generations of thermal neutron detectors, characterized by reasonable efficiency and gamma rejection comparable to 3He tubes. In this paper we show the state of the art of a promising low-cost technique, based on commercial solid state silicon detectors coupled with thin neutron converter layers of 6LiF deposited onto carbon fiber substrates. A few configurations were studied with the GEANT4 simulation code, and the intrinsic efficiency of the corresponding detectors was calibrated at the PTB Thermal Neutron Calibration Facility. The results show that the measured intrinsic detection efficiency is well reproduced by the simulations, therefore validating the simulation tool in view of new designs. These neutron detectors have also been tested at neutron beam facilities like ISIS (Rutherford Appleton Laboratory, UK) and n_TOF (CERN) where a few samples are already in operation for beam flux and 2D profile measurements. Forthcoming applications are foreseen for the online monitoring of spent nuclear fuel casks in interim storage sites.

Neutronics of pulsed spallation neutron sources

International Nuclear Information System (INIS)

Watanabe, Noboru

2003-01-01

Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, poisoning, etc are discussed, aiming at a high performance pulsed spallation source

Passive neutron coincidence counting with plastic scintillators for the characterization of radioactive waste drums

Energy Technology Data Exchange (ETDEWEB)

Deyglun, C.; Simony, B.; Perot, B.; Carasco, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Saurel, N.; Colas, S. [CEA, DAM, Valduc, F-21120 Is-sur-Tille (France); Collot, J. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Grenoble Alpes, CNRS/IN2P3, Grenoble (France)

2015-07-01

The quantification of radioactive material is essential in the fields of safeguards, criticality control of nuclear processes, dismantling of nuclear facilities and components, or radioactive waste characterization. The Nuclear Measurement Laboratory (LMN) of CEA is involved in the development of time-correlated neutron detection techniques using plastic scintillators. Usually, 3He proportional counters are used for passive neutron coincidence counting owing to their high thermal neutron capture efficiency and gamma insensitivity. However, the global {sup 3}He shortage in the past few years has made these detectors extremely expensive. In addition, contrary to {sup 3}He counters for which a few tens of microseconds are needed to thermalize fast neutrons, in view to maximize the {sup 3}He(n,p){sup 3}H capture cross section, plastic scintillators are based on elastic scattering and therefore the light signal is formed within a few nanoseconds, correlated pulses being detected within a few dozen- or hundred nanoseconds. This time span reflects fission particles time of flight, which allows reducing accordingly the duration of the coincidence gate and thus the rate of random coincidences, which may totally blind fission coincidences when using {sup 3}He counters in case of a high (α,n) reaction rate. However, plastic scintillators are very sensitive to gamma rays, requiring the use of a thick metallic shield to reduce the corresponding background. Cross talk between detectors is also a major issue, which consists on the detection of one particle by several detectors due to elastic or inelastic scattering, leading to true but undesired coincidences. Data analysis algorithms are tested to minimize cross-talk in simultaneously activated detectors. The distinction between useful fission coincidences and the correlated background due to cross-talk, (α,n) and induced (n,2n) or (n,n'γ) reactions, is achieved by measuring 3-fold coincidences. The performances of a

A programme for Euratom safeguards inspectors, used in the assay of high enriched (H.E.U.) and low enriched (L.E.U.) uranium fuel materials by active neutron interrogation

International Nuclear Information System (INIS)

Vocino, V.; Farese, N.; Maucq, T.; Nebuloni, M.

1991-01-01

The programme AECC (Active Euratom Coincidence Counters) has been developed at the Joint Research Center, Ispra by the Euratom Safeguards Directorate, Luxembourg and the Safety Technology Institute, Ispra for the acquisition, evaluation, management and storage of measurement data originating from active neutron interrogation of HEU and LEU fuel materials. The software accommodates the implementation of the NDA (Non Destructive Assay) procedures for the Active Well Coincidence Counters and Active Neutron Coincidence Counters deployed by the Euratom Safeguards Directorate, Luxembourg

Efficiency determination of whole-body counters by Monte Carlo method, using a microcomputer

International Nuclear Information System (INIS)

Fernandes Neto, J.M.

1987-01-01

A computing program using Monte Carlo method for calculate the whole efficiency of distributed radiation counters in human body is developed. A simulater of human proportions was used, of which was filled with a known and uniform solution containing a quantity of radioisopes. The 99m Tc, 131 I and 42 K were used in this experience, and theirs activities compared by a liquid scintillator. (C.G.C.) [pt

The Micro Trench Gas Counter

International Nuclear Information System (INIS)

Schmitz, J.

1991-07-01

A novel design is presented for a gas avalanche chamber with micro-strip gas readout. While existing gaseous microstrip detectors (Micro-strip Gas Counters, Knife edge chambers) have a minimum anode pitch of the order of 100 μm, the pitch of the discussed Micro Trench Gas Counter goes down to 30-50 μm. This leads to a better position resolution and two track separation, and a higher radiation resistivity. Its efficiency and signal speed are expected to be the same as the Microstrip Gas Counter. The energy resolution of the device is expected to be equal to or better than 10 percent for the 55 Fe peak. Since the anode strip dimensions are larger than those in a MSGC, the device may be not as sensitive to discharges and mechanical damage. In this report production of the device is briefly described, and predictions on its operation are made based on electric field calculations and experience with the Microstrip Gas Counter. The authors restrict themselves to the application in High Energy Physics. (author). 10 refs.; 9 figs

Calculation of neutron radiation energy deposition distribution in subcellular parts of tissue using recombination chamber microdosimetry

International Nuclear Information System (INIS)

Golnik, N.; Zielczynski, M.

1999-01-01

Recombination chamber microdosimetry was used as an instrument for determination of local neutron radiation energy deposition distribution. The method allows to simulate of subcellular regions of tissue of the order of 70 nm in size. The results obtained qualitatively correspond to relationship between biological efficiency and neutron energy, and show regular differences of distributions achieved by the recombination method and distributions measured using tissue equivalent proportional counters (TEPC), which simulates greater tissue regions of 1 μm in size

A proportional counter for efficient backscatter Moessbauer effect spectroscopy

International Nuclear Information System (INIS)

Pawlowski, Z.; Marzec, J.; Cudny, W.; Holnicka, J.; Walentek, J.

1979-01-01

The authors present a novel gas-tight proportional counter with flat beryllium windows for backscatter Moessbauer spectroscopy. The krypton-filled counter has a geometry that approaches 2π and a resolution of 12% fwhm for the 14.4 keV line of 57 Fe, and is easy to manufacture. (Auth.)

A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

Energy Technology Data Exchange (ETDEWEB)

Saion, E.B.; Watt, D.E. (Saint Andrews Univ. (UK). Dept. of Physics); East, B.W. (Scottish Universities Research and Reactor Centre, Glasgow (UK)); Colautti, P. (Istituto Nazionale di Fisica Nucleare, Padua (Italy))

1990-01-01

A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against {gamma} ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author).

A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

International Nuclear Information System (INIS)

Saion, E.B.; Watt, D.E.; Colautti, P.

1990-01-01

A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against γ ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author)

Study of micro pixel photon counters for a high granularity scintillator-based hadron calorimeter

International Nuclear Information System (INIS)

D'Ascenzo, N.; Eggemann, A.; Garutti, E.

2007-11-01

A new Geiger mode avalanche photodiode, the Micro Pixel Photon Counter (MPPC), was recently released by Hamamatsu. It has a high photo-detection efficiency in the 420 nm spectral region. This product can represent an elegant candidate for the design of a high granularity scintillator based hadron calorimeter for the International Linear Collider. In fact, the direct readout of the blue scintillation photons with a MPPC is a feasible techological solution. The readout of a plastic scintillator by a MPPC, both mediated by the traditional wavelength shifting fiber, and directly coupled, has been systematically studied. (orig.)

Evaluation of the Neutron Detector Response for Cosmic Ray Energy Spectrum by Monte Carlo Transport Simulation

International Nuclear Information System (INIS)

Pazianotto, Mauricio T.; Carlson, Brett V.; Federico, Claudio A.; Gonzalez, Odair L.

2011-01-01

Neutrons generated by the interaction of cosmic rays with the atmosphere make an important contribution to the dose accumulated in electronic circuits and aircraft crew members at flight altitude. High-energy neutrons are produced in spallation reactions and intranuclear cascade processes by primary cosmic-ray particle interactions with atoms in the atmosphere. These neutrons can produce secondary neutrons and also undergo a moderation process due to atmosphere interactions, resulting in a wider energy spectrum, ranging from thermal energies (0.025 eV) to energies of several hundreds of MeV. The Long-Counter (LC) detector is a widely used neutron detector designed to measure the directional flux of neutrons with about constant response over a wide energy range (thermal to 20 MeV). ). Its calibration process and the determination of its energy response for the wide-energy of cosmic ray induced neutron spectrum is a very difficult process due to the lack of installations with these capabilities. The goal of this study is to assess the behavior of the response of a Long Counter using the Monte Carlo (MC) computational code MCNPX (Monte Carlo N-Particle eXtended). The dependence of the Long Counter response on the angle of incidence, as well as on the neutron energy, will be carefully investigated, compared with the experimental data previously obtained with 241 Am-Be and 252 Cf neutron sources and extended to the neutron spectrum produced by cosmic rays. (Author)

Layered semiconductor neutron detectors

Science.gov (United States)

Mao, Samuel S; Perry, Dale L

2013-12-10

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

Nickel doped cobalt sulfide as a high performance counter electrode for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Kim, Hee-Je; Kim, Chul-Woo; Punnoose, Dinah; Gopi, Chandu V.V.M.; Kim, Soo-Kyoung; Prabakar, K.; Rao, S. Srinivasa, E-mail: srinu.krs@gmail.com

2015-02-15

Graphical abstract: - Highlights: • First ever employment of Ni doped CoS{sub 2} counter electrode as a replacement of Pt counter electrode. • Efficiency of 5.50% was achieved using Ni doped CoS{sub 2} counter electrode in contrast to 5.21% efficiency obtained using Pt electrode. • Dependency of efficiency on Ni dopant reported for the first time. • Cost effective chemical bath deposition was used for the fabrication of the counter electrode. - Abstract: The use of cells based on cobalt sulfide (CoS{sub 2}) and nickel sulfide (NiS) has found a steep upsurge in solar cell applications and as a substitute for conventional Pt-based cells owing to their low cost, low-temperature processing ability, and promising electro-catalytic activity. In this study, CoS{sub 2}, NiS and Ni-doped CoS{sub 2} nanoparticles were incorporated on a fluorine-doped tin oxide (FTO) substrate by simple chemical bath deposition (CBD). The surface morphology of the obtained films was analyzed by scanning electron microscope. Tafel polarization, electrochemical impedance spectroscopy and cyclic voltammograms of the Ni-doped CoS{sub 2} (Ni 15%) films indicated enhanced electro-catalytic activity for I{sub 3}{sup −} reduction in dye sensitized solar cells (DSSCs) compared to a Pt CE. The Ni-doped CoS{sub 2} CE also showed an impressive photovoltaic conversion efficiency of 5.50% under full sunlight illumination (100 mW cm{sup −2}, AM 1.5 G), exceeding that of DSSCs using a Pt CE (5.21%). We show that the highest conversion efficiency mainly depends on the charge transfer resistance and adequate Ni ion doping with CoS{sub 2} nanoparticles.

Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

Energy Technology Data Exchange (ETDEWEB)

Roeder, M.; Cowan, T.E.; Kempe, M.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Elekes, Z. [MTA ATOMKI, Debrecen (Hungary); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T.; Caesar, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt, Darmstadt (Germany); Bemmerer, D.; Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Prokofiev, A.V. [Uppsala University, The Svedberg Laboratory, Uppsala (Sweden); Reifarth, R. [Johann Wolfgang Goethe - Universitaet, Frankfurt am Main (Germany); Zilges, A. [Universitaet zu Koeln, Koeln (Germany); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany); Collaboration: R3B Collaboration

2014-07-15

Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment. (orig.)

Body counter

International Nuclear Information System (INIS)

Koeppe, P.

1975-01-01

The paper gives a survey on some applications of the whole body counter in clinical practice and a critical study of its application as a routine testing method. Remarks on the necessary precautions are followed by a more detailed discussion of the determination of the natural potassium content, the iron metabolism, the vitamin B12 test, investigations of the metabolism of the bone using 47 Ca and 85 Sr, investigations with iodine and iodine-labelled substances, clearance investigations (in particular the 51 Cr EDTA clearance test), as well as the possibilities of neutron activation in vivo. (ORU/AK) [de

System to detect nuclear materials by active neutron method

International Nuclear Information System (INIS)

Koroev, M.; Korolev, Yu.; Lopatin, Yu.; Filonov, V.

1999-01-01

The report presents the results of the development of the system to detect nuclear materials by active neutron method measuring delayed neutrons. As the neutron source the neutron generator was used. The neutron generator was controlled by the system. The detectors were developed on the base of the helium-3 counters. Each detector consist of 6 counters. Using a number of such detectors it is possible to verify materials stored in different geometry. There is an spectrometric scintillator detector in the system which gives an additional functional ability to the system. The system could be used to estimate the nuclear materials in waste, to detect the unauthorized transfer of the nuclear materials, to estimate the material in tubes [ru

Development of a filtered neutron field in KUR. In behalf of biological irradiation experiments

International Nuclear Information System (INIS)

Sato, Takashi; Utsuro, Masahiko; Utsumi, Hiroshi

1995-07-01

Very little direct measurements have been made of the biological effects of neutrons below 100keV. Recently, an iron-filtered 24keV neutron beam of Harwell Materials Testing Reactor, PLUTO, was reported to be highly efficient in inducing chromosome aberrations; the efficiency being comparable to that of fission neutrons. This results could have serious repercussions for radiation protection standards as the ICRP assume a decrease in neutron RBE below 100keV. The investigations reported here have as their primary purpose the production of neutron beams at the 24keV iron window energy, using the B-1 experimental facility of the Kyoto University Research Reactor (KUR) at the Research Reactor Institute, Kyoto University (KURRI). The filtered neutron filed for biomedical applications is designed to maximized the contributions of neutrons with other energies and gamma-rays. The characteristics of the radiation field were obtained by the simple transmission calculations for Fe(45cm) and Al(35cm) filters, by using the Monte Carlo code MCN P, and by the measurement of nuclear heating for Fe and Al filter pieces. The 24keV neutron flux and gamma-ray dose rate were measured using a proton recoil counter and TLDs, respectively. The measured findings are as follows: The 24keV neutron flux at the irradiation field was approximately 1x10 6 n/cm 2 /s, and the gamma-ray dose rate was 1.0Gy/h at the surface of the B-1 plug. Nuclear heating of the filter materials was 5.2mW/g for Fe and 4mW/g for Al, in maximum. (author)

Data reduction for a high-throughput neutron activation analysis system

International Nuclear Information System (INIS)

Bowman, W.W.

1979-01-01

To analyze samples collected as part of a geochemical survey for the National Uranium Resource Evaluation program, Savannah River Laboratory has installed a high-throughput neutron activation analysis system. As part of that system, computer programs have been developed to reduce raw data to elemental concentrations in two steps. Program RAGS reduces gamma-ray spectra to lists of photopeak energies, peak areas, and statistical errors. Program RICHES determines the elemental concentrations from photopeak and delayed-neutron data, detector efficiencies, analysis parameters (neutron flux and activation, decay, and counting times), and spectrometric and cross-section data from libraries. Both programs have been streamlined for on-line operation with a minicomputer, each requiring approx. 64 kbytes of core. 3 tables

Three-dimensional neutron dose distribution in the environment around a 1-GeV electron synchrotron facility at INS

International Nuclear Information System (INIS)

Uwamino, Y.; Nakamura, T.

1987-01-01

The three-dimensional (surface and altitude) skyshine neutron-dose-equivalent distribution around the 1-GeV electron synchrotron (ES) of the Institute for Nuclear Study, University of Tokyo, was measured with a high-sensitivity dose-equivalent counter. The neutron spectrum in the environment was also measured with a multimoderator spectrometer incorporating a 3 He counter. The dose-equivalent distribution and the leakage neutron spectrum at the surface of the ES building were measured with a Studsvik 2202D counter and the multimoderator spectrometer, including an indium activation detector. Skyshine neutron transport calculations, beginning with the photoneutron spectrum and yielding the dose-equivalent distribution in the environment, were performed with the DOT3.5 code and two Monte Carlo codes, MMCR-2 and MMCR-3, using the DLC-87/HILO group cross sections. The calculated neutron spectra at the top surface of the concrete ceiling and at a point 111 m from the ES agreed well with the measured results, and the calculated three-dimensional dose-equivalent distribution also agreed. The dose value increased linearly with altitude, and the slope was estimated for neutron-producing facilities. (author)

Spectral correction factors for conventional neutron dose meters used in high-energy neutron environments improved and extended results based on a complete survey of all neutron spectra in IAEA-TRS-403

International Nuclear Information System (INIS)

Oparaji, U.; Tsai, Y. H.; Liu, Y. C.; Lee, K. W.; Patelli, E.; Sheu, R. J.

2017-01-01

This paper presents improved and extended results of our previous study on corrections for conventional neutron dose meters used in environments with high-energy neutrons (E n > 10 MeV). Conventional moderated-type neutron dose meters tend to underestimate the dose contribution of high-energy neutrons because of the opposite trends of dose conversion coefficients and detection efficiencies as the neutron energy increases. A practical correction scheme was proposed based on analysis of hundreds of neutron spectra in the IAEA-TRS-403 report. By comparing 252 Cf-calibrated dose responses with reference values derived from fluence-to-dose conversion coefficients, this study provides recommendations for neutron field characterization and the corresponding dose correction factors. Further sensitivity studies confirm the appropriateness of the proposed scheme and indicate that (1) the spectral correction factors are nearly independent of the selection of three commonly used calibration sources: 252 Cf, 241 Am-Be and 239 Pu-Be; (2) the derived correction factors for Bonner spheres of various sizes (6''-9'') are similar in trend and (3) practical high-energy neutron indexes based on measurements can be established to facilitate the application of these correction factors in workplaces. (authors)

Soil biological shield exposed to high energy neutrons; Zemlja kao bioloski stit od neutrona visokih energija

Energy Technology Data Exchange (ETDEWEB)

Simovic, R; Marinkovic, N [Institute of nuclear sciences Vinca, Belgrade (Yugoslavia)

1993-04-15

Shielding efficiency of soil biological shield exposed to high energy neutrons was investigated. Dose rate equivalents for neutrons, secondary gamma and gamma radiation were computed on the surface of soil slabs having different thicknesses. Yields of primary and secondary nuclear radiation in the total dose were evaluated. Influence of the incident neutron spectrum, water content and chemical composition of the material on its shielding efficiency was examined. It was found that the soil density and the water content determine the quality of biological shield, the influence of other factors being less important. Comparison of shielding efficiencies for soil with sand, brick and ordinary concrete shields was done.

A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

Energy Technology Data Exchange (ETDEWEB)

Holley, A. T.; Pattie, R. W.; Young, A. R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Broussard, L. J. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Davis, J. L.; Ito, T. M.; Lyles, J. T. M.; Makela, M.; Morris, C. L.; Mortensen, R.; Saunders, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Hickerson, K.; Mendenhall, M. P. [W. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Liu, C.-Y. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States); Mammei, R. R. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Rios, R. [Department of Physics, Idaho State University, Pocatello, Idaho 83209 (United States)

2012-07-15

The UCNA collaboration is making a precision measurement of the {beta} asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be {epsilon}=0.9985(4).

PFPF canister counter for foreign plutonium (PCAS-3) hardware operations and procedures manual

International Nuclear Information System (INIS)

Menlove, H.O.; Baca, J.; Kroncke, K.E.; Miller, M.C.; Takahashi, S.; Seki, S.; Inose, S.; Yamamoto, T.

1993-01-01

A neutron coincidence counter has been designed for the measurement of plutonium powder contained in tall storage canisters. The counter was designed for installation in the Plutonium Fuel Production Facility fabrication plant. Each canister contains from one to five cans of PuO 2 . The neutron counter measures the spontaneous-fission rate from the plutonium and, when this is combined with the plutonium isotopic ratios, the plutonium mass is determined. The system can accommodate plutonium loadings up to 12 kg, with 10 kg being a typical loading. Software has been developed to permit the continuous operation of the system in an unattended mode. Authentication techniques have been developed for the system. This manual describes the system and its operation and gives performance and calibration parameters for typical applications

Neutron shielding properties of a new high-density concrete

International Nuclear Information System (INIS)

Lorente, A.; Gallego, E.; Vega Carrillo, H.R.; Mendez, R.

2008-01-01

The neutron shielding properties of a new high-density concrete (commercially available under the name Hormirad TM , developed in Spain by the company CT-RAD) have been characterized both experimentally and by Monte Carlo calculations. The shielding properties of this concrete against photons were previously studied and the material is being used to build bunkers, mazes and doors in medical accelerator facilities with good overall results. In this work, the objective was to characterize the material behaviour against neutrons, as well as to test alternative mixings including boron compounds in an effort to improve neutron shielding efficiency. With that purpose, Hormirad TM slabs of different thicknesses were exposed to an 241 Am-Be neutron source under controlled conditions in the neutron measurements laboratory of the Nuclear Engineering Department at UPM. The original mix, which includes a high fraction of magnetite, was then modified by adding different proportions of anhydrous borax (Na 2 B 4 O 7 ). In order to have a reference against common concrete used to shield medical accelerator facilities, the same experiment was repeated with ordinary (HA-25) concrete slabs. In parallel to the experiments, Monte Carlo calculations of the experiments were performed with MCNP5. The experimental results agree reasonably well with the Monte Carlo calculations. Therefore, the first and equilibrium tenth-value layers have been determined for the different types of concrete tested. The results show an advantageous behaviour of the Hormirad TM concrete, in terms of neutron attenuation against real thickness of the shielding. Borated concretes seem less practical since they did not show better neutron attenuation with respect to real thickness and their structural properties are worse. The neutron attenuation properties of Hormirad TM for typical neutron spectra in clinical LINAC accelerators rooms have been also characterized by Monte Carlo calculation. (author)

LUPIN, a new instrument for pulsed neutron fields

Energy Technology Data Exchange (ETDEWEB)

Caresana, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); Ferrarini, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Manessi, G.P., E-mail: giacomo.paolo.manessi@cern.ch [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Varoli, V. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy)

2013-06-01

A number of studies focused in the last decades on the development of survey meters to be used in pulsed radiation fields. This is a topic attracting widespread interest for applications such as radiation protection and beam diagnostics in accelerators. This paper describes a new instrument specifically conceived for applications in pulsed neutron fields (PNF). The detector, called LUPIN, is a rem counter type instrument consisting of a {sup 3}He proportional counter placed inside a spherical moderator. It works in current mode with a front-end electronics consisting of a current–voltage logarithmic amplifier, whose output signal is acquired with an ADC and processed on a PC. This alternative signal processing allows the instrument to be used in PNF without being affected by saturation effects. Moreover, it has a measurement capability ranging over many orders of burst intensity. Despite the fact that it works in current mode, it can measure a single neutron interaction. The LUPIN was first calibrated in CERN's calibration laboratory with a PuBe source. Measurements were carried out under various experimental conditions at the Helmholtz-Zentrum in Berlin, in the stray field at various locations of the CERN Proton Synchrotron complex and around a radiotherapy linear accelerator at the S. Raffaele hospital in Milan. The detector can withstand single bursts with values of H⁎(10) up to 16 nSv/burst without showing any saturation effect. It efficiently works in pulsed stray fields, where a conventional rem-counter underestimates by a factor of 2. It is also able to reject the very intense and pulsed photon contribution that often accompanies the neutron field with good reliability. -- Highlights: ► LUPIN is a new detector specifically conceived to work in neutron pulsed fields. ► The detector is a rem counter type instrument working in current mode. ► The performances of the detectors were studied under various experimental conditions. ► The detector

Case study for co and counter swirling domestic burners

Directory of Open Access Journals (Sweden)

Ashraf Kotb

2018-03-01

Full Text Available In this case study, the influence of equivalence ratio for co and counter-swirl domestic burners compared with non-swirl design on the thermal efficiency as well as CO emissions has been studied using liquefied petroleum gas (LPG. Also, the flame stability, and pot height, which is defined as the burner-to-pot distance (H, of the co and counter domestic burners were compared. The analysis of the results showed that, for both swirl burners co and counter one the thermal efficiency under all operation conditions tested is higher than the non-swirled burner (base burner. For example, the thermal efficiency increased by 8.8%, and 5.8% than base burner for co and counter swirl, respectively at Reynolds number equal 2000 and equivalence ratio 1. The co and counter swirl burners show lower CO emission than the base burner. The co swirl burner has wider operation range than counter swirl. With the increase of pot height, the thermal efficiency of all burners decreases because the flame and combustion gases are cooled due to mixing with ambient air. As a result, the heat transfer is decreased due to atmospheric loss, which decrease the thermal efficiency.

NiO-NF/MWCNT nanocomposite catalyst as a counter electrode for high performance dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Raissan Al-bahrani, Majid [Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China); Faculty of Science, Thi-Qar University, Nassiriya (Iraq); Liu, Linfeng [Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (China); Ahmad, Waqar; Tao, Jiayou; Tu, Fanfan [Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China); Cheng, Ze [School of Physics, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan 430074 (China); Gao, Yihua, E-mail: gaoyihua@hust.edu.cn [Center for Nanoscale Characterization & Devices (CNCD), Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology - HUST, Luoyu Road 1037, Wuhan 430074 (China)

2015-03-15

Highlights: • High-performance NiO-NF/MWCNT CE was incorporated in a Pt-CE in DSSCs. • NiO-NF/MWCNT CE exhibits a high power conversion efficiency (PCE) of 7.63%. • NiO-NF/MWCNT composite has a high catalytic activity for the reduction of I{sub 3}{sup −}. • NiO-NF/MWCNT composite has a low R{sub ct} on the electrolyte/CE interface. - Abstract: In this paper, we fabricated nickel oxide nanofilament/multiwall carbon nanotubes (NiO-NF/MWCNT) nanocomposite by a simple hydrothermal synthesis method as a counter- electrode (CE) in a dye-sensitized solar cell (DSSC). Transmission electron microscopy, scanning electron microscopy images and X-ray diffraction analysis clearly indicated the formation of NiO-NF/MWCNT nanocomposite. The electro-chemical properties of NiO-NF/MWCNT CE are studied by cyclic voltammetry and electrochemical impedance spectroscopy. In particular, current-voltage measurements indicated superior power conversion efficiency (PCE) of 7.63% of the NiO-NF/MWCNT CE compared to 6.72% for the platinum (Pt). The superior photovoltaic performance and low cost of the NiO-NF/MWCNT nanocomposite can be potentially exploited as a new counter-electrode in DSSCs.

Calculation of neutron detection efficiency for the thick lithium glass using Monte Carlo method

International Nuclear Information System (INIS)

Tang Guoyou; Bao Shanglian; Li Yulin; Zhong Wenguan

1989-08-01

The neutron detector efficiencies of a NE912 (45mm in diameter, 9.55 mm in thickness) and 2 pieces of ST601 (40mm in diameter, 3 and 10 mm in thickness respectively) lithium glasses have been calculated with a Monte Carlo computer code. The energy range in the calculation is 10 keV to 2.0 MeV. The effect of time delayed caused by neutron multiple scattering in the detectors (prompt neutron detection efficiency) has been considered

Proportional counter with a wire-anode lying on the dielectric surface

International Nuclear Information System (INIS)

Strelkov, A.V.

1983-01-01

Proportional coUnter with wire-anode lying on the dielectric surface is described. The result of the accumulation of charges on the dielectric surface immediately near the wire-anode surface is that such a counter possesses electrostatic memory relative to distribution of the gas amplification coefficient along the anode. SUch a distribution can be received for example by means of irradiation by the neutrons or the γ-rays. The disposition of the wire-anode on the convex dielectric surface allows one to make the ring-shaped counters or the nonplane proportional chambers practically of any profile. However, the energy resolution of the counter with anode on the dielectric is worse than the resolution of counter with free anode particularly at the large gas amplification coefficient

Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.

Energy Technology Data Exchange (ETDEWEB)

Mattingly, John K.

2009-11-01

Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

Polyethylene-reflected plutonium metal sphere: subcritical neutron and gamma measurements

International Nuclear Information System (INIS)

Mattingly, John K.

2009-01-01

Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

Microdosimetry for Boron Neutron Capture Therapy

International Nuclear Information System (INIS)

Maughan, R.L.; Kota, C.

2000-01-01

The specific aims of the research proposal were as follows: (1) To design and construct small volume tissue equivalent proportional counters for the dosimetry and microdosimetry of high intensity thermal and epithermal neutron beams used in BNCT, and of modified fast neutron beams designed for boron neutron capture enhanced fast neutron therapy (BNCEFNT). (2) To develop analytical methods for estimating the biological effectiveness of the absorbed dose in BNCT and BNCEFNT based on the measured microdosimetric spectra. (3) To develop an analytical framework for comparing the biological effectiveness of different epithermal neutron beams used in BNCT and BNCEFNT, based on correlated sets of measured microdosimetric spectra and radiobiological data. Specific aims (1) and (2) were achieved in their entirety and are comprehensively documented in Jay Burmeister's Ph.D. dissertation entitled ''Specification of physical and biologically effective absorbed dose in radiation therapies utilizing the boron neutron capture reaction'' (Wayne State University, 1999). Specific aim (3) proved difficult to accomplish because of a lack of sufficient radiobiological data

A large 2D PSD for thermal neutron detection

International Nuclear Information System (INIS)

Knott, R.B.; Watt, G.; Boldeman, J.W.; Smith, G.C.

1996-01-01

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 2 . To meet the specifications for neutron detection efficiency and spatial resolution, and to minimize parallax, the gas mixture was 190 kPa 3 He plus 100 kPa CF 4 and the active volume had a thickness of 30 mm. The design maximum neutron count-rate of the detector was 10 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 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

Advances in passive neutron instruments for safeguards use

International Nuclear Information System (INIS)

Menlove, H.O.; Krick, M.S.; Langner, D.G.; Miller, M.C.; Stewart, J.E.

1994-01-01

Passive neutron and other nondestructive assay techniques have been used extensively by the International Atomic Energy Agency to verify plutonium metal, powder, mixed oxide, pellets, rods, assemblies, scrap, and liquids. Normally, the coincidence counting rate is used to measure the 240 Pu-effective mass and gamma-ray spectrometry or mass spectrometry is used to verify the plutonium isotopic ratios. During the past few years, the passive neutron detectors have been installed in plants and operated in the unattended/continuous mode. These radiation data with time continuity have made it possible to use the totals counting rate to monitor the movement of nuclear material. Monte Carlo computer codes have been used to optimize the detector designs for specific applications. The inventory sample counter (INVS-III) has been designed to have a higher efficiency (43%) and a larger uniform counting volume than the original INVS. Data analyses techniques have been developed, including the ''known alpha'' and ''known multiplication'' methods that depend on the sample. For scrap and other impure or poorly characterized samples, we have developed multiplicity counting, initially implemented in the plutonium scrap multiplicity counter. For large waste containers such as 200-L drums, we have developed the add-a-source technique to give accurate corrections for the waste-matrix materials. This paper summarizes recent developments in the design and application of passive neutron assay systems

Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy

Science.gov (United States)

Combe, Rodolphe; Arbor, Nicolas; el Bitar, Ziad; Higueret, Stéphane; Husson, Daniel

2018-01-01

Neutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment. The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose. A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications.

In-Situ Spectrometry of Neutrons

Science.gov (United States)

Maurer, Richard H.

1999-01-01

High energy charged particles of extra-galactic, galactic and solar origin collide with spacecraft structures in Earth orbit outside the atmosphere and in interplanetary travel beyond the Earth's magnetosphere. These primaries create a number of secondary particles inside the structures that can produce a significant ionizing radiation environment. This radiation is a threat to long term inhabitants or travelers for space missions and produces an increased risk of cancer and DNA damage. The primary high energy cosmic rays and trapped protons collide with common spacecraft materials such as aluminum and silicon and create secondary particles inside structures that are mostly protons and neutrons. Charged protons are readily detected and instruments are already in existence for this task. Neutrons are electrically neutral and therefore much more difficult to measure and detect. These neutrons are reported to contribute 30-60% of the dose inside space structures and cannot be ignored. Currently there is no compact, portable and real time neutron detector instrumentation available for use inside spacecraft or on planetary surfaces where astronauts will live and work. We propose to design and build a portable, low power and robust neutron spectrometer that will measure the neutron spectrum from 10 KeV to 500 MeV with at least 10% energy resolution in the various energy intervals. This instrument will monitor the existing neutron environment both inside spacecraft structures and on planetary surfaces to determine the safest living areas, warn of high fluxes associated with solar storms and assist the NSBRI Radiation Effects Team in making an accurate assessment of increased cancer risk and DNA damage to astronauts. The instrument uses a highly efficient proportional counter Helium 3 tube at the lowest energy intervals where .equivalent damage factors for tissue are the highest (10 KeV-2 MeV). The Helium 3 tube may be shielded with a cadmium absorber to eliminate the much

Sequential measurements of spectrum and dose for cosmic-ray neutrons on the ground

International Nuclear Information System (INIS)

Hirabayashi, N.; Nunomiya, T.; Suzuki, H.; Nakamura, T.

2002-01-01

The earth is continually bathed in high-energy particles that come from outside the solar system, known as galactic cosmic rays. When these particles penetrate the magnetic fields of the solar system and the Earth and reach the Earth's atmosphere, they collide with atomic nuclei in air and secondary cosmic rays of every kind. On the other hand, levels of accumulation of the semiconductor increase recently, and the soft error that the cosmic-ray neutrons cause has been regarded as questionable. There have been long-term measurements of cosmic-ray neutron fluence at several places in the world, but no systematic study on cosmic-ray neutron spectrum measurements. This study aimed to measure the cosmic-ray neutron spectrum and dose on the ground during the solar maximum period of 2000 to 2002. Measurements have been continuing in a cabin of Tohoku University Kawauchi campus, by using five multi-moderator spectrometers (Bonner sphere), 12.7 cm diam by 12.7 cm long NE213 scintillator, and rem counter. The Bonner sphere uses a 5.08 cm diam spherical 3 He gas proportional counter and the rem counter uses a 12.7 cm diam 3 He gas counter. The neutron spectra were obtained by unfolding from the count rates measured with the Bonner sphere using the SAND code and the pulse height spectra measured with the NE213 scintillator using the FORIST code . The cosmic- ray neutron spectrum and ambient dose rates have been measured sequentially from April 2001. Furthermore, the correlation between ambient dose rate and the atmospheric pressure was investigated with a barometer. We are also very much interested in the variation of neutron spectrum following big solar flares. From the sequential measurements, we found that the cosmic-ray neutron spectrum has two peaks at around 1 MeV and at around 100 MeV, and the higher energy peak increases with a big solar flare

Needle counter

International Nuclear Information System (INIS)

Fujita, Yuzo

1977-01-01

Needle counter had been devised by Geiger about 60 years ago before the present GM counter appeared. It is suitable for the detection of weak radiation because it is limited in effective volume, if the background due to mainly cosmic ray is proportional to the effective volume of the counter. Recently the very low β detector having a needle counter as the main detector has been developed. It showed highly excellent performance in the measurements of small area samples, about ten times sensitive as compared with other detectors. The counter is installed in the very low radiation measuring well at Nokogiriyama, Chiba Prefecture, using a NaI scintillator as its guard counter. D. H. Wilkinson first treated a gas amplification counter theoretically and quantitatively. The authors have obtained good results in the comparison with the experiments of the counter using a generalized form of Wilkinson theory. The findings obtained through this study seem to be applicable to the electrode arrangement which is important for the counter design. It was found that the excellent rise time of induced pulses in a gas amplification counter was achieved in larger amplification factor and smaller convolution effect. In the detection of charged particles with small obstructing capability such as γ ray, faster rise time and higher pulses can be obtained with needle counters than wire counters. (Wakatsuki, Y.)

Measurement of the neutron detection efficiency of a 80% absorber-20% scintillating fibers calorimeter

Energy Technology Data Exchange (ETDEWEB)

Anelli, M.; Bertolucci, S. [Laboratori Nazionali di Frascati dell' INFN, Via E.Fermi 40, I-00044 Frascati (Italy); Bini, C., E-mail: cesare.bini@roma1.infn.i [Dipartimento di Fisica, Sapienza Universita di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); INFN Sezione di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); Branchini, P. [INFN Sezione di Roma Tre, Via della Vasca Navale, 84 I-00146 Roma (Italy); Corradi, G.; Curceanu, C. [Laboratori Nazionali di Frascati dell' INFN, Via E.Fermi 40, I-00044 Frascati (Italy); De Zorzi, G.; Di Domenico, A. [Dipartimento di Fisica, Sapienza Universita di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); INFN Sezione di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); Di Micco, B. [Dipartimento di Fisica dell' Universita ' Roma Tre' , Via della Vasca Navale, 84 I-00146 Roma (Italy); INFN Sezione di Roma Tre, Via della Vasca Navale, 84 I-00146 Roma (Italy); Ferrari, A. [Institute of Safety Research and Institute of Radiation Physics, Forschungszentrum Dresden-Rossendorf, PF 510119, 01314 Dresden (Germany); Fiore, S. [Dipartimento di Fisica, Sapienza Universita di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); INFN Sezione di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); Gauzzi, P., E-mail: paolo.gauzzi@roma1.infn.i [Dipartimento di Fisica, Sapienza Universita di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); INFN Sezione di Roma, P.le A.Moro, 2 I-00185 Roma (Italy); Giovannella, S.; Happacher, F. [Laboratori Nazionali di Frascati dell' INFN, Via E.Fermi 40, I-00044 Frascati (Italy); Iliescu, M. [Laboratori Nazionali di Frascati dell' INFN, Via E.Fermi 40, I-00044 Frascati (Italy); ' Horia Hulubei' National Institute of Physics and Nuclear Engineering, Str. Atomistilor no. 407, P.O. Box MG-6 Bucharest-Magurele (Romania); Luca, A.; Martini, M.; Miscetti, S. [Laboratori Nazionali di Frascati dell' INFN, Via E.Fermi 40, I-00044 Frascati (Italy)

2011-01-21

The neutron detection efficiency of a sampling calorimeter made of 1 mm diameter scintillating fibers embedded in a lead/bismuth structure has been measured at the neutron beam of The Svedberg Laboratory at Uppsala. A significant enhancement of the detection efficiency with respect to a bulk organic scintillator detector with the same thickness is observed.

A neutron monitor for D-T neutron generator in the PGNAA-based online measurement system

Science.gov (United States)

Shan, Qing; Shengnan, Chu; Yongsheng, Ling; Pingkun, Cai; Wenbao, Jia

2017-06-01

A new type of neutron detector, which consists of polyethylene, an EJ200 plastic scintillator and fused silica, was proposed and optimized by the GEANT4 Monte Carlo simulation toolkit in our previous studies. The calculation method was also described for calculating the neutron flux in the preset condition. This paper reports the manufacturing of the prototype detector. Experiments are conducted to validate the feasibility of this detector. A D-T neutron generator and a 60Co gamma-ray source are used in the experiments. The designed detector and a He-3 proportional counter are simultaneously used to monitor the yield of the D-T neutron generator. A more universal calculation method is developed to enable the application of this detector to common conditions. The experimental results show that the performance of the designed detector is comparable to that of the He-3 proportional counter. The relative deviations between their normalized counts are less than 5%.

MCNP-REN: a Monte Carlo tool for neutron detector design

International Nuclear Information System (INIS)

Abhold, M.E.; Baker, M.C.

2002-01-01

The development of neutron detectors makes extensive use of the predictions of detector response through the use of Monte Carlo techniques in conjunction with the point reactor model. Unfortunately, the point reactor model fails to accurately predict detector response in common applications. For this reason, the general Monte Carlo code developed at Los Alamos National Laboratory, Monte Carlo N-Particle (MCNP), was modified to simulate the pulse streams that would be generated by a neutron detector and normally analyzed by a shift register. This modified code, MCNP-Random Exponentially Distributed Neutron Source (MCNP-REN), along with the Time Analysis Program, predicts neutron detector response without using the point reactor model, making it unnecessary for the user to decide whether or not the assumptions of the point model are met for their application. MCNP-REN is capable of simulating standard neutron coincidence counting as well as neutron multiplicity counting. Measurements of mixed oxide fresh fuel were taken with the Underwater Coincidence Counter, and measurements of highly enriched uranium reactor fuel were taken with the active neutron interrogation Research Reactor Fuel Counter and compared to calculation. Simulations completed for other detector design applications are described. The method used in MCNP-REN is demonstrated to be fundamentally sound and shown to eliminate the need to use the point model for detector performance predictions

Efficient Preparation of Streptochlorin from Marine Streptomyces sp. SYYLWHS-1-4 by Combination of Response Surface Methodology and High-Speed Counter-Current Chromatography.

Science.gov (United States)

Li, Lin; He, Shan; Ding, Lijian; Yuan, Ye; Zhu, Peng; Epstein, Slava; Fan, Jianzhong; Wu, Xiaokai; Yan, Xiaojun

2016-05-27

Since first isolated from the lipophilic extract of Streptomyces sp. SF2583, streptochlorin, has attracted a lot of attention because of its various pharmacological properties, such as antibiotic, antiallergic, antitumor, and anti-inflammatory activities. For the efficient preparation of streptochlorin from a producing strain Streptomyces sp. SYYLWHS-1-4, we developed a combinative method by using response surface methodology (RSM) and high-speed counter-current chromatography (HSCCC). In the fermentation process, we used RSM to optimize the condition for the efficient accumulation of streptochlorin, and the optimal parameters were: yeast extract 1.889 g/L, soluble starch 8.636 g/L, K₂HPO₄ 0.359 g/L, CaCl₂ 2.5 g/L, MgSO₄ 0.625 g/L, marine salt 25 g/L, medium volume 50%, initial pH value 7.0, temperature 27.5 °C, which enhanced streptochlorin yield by 17.7-fold. During the purification process, the preparative HSCCC separation was performed using a petroleum ether-ethyl acetate-methanol-water (9:0.8:5:5, v/v/v/v) biphasic solvent system, where 300 mg of crude sample yielded 16.5 mg streptochlorin with over 95% purity as determined by UPLC. Consequently, the combination method provided a feasible strategy for highly effective preparation of streptochlorin, which ensured the supply of large amounts of streptochlorin for in vivo pharmacological assessments or other requirements.

Development of highly effective neutron shields and neutron absorbing materials

International Nuclear Information System (INIS)

Tsuda, K.; Matsuda, F.; Taniuchi, H.; Yuhara, T.; Iida, T.

1993-01-01

A wide range of materials, including polymers and hydrogen-occluded alloys that might be usable as the neutron shielding material were examined. And a wide range of materials, including aluminum alloys that might be usable as the neutron-absorbing material were examined. After screening, the candidate material was determined on the basis of evaluation regarding its adaptabilities as a high-performance neutron-shielding and neutron-absorbing material. This candidate material was manufactured for trial, after which material properties tests, neutron-shielding tests and neutron-absorbing tests were carried out on it. The specifications of this material were thus determined. This research has resulted in materials of good performance; a neutron-shielding material based on ethylene propylene rubber and titanium hydride, and a neutron-absorbing material based on aluminum and titanium hydride. (author)

A High Temperature-Tolerant and Radiation-Resistant In-Core Neutron Sensor for Advanced Reactors. Final report

Energy Technology Data Exchange (ETDEWEB)

Cao, Lei [The Ohio State Univ., Columbus, OH (United States); Miller, Don [The Ohio State Univ., Columbus, OH (United States)

2015-01-23

The objectives of this project are to develop a small and reliable gallium nitride (GaN) neutron sensor that is capable of withstanding high neutron fluence and high temperature, isolating gamma background, and operating in a wide dynamic range. The first objective will be the understanding of the fundamental materials properties and electronic response of a GaN semiconductor materials and device in an environment of high temperature and intense neutron field. To achieve such goal, an in-situ study of electronic properties of GaN device such as I-V, leakage current, and charge collection efficiency (CCE) in high temperature using an external neutron beam will be designed and implemented. We will also perform in-core irradiation of GaN up to the highest yet fast neutron fluence and an off-line performance evaluation.

A High Temperature-Tolerant and Radiation-Resistant In-Core Neutron Sensor for Advanced Reactors. Final report

International Nuclear Information System (INIS)

Cao, Lei; Miller, Don

2015-01-01

The objectives of this project are to develop a small and reliable gallium nitride (GaN) neutron sensor that is capable of withstanding high neutron fluence and high temperature, isolating gamma background, and operating in a wide dynamic range. The first objective will be the understanding of the fundamental materials properties and electronic response of a GaN semiconductor materials and device in an environment of high temperature and intense neutron field. To achieve such goal, an in-situ study of electronic properties of GaN device such as I-V, leakage current, and charge collection efficiency (CCE) in high temperature using an external neutron beam will be designed and implemented. We will also perform in-core irradiation of GaN up to the highest yet fast neutron fluence and an off-line performance evaluation.

Preparation of Platinum (Pt) Counter Electrode Coated by Electrochemical Technique at High Temperature for Dye-sensitized Solar Cell (DSSC) Application

Science.gov (United States)

Ponken, Tanachai; Tagsin, Kamonlapron; Suwannakhun, Chuleerat; Luecha, Jakkrit; Choawunklang, Wijit

2017-09-01

Pt counter electrode was coated by electrochemical method. Electrolyte solution was synthesized by platinum (IV) choloride (PtCl4) powder dissolved in hydrochloric acid solution. Pt films were deposited on the FTO substrate. Deposition time of 10, 30 and 60 minutes, the coating current of 5, 10, 15 and 20 mA and electrolyte solution temperatures for Pt layer synthesis of 25, 30 and 40°C were varied. Surface morphology and optical properties was analyzed by digital microscopic and UV-vis spectrophotometer. Pt films exhibit uniform surface area highly for all the conditions of coating current in the deposition time of 30 and 40 minutes at 40°C. Transmittance values of Pt films deposited on FTO substrate has approximately of 5 to 50 % show that occur high reflection corresponding to dye molecule absorption increases. DSSC device was fabricated from the TiO2 standard and immersed in dye N719 for 24 hours. Efficiency was measured by solar simulator. Efficiency value obtains as high as 5.91 % for the coating current, deposition time and solution temperature of 15 mA, 30 minutes and 40°C. Summary, influence of temperature effects efficiency increasing. Pt counter electrode can be prepared easily and the suitable usefully for DSSC.

High power klystrons for efficient reliable high power amplifiers

Science.gov (United States)

Levin, M.

1980-11-01

This report covers the design of reliable high efficiency, high power klystrons which may be used in both existing and proposed troposcatter radio systems. High Power (10 kW) klystron designs were generated in C-band (4.4 GHz to 5.0 GHz), S-band (2.5 GHz to 2.7 GHz), and L-band or UHF frequencies (755 MHz to 985 MHz). The tubes were designed for power supply compatibility and use with a vapor/liquid phase heat exchanger. Four (4) S-band tubes were developed in the course of this program along with two (2) matching focusing solenoids and two (2) heat exchangers. These tubes use five (5) tuners with counters which are attached to the focusing solenoids. A reliability mathematical model of the tube and heat exchanger system was also generated.

Spatial distribution of moderated neutrons along a Pb target irradiated by high-energy protons

International Nuclear Information System (INIS)

Fragopoulou, M.; Manolopoulou, M.; Stoulos, S.; Brandt, R.; Westmeier, W.; Kulakov, B.A.; Krivopustov, M.I.; Sosnin, A.N.; Debeauvais, M.; Adloff, J.C.; Zamani Valasiadou, M.

2006-01-01

High-energy protons in the range of 0.5-7.4 GeV have irradiated an extended Pb target covered with a paraffin moderator. The moderator was used in order to shift the hard Pb spallation neutron spectrum to lower energies and to increase the transmutation efficiency via (n,γ) reactions. Neutron distributions along and inside the paraffin moderator were measured. An analysis of the experimental results was performed based on particle production by high-energy interactions with heavy targets and neutron spectrum shifting by the paraffin. Conclusions about the spallation neutron production in the target and moderation through the paraffin are presented. The study of the total neutron fluence on the moderator surface as a function of the proton beam energy shows that neutron cost is improved up to 1 GeV. For higher proton beam energies it remains constant with a tendency to decline

Counter-Stereotypes and Feminism Promote Leadership Aspirations in Highly Identified Women

OpenAIRE

Leicht, Carola; Goclowska, Malgorzata A.; Van Breen, Jolien A.; de Lemus, Soledad; Randsley de Moura, Georgina

2017-01-01

Although women who highly identify with other women are more susceptible to stereotype threat effects, women's identification might associate with greater leadership aspirations contingent on (1) counter-stereotype salience and (2) feminist identification. When gender counter-stereotypes are salient, women's identification should associate with greater leadership aspiration regardless of feminism, while when gender stereotypes are salient, women's identification would predict greater leadersh...

Neutronics of pulsed spallation neutron sources

CERN Document Server

Watanabe, N

2003-01-01

Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, po...