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).

Design characteristics of a three-component AEOI Neutriran Albedo Neutron Personnel Dosimeter

International Nuclear Information System (INIS)

Sohrabi, M.; Katouzi, M.

1991-01-01

In establishing a national personnel neutron dosimetry service in Iran, different parameters of the AEOI Neutriran Albedo Neutron Personnel Dosimeter (NANPD) have been optimized. A NANPD was designed with three dosimetry components to measure (a) direct thermal neutrons, (b) direct fast neutrons and (C) direct neutrons by the detection of the albedo neutrons reflected from the body. The dosimeter consists of one or more Lexan polycarbonate and/or CR-39 foils and two 10 B (n,α) 7 Li converters in a cadmium cover so arranged as to efficiently measure the three neutron dose components separately. The boron converter thickness, its position relative to the beam direction and its distance from the PC foil were studied and the results were incorporated into the design. The dose response of the dosimeter, its lower detection limit as well as the correction factors related to the field neutrons and albedo neutrons were also determined for a 238 Pu-Be, an 241 Am-Be and a 252 Cf sources. In this paper, the dosimeter design and its dosimetric characteristics are presented and discussed. (author)

Calibration experiments of neutron source identification and detection in soil

International Nuclear Information System (INIS)

Gorin, N. V.; Lipilina, E. N.; Rukavishnikov, G. V.; Shmakov, D. V.; Ulyanov, A. I.

2007-01-01

In the course of detection of fissile materials in soil, series of calibration experiments were carried out on in laboratory conditions on an experimental installation, presenting a mock-up of an endless soil with various heterogeneous bodies in it, fissile material, measuring boreholes. A design of detecting device, methods of neutrons detection are described. Conditions of neutron background measuring are given. Soil density, humidity, chemical composition of soil was measured. Sensitivity of methods of fissile materials detection and identification in soil was estimated in the calibration experiments. Minimal detectable activity and the distance at which it can be detected were defined. Characteristics of neutron radiation in a borehole mock-up were measured; dependences of method sensitivities from water content in soil, source-detector distance and presence of heterogeneous bodies were examined. Possibility of direction detection to a fissile material as neutron source from a borehole using a collimator is shown. Identification of fissile material was carried out by measuring the gamma-spectrum. Mathematical modeling was carried out using the PRIZMA code (Developed in RFNC-VNIITF) and MCNP code (Developed in LANL). Good correlation of calculational and experimental values was shown. The methodic were shown to be applicable in the field conditions

Neutron imaging integrated circuit and method for detecting neutrons

Science.gov (United States)

Nagarkar, Vivek V.; More, Mitali J.

2017-12-05

The present disclosure provides a neutron imaging detector and a method for detecting neutrons. In one example, a method includes providing a neutron imaging detector including plurality of memory cells and a conversion layer on the memory cells, setting one or more of the memory cells to a first charge state, positioning the neutron imaging detector in a neutron environment for a predetermined time period, and reading a state change at one of the memory cells, and measuring a charge state change at one of the plurality of memory cells from the first charge state to a second charge state less than the first charge state, where the charge state change indicates detection of neutrons at said one of the memory cells.

Wide range neutron detection system

International Nuclear Information System (INIS)

Todt, W.H. Sr.

1978-01-01

A neutron detection system for reactor control is described which is operable over a wide range of neutron flux levels. The system includes a fission type ionization chamber neutron detector, means for gamma and alpha signal compensation, and means for operating the neutron detector in the pulse counting mode for low neutron flux levels, and in the direct current mode for high neutron flux levels

Applications and characteristics of imaging plates as detector in neutron radiography at SINQ

CERN Document Server

Kolbe, H; Gunia, W; Körner, S

1999-01-01

Imaging plate technique is a commonly accepted method in many fields as in medicine, biology and physics for detection of the distribution of beta- and gamma-radiation or X-rays on large areas. Recently a new type of imaging plate sensitive to neutrons has been developed. The storage layer is doped with gadolinium, which, after absorption of neutrons, produces radiation detectable by the same sensitive crystals used in conventional imaging plates. At the spallation neutron source, SINQ, at the Paul Scherrer Institut (CH) some of the characteristics of the neutron radiography station in combination with the imaging plate technique were investigated. The intensity distribution of the source was measured to check the accuracy for quantification of the image data. Also, the reproducibility of results obtained by this detection system was stated. For a test object, the high selectivity for different neutron absorption is demonstrated at details with low contrast. The obtainable spatial resolution was determined re...

Contraband detection with fast neutrons

Energy Technology Data Exchange (ETDEWEB)

Buffler, Andy E-mail: abuffler@science.uct.ac.za

2004-11-01

Recent terror events and the increase in the trade of illicit drugs have fuelled the exploration of the use of fast neutrons as probes for the detection of hidden contraband, especially explosives, in packages ranging in size from small mail items to cargo containers. The various approaches using fast neutrons for contraband detection, presently under development, are reviewed. The role that a neutron system might play in the non-intrusive interrogation of airline luggage is discussed.

Detection of hidden explosives by fast neutron activation analysis

International Nuclear Information System (INIS)

Li Xinnian; Guo Junpeng; Luo Wenyun; Wang Chuanshan; Fang Xiaoming; Yu Tailiu

2008-01-01

The paper describes the method and principle for detection of hidden explosive by fast neutron activation analysis (FNAA). The method of detection of explosives by FNAA has the specific properties of simple determination equipments, high reliability, and low detecting cost, and would be beneficial to the applicability and popularization in the field of protecting and securing nation. The contents of nitrogen and oxygen in four explosives, more then ten common materials and TNT samples covered with soil, were measured by FNAA. 14 MeV fast neutrons were generated from (d, t) reaction with a 400 kV Cockcroft Walton type accelerator. The two-dimension distributions for nitro- gen and oxygen counting rates per unit mass of determined matters were obtained, and the characteristic area of explosives and non-explosives can be defined. By computer aided pattern recognition, the samples were identified with low false alarm or omission rates. The Monte-Carlo simulation indicates that there is no any radiation at 15 m apart from neutron source and is safe for irradiation after 1 h. It is suggested that FNAA may be potential in remote controlling for detection hidden explosive system with multi-probe large array. (authors)

Microcantilever-Enabled Neutron Detection

Directory of Open Access Journals (Sweden)

Kevin R. Kyle

2014-04-01

Full Text Available A new concept for neutron radiation detection was demonstrated using piezoresistive microcantilevers as the active sensing element. Microcantilevers were used to measure the tiny volumetric changes in a sensing material upon absorption of neutron radiation and transmutation into a new element. Highly ordered inorganic crystalline lattices of boron-rich materials dispersed in polymeric rubber matrices were shown to act as volumetric neutron transducers.

Exciton luminescence characteristic of ZnO. Ga scintillator for neutron detection

International Nuclear Information System (INIS)

Kinoshita, A.; Fujiwara, A.; Koyama, S.; Takei, Y.; Nanto, H.; Katagiri, Masaki

2008-01-01

ZnO family phosphors as novel phosphor materials for neutron detector have prepared using Spark Plasma Sintering method. The optical properties of ZnO phosphor prepared are investigated. The following results were obtained. Two dominant PL emission peaks at 395 nm and 495 nm were observed. The lifetime of the PL emission peak at 395 nm (UV emission band) is about 20 ns, which is suitable for neutron detection. The Ga (30 mol%)-doped ZnO phosphor exhibited an intense UV emission band without the visible emission band. The Ga-doped ZnO phosphor can be prepared at the atmospheric pressure of about 8 Pa using SPS method. It was found that the PL intensity of UV emission band is increased with improving the crystallinity of the ZnO phosphor. (author)

The synchronous active neutron detection assay system

International Nuclear Information System (INIS)

Pickrell, M.M.; Kendall, P.K.

1994-01-01

We have begun to develop a novel technique for active neutron assay of fissile material in spent nuclear fuel. This approach will exploit a 14-MeV neutron generator developed by Schlumberger. The technique, termed synchronous active neutron detection (SAND), follows a method used routinely in other branches of physics to detect very small signals in presence of large backgrounds. Synchronous detection instruments are widely available commercially and are termed ''lock-in'' amplifiers. We have implemented a digital lock-in amplifier in conjunction with the Schlumberger neutron generator to explore the possibility of synchronous detection with active neutrons. The Schlumberger system can operate at up to a 50% duty factor, in effect, a square wave of neutron yield. Results are preliminary but promising. The system is capable of resolving the fissile material contained in a small fraction of the fuel rods in a cold fuel assembly; it also appears resilient to background neutron interference. The interrogating neutrons appear to be non-thermal and penetrating. Work remains to fully explore relevant physics and optimize instrument design

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.

Interface detection by neutron scattering

International Nuclear Information System (INIS)

De Monchy, A.R.; Kok, C.A.; Dorrepaal, J.

1979-01-01

A method and apparatus for detecting an interface of materials having different hydrogen content present in a metal vessel or pipe eg. made of steel, are described. Steel walls of columns, reactors, pipelines etc can be monitored. It is very suitable for detection of liquid water or hydrocarbons present in gas pipelines and also for the detection of a liquid hydrocarbon in a vessel or column. A series of measurements of the hydrogen density of the contents of a vessel or pipe are made using at least one californium-252 neutron source located near the outer side of the pipe. Neutrons are emitted and are scattered by the contents of the pipe. At least one neutron detector is located near the outer side of the metal wall. The detectors have a higher sensitivity for scattered neutrons (from the light hydrogen nuclei present in water or hydrocarbons). A source of 0.1 - 1 micrograms produces enough neutrons for most technical applications so the handling is relatively safe although shielding is advocated. The detectors contain helium-3 at a pressure of about 10 bar. Current pulses from the detector are counted. (U.K.)

Fast-neutron detecting system with n, γ discrimination

International Nuclear Information System (INIS)

Ouyang Xiaoping; Huang Bao; Cao Jinyun

1997-11-01

In the present work, a new type neutron detecting system is reported, which can absolutely measure neutron parameters in n + γ mixed fields and has a long continuance of static high vacuum of 10 -4 Pa. The detecting system, with middle neutron-detecting sensitivity, short time response and big linear current output, has applied successfully in pulsed neutron beam measurement

Neutron detection using boron gallium nitride semiconductor material

Directory of Open Access Journals (Sweden)

Katsuhiro Atsumi

2014-03-01

Full Text Available In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after α-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

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.

Neutron irradiation facility and its characteristics

International Nuclear Information System (INIS)

Oyama, Yukio; Noda, Kenji

1995-01-01

A neutron irradiation facility utilizing spallation reactions with high energy protons is conceived as one of the facilities in 'Proton Engineering center (PEC)' proposed at JAERI. Characteristics of neutron irradiation field of the facility for material irradiation studies are described in terms of material damage parameters, influence of the pulse irradiation, irradiation environments other than neutronics features, etc., comparing with the other sorts of neutron irradiation facilities. Some perspectives for materials irradiation studies using PEC are presented. (author)

Review of current neutron detection systems for emergency response

Science.gov (United States)

Mukhopadhyay, Sanjoy; Maurer, Richard; Guss, Paul; Kruschwitz, Craig

2014-09-01

Neutron detectors are used in a myriad of applications—from safeguarding special nuclear materials (SNM) to determining lattice spacing in soft materials. The transformational changes taking place in neutron detection and imaging techniques in the last few years are largely being driven by the global shortage of helium-3 (3He). This article reviews the status of neutron sensors used specifically for SNM detection in radiological emergency response. These neutron detectors must be highly efficient, be rugged, have fast electronics to measure neutron multiplicity, and be capable of measuring direction of the neutron sources and possibly image them with high spatial resolution. Neutron detection is an indirect physical process: neutrons react with nuclei in materials to initiate the release of one or more charged particles that produce electric signals that can be processed by the detection system. Therefore, neutron detection requires conversion materials as active elements of the detection system; these materials may include boron-10 (10B), lithium-6 (6Li), and gadollinium-157 (157Gd), to name a few, but the number of materials available for neutron detection is limited. However, in recent years, pulse-shape-discriminating plastic scintillators, scintillators made of helium-4 (4He) under high pressure, pillar and trench semiconductor diodes, and exotic semiconductor neutron detectors made from uranium oxide and other materials have widely expanded the parameter space in neutron detection methodology. In this article we will pay special attention to semiconductor-based neutron sensors. Modern microfabricated nanotubes covered inside with neutron converter materials and with very high aspect ratios for better charge transport will be discussed.

Characteristics of a Portable Neutron Generator

International Nuclear Information System (INIS)

Jin, Jeong-Tae; Oh, Byung-Hoon; Chang, Dae-Sik; In, Sang-Yeol; Huh, Sung-Ryul; Hong, Kwang-Pyo

2015-01-01

Neutron generators can be excellent tools for materials analysis, explosive material detection, nuclear weapon detection, and high quality radiography. D + D : 3He + n (2.5 MeV) D + T : 4He + n (14 MeV) Recent commercial neutron generators, fast neutron yield from 10 7 to 10 11 n/s, are produced by several companies and research groups around the world. But limited life time, high price, and frequent troubles make it difficult to develop related application systems by domestic companies or research groups. To remove such problems, it is necessary to develop our own domestic neutron generators. In this presentation, the design and experimental results on the developed small neutron generator are summarized. Experiments on deuterium beam extraction and fast neutron measurement by injecting deuterium beams on a drive-in target are executed. The stable deuterium beam of the energy higher than 100 keV was achieved by introducing metal cover which reduces the effect of metal-vacuum-insulator triple junction. The neutron flux of 5 n/s is measured by RadEye GN gamma Neutron (Thermo scientific) detector with about 200 mm distance and insertion of 40 mm PE plate between neutron source and the detector. The precise detector calibration is not carried out yet, so more detailed experimental results will be summarized at the presentation

Characteristics of a Portable Neutron Generator

Energy Technology Data Exchange (ETDEWEB)

Jin, Jeong-Tae; Oh, Byung-Hoon; Chang, Dae-Sik; In, Sang-Yeol; Huh, Sung-Ryul; Hong, Kwang-Pyo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

Neutron generators can be excellent tools for materials analysis, explosive material detection, nuclear weapon detection, and high quality radiography. D + D : 3He + n (2.5 MeV) D + T : 4He + n (14 MeV) Recent commercial neutron generators, fast neutron yield from 10{sup 7} to 10{sup 11} n/s, are produced by several companies and research groups around the world. But limited life time, high price, and frequent troubles make it difficult to develop related application systems by domestic companies or research groups. To remove such problems, it is necessary to develop our own domestic neutron generators. In this presentation, the design and experimental results on the developed small neutron generator are summarized. Experiments on deuterium beam extraction and fast neutron measurement by injecting deuterium beams on a drive-in target are executed. The stable deuterium beam of the energy higher than 100 keV was achieved by introducing metal cover which reduces the effect of metal-vacuum-insulator triple junction. The neutron flux of 5 n/s is measured by RadEye GN gamma Neutron (Thermo scientific) detector with about 200 mm distance and insertion of 40 mm PE plate between neutron source and the detector. The precise detector calibration is not carried out yet, so more detailed experimental results will be summarized at the presentation.

New Organic Scintillators for Neutron Detection

Science.gov (United States)

2016-03-01

gamma rays. For heterogeneous or dense materials such as samples of metals , oxides , and nuclear waste, gamma ray attenuation can be too high to...highly enriched uranium and weapons grade plutonium. Neutrons and gamma rays are two signatures of these materials. Gamma ray detection techniques are... uranium ). Thus, neutron detection is an important component of the overall detection techniques used in identifying SNMs. Important requirements for

The thermal neutron detection using 4H-SiC detectors with 6LiF conversion layer

International Nuclear Information System (INIS)

Zatko, B.; Bohacek, P.; Sekacova, M.; Arbet, J.; Sagatova, A.; Necas, V.

2016-01-01

In this paper we have examined 4H-SiC detector using a thermal neutron source and studied its detection properties. The detector was exposed to neutrons generated by 238 Pu-Be radiation source. The detection properties of 4H-SiC detectors were evaluated considering the use of the 6 LiF conversion. We prepared 4H-SiC Schottky contact detectors based on high-quality of epitaxial layer. The current-voltage characteristic show operating region between 100 V and 400 V. The detector was connected to the spectrometric set-up and used for detection of alpha particles from 241 Am. Following the 6 LiF conversion layer was applied on the Schottky contact of detector and the detection of thermal neutrons was performed. We are able to resolve alpha particles and tritons which are products of nuclear reaction between thermal neutrons and conversion layer. Also bare detector was used for neutron detection to clearly show significant influence of the used conversion layer.(authors)

Detection of SNM by Pulsed Neutron Interrogation

International Nuclear Information System (INIS)

Pedersen, Bent; Mayorov, Valeriy; Roesgen, Eric; Mosconi, Marita; Crochemore, Jean-Michel; Ocherashvili, Aharon; Beck, Arie; Ettedgui, Hanania

2014-01-01

A method for the detection of special nuclear materials (SNM) in shielded containers which is both sensitive and easily applicable under field conditions is presented. The method applies neutron induced fission in SNM by means of an external pulsed neutron source with subsequent detection of the fast prompt fission neutrons. Liquid scintillation detectors surrounding the container under investigation are able to discriminate gamma rays from fast neutrons by the so-called pulse shape discrimination technique (PSD)

Detection of explosives by neutron scattering

International Nuclear Information System (INIS)

Brooks, F.D.; Buffler, A.; Allie, M.S.; Nchodu, M.R.; Bharuth-Ram, K.

1998-01-01

For non-intrusive detection of hidden explosives or other contraband such as narcotics a fast neutron scattering analysis (FNSA) technique is proposed. An experimental arrangement uses a collimated, pulsed beam of neutrons directed at the sample. Scattered neutrons are detected by liquid scintillation counters at different scattering angles. A scattering signature is derived from two-parameter data, counts vs pulse height and time-of-flight measured for each element (H, C, N or O) at each of two scattering angles and two neutron energies. The elemental signatures are very distinctive and constitute a good response matrix for unfolding elemental components from the scattering signatures measured for different compounds

Simulation and prototyping of 2 m long resistive plate chambers for detection of fast neutrons and multi-neutron event identification

Energy Technology Data Exchange (ETDEWEB)

Elekes, Z., E-mail: z.elekes@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Bemmerer, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Caesar, C. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Cowan, T.C. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Hehner, J.; Heil, M. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Rossi, D. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Röder, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Simon, H. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Sobiella, M.; Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Reinhardt, T. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Wagner, A.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [Universität zu Köln, Köln (Germany); Zuber, K. [Technische Universität Dresden, Dresden (Germany)

2013-02-11

Resistive plate chamber (RPC) prototypes of 2 m length were simulated and built. The experimental tests using a 31 MeV electron beam, discussed in details, showed an efficiency higher than 90% and an excellent time resolution of around σ=100ps. Furthermore, comprehensive simulations were performed by GEANT4 toolkit in order to study the possible use of these RPCs for fast neutron (200 MeV–1 GeV) detection and multi-neutron event identification. The validation of simulation parameters was carried out via a comparison to experimental data. A possible setup for invariant mass spectroscopy of multi-neutron emission is presented and the characteristics are discussed. The results show that the setup has a high detection efficiency. Its capability of determining the momentum of the outgoing neutrons and reconstructing the relative energy between the fragments from nuclear reactions is demonstrated for different scenarios.

Some characteristics of a miniature neutron spectrometer

International Nuclear Information System (INIS)

Sekimoto, H.; Oishi, K.; Hojo, K.; Hojo, T.

1984-01-01

Some characteristics of an NE213 miniature spherical spectrometer for in-assembly fast-neutron spectrometry were measured. As the bubbling time changed, the pulse-height did not change appreciably, but the n-γ discrimination characteristics changed considerably. As the count rate changed, the pulse-height did not change appreciably, and the change of the n-γ discrimination characteristics was acceptable. The neutron response function was measured to be almost isotropic except for the backward direction. (orig.)

Neutron gauging to detect voids in polyurethane

International Nuclear Information System (INIS)

Tsang, F.Y.; Alger, D.M.; Brugger, R.M.

1978-01-01

Thermal-neutron radiography and fast-neutron gauging measurements were made to evaluate the feasibility of detecting voids in a polyurethane block placed between steel plates. This sandwich of polyurethane and steel simulates the walls of a canister being designed to hold explosive devices. The polyurethane would act as a shock absorber in the canister. A large fabrication cost saving would result by casting the polyurethane, but a nondestructive testing (NDT) method is needed to determine the uniformity of the polyurethane fill. The radiography measurements used a beam of thermal neutrons, while the gauging used filtered beams of 24 keV and fission spectrum neutrons. For the 83-mm-thick polyurethane and 130-mm-thick steel matrix, the thermal-neutron radiography was able to detect only those voids equal to about one-half the polyurethane thickness. The gauging detected voids in the path of the neutron beam of a few millimetres thickness in seconds to minutes. The gauging is feasible as an NDT method for the canister application

Subthreshold neutron interrogator for detection of radioactive materials

Science.gov (United States)

Evans, Michael L.; Menlove, Howard O.; Baker, Michael P.

1980-01-01

A device for detecting fissionable material such as uranium in low concentrations by interrogating with photoneutrons at energy levels below 500 keV, and typically about 26 keV. Induced fast neutrons having energies above 500 keV by the interrogated fissionable material are detected by a liquid scintillator or recoil proportional counter which is sensitive to the induced fast neutrons. Since the induced fast neutrons are proportional to the concentration of fissionable material, detection of induced fast neutrons indicate concentration of the fissionable material.

RE-EVALUATION OF THE NEUTRON EMISSION FROM THE SOLAR FLARE OF 2005 SEPTEMBER 7, DETECTED BY THE SOLAR NEUTRON TELESCOPE AT SIERRA NEGRA

Energy Technology Data Exchange (ETDEWEB)

González, L. X. [SCiESMEX, Instituto de Geofísica Unidad Michoacán, Universidad Nacional Autónoma de México, 58190, Morelia, Michoacán (Mexico); Valdés-Galicia, J. F.; Musalem, O.; Hurtado, A. [Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510, D. F. Mexico (Mexico); Sánchez, F. [Instituto de Tecnologías en Detección de Astropartículas, Comisión Nacional de Energía Atómica, 1429, Buenos Aires (Argentina); Muraki, Y.; Sako, T.; Matsubara, Y.; Nagai, Y. [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Watanabe, K. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai, chuo-ku, Sagamihara 252-5210 (Japan); Shibata, S. [College of Engineering, Chubu University, Kasugai, Aichi 487-8501 (Japan); Sakai, T. [College of Industrial Technologies, Nihon University, Narashino 275-0005 (Japan)

2015-12-01

The X17.0 solar flare of 2005 September 7 released high-energy neutrons that were detected by the Solar Neutron Telescope (SNT) at Sierra Negra, Mexico. In three separate and independent studies of this solar neutron event, several of its unique characteristics were studied; in particular, a power-law energy spectra was estimated. In this paper, we present an alternative analysis, based on improved numerical simulations of the detector using GEANT4, and a different technique for processing the SNT data. The results indicate that the spectral index that best fits the neutron flux is around 3, in agreement with previous works. Based on the numerically calculated neutron energy deposition on the SNT, we confirm that the detected neutrons might have reached an energy of 1 GeV, which implies that 10 GeV protons were probably produced; these could not be observed at Earth, as their parent flare was an east limb event.

Characteristics of uranium oxide cathode for neutron streak camera

International Nuclear Information System (INIS)

Niki, H.; Itoga, K.; Yamanaka, M.; Yamanaka, T.; Yamanaka, C.

1986-01-01

In laser fusion research, time-resolved neutron measurements require 20ps resolution in order to obtain the time history of the D-T burn. Uranium oxide was expected to be a sensitive material as a cathode of a neutron streak camera because of its large fission cross section. The authors report their measurements of some characteristics of the uranium oxide cathode connected to a conventional streak tube. 14 MeV neutron signal were observed as the bright spots on a TV monitor using a focus mode opration. Detection efficiency was ∼ 1 x 10 -6 for 1 μm thick cathode. Each signal consisted of more than several tens of components, which were corresponding to the secondary electrons dragged out from the cathode by a fission fragment. Time resolution is thought to be limited mainly by the transit time spread of the secondary electrons. 14ps resolution was obtained by a streak mode operation for a single fission event

Characteristics of the JRR-3M neutron guide tubes

International Nuclear Information System (INIS)

Suzuki, Masatoshi; Ichikawa, Hiroki; Kawabata, Yuji.

1993-01-01

Large scale neutron guide tubes have been installed in the upgraded JRR-3 (Japan Research Reactor No.3, JRR-3M). The total length of the guide tubes is 232m. The neutron fluxes and spectra were measured at the end of the neutron guide tubes. The neutron fluxes of thermal neutron guide tubes with characteristic wavelength of 2A are 1.2 x 10 8 n/cm 2 · s. The neutron fluxes of cold guide tubes are 1.4 x 10 8 n/cm 2 · s with characteristic wavelength of 4A and 2.0 x 10 8 n/cm 2 · s with 6A when the cold neutron source is operated. The neutron spectra measured by time-of-flight method agree well with their designed ones. (author)

Detection of renal cell carcinoma using neutron time of flight spectroscopy

International Nuclear Information System (INIS)

Viana, Rodrigo S.; Yoriyaz, Helio; Lakshmanan, Manu N.; Agasthya, Greeshma A.; Kapadia, Anuj J.

2013-01-01

The diagnosis of renal cell carcinoma (RCC) is challenging because the symptoms accompanying it are not unique to the disease, and can therefore be misdiagnosed as other diseases. Due to this characteristic, detection of renal cancer is incidental most of time, occurring via abdominal radiographic examinations unrelated to the disease. Presently, biopsy, which is invasive and an unpleasant procedure for the patient, is the most commonly used technique to diagnose RCC. In this study, we demonstrate the application of a novel noninvasive technique for detecting and imaging RCC in vivo. The elemental composition of biological tissues including kidneys has been investigated using a new technique called Neutron Stimulated Emission Computed Tomography (NSECT). This technique is based on detecting the energy signature emitted by the stable isotopes of elements in the body, which are stimulated to emit gamma radiation via inelastic neutron scattering. Methods for improving detection sensitivity and reducing dose, such as time-of-flight neutron spectroscopy have been explored. MCNP5 simulations were used to model the NSECT scanning of the human kidney where the energy and time of arrival of gamma photons were recorded in an ideal detector placed around the human torso. A 5 MeV collimated neutron beam was used to irradiate the kidney containing an RCC lesion. The resulting spectra were resolved in 100 picosecond and 1 keV time and energy bins, respectively. The preliminary results demonstrate the ability to localize the lesion through neutron time of flight spectroscopy and generate a tomographic image at a low dose to the patient. (author)

Neutron detection with cryogenics and semiconductors

International Nuclear Information System (INIS)

Bell, Zane W.; Carpenter, D.A.; Cristy, S.S.; Lamberti, V.E.; Burger, Arnold; Woodfield, Brian F.; Niedermayr, Thomas; Dragos Hau, I.; Labov, Simon E.; Friedrich, Stephan; Geoffrey West, W.; Pohl, Kenneth R.; Berg, Lodewijk van den

2005-01-01

The common methods of neutron detection are reviewed with special attention paid to the application of cryogenics and semiconductors to the problem. The authors' work with LiF- and boron-based cryogenic instruments is described as well as the use of CdTe and HgI 2 for direct detection of neutrons. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Medical applications of in vivo neutron inelastic scattering and neutron activation analysis: Technical similarities to detection of explosives and contraband

International Nuclear Information System (INIS)

Kehayias, J.J.

2001-01-01

Nutritional status of patients can be evaluated by monitoring changes in elemental body composition. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used in vivo to assess elements characteristic of specific body compartments. There are similarities between the body composition techniques and the detection of hidden explosives and narcotics. All samples have to be examined in depth and the ratio of elements provides a 'signature' of the chemical of interest. The N/H and C/O ratios measure protein and fat content in the body. Similarly, a high C/O ratio is characteristic of narcotics and a low C/O together with a strong presence of N is a signature of some explosives. The available time for medical applications is about 20 min - compared to a few seconds for the detection of explosives - but the permitted radiation exposure is limited. In vivo neutron analysis is used to measure H, O, C, N, P, Na, Cl, and Ca for the study of the mechanisms of lean tissue depletion with aging and wasting diseases, and to investigate methods of preserving function and quality of life in the elderly

Investigation on feasibility and detection limits for determination of coating film thickness by neutron activation analysis

International Nuclear Information System (INIS)

Yao Maoying; Xu Jiayun; Zhang Dida; Yang Zunyong; Yao Zhenqiang; Wang Mingqiu; Gao Dangzhong

2010-01-01

A method for the determination of coating film thickness by neutron activation was proposed in this paper. After Au, Al and Cu et al.films were activated with a Am-Be neutron source, the characteristic γ-rays emitted by the activated nuclides in the films were counted with a HPGe γ spectrometer. The detection limits of film thickness by using a nuclear reactor neutron source were deduced on the basis of the γ-ray counts and the Monte-Carlo simulated detection efficiencies. The possible detection limits are typically 4-5 orders of magnitude better than those by fluorescent X-ray method, which is currently widely used to determine coating film thickness. (authors)

Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

Science.gov (United States)

Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

2017-07-01

Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

Novel semiconducting boron carbide/pyridine polymers for neutron detection at zero bias

Energy Technology Data Exchange (ETDEWEB)

Echeverria, Elena; Enders, A.; Dowben, P.A. [University of Nebraska-Lincoln, Department of Physics and Astronomy, Lincoln, NE (United States); James, Robinson; Chiluwal, Umesh; Gapfizi, Richard; Tae, Jae-Do; Driver, M. Sky; Kelber, Jeffry A. [University of North Texas, Department of Chemistry, Denton, TX (United States); Pasquale, Frank L. [University of North Texas, Department of Chemistry, Denton, TX (United States); Lam Research Corporation, PECVD Business Unit, Tualatin, OR (United States); Colon Santana, Juan A. [Center for Energy Sciences Research, Lincoln, NE (United States)

2014-09-19

Thin films containing aromatic pyridine moieties bonded to boron, in the partially dehydrogenated boron-rich icosahedra (B{sub 10}C{sub 2}H{sub X}), prove to be an effective material for neutron detection applications when deposited on n-doped (100) silicon substrates. The characteristic I-V curves for the heterojunction diodes exhibit strong rectification and largely unperturbed normalized reverse bias leakage currents with increasing pyridine content. The neutron capture generated pulses from these heterojunction diodes were obtained at zero bias voltage although without the signatures of complete electron-hole collection. These results suggest that modifications to boron carbide may result in better neutron voltaic materials. (orig.)

A study on the linearity characteristics of neutron power measurement system for Hanaro

International Nuclear Information System (INIS)

Kang, Tai Ki; Kim, Young Ki; Lee, Byung Chul; Park, Sang Jun

1999-06-01

It is briefly described the general principles of neutron detection and the method of neutron measurement in the nuclear reactor which neutron flux varies widely and gamma radiation also exists. Wide-range Fission Chamber System which is excellent in electrical and mechanical performances has been selected for neutron power measurement system for Hanaro. The linearity characteristics of neutron power signals is a critical factor of the reliability in reactor power control. In particular , the linearity of the log power signal, which covers 10 decade form 10 -8 %FP to 200 %FP was a matter of primary concern during commissioning. In case of the linear power signal for reactor control at high power condition, the output signals were additionally analyzed in connection with the reactor thermal power and the delayed neutron signal from the primary pipe as well as the output signal from the compensated ion chamber as a reference signal. (author). 13 refs., 7 tabs., 33 figs

A study on the linearity characteristics of neutron power measurement system for Hanaro

Energy Technology Data Exchange (ETDEWEB)

Kang, Tai Ki; Kim, Young Ki; Lee, Byung Chul; Park, Sang Jun

1999-06-01

It is briefly described the general principles of neutron detection and the method of neutron measurement in the nuclear reactor which neutron flux varies widely and gamma radiation also exists. Wide-range Fission Chamber System which is excellent in electrical and mechanical performances has been selected for neutron power measurement system for Hanaro. The linearity characteristics of neutron power signals is a critical factor of the reliability in reactor power control. In particular , the linearity of the log power signal, which covers 10 decade form 10 {sup -8} %FP to 200 %FP was a matter of primary concern during commissioning. In case of the linear power signal for reactor control at high power condition, the output signals were additionally analyzed in connection with the reactor thermal power and the delayed neutron signal from the primary pipe as well asthe output signal from the compensated ion chamber as a reference signal. (author). 13 refs., 7 tabs., 33 figs.

Detection of drugs and plastic explosives using neutron tomography

Energy Technology Data Exchange (ETDEWEB)

Ferreira, F.J.O. [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)], E-mail: fferreira@ien.gov.br; Crispim, V.R; Silva, A.X. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Programa de Engenharia Nuclear], E-mail: ademir@con.ufrj.br, E-mail: verginia@com.ufrj.br

2007-07-01

The unique ability of neutrons to image certain elements and isotopes that are either completely undetectable or poorly detected by other Non-Destructive-Assay (NDA) methods makes neutron radiography an important tool for the NDA community. Neutron radiography, like other imaging techniques takes a number of different forms (i.e. / that is film, radioscopic, transfer methods, tomography, etc.) In this work report the Neutron Tomography System developed, which will allow inspections NDA of samples with high efficiency, in terms of minors measure time and the result analysis, and the application for detection of drugs and plastic explosives, which is very important for the combat to the terrorism and drug trafficking. The neutron tomography system developed is third generation. Therefore a rotary table driven by a step motor connected to a computerized motion control system has been installed at the sample position. In parallel to this a suitable electronic imaging device has been designed and can be controlled by a computer in order to synchronize the software the detector and of the rotary table with the aim of an automation of measurements. To obtain 2D tomography image, a system with an electronic imaging system for producing real time neutron radiography. Images are processing digital for cancel random noise effects and to optimize spatial resolution. Finally, using a (ARIEN) algorithm reconstruction of tomography images by finite element maximum entropy. The system was installed adjacent to the exit of the J-9 irradiation channel of the Argonauta Reactor in the Nuclear Engineering Institute (IEN) - which is an organ of the National Nuclear Energy Commission (CNEN - Brazil).The Argonauta reactor operates at 340 watts, being that the characteristics of the neutron beam on the plane of the image: thermal neutron flux 4,46 x10{sup 5} n/cm{sup 2}s. In the tomography assays, several encapsulated samples of paste, rock and cocaine powder and plastic explosives devices

Detection of drugs and plastic explosives using neutron tomography

International Nuclear Information System (INIS)

Ferreira, F.J.O.; Crispim, V.R; Silva, A.X.

2007-01-01

The unique ability of neutrons to image certain elements and isotopes that are either completely undetectable or poorly detected by other Non-Destructive-Assay (NDA) methods makes neutron radiography an important tool for the NDA community. Neutron radiography, like other imaging techniques takes a number of different forms (i.e. / that is film, radioscopic, transfer methods, tomography, etc.) In this work report the Neutron Tomography System developed, which will allow inspections NDA of samples with high efficiency, in terms of minors measure time and the result analysis, and the application for detection of drugs and plastic explosives, which is very important for the combat to the terrorism and drug trafficking. The neutron tomography system developed is third generation. Therefore a rotary table driven by a step motor connected to a computerized motion control system has been installed at the sample position. In parallel to this a suitable electronic imaging device has been designed and can be controlled by a computer in order to synchronize the software the detector and of the rotary table with the aim of an automation of measurements. To obtain 2D tomography image, a system with an electronic imaging system for producing real time neutron radiography. Images are processing digital for cancel random noise effects and to optimize spatial resolution. Finally, using a (ARIEN) algorithm reconstruction of tomography images by finite element maximum entropy. The system was installed adjacent to the exit of the J-9 irradiation channel of the Argonauta Reactor in the Nuclear Engineering Institute (IEN) - which is an organ of the National Nuclear Energy Commission (CNEN - Brazil).The Argonauta reactor operates at 340 watts, being that the characteristics of the neutron beam on the plane of the image: thermal neutron flux 4,46 x10 5 n/cm 2 s. In the tomography assays, several encapsulated samples of paste, rock and cocaine powder and plastic explosives devices. (author)

Neutron Detection with Large Plastic Scintillators for RPM Applications

International Nuclear Information System (INIS)

Corre, G.; Boudergui, K.; Sannie, G.; Kondrasovs, V.

2015-01-01

Homeland security requests the use Radiation Portal Monitor (RPM). They must be able to detect and differentiate gamma and neutron radiation. Gamma detection is required for illicit transportation of radioactive matter detection. Neutron detection is important to control nonproliferation of enriched material. Manufacturers worldwide propose sensors based on 3 He which give the actual state of art in term of neutron detection. The imminent shortage of 3 He forces manufacturers to find viable alternative. From 10 years sensors providers have the challenge to replace previous 3 He detectors that are known to be the most commonly deployed neutron sensor. As 3 He detectors can only detect neutron, they must be completed with gamma detector. The proposed approach is based on pulse time correlation between adjacent sensors from signal collected by EJ200 plastic scintillators. Results obtained during FP7 Scintilla project test campaigns show the system relevance for replacement of today's 3 He detectors. (authors)

Neutron-based techniques for detection of explosives and drugs

International Nuclear Information System (INIS)

Kiraly, B.; Olah, L.; Csikai, G.J.

2000-01-01

Neutron reflection, scattering and transmission methods combined with the detection of characteristic gamma rays have an increasing role in the identification of hidden explosives, illicit drugs and other contraband materials. There are about 100 million land mines buried in some 70 countries. Among the abandoned anti-personnel land mines (APL) certain types have low mass (about 100 g) and contain little or no metal. Therefore, these plastic APL cannot be detected by the usual metal detectors. The IAEA Physics Section has organized a CRP in 1999 for the development of novel methods in order to speed up the removing process of APL. The transportation of illicit drugs has shown an increasing trend during the last decade. Developments of fast, non-destructive interrogation methods are required for the inspection of cargo containers, trucks and airline baggage. The major constituents of plastic APL and drugs are H, C, N and O which can be identified by the different neutron interactions. The atom fractions of these elements, in particular the C/O, C/N and C/H ratios, are quite different for drugs and explosives as compared to other materials used to hide them. Recently, we have carried out systematic measurements and calculations on the neutron fields from the 9 Be(d,n), 2 H(d,n), 252 Cf and Pu-Be sources passing through different bulky samples, on the possible use of elastically backscattered Pu-Be neutrons in elemental analysis and on the advantages and limitations of the thermal neutron reflection method in the identification of land mines and illicit drugs. The measured spectral shapes of neutrons were compared with the calculated results using the MCNP-4A and MCNP-4B codes. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-07

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

Testing the characteristics of a neutron detector array by Monte-Carlo simulations

International Nuclear Information System (INIS)

Timis, C.; Cruceru, I.; Sandu, M.; Borcea, C.; Buta, A.; Negoita, F.; Angelique, J.C.; Martin, T.; Peter, J.; Grevy, S.; Lienard, E.; Orr, N.A.

1998-01-01

The characteristics of the neutron detector array TONNERRE have been determined experimentally via preliminary tests with a 252 Cf source and by means of simulation using a modified version of the Monte-Carlo program of Cecil et al. Of particular interest is the intrinsic detection efficiency. As it is well known, the neutron detection efficiency for one element of the detector array, depends on the threshold for the light collection (bias) expressed in energy electron equivalent. The experimental efficiencies for five neutron energies and for a bias of 80 KeV ee are presented. The efficiencies for three thresholds and neutron energies between 1-10 MeV are simulated. The neutron energy is determined by TOF over a flight path, s, and the relative energy resolution is given as a function of σ s and σ t (the uncertainties in the flight path), s (uniform as a function of depth) and flight time, t. The mean time resolution was 1.13 ns which gives a TOF resolution of 1.48 ns. That gives a relative energy resolution which increases slowly from 2% at E n =1 MeV to 3.5% at 5 MeV. Position resolution along one module is 12 cm. To help boosting the efficiency, the elements can be arranged in two layers, but that complicates the analysis by enhancing the effects of cross-talk and out-scattering. Cross-talk is the familiar problem of one neutron creating signals in two separate detectors. In out-scattering, a neutron scatters from the non-active part of a detector and is then detected in a different detector with incorrect position and TOF. While methods exist for identifying and eliminating cross-talk events, there are no methods available for identifying out-scattered events. For the case of two layers and a bias of 80 KeV ee, simulated efficiency of two superposed elements versus neutron energy, the out-scattering probability and the probability of cross-talk are presented. The out-scattering probability comes mainly from events when neutrons scatter first on carbon nuclei

Prospects in MPGDs development for neutron detection

CERN Document Server

Guerard, Bruno; Murtas, Fabrizio

2014-01-01

Compared to Multi Wires Proportional Chambers (MWPC), Micro-Pattern Gas Detectors (MPGD) used in HEP to detect MIPs offer better spatial resolution, counting rate capability, and radiation hardness; their fabrication is also more reproducible. Provided similar advantages are applicable to detect neutrons, MPGDs might contribute significantly to the development of neutron scientific instrumentation. In order to evaluate the prospects of neutron MPGDs, it is worth knowing the applications which would benefit from a gain in performance, and if they offer a competitive alternative to conventional 3He detectors. These questions have been at the focus of the workshop "Neutron Detection with Micro-Pattern Gaseous Detectors" organized by RD51 in collaboration with HEPTech, which took place at CERN on October 14-15, 2013. The goal of this workshop was to help disseminating MPGD technologies beyond High Energy Physics, and to give the possibility to academic institutions, potential users and industry to meet together. ...

A review of conventional explosives detection using active neutron interrogation

International Nuclear Information System (INIS)

Whetstone, Z.D.; Kearfott, K.J.

2014-01-01

Conventional explosives are relatively easy to obtain and may cause massive harm to people and property. There are several tools employed by law enforcement to detect explosives, but these can be subverted. Active neutron interrogation is a viable alternative to those techniques, and includes: fast neutron analysis, thermal neutron analysis, pulsed fast/thermal neutron analysis, neutron elastic scatter, and fast neutron radiography. These methods vary based on neutron energy and radiation detected. A thorough review of the principles behind, advantages, and disadvantages of the different types of active neutron interrogation is presented. (author)

New neutron imaging using pulsed sources. Characteristics of a pulsed neutron source and principle of pulsed neutron imaging

International Nuclear Information System (INIS)

Kiyanagi, Yoshiaki

2012-01-01

Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method. (author)

Design, building and evaluation of a neutron detection device based on boron loaded plastic scintillator

International Nuclear Information System (INIS)

Normand, St.

2001-10-01

This work focuses on the study, the characterization and the fabrication of Boron-loaded plastic scintillators. Their use in thermal and fast neutron detection devices is also investigated. Fabrication process, especially boron doping, is explained in the first part of this work. Several FTIR, UV-visible and NMR analysis methods were used in order to characterize the material and to check its structure and stoichiometry. Experiences were done using alpha particles and proton beams to measure the scintillation characteristics. Light emission could therefore be completely determined by the Birks semi-empirical relation. In the second part, the whole detector simulation is undergone: interaction between material and radiation, light generation, paths and signal generation. Neutron simulation by MCNP (Monte Carlo N-Particles) is coupled to a light generation and propagation code developed especially during this work. These simulation tools allow us to optimize the detector geometry for neutron detection and to determine the geometry influence to the photon collection efficiency. Neutron detection efficiency and mean lifetime in this scintillator are also simulated. The close fit obtained between experimental measurements and simulations demonstrate the reliability of the method used. The third part deals with the discrimination methods between neutron and gamma, such as analog (zero crossing) and digital (charge comparison) ones. Their performances were explained and compared. The last part of this work reports on few applications where neutron detection is essential and can be improved with the use of boron loaded plastic scintillators. In particular, the cases of doped scintillation fibers, neutron spectrometry devices and more over neutron multiplicity counting devices are presented. (author)

Footprint Characteristics of Cosmic-Ray Neutron Sensors for Soil Moisture Monitoring

Science.gov (United States)

Schrön, Martin; Köhli, Markus; Zreda, Marek; Dietrich, Peter; Zacharias, Steffen

2015-04-01

Cosmic-ray neutron sensing is a unique and an increasingly accepted method to monitor the effective soil water content at the field scale. The technology is famous for its low maintenance, non-invasiveness, continuous measurement, and most importantly, for its large footprint. Being more representative than point data and finer resolved than remote-sensing products, cosmic-ray neutron derived soil moisture products provide unrivaled advantage for mesoscale hydrologic and land surface models. The method takes advantage of neutrons induced by cosmic radiation which are extraordinarily sensitive to hydrogen and behave like a hot gas. Information about nearby water sources are quickly mixed in a domain of tens of hectares in air. Since experimental determination of the actual spatial extent is hardly possible, scientists have applied numerical models to address the footprint characteristics. We have revisited previous neutron transport simulations and present a modified conceptual design and refined physical assumptions. Our revised study reveals new insights into probing distance and water sensitivity of detected neutrons under various environmental conditions. These results sharpen the range of interpretation concerning the spatial extent of integral soil moisture products derived from cosmic-ray neutron counts. Our findings will have important impact on calibration strategies, on scales for data assimilation and on the interpolation of soil moisture data derived from mobile cosmic-ray neutron surveys.

Neutron detector

Science.gov (United States)

Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN

2011-04-05

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

Proton Neutron Gamma-X Detection (PNGXD): An introduction to contrast agent detection during proton therapy via prompt gamma neutron activation

Science.gov (United States)

Gräfe, James L.

2017-09-01

Proton therapy is an alternative external beam cancer treatment modality to the conventional linear accelerator-based X-ray radiotherapy. An inherent by-product of proton-nuclear interactions is the production of secondary neutrons. These neutrons have long been thought of as a secondary contaminant, nuisance, and source of secondary cancer risk. In this paper, a method is proposed to use these neutrons to identify and localize the presence of the tumor through neutron capture reactions with the gadolinium-based MRI contrast agent. This could provide better confidence in tumor targeting by acting as an additional quality assurance tool of tumor position during treatment. This effectively results in a neutron induced nuclear medicine scan. Gadolinium (Gd), is an ideal candidate for this novel nuclear contrast imaging procedure due to its unique nuclear properties and its widespread use as a contrast agent in MRI. Gd has one of the largest thermal neutron capture cross sections of all the stable nuclides, and the gadolinium-based contrast agents localize in leaky tissues and tumors. Initial characteristics of this novel concept were explored using the Monte Carlo code MCNP6. The number of neutron capture reactions per Gy of proton dose was found to be approximately 50,000 neutron captures/Gy, for a 8 cm3 tumor containing 300 ppm Gd at 8 cm depth with a simple simulation designed to represent the active delivery method. Using the passive method it is estimated that this number can be up to an order of magnitude higher. The thermal neutron distribution was found to not be localized within the spread out Bragg peak (SOBP) for this geometrical configuration and therefore would not allow for the identification of a geometric miss of the tumor by the proton SOBP. However, this potential method combined with nuclear medicine imaging and fused with online CBCT and prior MRI or CT imaging could help to identify tumor position during treatment. More computational and

Neutron characteristic and spectroscopy logging methods and apparatus

International Nuclear Information System (INIS)

Antkiw, S.

1977-01-01

Earth formations surrounding a well bore are irradiated with pulses of fast neutrons, and gamma rays resulting from the ensuring thermal neutron capture interactions with nuclei of the formations are detected, from which measurements of the thermal neutron decay times characterizing the respective formations are derived. The gamma ray energy spectra of the respective formations are analyzed. Gating of the gamma ray detection periods is automatically controlled, both for the decay time and the spectroscopy functions, in accrdance with the measured values of the decay times. The duration and repetition rate of the neutron pulses are also controlled as a function of the measured decay times to provide an overall optimized decay time-spectroscopy operating cycle. spectroscopy outputs representative of formation lithology, salinity, porosity and shaliness are developed to supplement and improve decay time log interpretation

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)

Systems and methods for neutron detection using scintillator nano-materials

Science.gov (United States)

Letant, Sonia Edith; Wang, Tzu-Fang

2016-03-08

In one embodiment, a neutron detector includes a three dimensional matrix, having nanocomposite materials and a substantially transparent film material for suspending the nanocomposite materials, a detector coupled to the three dimensional matrix adapted for detecting a change in the nanocomposite materials, and an analyzer coupled to the detector adapted for analyzing the change detected by the detector. In another embodiment, a method for detecting neutrons includes receiving radiation from a source, converting neutrons in the radiation into alpha particles using converter material, converting the alpha particles into photons using quantum dot emitters, detecting the photons, and analyzing the photons to determine neutrons in the radiation.

Detection of Special Nuclear Material in Cargo Containers Using Neutron Interrogation

International Nuclear Information System (INIS)

Slaughter, D.; Accatino, M.; Bernstein, A.; Candy, J.; Dougan, A.; Hall, J.; Loshak, A.; Manatt, D.; Meyer, A.; Pohl, B.; Prussin, S.; Walling, R.; Weirup, D.

2003-01-01

The goal of the work reported here is to develop a concept for an active neutron interrogation system that can detect small targets of SNM contraband in cargo containers, roughly 5 kg HEU or 1 kg Pu, even when well shielded by a thick cargo. It is essential that the concept be reliable and have low false-positive and false-negative error rates. It also must be rapid to avoid interruption of commerce, completing the analysis in minutes. A new radiation signature unique to SNM has been identified that utilizes high-energy (E γ = 3-7 MeV) fission product γ-ray emission. Fortunately, this high-energy γ-ray signature is robust in that it is very distinct compared to normal background radiation where there is no comparable high-energy γ-ray radiation. Equally important, it has a factor of 10 higher yield than delayed neutrons that are the basis of classical interrogation technique normally used on small unshielded specimens of SNM. And it readily penetrates two meters of low-Z and high-Z cargo at the expected density of ∼ 0.5 gm/cm 3 . Consequently, we expect that in most cases the signature flux at the container wall is at least 2-3 decades more intense than delayed neutron signals used historically and facilitates the detection of SNM even when shielded by thick cargo. Experiments have verified this signature and its predicted characteristics. However, they revealed an important interference due to the activation of 16 O by the 16 O(n,p) 16 N reaction that produces a 6 MeV γ-ray following a 7-sec β-decay of the 16 N. This interference is important when irradiating with 14 MeV neutrons but is eliminated when lower energy neutron sources are utilized since the reaction threshold for 16 O(n,p) 16 N is 10 MeV. The signature γ-ray fluxes exiting a thick cargo can be detected in large arrays of scintillation detectors to produce useful signal count rates of 2-4 x 10 4 cps. That is high enough to quickly identify SNM fission by its characteristic high energy �

Experimental method research on neutron equal dose-equivalent detection

International Nuclear Information System (INIS)

Ji Changsong

1995-10-01

The design principles of neutron dose-equivalent meter for neutron biological equi-effect detection are studied. Two traditional principles 'absorption net principle' and 'multi-detector principle' are discussed, and on the basis of which a new theoretical principle for neutron biological equi-effect detection--'absorption stick principle' has been put forward to place high hope on both increasing neutron sensitivity of this type of meters and overcoming the shortages of the two traditional methods. In accordance with this new principle a brand-new model of neutron dose-equivalent meter BH3105 has been developed. Its neutron sensitivity reaches 10 cps/(μSv·h -1 ), 18∼40 times higher than that of all the same kinds of meters 0.23∼0.56 cps/(μSv·h -1 ), available today at home and abroad and the specifications of the newly developed meter reach or surpass the levels of the same kind of meters. Therefore the new theoretical principle of neutron biological equi-effect detection--'absorption stick principle' is proved to be scientific, advanced and useful by experiments. (3 refs., 3 figs., 2 tabs.)

Neutron threshold activation detectors (TAD) for the detection of fissions

Science.gov (United States)

Gozani, Tsahi; Stevenson, John; King, Michael J.

2011-10-01

Prompt fission neutrons are one of the strongest signatures of the fission process. Depending on the fission inducing radiation, their average number ranges from 2.5 to 4 neutrons per fission. They are more energetic and abundant, by about 2 orders of magnitude, than the delayed neutrons (≈3 vs. ≈0.01) that are commonly used as indicators for the presence of fissionable materials. The detection of fission prompt neutrons, however, has to be done in the presence of extremely intense probing radiation that stimulated them. During irradiation, the fission stimulation radiation, X-rays or neutrons, overwhelms the neutron detectors and temporarily incapacitate them. Consequently, by the time the detectors recover from the source radiation, fission prompt neutrons are no longer emitted. In order to measure the prompt fission signatures under these circumstances, special measures are usually taken with the detectors such as heavy shielding with collimation, use of inefficient geometries, high pulse height bias and gamma-neutron separation via pulse-shape discrimination with an appropriate organic scintillator. These attempts to shield the detector from the flash of radiation result in a major loss of sensitivity. It can lead to a complete inability to detect the fission prompt neutrons. In order to overcome the blinding induced background from the source radiation, the detection of prompt fission neutrons needs to occur long after the fission event and after the detector has fully recovered from the source overload. A new approach to achieve this is to detect the delayed activation induced by the fission neutrons. The approach demonstrates a good sensitivity in adverse overload situations (gamma and neutron "flash") where fission prompt neutrons could normally not be detected. The new approach achieves the required temporal separation between the detection of prompt neutrons and the detector overload by the neutron activation of the detector material. The technique

Neutron threshold activation detectors (TAD) for the detection of fissions

International Nuclear Information System (INIS)

Gozani, Tsahi; Stevenson, John; King, Michael J.

2011-01-01

Prompt fission neutrons are one of the strongest signatures of the fission process. Depending on the fission inducing radiation, their average number ranges from 2.5 to 4 neutrons per fission. They are more energetic and abundant, by about 2 orders of magnitude, than the delayed neutrons (∼3 vs. ∼0.01) that are commonly used as indicators for the presence of fissionable materials. The detection of fission prompt neutrons, however, has to be done in the presence of extremely intense probing radiation that stimulated them. During irradiation, the fission stimulation radiation, X-rays or neutrons, overwhelms the neutron detectors and temporarily incapacitate them. Consequently, by the time the detectors recover from the source radiation, fission prompt neutrons are no longer emitted. In order to measure the prompt fission signatures under these circumstances, special measures are usually taken with the detectors such as heavy shielding with collimation, use of inefficient geometries, high pulse height bias and gamma-neutron separation via pulse-shape discrimination with an appropriate organic scintillator. These attempts to shield the detector from the flash of radiation result in a major loss of sensitivity. It can lead to a complete inability to detect the fission prompt neutrons. In order to overcome the blinding induced background from the source radiation, the detection of prompt fission neutrons needs to occur long after the fission event and after the detector has fully recovered from the source overload. A new approach to achieve this is to detect the delayed activation induced by the fission neutrons. The approach demonstrates a good sensitivity in adverse overload situations (gamma and neutron 'flash') where fission prompt neutrons could normally not be detected. The new approach achieves the required temporal separation between the detection of prompt neutrons and the detector overload by the neutron activation of the detector material. The technique

Neutron threshold activation detectors (TAD) for the detection of fissions

Energy Technology Data Exchange (ETDEWEB)

Gozani, Tsahi, E-mail: tgozani@rapiscansystems.com [Rapiscan Laboratories, Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States); Stevenson, John; King, Michael J. [Rapiscan Laboratories, Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)

2011-10-01

Prompt fission neutrons are one of the strongest signatures of the fission process. Depending on the fission inducing radiation, their average number ranges from 2.5 to 4 neutrons per fission. They are more energetic and abundant, by about 2 orders of magnitude, than the delayed neutrons ({approx}3 vs. {approx}0.01) that are commonly used as indicators for the presence of fissionable materials. The detection of fission prompt neutrons, however, has to be done in the presence of extremely intense probing radiation that stimulated them. During irradiation, the fission stimulation radiation, X-rays or neutrons, overwhelms the neutron detectors and temporarily incapacitate them. Consequently, by the time the detectors recover from the source radiation, fission prompt neutrons are no longer emitted. In order to measure the prompt fission signatures under these circumstances, special measures are usually taken with the detectors such as heavy shielding with collimation, use of inefficient geometries, high pulse height bias and gamma-neutron separation via pulse-shape discrimination with an appropriate organic scintillator. These attempts to shield the detector from the flash of radiation result in a major loss of sensitivity. It can lead to a complete inability to detect the fission prompt neutrons. In order to overcome the blinding induced background from the source radiation, the detection of prompt fission neutrons needs to occur long after the fission event and after the detector has fully recovered from the source overload. A new approach to achieve this is to detect the delayed activation induced by the fission neutrons. The approach demonstrates a good sensitivity in adverse overload situations (gamma and neutron 'flash') where fission prompt neutrons could normally not be detected. The new approach achieves the required temporal separation between the detection of prompt neutrons and the detector overload by the neutron activation of the detector

Neutron detection in the frame of spatial magnetic spin resonance

Energy Technology Data Exchange (ETDEWEB)

Jericha, Erwin, E-mail: jericha@ati.ac.at [TU Wien, Atominstitut, Stadionallee 2, 1020 Wien (Austria); Bosina, Joachim [TU Wien, Atominstitut, Stadionallee 2, 1020 Wien (Austria); Austrian Academy of Sciences, Stefan Meyer Institute, Boltzmanngasse 3, 1090 Wien (Austria); Institut Laue–Langevin, 71 Avenue des Martyrs, 38042 Grenoble (France); Geltenbort, Peter [Institut Laue–Langevin, 71 Avenue des Martyrs, 38042 Grenoble (France); Hino, Masahiro [Kyoto University, Research Reactor Institute, Kumatori, Osaka 590-0494 (Japan); Mach, Wilfried [TU Wien, Atominstitut, Stadionallee 2, 1020 Wien (Austria); Oda, Tatsuro [Kyoto University, Department of Nuclear Engineering, Kyoto 615-8540 (Japan); Badurek, Gerald [TU Wien, Atominstitut, Stadionallee 2, 1020 Wien (Austria)

2017-02-11

This work is related to neutron detection in the context of the polarised neutron optics technique of spatial magnetic spin resonance. By this technique neutron beams may be tailored in their spectral distribution and temporal structure. We have performed experiments with very cold neutrons (VCN) at the high-flux research reactor of the Institut Laue Langevin (ILL) in Grenoble to demonstrate the potential of this method. A combination of spatially and temporally resolving neutron detection allowed us to characterize a prototype neutron resonator. With this detector we were able to record neutron time-of-flight spectra, assess and minimise neutron background and provide for normalisation of the spectra owing to variations in reactor power and ambient conditions at the same time.

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

Detection of fission signatures induced by a low-energy neutron source

International Nuclear Information System (INIS)

Ocherashvili, A.; Becka, A.; Mayorovb, V.; Roesgen, E.; Crochemoreb, J.-M.; Mosconi, M.; Pedersen, B.; Heger, C.

2015-01-01

We present a method for the detection of special nuclear materials (SNM) in shielded containers which is both sensitive and applicable under field conditions. The method uses an external pulsed neutron source to induce fission in SNM and subsequent detection of the fast prompt fission neutrons. The detectors surrounding the container under investigation are liquid scintillation detectors able to distinguish gamma rays from fast neutrons by means of the pulse shape discrimination method (PSD). One advantage of these detectors, besides the ability for PSD analysis, is that the analogue signal from a detection event is of very short duration (typically few tens of nanoseconds). This allows the use of very short coincidence gates for the detection of the prompt fission neutrons in multiple detectors while benefiting from a low accidental (background) coincidence rate yielding a low detection limit. Another principle advantage of this method derives from the fact that the external neutron source is pulsed. By proper time gating the interrogation can be conducted by epithermal and thermal source neutrons only. These source neutrons do not appear in the fast neutron signal following the PSD analysis thus providing a fundamental method for separating the interrogating source neutrons from the sample response in form of fast fission neutrons. The paper describes laboratory tests with a configuration of eight detectors in the Pulsed Neutron Interrogation Test Assembly (PUNITA). The sensitivity of the coincidence signal to fissile mass is investigated for different sample configurations and interrogation regimes.

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.

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

Mechanical approach to the neutrons spectra collimation and detection

Energy Technology Data Exchange (ETDEWEB)

Sadeghi, H.; Roshan, M. V. [Energy Engineering and Physics Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2014-11-15

Neutrons spectra from most of known sources require being collimated for numerous applications; among them one is the Neutron Activation Analysis. High energy neutrons are collimated through a mechanical procedure as one of the most promising methods. The output energy of the neutron beam depends on the velocity of the rotating Polyethylene disks. The collimated neutrons are then measured by an innovative detection technique with high accuracy.

High sensitivity neutron bursts detecting system

International Nuclear Information System (INIS)

Shyam, A.; Kaushik, T.C.; Srinivasan, M.; Kulkarni, L.V.

1993-01-01

Technique and instrumentation to detect multiplicity of fast neutrons, emitted in sharp bursts, has been developed. A bank of 16 BF 3 detectors, in an appropriate thermalising assembly, efficiency ∼ 16%, is used to detect neutron bursts. The output from this setup, through appropriate electronics, is divided into two paths. The first is directly connected to a computer controlled scalar. The second is connected to another similar scalar through a delay time unit (DTU). The DTU design is such that once it is triggered by a count pulse than it does not allow any counts to be recorded for a fixed dead time set at ∼ 100 μs. The difference in counts recorded directly and through DTU gives the total number of neutrons produced in bursts. This setup is being used to study lattice cracking, anomalous effects in solid deuterium systems and various reactor physics experiments. (author). 3 refs., 1 fig

Improvement of radiation response characteristic on CdTe detectors using fast neutron irradiation

International Nuclear Information System (INIS)

Miyamaru, Hiroyuki; Takahashi, Akito; Iida, Toshiyuki

1999-01-01

The treatment of fast neutron pre-irradiation was applied to a CdTe radiation detector in order to improve radiation response characteristic. Electron transport property of the detector was changed by the irradiation effect to suppress pulse amplitude fluctuation in risetime. Spectroscopic performance of the pre-irradiated detector was compared with the original. Additionally, the pre-irradiated detector was employed with a detection system using electrical signal processing of risetime discrimination (RTD). Pulse height spectra of 241 Am, 133 Ba, and 137 Cs gamma rays were measured to examine the change of the detector performance. The experimental results indicated that response characteristic for high-energy photons was improved by the pre-irradiation. The combination of the pre-irradiated detector and the RTD processing was found to provide further enhancement of the energy resolution. Application of fast neutron irradiation effect to the CdTe detector was demonstrated. (author)

The synchronous active neutron detection system for spent fuel assay

International Nuclear Information System (INIS)

Pickrell, M.M.; Kendall, P.K.

1994-01-01

The authors have begun to develop a novel technique for active neutron assay of fissile material in spent nuclear fuel. This approach will exploit the unique operating features of a 14-MeV neutron generator developed by Schlumberger. This generator and a novel detection system will be applied to the direct measurement of the fissile material content in spent fuel in place of the indirect measures used at present. The technique they are investigating is termed synchronous active neutron detection (SAND). It closely follows a method that has been used routinely in other branches of physics to detect very small signals in the presence of large backgrounds. Synchronous detection instruments are widely available commercially and are termed open-quotes lock-inclose quotes amplifiers. The authors have implemented a digital lock-in amplifier in conjunction with the Schlumberger neutron generator to explore the possibility of synchronous detection with active neutrons. This approach is possible because the Schlumberger system can operate at up to a 50% duty factor, in effect, a square wave of neutron yield. The results to date are preliminary but quite promising. The system is capable of resolving the fissile material contained in a small fraction of the fuel rods in a cold fuel assembly. It also appears to be quite resilient to background neutron interference. The interrogating neutrons appear to be nonthermal and penetrating. Although a significant amount of work remains to fully explore the relevant physics and optimize the instrument design, the underlying concept appears sound

Detection of special nuclear material from delayed neutron emission induced by a dual-particle monoenergetic source

Energy Technology Data Exchange (ETDEWEB)

Mayer, M. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Nattress, J.; Jovanovic, I., E-mail: ijov@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2016-06-27

Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the {sup 11}B(d,n γ){sup 12}C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass–polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time-dependent buildup and decay of delayed neutron emission from {sup 238}U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

Fast neutron spectrometry by bolometers lithium target for the reduction of background experiences of direct detection of dark matter

International Nuclear Information System (INIS)

Gironnet, J.

2010-01-01

Fast neutron spectrometry is a common interest for both direct dark matter detection and for nuclear research centres. Fast neutrons are usually detected indirectly. Neutrons are first slowed down by moderating materials for being detected in low energy range. Nevertheless, these detection techniques are and are limited in energy resolution. A new kind of fast neutron spectroscopy has been developed at the Institut d'Astrophysique Spatiale (IAS) in the aim of having a better knowledge of neutron backgrounds by the association of the bolometric technique with neutron sensitive crystals containing Li. Lithium-6 is indeed an element which has one the highest cross section for neutron capture with the 6 Li(n,α) 3 H reaction. This reaction releases 4,78 MeV tagging energetically each neutron capture. In particular for fast neutrons, the total energy measured by the bolometer would be the sum of this energy reaction and of the incoming fast neutron energy. To validate this principle, a spectrometer for fast neutrons, compact and semi-transportable, was built in IAS. This cryogenic detector, operated at 300 - 400 mK, consists of a 0.5 g LiF 95% 6 Li enriched crystal read out by a NTD-Ge sensor. This PhD thesis was on the study of the spectrometer characteristics, from the first measurements at IAS, to the measurements in the nuclear research centre of the Paul Scherrer Institute (PSI) until the final calibration with the Amande instrument of the Institut de Radioprotection et de Surete Nucleaire (IRSN). (author)

Pulsed White Spectrum Neutron Generator for Explosive Detection

International Nuclear Information System (INIS)

King, Michael J.; Miller, Gill T.; Reijonen, Jani; Ji, Qing; Andresen, Nord; Gicquel, Frederic; Kavlas, Taneli; Leung, Ka-Ngo; Kwan, Joe

2008-01-01

Successful explosive material detection in luggage and similar sized containers is a critical issue in securing the safety of all airline passengers. Tensor Technology Inc. has recently developed a methodology that will detect explosive compounds with pulsed fast neutron transmission spectroscopy. In this scheme, tritium beams will be used to generate neutrons with a broad energy spectrum as governed by the T(t,2n)4He fission reaction that produces 0-9 MeV neutrons. Lawrence Berkeley National Laboratory (LBNL), in collaboration with Tensor Technology Inc., has designed and fabricated a pulsed white-spectrum neutron source for this application. The specifications of the neutron source are demanding and stringent due to the requirements of high yield and fast pulsing neutron emission, and sealed tube, tritium operation. In a unique co-axial geometry, the ion source uses ten parallel rf induction antennas to externally couple power into a toroidal discharge chamber. There are 20 ion beam extraction slits and 3 concentric electrode rings to shape and accelerate the ion beam into a titanium cone target. Fast neutron pulses are created by using a set of parallel-plate deflectors switching between +-1500 volts and deflecting the ion beams across a narrow slit. The generator is expected to achieve 5 ns neutron pulses at tritium ion beam energies between 80-120 kV. First experiments demonstrated ion source operation and successful beam pulsing

Neutron stars at the dark matter direct detection frontier

Science.gov (United States)

Raj, Nirmal; Tanedo, Philip; Yu, Hai-Bo

2018-02-01

Neutron stars capture dark matter efficiently. The kinetic energy transferred during capture heats old neutron stars in the local galactic halo to temperatures detectable by upcoming infrared telescopes. We derive the sensitivity of this probe in the framework of effective operators. For dark matter heavier than a GeV, we find that neutron star heating can set limits on the effective operator cutoff that are orders of magnitude stronger than possible from terrestrial direct detection experiments in the case of spin-dependent and velocity-suppressed scattering.

Discussions in symposium 'neutron dosimetry in neutron fields - from detection techniques to medical applications'

International Nuclear Information System (INIS)

Tanimura, Y.; Sato, T.; Kumada, H.; Terunuma, T.; Sakae, T.; Harano, H.; Matsumoto, T.; Suzuki, T.; Matsufuji, N.

2008-01-01

Recently the traceability system (JCSS) of neutron standard based on the Japanese law 'Measurement Act' has been instituted. In addition, importance of the neutron dose evaluation has been increasing in not only the neutron capture medical treatment but also the proton or heavy particle therapy. Against such a background, a symposium 'Neutron dosimetry in neutron fields - From detection techniques to medical applications-' was held on March 29, 2008 and recent topics on the measuring instruments and their calibration, the traceability system, the simulation technique and the medical applications were introduced. This article summarizes the key points in the discussion at the symposium. (author)

Development of the environmental neutron detection system

International Nuclear Information System (INIS)

Kume, Kyo

2002-03-01

Environmental neutron detection system was proposed and developed. The main goal of this system was set to detect fast and thermal neutrons with the identical detectors setup without degraders. This system consists of a 10 B doped liquid scintillator for n detection and CsI scintillators for simultaneous γ emission from 10 B doped in the liquid scintillator after the n capture reaction. The first setup was optimized for the thermal n detection, while the second setup was for the fast n detection. It was shown that the thermal n flux was obtained in the first setup by using the method of the γ coincidence method with the help of the Monte Carlo calculation. The second setup was designed to improve the detection efficiency for the fast n, and was shown qualitatively that both the pulse shape discrimination and the coincidence methods are efficient. There will be more improvements, particularly for the quantitative discussion. (author)

Direct fast neutron detection: A status report

International Nuclear Information System (INIS)

Peurrung, A.J.; Hansen, R.R.; Craig, R.A.; Hensley, W.K.; Hubbard, C.W.; Keller, P.E.; Reeder, P.L.; Sunberg, D.S.

1997-12-01

This report describes the status of efforts to develop direct fast-neutron detection via proton recoil within plastic scintillator. Since recording proton recoil events is of little practical use without a means to discriminate effectively against gamma-ray interactions, the present effort is concentrated on demonstrating a method that distinguishes between pulse types. The proposed method exploits the different pulse shapes that are to be expected primarily on the basis of the slower speed of the recoiling fission neutrons. Should this effort ultimately prove successful, the resulting novel technology will have the potential to significantly lower cost and increase capability for a number of critical neutron-detection applications. Considerable progress has been made toward a clear and compelling demonstration of this new technique. An exhaustive theoretical and numerical investigation of the method has been completed. The authors have been able to better understand the laboratory results and estimate the performance that could ultimately be achieved using the proposed technique. They have assessed the performance of a number of different algorithms for discriminating between neutron and gamma ray events. The results of this assessment will be critical when the construction of low-cost, field-portable neutron detectors becomes necessary. Finally, a laboratory effort to realize effective discrimination is well underway and has resulted in partial success

Conducting Polymers for Neutron Detection

International Nuclear Information System (INIS)

Clare Kimblin; Kirk Miller; Bob Vogel; Bill Quam; Harry McHugh; Glen Anthony; Steve Jones; Mike Grover

2007-01-01

Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number

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

Differential and integral characteristics of prompt fission neutrons in the statistical theory

International Nuclear Information System (INIS)

Gerasimenko, B.F.; Rubchenya, V.A.

1989-01-01

Hauser-Feshbach statistical theory is the most consistent approach to the calculation of both spectra and prompt fission neutrons characteristics. On the basis of this approach a statistical model for calculation of differential prompt fission neutrons characteristics of low energy fission has been proposed and improved in order to take into account the anisotropy effects arising at prompt fission neutrons emission from fragments. 37 refs, 6 figs

Design of a versatile detector for the detection of charged particles, neutrons and gamma rays. Neutron interaction with the matter

International Nuclear Information System (INIS)

Perez P, J.J.

1991-01-01

The Fostron detector detects charged particles, neutrons and gamma rays with a reasonable discrimination power. Because the typical detectors for neutrons present a great uncertainty in the detection, this work was focused mainly to the neutron detection in presence of gamma radiation. Also there are mentioned the advantages and disadvantages of the Fostron detector

Study on development and actual application of scientific crime detection technique using small scale neutron radiation source

International Nuclear Information System (INIS)

Suzuki, Yasuhiro; Kishi, Toru; Tachikawa, Noboru; Ishikawa, Isamu.

1997-01-01

PGA (Prompt γ-ray Analysis) is an analytic method of γ-ray generated from atomic nuclei of elements in the specimen just after irradiation (within 10(exp-14)sec.) of neutron to it. As using neutron with excellent transmission for an exciting source, this method can be used for inspecting the matters in closed containers non-destructively, and can also detect non-destructively light elements such as boron, nitrogen and others difficult by other non-destructive analysis. Especially, it is found that this method can detect such high concentration of nitrogen, chlorine and others which are characteristic elements for the explosives. However, as there are a number of limitations at the nuclear reactor site, development of an analytical apparatus for small scale neutron radiation source was begun, at first. In this fiscal year, analysis of the light elements such as nitrogen, chlorine and others using PGA was attempted by using 252-Cf as the simplest neutron source in its operation. As the 252-Cf neutron flux was considerably lower than that of nuclear reactor, its analytical sensitivity was also investigated. (G.K.)

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.)

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

Real‑time, fast neutron detection for stimulated safeguards assay

International Nuclear Information System (INIS)

Joyce, Malcolm J.; Adamczyk, Justyna; Plenteda, Romano; Aspinall, Michael D.; Cave, Francis D.

2015-01-01

The advent of low‑hazard organic liquid scintillation detectors and real‑time pulse‑shape discrimination (PSD) processing has suggested a variety of modalities by which fast neutrons, as opposed to neutrons moderated prior to detection, can be used directly to benefit safeguards needs. In this paper we describe a development of a fast‑neutron based safeguards assay system designed for the assessment of 235 U content in fresh fuel. The system benefits from real‑time pulse‑shape discrimination processing and auto‑calibration of the detector system parameters to ensure a rapid and effective set‑up protocol. These requirements are essential in optimising the speed and limit of detection of the fast neutron technique, whilst minimising the intervention needed to perform the assay.

Simulation of Neutron Backscattering applied to organic material detection

International Nuclear Information System (INIS)

Forero, N. C.; Cruz, A. H.; Cristancho, F.

2007-01-01

The Neutron Backscattering technique is tested when performing the task of localizing hydrogenated explosives hidden in soil. Detector system, landmine, soil and neutron source are simulated with Geant4 in order to obtain the number of neutrons detected when several parameters like mine composition, relative position mine-source and soil moisture are varied

Delayed neutron detection in canning burst detection studies (1961); Etude sur la detection des neutrons differes en vue de la detection des ruptures de gaines (1961)

Energy Technology Data Exchange (ETDEWEB)

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

1961-07-01

This paper describes a theoretical and experimental study on the detection of neutrons present in the primary cooling circuit of a reactor cooled by heavy or light water, with a view to the installation of a canning burst detection unit. The concentration of background neutrons is first calculated, taking into account the neutrons from nitrogen 17 decay, and the photoneutrons produced by the decay of nitrogen 16 and sodium 24. The emission of delayed fission neutrons, originating at a given crack in the canning, has been estimated. Using the D{sub 2}O circuit of the pile EL-3, three units have been developed by means of which the following three types of detector may be compared: 1) BF{sub 3} proportional counter 2) Boron scintillator 3) Fission chamber Under the present experimental conditions the BF{sub 3} counter gave the best results. The influence on these detectors of the {gamma} flux, which in certain cases reaches 200 R/h, is analysed. Finally a calibration is carried out with an experimental crack of 30 mm{sup 2} of uranium exposed to a flux of 5.8 x 10{sup 13} n.cm{sup -2}.s{sup -1}. The sensitivity obtained with the BF{sub 3} counter during this test is 2 counts/s per mm{sup 2} of exposed uranium. (author) [French] Le present rapport est une etude theorique et experimentale sur la detection des neutrons presents dans le circuit primaire de refroidissement d'un reacteur refrigere par l'eau lourde ou l'eau legere, en vue d'une installation de detection de ruptures de gaines. On fait d'abord un calcul sur la concentration des neutrons de bruit de fond en tenant compte: des neutrons de decroissance de l'azote 17 et des photoneutrons produits par les decroissances de l'azote 16 et du sodium 24. L'emission des neutrons differes de fission, qui ont pour origine une fissure de gaine donnee, a ete evaluee. Utilisant le circuit D{sub 2}O de la pile EL3, trois installations ont ete mises au point permettant de comparer les trois types de detecteurs suivants: 1

Scintillator Based Coded-Aperture Imaging for Neutron Detection

International Nuclear Information System (INIS)

Hayes, Sean-C.; Gamage, Kelum-A-A.

2013-06-01

In this paper we are going to assess the variations of neutron images using a series of Monte Carlo simulations. We are going to study neutron images of the same neutron source with different source locations, using a scintillator based coded-aperture system. The Monte Carlo simulations have been conducted making use of the EJ-426 neutron scintillator detector. This type of detector has a low sensitivity to gamma rays and is therefore of particular use in a system with a source that emits a mixed radiation field. From the use of different source locations, several neutron images have been produced, compared both qualitatively and quantitatively for each case. This allows conclusions to be drawn on how suited the scintillator based coded-aperture neutron imaging system is to detecting various neutron source locations. This type of neutron imaging system can be easily used to identify and locate nuclear materials precisely. (authors)

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)

Evaluation of neutron techniques for illicit substance detection

International Nuclear Information System (INIS)

Fink, C.L.; Micklich, B.J.; Yule, T.J.; Humm, P.; Sagalovsky, L.; Martin, M.M.

1995-01-01

We are studying inspection systems based on the use of fast neutrons for detecting illicit substances such as explosives and drugs in luggage and cargo containers. Fast-neutron techniques can determine the quantities of light elements such as carbon, nitrogen, and oxygen in a volume element. Illicit substances containing these elements are characterized by distinctive elemental densities or density ratios. We discuss modeling and tomographic reconstruction studies for fast-neutron transmission spectroscopy. (orig.)

Evaluation of neutron techniques for illicit substance detection

International Nuclear Information System (INIS)

Fink, C.L.; Micklich, B.J.; Yule, T.J.; Humm, P.; Sagalovsky, L.; Martin, M.M.

1994-01-01

The authors are studying inspection systems based on the use of fast neutrons for detecting illicit substances such as explosives and drugs in luggage and cargo containers. Fast neutron techniques can determine the quantities of light elements such as carbon, nitrogen, and oxygen in a volume element. Illicit substances containing these elements are characterized by distinctive elemental densities or density ratios. They discuss modeling and tomographic reconstruction studies for fast-neutron transmission spectroscopy

Illicit substance detection using fast-neutron transmission spectroscopy

International Nuclear Information System (INIS)

Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

1994-01-01

Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d, n) source (E d =5 MeV). The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification. ((orig.))

Illicit substance detection using Fast-Neutron Transmission Spectroscopy

International Nuclear Information System (INIS)

Micklich, B.J.; Harper, M.K.; Novick, A.H.; Smith, D.L.

1994-01-01

Fast-neutron interrogation techniques are of interest for detecting illicit substances such as explosives and drugs because of their ability to identify light elements such as carbon, nitrogen, and oxygen. Fast-Neutron Transmission Spectroscopy (FNTS) uses standard time-of-flight techniques to measure the energy spectrum of neutrons emitted from a collimated continuum source before and after transmission through the interrogated sample. The Monte Carlo transport code MCNP is used to model fast-neutron transmission experiments using a 9 Be(d,n) source [E d = 5 MeV]. The areal densities (number of atoms per cm 2 ), and the uncertainties, of various elements present in the sample are determined by an unfolding algorithm which includes the effects of cross-section errors and correlations. Results are displayed in the form of normalized densities, including their errors and correlations, which are then compared to the values for explosives and benign substances. Probabilistic interpretations of the results are discussed in terms of substance detection and identification

YAP scintillators for resonant detection of epithermal neutrons at pulsed neutron sources

International Nuclear Information System (INIS)

Tardocchi, M.; Gorini, G.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Rhodes, N.; Schooneveld, E. M.

2004-01-01

Recent studies indicate the resonance detector (RD) technique as an interesting approach for neutron spectroscopy in the electron volt energy region. This work summarizes the results of a series of experiments where RD consisting of YAlO 3 (YAP) scintillators were used to detect scattered neutrons with energy in the range 1-200 eV. The response of YAP scintillators to radiative capture γ emission from a 238 U analyzer foil was characterized in a series of experiments performed on the VESUVIO spectrometer at the ISIS pulsed neutron source. In these experiments a biparametric data acquisition allowed the simultaneous measurements of both neutron time-of-flight and γ pulse height (energy) spectra. The analysis of the γ pulse height and neutron time of flight spectra permitted to identify and distinguish the signal and background components. These measurements showed that a significant improvement in the signal-to-background ratio can be achieved by setting a lower level discrimination on the pulse height at about 600 keV equivalent photon energy. Present results strongly indicate YAP scintillators as the ideal candidate for neutron scattering studies with epithermal neutrons at both very low (<5 deg.) and intermediate scattering angles

Detection of buried land mines using back scattered neutron induced γ-ray analysis

International Nuclear Information System (INIS)

Aziz, M.; Megahd, R.

2003-01-01

The application of nuclear technique to detection buried land mine is examined. MCNP code was used to design a computer model that calculate the back scattered neutron induced γ rays from buried simulate explosive materials. The characteristic γ rays for each isotopes were used to distinguish materials. The advantage of the nuclear technique was discussed. The results were compared with experimental measurements which show good agreement

A large 2D PSD for thermal neutron detection

Energy Technology Data Exchange (ETDEWEB)

Knott, R.B.; Watt, G.; Boldeman, J.W. [Australian Nucl. Sci. and Tech. Organ., Menai, NSW (Australia). Phys. Div.; Smith, G.C. [Instrumentation Division, Brookhaven National Laboratory, Upton, NY 11973 (United States)

1997-06-21

A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 x 640 mm{sup 2}. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimise parallax, the gas mixture was 190 kPa {sup 3}He plus 100 kPa CF{sub 4}, and the active volume had a thickness of 30 mm. The design maximum neutron count rate of the detector was 10{sup 5} events per second. The (calculated) neutron detection efficiency was 60% for 2 A neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 x 5 mm{sup 2}) was thereby defined by the wire geometry. A 16-channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise line width 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. (orig.).

Neutron sources and its dosimetric characteristics

International Nuclear Information System (INIS)

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

2005-01-01

By means of Monte Carlo methods the spectra of the produced neutrons 252 Cf, 252 Cf/D 2 O, 241 Am Be, 239 Pu Be, 140 La Be, 239 Pu 18 O 2 and 226 Ra Be have been calculated. With the information of the spectrum it was calculated the average energy of the neutrons of each source. By means of the fluence coefficients to dose it was determined, for each one of the studied sources, the fluence factors to dose. The calculated doses were H, H * (10), H p,sIab (10, 0 0 ), E AP and E ISO . During the phase of the calculations the sources were modeled as punctual and their characteristics were determined to 100 cm in the hole. Also, for the case of the sources of 239 Pu Be and 241 Am Be, were carried out calculations modeling the sources with their respective characteristics and the dosimetric properties were determined in a space full with air. The results of this last phase of the calculations were compared with the experimental results obtained for both sources. (Author)

Fundamental of neutron radiography and the present of neutron radiography in Japan

International Nuclear Information System (INIS)

Sekita, Junichiro

1988-01-01

Neutron radiography refers to the application of transmitted neutrons to analysis. In general, thermal neutron is used for neutron radiography. Thermal neutron is easily absorbed by light atoms, including hydrogen, boron and lithium, while it is not easily absorbed by such heavy atoms as tungsten, lead and uranium, permitting detection of impurities in heavy metals. Other neutrons than thermal neutron can also be applied. Cold neutron is produced from fast neutron using a moderator to reduce its energy down to below that of thermal neutron. Cold neutron is usefull for analysis of thick material. Epithermal neutron can induce resonance characteristic of each substance. With a relatively small reaction area, fast neutron permits observation of thick samples. Being electrically neutral, neutrons are difficult to detect by direct means. Thus a substance that releases charged particles is put in the path of neutrons for indirect measurement. X-ray film combined with converter screen for conversion of neutrons to charge particles is placed behind the sample. Photographing is carried out by a procedure similar to X-ray photography. Major institues and laboratories in Japan provided with neutron radiography facilities are listed. (Nogami, K.)

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

Accelerating fissile material detection with a neutron source

Science.gov (United States)

Rowland, Mark S.; Snyderman, Neal J.

2018-01-30

A neutron detector system for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly to count neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. The system includes a Poisson neutron generator for in-beam interrogation of a possible fissile neutron source and a DC power supply that exhibits electrical ripple on the order of less than one part per million. Certain voltage multiplier circuits, such as Cockroft-Walton voltage multipliers, are used to enhance the effective of series resistor-inductor circuits components to reduce the ripple associated with traditional AC rectified, high voltage DC power supplies.

Device for detecting neutron flux in nuclear reactor. [BWR

Energy Technology Data Exchange (ETDEWEB)

Bessho, Y; Nishizawa, Y

1976-07-30

The object of the invention is to ensure accuracy in the operation of the nuclear reactor by reducing the difference that results between the readings of a Traversing Incore Probe (TIP) and a Local Power Range Monitor (LPRM) when the neutron flux distribution undergoes a change. In an apparatus for detecting neutrons in a nuclear reactor, an LPRM sensor comprising a layer containing a substance capable of nuclear fission, a section filled with argon gas and a collector is constructed so as to surround a TIP within a TIP guide tube at the height of the reactor axis. In this way, the LPRM detects the average value of neutron distribution in the region surrounding the TIP, so that no great difference between the readings of both the sensors is produced even if the neutron flux distribution is changed.

Gadolinium-Based GaN for Neutron Detection with Gamma Discrimination

Science.gov (United States)

2016-06-01

Gadolinium-Based GaN for Neutron Detection with Gamma Discrimination Distribution Statement A. Approved for public release; distribution is...Final Technical Report BRBAA08-Per5-Y-1-2-0030 Title: “Gadolinium-Based GaN for Neutron Detection with Gamma Discrimination ” Grant...Analysis  .............................................................................................  23   6.   Gamma-ray Discrimination

Gadolinium for neutron detection in current nuclear instrumentation research: A review

Science.gov (United States)

Dumazert, J.; Coulon, R.; Lecomte, Q.; Bertrand, G. H. V.; Hamel, M.

2018-02-01

Natural gadolinium displays a number of remarkable physical properties: it is a rare earth element, composed of seven stable or quasi-stable isotopes, with an exceptionally high magnetization and a Curie point near room temperature. Its use in the field of nuclear instrumentation historically relates to its efficiency as a neutron poison in power reactors. Gadolinium is indeed the naturally occurring element with the highest interaction probability with neutrons at thermal energy, shared between Gd-157 (15.65%, 254000 b cross section) and Gd-155 (14.8%, 60900 b) isotopes. Considering that neutron capture results in an isotopic change, followed by a radiative rearrangement of nuclear and atomic structures, Gd may be embodied not merely as a neutron poison but as a neutron converter into a prompt photon and an electron source term. Depending on the nature and energy of the reaction products (from a few-keV Auger electrons up to 8 MeV gamma rays) that the detector aims at isolating as an indirect neutron signature, a variety of sensor media and counting methods have been introduced during the last decades. This review first draws a theoretical description of the radiative cascade following Gd(n , γ) capture. The cascade may be subdivided into regions of interest, each corresponding to dedicated detection designs and optimizations whose current status is detailed. This inventory has allowed the authors to extract and benchmark key figures of merit for the definition of a detection scheme: neutron attenuation, neutron sensitivity (cps/nv), gamma rejection, neutron detection limit in a mixed field, intrinsic or extrinsic moderation, and transportability. On this basis, the authors have identified promising paths for Gd-based neutron detection in contemporary instrumentation.

Novel concept for neutron detection: proportional counter filled with 10B nanoparticle aerosol

Science.gov (United States)

Amaro, F. D.; Monteiro, C. M. B.; dos Santos, J. M. F.; Antognini, A.

2017-01-01

The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of 3He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. 3He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF3, which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the 3He atoms are replaced by nanoparticles made of another neutron sensitive material, 10B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of 3He in proportional counters. PMID:28181520

Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

Energy Technology Data Exchange (ETDEWEB)

Gozani, Tsahi, E-mail: tgmaven@gmail.com [1050 Harriet St., Palo Alto, CA 94301 (United States); King, Michael J. [Rapiscan Laboratories Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)

2016-01-01

Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time (“E–T” correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple “one-group” models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E–T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

A neutron Albedo system with time rejection for landmine and IED detection

Science.gov (United States)

Kovaltchouk, V. D.; Andrews, H. R.; Clifford, E. T. H.; Faust, A. A.; Ing, H.; McFee, J. E.

2011-10-01

A neutron Albedo system has been developed for imaging of buried landmines and improvised explosive devices (IEDs). It involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons that return. A scintillating 6Li loaded ZnS(Ag) screen with a sensitive area of 40 cm×40 cm is used as a thermal neutron detector. Scintillation light is captured by orthogonal arrays of wavelength-shifting fibers placed on either side of the scintillator surface and then transferred to X and Y multi-pixel PMTs. A timing circuit, used with pulsed neutron sources, records the time when a neutron detection takes place relative to an external synchronization pulse from the pulsed source. Experimental tests of the Albedo system performance have been done in a sand box with a 252Cf neutron source (no time gating) and with pulsed D-D (2.6 MeV) neutrons from the Defense R&D Ottawa Van de Graaff accelerator (with time gating). Information contained in the time evolution of the thermal neutron field provided improved detection capability and image reconstruction. The detector design is described and experimental results are discussed.

Detection system for neutron β decay correlations in the UCNB and Nab experiments

Energy Technology Data Exchange (ETDEWEB)

Broussard, L.J., E-mail: broussardlj@ornl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zeck, B.A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); North Carolina State University, Raleigh, NC 27695 (United States); Adamek, E.R. [Indiana University, Bloomington, IN 47405 (United States); Baeßler, S. [University of Virginia, Charlottesville, VA 22904 (United States); Birge, N. [University of Tennessee, Knoxville, TN 37996 (United States); Blatnik, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Cleveland State University, Cleveland, OH 44115 (United States); Bowman, J.D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Brandt, A.E. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); North Carolina State University, Raleigh, NC 27695 (United States); Brown, M. [University of Kentucky, Lexington, KY 40506 (United States); Burkhart, J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Callahan, N.B. [Indiana University, Bloomington, IN 47405 (United States); Clayton, S.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Crawford, C. [University of Kentucky, Lexington, KY 40506 (United States); Cude-Woods, C. [North Carolina State University, Raleigh, NC 27695 (United States); Currie, S. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Dees, E.B. [North Carolina State University, Raleigh, NC 27695 (United States); Ding, X. [Virginia Polytechnic Institute & State University, Blacksburg, VA 24061 (United States); Fomin, N. [University of Tennessee, Knoxville, TN 37996 (United States); Frlez, E.; Fry, J. [University of Virginia, Charlottesville, VA 22904 (United States); and others

2017-03-21

We describe a detection system designed for precise measurements of angular correlations in neutron β decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for β electron detection with energy thresholds below 10 keV, energy resolution of ∼3 keV FWHM, and rise time of ∼50 ns with 19 of the 127 detector pixels instrumented. Using ultracold neutrons at the Los Alamos Neutron Science Center, we have demonstrated the coincident detection of β particles and recoil protons from neutron β decay. The fully instrumented detection system will be implemented in the UCNB and Nab experiments to determine the neutron β decay parameters B, a, and b.

Detection and measurement of neutron-irradiated gemstones

International Nuclear Information System (INIS)

Bunnak, S.; Jerachanchai, S.; Chinudomsub, K.; Saiyut, K.

1990-01-01

Color enhance gemstone, neutron-irradiated topaz, was analyzed by gamma spectrometry for examining characteristic and activity. Topaz was irradiated in the wet-tube facility of the Research Reactor TRR/1 which neutron fluence is 2.52x10 17 neutron per square centimeter. After 100 days of decay, topaz was sampling to the qualitative and quantitative analysis using multichannel analyzer of Nuclear Data Model ND65 and hyper pure germanium detector. Calculation and evaluation were done by microcomputer IBM/PC 640 KB RAM. The qualitative analysis showed that the neutron-irradiated topaz has 2 major isotopes, i.e., Ta-182 and Sc-46. Quantitative activity was compared with reference standard source Eu-152 (NBS) and the results were shown in the table 1. The Health Physics Division, OAEP, inspected on 6240.9 gm of the neutron-irradiated topaz using standard release limit 2 nCi/gm (74 Bq/gm). It was found that only 423.9 gm out of the total amount were over the standard release limit

Verification of threshold activation detection (TAD) technique in prompt fission neutron detection using scintillators containing 19F

Science.gov (United States)

Sibczynski, P.; Kownacki, J.; Moszyński, M.; Iwanowska-Hanke, J.; Syntfeld-Każuch, A.; Gójska, A.; Gierlik, M.; Kaźmierczak, Ł.; Jakubowska, E.; Kędzierski, G.; Kujawiński, Ł.; Wojnarowicz, J.; Carrel, F.; Ledieu, M.; Lainé, F.

2015-09-01

In the present study ⌀ 5''× 3'' and ⌀ 2''× 2'' EJ-313 liquid fluorocarbon as well as ⌀ 2'' × 3'' BaF2 scintillators were exposed to neutrons from a 252Cf neutron source and a Sodern Genie 16GT deuterium-tritium (D+T) neutron generator. The scintillators responses to β- particles with maximum endpoint energy of 10.4 MeV from the n+19F reactions were studied. Response of a ⌀ 5'' × 3'' BC-408 plastic scintillator was also studied as a reference. The β- particles are the products of interaction of fast neutrons with 19F which is a component of the EJ-313 and BaF2 scintillators. The method of fast neutron detection via fluorine activation is already known as Threshold Activation Detection (TAD) and was proposed for photofission prompt neutron detection from fissionable and Special Nuclear Materials (SNM) in the field of Homeland Security and Border Monitoring. Measurements of the number of counts between 6.0 and 10.5 MeV with a 252Cf source showed that the relative neutron detection efficiency ratio, defined as epsilonBaF2 / epsilonEJ-313-5'', is 32.0% ± 2.3% and 44.6% ± 3.4% for front-on and side-on orientation of the BaF2, respectively. Moreover, the ⌀ 5'' EJ-313 and side-on oriented BaF2 were also exposed to neutrons from the D+T neutron generator, and the relative efficiency epsilonBaF2 / epsilonEJ-313-5'' was estimated to be 39.3%. Measurements of prompt photofission neutrons with the BaF2 detector by means of data acquisition after irradiation (out-of-beam) of nuclear material and between the beam pulses (beam-off) techniques were also conducted on the 9 MeV LINAC of the SAPHIR facility.

Proton detection in the neutron lifetime experiment PENeLOPE

Energy Technology Data Exchange (ETDEWEB)

Tietze, Christian [Technische Universitaet Muenchen, Physik Department E18 (Germany); Collaboration: PENeLOPE-Collaboration

2015-07-01

Although neutron lifetime plays an important role in the Standard Model of particle physics, τ{sub n} is not very precisely know and often discussed. The official PDG mean value has been lowered during the last years by more than 6σ to the new value of 880.3 ± 1.1 s. The new precision experiment PENeLOPE, which is currently developed at Technische Universitaet Muenchen, will help to clear this up. Ultra-cold neutrons are lossless stored in a magneto-gravitational trap, formed by superconducting coils. The combined determination of τ{sub n} by counting the surviving neutrons after each storage cycle on one side and in-situ detection of the decay protons on the other side together with a very good handle on systematic errors leads to an unprecedented precision of the neutron lifetime value of 0.1s. This contribution will give an overview of the challenges concerning proton detection under the exceptional requirements of this experiment. The developed concept of using avalanche photodiodes for direct proton detection will be presented as well as results from first measurements with a prototype detector read out by particular developed electronics.

Fission meter and neutron detection using poisson distribution comparison

Science.gov (United States)

Rowland, Mark S; Snyderman, Neal J

2014-11-18

A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

Directory of Open Access Journals (Sweden)

Sunardi Sunardi

2010-06-01

Full Text Available Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec.  At this research condition of neutron generator was set at current 1 mA that produced neutron flux about 5,47.107 n/cm2.s and  experimental result shown that the limit detection for the elements N, P, K, Si, Al, Fe, Cu, Cd are  2,44 ppm, 1,88 ppm, 2,15 ppm, 1,44 ppm, 1,26 ppm, 1,35 ppm, 1,05 ppm, 2,99 ppm, respectively.  The data  indicate that the limit detection or sensitivity of appliance of neutron generator to analyze the element is very good, which is feasible to get accreditation AANC laboratory using neutron generator.   Keywords: limit detection, AANC, neutron generator

DETECTION OF COATING FAILURES IN A NEUTRONIC REACTOR

Science.gov (United States)

Snell, A.H.; Allison, S.K.

1958-02-11

This patent relates to water-cooled reactor systems and discloses a means to detect leaks in the jackets of jacketed fuel elements comprising a neutron detector located in the cooling water discharge pipe,the pipe being provided with an enlarged portion for housing the detector so that the latter is completely surrounded by the water in its passage through the pipe, said enlarged portion and detector being shielded from the reactor for the purpose of detecting only those delayed neutrons emitted in the cooling water and due to the latter picking up fission fragments from the defective fuel elements.

Studies on neutron detection with solid state nuclear track detectors

International Nuclear Information System (INIS)

Khouri, M.C.; Vilela, E.C.; Andrade, C. de.

1993-03-01

The detection of thermal and fast neutrons was studied. For thermal neutrons, alpha sensitive plastic was used in order to register the products of nuclear reactions taking place in boron and /or lithium converters. Fast neutrons produce recoil tracks within the detector. In the present case, CR-39 and Makrofol E were used. Chemical and electrochemical etching processes were used for thermal and fast neutron detectors, respectively. (F.E.). 6 refs, 4 figs, 6 tabs

Nuclear characteristics of epoxy resin as a space environment neutron shielding

Energy Technology Data Exchange (ETDEWEB)

Adeli, Ruhollah [Nuclear Science and Technology Research Institute, Yazd (Iran, Islamic Republic of). Central Iran Research Complex; Shirmardi, Seyed Pezhman [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School; Mazinani, Saideh [Amirkabir Nanotechnology Research Institute, Tehran (Iran, Islamic Republic of); Ahmadi, Seyed Javad [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Nuclear Fuel Cycle Research School

2017-03-15

In recent years many investigations have been done for choosing applicable light neutron shielding in space environmental applications. In this study, we have considered the neutron radiation-protective characteristics of neat epoxy resin, a thermoplastic polymer material and have compared it with various candidate materials in neutron radiation protection such as Al 6061 alloy and Polyethylene. The aim of this investigation is the effect of type of moderator for fast neutron, notwithstanding neutron absorbers fillers. The nuclear interactions and the effective dose at shields have been studied with the Monte Carlo N-Particle transport code (MCNP), using variance reductions to reduce the relative error. Among the candidates, polymer matrix showed a better performance in attenuating fast neutrons and caused a lower neutron and secondary photon effective dose.

Neutron detection and applications using a BC454/BGO array

International Nuclear Information System (INIS)

Miller, M.C.; Biddle, R.S.; Bourret, S.C.

1998-01-01

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator (BC454)/bismuth germanate (BGO) 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. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on an event-by-event basis using custom integrator and timing circuits, enabling a prompt coincidence requirement between the BC454 and BGO to be used to identify neutron captures. In addition, a custom time-tag module was used to provide a time for each detector event. Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates

Neutron detection and applications using a BC454/BGO array

Energy Technology Data Exchange (ETDEWEB)

Miller, M.C.; Biddle, R.S.; Bourret, S.C.; Byrd, R.C.; Ensslin, N.; Feldman, W.C.; Kuropatwinski, J.J.; Longmire, J.L.; Krick, M.S.; Mayo, D.R.; Russo, P.A.; Sweet, M.R

1999-02-11

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array. The boron-loaded plastic combines neutron moderation (H) and detection ({sup 10}B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on an event-by-event basis using custom integrator and timing circuits, enabling a prompt coincidence requirement between the BC454 and BGO to be used to identify neutron captures. In addition, a custom time-tag module was used to provide a time for each detector event. Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates.

Neutron detection and applications using a BC454/BGO array

International Nuclear Information System (INIS)

Miller, M.C.; Biddle, R.S.; Bourret, S.C.; Byrd, R.C.; Ensslin, N.; Feldman, W.C.; Kuropatwinski, J.J.; Longmire, J.L.; Krick, M.S.; Mayo, D.R.; Russo, P.A.; Sweet, M.R.

1999-01-01

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array. The 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. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on an event-by-event basis using custom integrator and timing circuits, enabling a prompt coincidence requirement between the BC454 and BGO to be used to identify neutron captures. In addition, a custom time-tag module was used to provide a time for each detector event. Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates

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

International Nuclear Information System (INIS)

Stroud, Phillip D.; Saeger, Kevin J.

2009-01-01

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

Modern trends in position-sensitive neutron detectors development for condensed matter research

International Nuclear Information System (INIS)

Belushkin, A.V.

2007-01-01

Detecting neutrons is a more complicated task compared to the detection of ionizing particles or ionizing radiation. This is why the variety of neutron detectors is much more limited. Meanwhile, different types of neutron experiments pose specific and often contradictory requirements for detector characteristics. For experiments on the high-intensity neutron sources, the high counting rate is one of the key issues. This is very important, for example, for small-angle neutron scattering and neutron reflectometry. For other experiments, characteristics like detection efficiency, high position resolution, high time resolution, neutron/gamma discrimination, large-area imaging, or compactness, are very important. Today, the cost of the detector also became one of the most important factors. There is no single type of detector which satisfies all the above criteria. Therefore, compromise is inevitable and some of the characteristics are trade off in favor of others. The present report gives an overview of detector systems presently operating at the leading neutron scattering facilities as well as some development work around the globe

Explosives detection via fast neutron transmission spectroscopy

International Nuclear Information System (INIS)

Overley, J.C.; Chmelik, M.S.; Rasmussen, R.J.; Schofield, R.M.S.; Sieger, G.E.; Lefevre, H.W.

2006-01-01

A review of a five-year project on detection of explosives in luggage is presented. Experimental methods are described. Explosive detection algorithms based on elemental distributions in a 5-dimensional space are also described. Single-blind tests of the method suggest that a false-alarm rate of 4% and a detection rate of 93% are possible. Improvements in the method are suggested. Measurements of neutron total cross sections for chlorine are presented

Apparatus and method for the simultaneous detection of neutrons and ionizing electromagnetic radiation

Science.gov (United States)

Bell, Zane W.

2000-01-01

A sensor for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising: a sensor for the detection of gamma radiation, the sensor defining a sensing head; the sensor further defining an output end in communication with the sensing head; and an exterior neutron-sensitive material configured to form around the sensing head; wherein the neutron-sensitive material, subsequent to the capture of the neutron, fissions into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the first excited state decaying via the emission of a single gamma ray at 478 keV which can in turn be detected by the sensing head; and wherein the sensing head can also detect the ionizing electromagnetic radiation from an incident radiation field without significant interference from the neutron-sensitive material. A method for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising the steps of: providing a gamma ray sensitive detector comprising a sensing head and an output end; conforming an exterior neutron-sensitive material configured to form around the sensing head of the detector; capturing neutrons by the sensing head causing the neutron-sensitive material to fission into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the state decaying via the emission of a single gamma ray at 478 keV; sensing gamma rays entering the detector through the neutron-sensitive material; and producing an output through a readout device coupled to the output end; wherein the detector provides an output which is proportional to the energy of the absorbed ionizing electromagnetic radiation.

Detection of supernova neutrinos at spallation neutron sources

Science.gov (United States)

Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin

2016-07-01

After considering supernova shock effects, Mikheyev-Smirnov-Wolfenstein effects, neutrino collective effects, and Earth matter effects, the detection of supernova neutrinos at the China Spallation Neutron Source is studied and the expected numbers of different flavor supernova neutrinos observed through various reaction channels are calculated with the neutrino energy spectra described by the Fermi-Dirac distribution and the “beta fit” distribution respectively. Furthermore, the numerical calculation method of supernova neutrino detection on Earth is applied to some other spallation neutron sources, and the total expected numbers of supernova neutrinos observed through different reactions channels are given. Supported by National Natural Science Foundation of China (11205185, 11175020, 11275025, 11575023)

Neutron-Star Merger Detected By Many Eyes and Ears

Science.gov (United States)

Kohler, Susanna

2017-10-01

Where were you on Thursday, 17 August 2017? I was in Idaho, getting ready for Monday mornings solar eclipse. What I didnt know was that, at the time, around 70 teams around the world were mobilizing to point their ground- and space-based telescopes at a single patch of sky suspected to host the first gravitational-wave-detected merger of two neutron stars.Sudden Leaps for ScienceThe masses for black holes detected through electromagnetic observations (purple), black holes measured by gravitational-wave observations (blue), neutron stars measured with electromagnetic observations (yellow), and the neutron stars that merged in GW170817 (orange). [LIGO-Virgo/Frank Elavsky/NorthwesternUniversity]The process of science is long and arduous, generally occurring at a slow plod as theorists make predictions, and observations are then used to chip away at these theories, gradually confirming or disproving them. It is rare that science progresses forward in a giant leap, with years upon years of theories confirmed in one fell swoop.14 September 2015 marked the day of one such leap, as the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves for the first time simultaneously verifying that black holes exist, that black-hole binaries exist, and that they can merge on observable timescales, emitting signals that directly confirm the predictions of general relativity.As it turns out, 17 August 2017 was another such day. On this day, LIGO observed a gravitational-wave signal unlike its previous black-hole detections. Instead, this was a signal consistent with the merger of two neutron stars.Artists illustrations of the stellar-merger model for short gamma-ray bursts. In the model, 1) two neutron stars inspiral, 2) they merge and produce a gamma-ray burst, 3) a small fraction of their mass is flung out and radiates as a kilonova, 4) a massive neutron star or black hole with a disk remains after the event. [NASA, ESA, and A. Feild (STScI)]What We

Pulsed neutron uranium borehole logging with prompt fission neutrons

International Nuclear Information System (INIS)

Bivens, H.M.; Smith, G.W.; Jensen, D.H.

1976-01-01

The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy

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

SWAN - Detection of explosives by means of fast neutron activation analysis

International Nuclear Information System (INIS)

Gierlik, M.; Borsuk, S.; Guzik, Z.; Iwanowska, J.; Kaźmierczak, Ł.; Korolczuk, S.; Kozłowski, T.; Krakowski, T.; Marcinkowski, R.; Swiderski, L.; Szeptycka, M.; Szewiński, J.; Urban, A.

2016-01-01

In this work we report on SWAN, the experimental, portable device for explosives detection. The device was created as part of the EU Structural Funds Project “Accelerators & Detectors” (POIG.01.01.02-14-012/08-00), with the goal to increase beneficiary's expertise and competencies in the field of neutron activation analysis. Previous experiences and budged limitations lead toward a less advanced design based on fast neutron interactions and unsophisticated data analysis with the emphasis on the latest gamma detection and spectrometry solutions. The final device has been designed as a portable, fast neutron activation analyzer, with the software optimized for detection of carbon, nitrogen and oxygen. SWAN's performance in the role of explosives detector is elaborated in this paper. We demonstrate that the unique features offered by neutron activation analysis might not be impressive enough when confronted with practical demands and expectations of a generic homeland security customer.

Thermal neutron detection by means of an organic solid-state track detector

International Nuclear Information System (INIS)

Doerschel, B.; Streubel, G.

1979-01-01

Thermal neutrons can be detected by means of organic solid-state track detectors if they are combined with radiators in which charged secondary particles are produced in neutron interaction processes. The secondary particles can produce etchable tracks in the detector material. For thermal neutron fluence determination from the track densities, the thermal neutron sensitivity was calculated for cellulose triacetate detectors with LiF radiators, taking into account energy and angular distribution of the alpha particles produced in the LiF radiator. This value is in good agreement with the sensitivity measured during irradiation in different neutron fields if corrections are considered the production of etchable or visuable tracks. Measuring range and measuring accuracy meet the requirements of thermal neutron detection in personnel dosimetry. Possibilities of extending the measuring range are discussed. (author)

Monte Carlo simulations of a D-T neutron generator shielding for landmine detection

International Nuclear Information System (INIS)

Reda, A.M.

2011-01-01

Shielding for a D-T sealed neutron generator has been designed using the MCNP5 Monte Carlo radiation transport code. The neutron generator will be used in field for the detection of explosives, landmines, drugs and other 'threat' materials. The optimization of the detection of buried objects was started by studying the signal-to-noise ratio for different geometric conditions. - Highlights: → A landmine detection system based on neutron fast/slow analysis has been designed. → Shielding for a D-T sealed neutron generator tube has been designed using Monte Carlo radiation transport code. → Detection of buried objects was started by studying the signal-to-noise ratio for different geometric conditions. → The signal-to-background ratio optimized at one position for all depths.

Chemical warfare agents identification by thermal neutron detection

International Nuclear Information System (INIS)

Liu Boxue; Ai Xianyun; Tan Daoyuan; Zhang Dianqin

2000-01-01

The hydrogen concentration determination by thermal neutron detection is a non-destructive, fast and effective method to identify chemical warfare agents and TNT that contain different hydrogen fraction. When an isotropic neutron source is used to irradiate chemical ammunition, hydrogen atoms of the agent inside shell act as a moderator and slow down neutrons. The number of induced thermal neutrons depends mainly upon hydrogen content of the agent. Therefore measurement of thermal neutron influence can be used to determine hydrogen atom concentration, thereby to determine the chemical warfare agents. Under a certain geometry three calibration curves of count rate against hydrogen concentration were measured. According to the calibration curves, response of a chemical agent or TNT could be calculated. Differences of count rate among chemical agents and TNT for each kind of shells is greater than five times of standard deviations of count rate for any agent, so chemical agents or TNT could be identified correctly. Meanwhile, blast tube or liquid level of chemical warfare agent could affect the response of thermal neutron count rate, and thereby the result of identification. (author)

Feasibility study of Self Powered Neutron Detectors in Fast Reactors for detecting local change in neutron flux distribution

International Nuclear Information System (INIS)

Jammes, Christian; Filliatre, Philippe; Verma, Vasudha; Hellesen, Carl; Jacobsson Svard, Staffan

2015-01-01

Neutron flux monitoring system forms an integral part of the design of a Generation IV sodium cooled fast reactor system. Diverse possibilities of detector systems installation have to be investigated with respect to practicality and feasibility according to the detection parameters. In this paper, we demonstrate the feasibility of using self powered neutron detectors as in-core detectors in fast reactors for detecting local change in neutron flux distribution. We show that the gamma contribution from fission products decay in the fuel and activation of structural materials is very small compared to the fission gammas. Thus, it is possible for the in-core SPND signal to follow changes in local neutron flux as they are proportional to each other. This implies that the signal from an in-core SPND can provide dynamic information on the neutron flux perturbations occurring inside the reactor core. (authors)

Feasibility study of Self Powered Neutron Detectors in Fast Reactors for detecting local change in neutron flux distribution

Energy Technology Data Exchange (ETDEWEB)

Jammes, Christian; Filliatre, Philippe [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St Paul-Lez-Durance, (France); Verma, Vasudha; Hellesen, Carl; Jacobsson Svard, Staffan [Division of Applied Nuclear Physics, Uppsala University, SE-75120 Uppsala, (Sweden)

2015-07-01

Neutron flux monitoring system forms an integral part of the design of a Generation IV sodium cooled fast reactor system. Diverse possibilities of detector systems installation have to be investigated with respect to practicality and feasibility according to the detection parameters. In this paper, we demonstrate the feasibility of using self powered neutron detectors as in-core detectors in fast reactors for detecting local change in neutron flux distribution. We show that the gamma contribution from fission products decay in the fuel and activation of structural materials is very small compared to the fission gammas. Thus, it is possible for the in-core SPND signal to follow changes in local neutron flux as they are proportional to each other. This implies that the signal from an in-core SPND can provide dynamic information on the neutron flux perturbations occurring inside the reactor core. (authors)

Characteristics of neutron irradiation facility and dose estimation method for neutron capture therapy at Kyoto University research reactor institute

International Nuclear Information System (INIS)

Kobayashi, T.; Sakurai, Y.; Kanda, K.

2001-01-01

The neutron irradiation characteristics of the Heavy Water Neutron Irradiation Facility (HWNIF) at the Kyoto University Research Reactor Institute (KIJRRI) for boron neutron capture therapy (BNCT), is described. The present method of dose measurement and its evaluation at the KURRI, is explained. Especially, the special feature and noticeable matters were expounded for the BNCT with craniotomy, which has been applied at present only in Japan. (author)

APSTNG: Neutron interrogation for detection of nuclear and CW weapons, explosives, and drugs

International Nuclear Information System (INIS)

Rhodes, E.; Dickerman, C.E.; De Volpi, A.; Peters, C.W.

1992-01-01

A recently developed neutron diagnostic probe system has the potential to satisfy a significant number of van-mobile and fixed- portal requirements for nondestructive verification of sealed munitions and detection of contraband explosives and drugs. The probe is based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14-MeV neutrons generated from the deuterium-tritium reaction and that detects the alpha-particle associated with each neutron. Gamma-ray spectra of resulting neutron inelastic scattering and fission reactions identify nuclides associated with all major chemicals in chemical warfare agents, explosives, and drugs, as well as many pollutants and fissile and fertile special nuclear material. Flight times determined from determined from detection times of the gamma-rays and alpha-particles yield a separate tomographic image of each identified nuclide. The APSTNG also forms the basis for a compact fast-neutron transmission imaging system that can be used along with or instead of the emission imaging system; a collimator is not required since scattered neutrons are removed by ''electronic collimation'' (detected neutrons not having the proper flight time to be uncollided are discarded). The small and relatively inexpensive APSTNG exhibits high reliability and can be quickly replaced. Proof-of-concept experiments have been performed under laboratory conditions for simulated nuclear and chemical warfare munitions and for explosives and drugs

SWAN - Detection of explosives by means of fast neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Gierlik, M., E-mail: m.gierlik@ncbj.gov.pl; Borsuk, S.; Guzik, Z.; Iwanowska, J.; Kaźmierczak, Ł.; Korolczuk, S.; Kozłowski, T.; Krakowski, T.; Marcinkowski, R.; Swiderski, L.; Szeptycka, M.; Szewiński, J.; Urban, A.

2016-10-21

In this work we report on SWAN, the experimental, portable device for explosives detection. The device was created as part of the EU Structural Funds Project “Accelerators & Detectors” (POIG.01.01.02-14-012/08-00), with the goal to increase beneficiary's expertise and competencies in the field of neutron activation analysis. Previous experiences and budged limitations lead toward a less advanced design based on fast neutron interactions and unsophisticated data analysis with the emphasis on the latest gamma detection and spectrometry solutions. The final device has been designed as a portable, fast neutron activation analyzer, with the software optimized for detection of carbon, nitrogen and oxygen. SWAN's performance in the role of explosives detector is elaborated in this paper. We demonstrate that the unique features offered by neutron activation analysis might not be impressive enough when confronted with practical demands and expectations of a generic homeland security customer.

Parameters of explosives detection through tagged neutron method

Energy Technology Data Exchange (ETDEWEB)

Bagdasaryan, Kh.E.; Batyaev, V.F.; Belichenko, S.G., E-mail: consul757@mail.ru; Bestaev, R.R.; Gavryuchenkov, A.V.; Karetnikov, M.D.

2015-06-01

The potentialities of tagged neutron method (TNM) for explosives detection are examined on the basis of an idealized geometrical model. The model includes ING-27 14 MeV neutron generator with a built-in α-detector, a LYSO γ-detector and samples of material to be identified of approximately 0.3 kg each: explosives imitators (trinitrotoluene - TNT, tetryl, RDX and ammonium nitrate), legal materials (sugar, water, silk and polyethylene). The samples were unshielded or shielded by a paper layer of various thicknesses. The experimental data were interpreted by numerical simulation using a Poisson distribution of signals with the statistical parameters defined experimentally. The detection parameters were obtained by a pattern classification theory and a Bayes classifier.

A 'hybrid' neutron area survey instrument for the determination of neutron dose quantities in the workplace

International Nuclear Information System (INIS)

Tanner, R.J.; Jenkins, R.; Lowe, T.; Silvie, J.; Joyce, M.J.; Winsby, A.; Molinos, C.

2005-01-01

Full text: Neutron survey instruments are used routinely to determine the dose rates in areas where persons may be occupationally exposed. With a few exceptions, these instruments generally use a proportional counter with a high thermal neutron response located in a moderating sphere of CH 2 . The moderating sphere in such designs contains a thermal neutron absorber to reduce the over-response to thermal and intermediate energy neutrons. However, the commercially available examples of such instruments tend to have strongly energy dependent ambient dose equivalent response characteristics. In particular, they often over-respond in the energy range between 1 eV and 10 keV. A prototype of a novel design has been produced that uses seven detectors located in a moderating sphere of CH 2 , six near the surface to detect thermal and epithermal neutrons, and one in the centre to detect fast neutrons. This has been characterized using a combination of MCNP modelling and measurements to produce an instrument that has improved energy dependence of response characteristics. Additionally, the use of seven detectors offers direction and field hardness information. The design and calibration of the instrument are described and its response in workplaces calculated. (author)

Search Strategy of Detector Position For Neutron Source Multiplication Method by Using Detected-Neutron Multiplication Factor

International Nuclear Information System (INIS)

Endo, Tomohiro

2011-01-01

In this paper, an alternative definition of a neutron multiplication factor, detected-neutron multiplication factor kdet, is produced for the neutron source multiplication method..(NSM). By using kdet, a search strategy of appropriate detector position for NSM is also proposed. The NSM is one of the practical subcritical measurement techniques, i.e., the NSM does not require any special equipment other than a stationary external neutron source and an ordinary neutron detector. Additionally, the NSM method is based on steady-state analysis, so that this technique is very suitable for quasi real-time measurement. It is noted that the correction factors play important roles in order to accurately estimate subcriticality from the measured neutron count rates. The present paper aims to clarify how to correct the subcriticality measured by the NSM method, the physical meaning of the correction factors, and how to reduce the impact of correction factors by setting a neutron detector at an appropriate detector position

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.

Self-powered in-core neutron detector assembly with uniform perturbation characteristics

International Nuclear Information System (INIS)

Todt, W.H.; Playfoot, K.C.

1979-01-01

Disclosed is a self-powered in-core neutron detector assembly in which a plurality of longitudinally extending self-powered detectors have neutron responsive active portions spaced along a longitudinal path. A low neutron absorptive extension extends from the active portions of the spaced active portions of the detectors in symmetrical longitudinal relationship with the spaced active detector portions of each succeeding detector. The detector extension terminates with the detector assembly to provide a uniform perturbation characteristic over the entire assembly length

Detection of the weak γ activities from new neutron-rich nuclei

International Nuclear Information System (INIS)

Zhang Li; Wang Jicheng; Zhao Jinhua; Yang Yongfeng; Zheng Jiwen; Hu Qingyuan; Guo Tianrui

2003-01-01

Energic signals of γ rays detected by a HPGe γ detector were coincided with γ-ray, energy-loss signals detected by a 4πΔEβ detector. Then the coinciding β-ray spectra was anticoincided with timing logical signals of 511 keV γ ray created in positron annihilate, detected by a large BGO detector. This special coincidence-anticoincidence system has played an important role in the first observation of the new neutron-rich nuclide 209 Hg. It is shown that this is an effective method to detecting very weak γ-ray activities of neutron-rich isotope in an element-separation sample

Associated-particle sealed-tube neutron probe: Detection of explosives, contraband, and nuclear materials

International Nuclear Information System (INIS)

Rhodes, E.; Dickerman, C.E.

1996-01-01

Continued research and development of the APSTNG shows the potential for practical field use of this technology for detection of explosives, contraband, and nuclear materials. The APSTNG (associated-particle sealed-tube generator) inspects the item to be examined using penetrating 14-MeV neutrons generated by the deuterium-tritium reaction inside a compact accelerator tube. An alpha detector built into the sealed tube detects the alpha-particle associated with each neutron emitted in a cone encompassing the volume to be inspected. Penetrating high-energy gamma-rays from the resulting neutron reactions identify specific nuclides inside the volume. Flight-times determined from the detection times of gamma-rays and alpha-particles separate the prompt and delayed gamma-ray spectra and allow a coarse 3-D image to be obtained of nuclides identified in the prompt spectrum. The generator and detectors can be on the same side of the inspected object, on opposite sides, or with intermediate orientations. Thus, spaces behind walls and other confined regions can be inspected. Signals from container walls can be discriminated against using the flight-time technique. No collimators or shielding are required, the neutron generator is relatively small, and commercial-grade electronics are employed. The use of 14-MeV neutrons yields a much higher cross-section for detecting nitrogen than that for systems based on thermal-neutron reactions alone, and the broad range of elements with significant 14-MeV neutron cross-sections extends explosives detection to other elements including low-nitrogen compounds, and allows detection of many other substances. Proof-of-concept experiments have been successfully performed for conventional explosives, chemical warfare agents, cocaine, and fissionable materials

Detecting gravitational waves from accreting neutron stars

NARCIS (Netherlands)

Watts, A.L.; Krishnan, B.

2009-01-01

The gravitational waves emitted by neutron stars carry unique information about their structure and composition. Direct detection of these gravitational waves, however, is a formidable technical challenge. In a recent study we quantified the hurdles facing searches for gravitational waves from the

Semiconductor Thermal Neutron Detector

Directory of Open Access Journals (Sweden)

Toru Aoki

2014-02-01

Full Text Available The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g156Gd,  157Gd(n,  g158Gd  and  113Cd(n,  g114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. 

Characterization of the internal background for thermal and fast neutron detection with CLLB

Energy Technology Data Exchange (ETDEWEB)

Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F.; Wulf, Eric A.

2016-12-01

We report on a set of experiments conducted to determine what effects, if any, the internal background in the CLLB scintillation detector has on the thermal neutron detection performance. We conducted source measurements using an unmoderated and moderated {sup 252}Cf neutron/γ-ray source and long (48-h), unshielded and shielded, background measurements to characterize the internal background with and without a source present. These measurements allowed us to determine the 2-d event selections needed to isolate the thermal neutron peak observed in pulse shape vs. energy space and apply those selections to our background measurements. Our results indicate that the thermal neutron detection capabilities of the CLLB are marginally affected by the presence of internal background. An unmoderated 113-µCi {sup 252}Cf source at 15 cm from the detector yields a thermal neutron rate of 8×10{sup −2}/s cm{sup 3}, while moderating the source with 5 cm of polyethylene yields a thermal neutron rate of 5.5×10{sup −1}/s cm{sup 3}. The measured background rate for events that fall within the selected thermal neutron region is 1.2×10{sup −3}/s cm{sup 3}. Lastly, the potential for CLLB for detecting fast neutrons was investigated.

Fissile material detection and control facility with pulsed neutron sources and digital data processing

International Nuclear Information System (INIS)

Romodanov, V.L.; Chernikova, D.N.; Afanasiev, V.V.

2010-01-01

Full text: In connection with possible nuclear terrorism, there is long-felt need of devices for effective control of radioactive and fissile materials in the key points of crossing the state borders (airports, seaports, etc.), as well as various customs check-points. In International Science and Technology Center Projects No. 596 and No. 2978, a new physical method and digital technology have been developed for the detection of fissile and radioactive materials in models of customs facilities with a graphite moderator, pulsed neutron source and digital processing of responses from scintillation PSD detectors. Detectability of fissile materials, even those shielded with various radiation-absorbing screens, has been shown. The use of digital processing of scintillation signals in this facility is a necessary element, as neutrons and photons are discriminated in the time dependence of fissile materials responses at such loads on the electronic channels that standard types of spectrometers are inapplicable. Digital processing of neutron and photon responses practically resolves the problem of dead time and allows implementing devices, in which various energy groups of neutrons exist for some time after a pulse of source neutrons. Thus, it is possible to detect fissile materials deliberately concealed with shields having a large cross-section of absorption of photons and thermal neutrons. Two models of detection and the control of fissile materials were advanced: 1. the model based on graphite neutrons moderator and PSD scintillators with digital technology of neutrons and photons responses separation; 2. the model based on plastic scintillators and detecting of time coincidences of fission particles by digital technology. Facilities that count time coincidences of neutrons and photons occurring in the fission of fissile materials can use an Am Li source of neutrons, e.g. that is the case with the AWCC system. The disadvantages of the facility are related to the issues

Neutron detection of the Triga Mark III reactor, using nuclear track methodology

Energy Technology Data Exchange (ETDEWEB)

Espinosa, G., E-mail: espinosa@fisica.unam.mx; Golzarri, J. I. [Instituto de Física, Universidad Nacional Autónoma de México Circuito de la Investigación Científica, Ciudad Universitaria. México, DF (Mexico); Raya-Arredondo, R.; Cruz-Galindo, S. [Instituto Nacional de Investigaciones Nucleares (Mexico); Sajo-Bohus, L. [Universidad Simón Bolivar, Laboratorio de Física Nuclear, Caracas (Venezuela, Bolivarian Republic of)

2015-07-23

Nuclear Track Methodology (NTM), based on the neutron-proton interaction is one often employed alternative for neutron detection. In this paper we apply NTM to determine the Triga Mark III reactor operating power and neutron flux. The facility nuclear core, loaded with 85 Highly Enriched Uranium as fuel with control rods in a demineralized water pool, provide a neutron flux around 2 × 10{sup 12} n cm{sup −2} s{sup −1}, at the irradiation channel TO-2. The neutron field is measured at this channel, using Landauer{sup ®} PADC as neutron detection material, covered by 3 mm Plexiglas{sup ®} as converter. After exposure, plastic detectors were chemically etched to make observable the formed latent tracks induced by proton recoils. The track density was determined by a custom made Digital Image Analysis System. The resulting average nuclear track density shows a direct proportionality response for reactor power in the range 0.1-7 kW. We indicate several advantages of the technique including the possibility to calibrate the neutron flux density measured at low reactor power.

Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons

International Nuclear Information System (INIS)

Ghilardi, A.J.P.

1988-01-01

An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of γ-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF 3 ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs

Coded moderator approach for fast neutron source detection and localization at standoff

Energy Technology Data Exchange (ETDEWEB)

Littell, Jennifer [Department of Nuclear Engineering, University of Tennessee, 305 Pasqua Engineering Building, Knoxville, TN 37996 (United States); Lukosi, Eric, E-mail: elukosi@utk.edu [Department of Nuclear Engineering, University of Tennessee, 305 Pasqua Engineering Building, Knoxville, TN 37996 (United States); Institute for Nuclear Security, University of Tennessee, 1640 Cumberland Avenue, Knoxville, TN 37996 (United States); Hayward, Jason; Milburn, Robert; Rowan, Allen [Department of Nuclear Engineering, University of Tennessee, 305 Pasqua Engineering Building, Knoxville, TN 37996 (United States)

2015-06-01

Considering the need for directional sensing at standoff for some security applications and scenarios where a neutron source may be shielded by high Z material that nearly eliminates the source gamma flux, this work focuses on investigating the feasibility of using thermal neutron sensitive boron straw detectors for fast neutron source detection and localization. We utilized MCNPX simulations to demonstrate that, through surrounding the boron straw detectors by a HDPE coded moderator, a source-detector orientation-specific response enables potential 1D source localization in a high neutron detection efficiency design. An initial test algorithm has been developed in order to confirm the viability of this detector system's localization capabilities which resulted in identification of a 1 MeV neutron source with a strength equivalent to 8 kg WGPu at 50 m standoff within ±11°.

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

The electronic band structures of gadolinium chalcogenides: a first-principles prediction for neutron detecting.

Science.gov (United States)

Li, Kexue; Liu, Lei; Yu, Peter Y; Chen, Xiaobo; Shen, D Z

2016-05-11

By converting the energy of nuclear radiation to excited electrons and holes, semiconductor detectors have provided a highly efficient way for detecting them, such as photons or charged particles. However, for detecting the radiated neutrons, those conventional semiconductors hardly behave well, as few of them possess enough capability for capturing these neutral particles. While the element Gd has the highest nuclear cross section, here for searching proper neutron-detecting semiconductors, we investigate theoretically the Gd chalcogenides whose electronic band structures have never been characterized clearly. Among them, we identify that γ-phase Gd2Se3 should be the best candidate for neutron detecting since it possesses not only the right bandgap of 1.76 eV for devices working under room temperature but also the desired indirect gap nature for charge carriers surviving longer. We propose further that semiconductor neutron detectors with single-neutron sensitivity can be realized with such a Gd-chalcogenide on the condition that their crystals can be grown with good quality.

Neutronic analysis of the 1D and 1E banks reflux detection system

Energy Technology Data Exchange (ETDEWEB)

Blanchard, A.

1999-12-21

Two H Canyon neutron monitoring systems for early detection of postulated abnormal reflux conditions in the Second Uranium Cycle 1E and 1D Mixer-Settle Banks have been designed and built. Monte Carlo neutron transport simulations using the general purpose, general geometry, n-particle MCNP code have been performed to model expected response of the monitoring systems to varying conditions.The confirmatory studies documented herein conclude that the 1E and 1D neutron monitoring systems are able to achieve adequate neutron count rates for various neutron source and detector configurations, thereby eliminating excessive integration count time. Neutron count rate sensitivity studies are also performed. Conversely, the transport studies concluded that the neutron count rates are statistically insensitive to nitric acid content in the aqueous region and to the transition region length. These studies conclude that the 1E and 1D neutron monitoring systems are able to predict the postulated reflux conditions for all examined perturbations in the neutron source and detector configurations. In the cases examined, the relative change in the neutron count rates due to postulated transitions from normal {sup 235}U concentration levels to reflux levels remain satisfactory detectable.

Neutronic analysis of the 1D and 1E banks reflux detection system

International Nuclear Information System (INIS)

Blanchard, A.

1999-01-01

Two H Canyon neutron monitoring systems for early detection of postulated abnormal reflux conditions in the Second Uranium Cycle 1E and 1D Mixer-Settle Banks have been designed and built. Monte Carlo neutron transport simulations using the general purpose, general geometry, n-particle MCNP code have been performed to model expected response of the monitoring systems to varying conditions.The confirmatory studies documented herein conclude that the 1E and 1D neutron monitoring systems are able to achieve adequate neutron count rates for various neutron source and detector configurations, thereby eliminating excessive integration count time. Neutron count rate sensitivity studies are also performed. Conversely, the transport studies concluded that the neutron count rates are statistically insensitive to nitric acid content in the aqueous region and to the transition region length. These studies conclude that the 1E and 1D neutron monitoring systems are able to predict the postulated reflux conditions for all examined perturbations in the neutron source and detector configurations. In the cases examined, the relative change in the neutron count rates due to postulated transitions from normal 235 U concentration levels to reflux levels remain satisfactory detectable

A portable neutron spectroscope (NSPECT) for detection, imaging and identification of nuclear material

Science.gov (United States)

Ryan, James M.; Bancroft, Christopher; Bloser, Peter; Bravar, Ulisse; Fourguette, Dominique; Frost, Colin; Larocque, Liane; McConnell, Mark L.; Legere, Jason; Pavlich, Jane; Ritter, Greg; Wassick, Greg; Wood, Joshua; Woolf, Richard

2010-08-01

We have developed, fabricated and tested a prototype imaging neutron spectrometer designed for real-time neutron source location and identification. Real-time detection and identification is important for locating materials. These materials, specifically uranium and transuranics, emit neutrons via spontaneous or induced fission. Unlike other forms of radiation (e.g. gamma rays), penetrating neutron emission is very uncommon. The instrument detects these neutrons, constructs images of the emission pattern, and reports the neutron spectrum. The device will be useful for security and proliferation deterrence, as well as for nuclear waste characterization and monitoring. The instrument is optimized for imaging and spectroscopy in the 1-20 MeV range. The detection principle is based upon multiple elastic neutron-proton scatters in organic scintillator. Two detector panel layers are utilized. By measuring the recoil proton and scattered neutron locations and energies, the direction and energy spectrum of the incident neutrons can be determined and discrete and extended sources identified. Event reconstruction yields an image of the source and its location. The hardware is low power, low mass, and rugged. Its modular design allows the user to combine multiple units for increased sensitivity. We will report the results of laboratory testing of the instrument, including exposure to a calibrated Cf-252 source. Instrument parameters include energy and angular resolution, gamma rejection, minimum source identification distances and times, and projected effective area for a fully populated instrument.

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

Science.gov (United States)

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

2014-12-01

An explosive detection system based on a Deuterium-Deuterium (D-D) neutron generator has been simulated using the Monte Carlo N-Particle Transport Code (MCNP5). Nuclear-based explosive detection methods can detect explosives by identifying their elemental components, especially nitrogen. Thermal neutron capture reactions have been used for detecting prompt gamma emission (10.82MeV) following radiative neutron capture by (14)N nuclei. The explosive detection system was built based on a fully high-voltage-shielded, axial D-D neutron generator with a radio frequency (RF) driven ion source and nominal yield of about 10(10) fast neutrons per second (E=2.5MeV). Polyethylene and paraffin were used as moderators with borated polyethylene and lead as neutron and gamma ray shielding, respectively. The shape and the thickness of the moderators and shields are optimized to produce the highest thermal neutron flux at the position of the explosive and the minimum total dose at the outer surfaces of the explosive detection system walls. In addition, simulation of the response functions of NaI, BGO, and LaBr3-based γ-ray detectors to different explosives is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

Research and development of a compact fusion neutron source for humanitarian landmine detection

International Nuclear Information System (INIS)

Yoshikawa, K.; Masuda, K.; Yamamoto, Y.; Takamatsu, T.; Toku, H.; Nagasaki, K.; Hotta, E.; Yamauchi, K.; Ohnishi, M.; Osawa, H.

2005-01-01

Research and development of the advanced anti-personnel landmine detection system by using a compact discharge-type D-D fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion) are described. Landmines are to be identified through increased backscattering of neutrons by the hydrogen atoms, and specific-energy capture γ-ray emission by hydrogen and nitrogen atoms with thermalized neutrons in the landmine explosives. For this purpose, improvements of the IECF device were studied for drastic enhancement of neutron production rates of more than 10 8 n/s in pulsed operation including R and D of robust power sources, as well as analyses of envisaged detection system with multi-sensors in parallel in order to show promising and practical features of this detection system for humanitarian landmine detection, particularly, in the aridic, or dry Afghanistan deserted area, where the soil moisture remains between 3-8%, which eventually enables effectively detection of hydrogen anomaly inherent in the landmine explosives. In this paper, improvements of the IECF are focused to be described. (author)

A cement channel-detection technique using the pulsed-neutron log

International Nuclear Information System (INIS)

Myers, G.D.

1991-01-01

A channel-detection technique has been developed using boron solutions and pulsed-neutron logging (PNL) tools. This technique relies on the extremely high-neutron-absorption cross section that boron exhibits relative to other common elements, including chlorine. The PNL tool is used to detect movement of a boron solution in a log-inject-log procedure. The technique has identified channels in such difficult applications as logging through two strings of pipe and in highly deviated wellbores. Logging procedures are simple and cement channels can be readily identified. The boron solutions are relatively inexpensive, safe to handle, and nonradioactive. Additional PNL information for reservoir performance evaluation is collected simultaneously during channel-detection logging. This paper describes the theory, development, field application, and limitations of this channel-detection logging technique

Detection of plastic explosives using thermal neutron radiography

International Nuclear Information System (INIS)

Hacidume, Leo Ryoske

1999-12-01

The work aims to demonstrate the potentiality of the neutron radiography technique, allied to the computerized tomography by transmission, to both detect and visualize plastic explosive samples in several hidden conditions, using a simple scanner as a digitalisation instrument. Each tomographic essay was obtained in the J-9 channel of the Argonauta Research Reactor of IEN/CNEN, in groups of six neutron radiographic projections, performed with an angular increment of 30 deg C, in a period of time of 30 minutes for each projection. Two groups of tomographic reconstructions were generated, distinguished by the digitalisation process of the interested lines in the reconstruction plane coming from the projection groups, utilization a scanner and a microdensitometer, respectively. The reconstruction of the bi-dimensional image of the transverse section, in relation to this plane, was processed making use of the Image Reconstruction Algorithmic of an Image based on the Maximum Entropy principle (ARIEM). From the qualitative analysis of the images, we conclude that the neutron radiographic system was able to detect the explosive sample in a satisfactory way while the quantitative analysis confirmed the application effectiveness of a scanner to acquire the projection dates whose objective is only a reconnaissance. (author)

Detection of plastic explosives by thermic neutron radiography

International Nuclear Information System (INIS)

Hacidume, Leo R.; Crispim, Verginia R.; Silva, Ademir X. da

2000-01-01

This work aims to demonstrate the potentiality of the neutron radiography technique, allied to the computerized tomography by transmission, to both detect and visualize plastic explosive samples in several hidden conditions, using a simple scanner as a digitalisation instrument. Each tomographic essay was obtained in the J-9 channel of the Argonauta Research Reactor of IEN/CNEN, in groups of six neutron radiographic projections, performed with an angular increment of 30 in a period of time of 30 minutes for each projection. Two groups of tomographic reconstructions were generated, distinguished by the digitalisation process of the interested lines in the reconstruction plane coming from the projection groups, utilizing a scanner and a microdensitometer, respectively. The reconstruction of the bi-dimensional image of the transverse section, in relation to this plane, was processed making use of the Image reconstruction algorithmic of an image based on the maximum entropy principle (ARIEM). From the qualitative analysis of the images, we conclude that the neutron radiographic system was able to detect the explosive sample in a satisfactory way while the quantitative analysis confirmed the application effectiveness of a scanner to acquire the projection dates whose objective is only a reconnaissance. (author)

Sodium boiling detection in LMFBRs by acoustic-neutronic cross correlation

International Nuclear Information System (INIS)

Wright, S.A.

1977-01-01

The acoustic and neutronic noise signals caused by boiling are the signals primarily considered likely to detect sodium boiling in an LMFBR. Unfortunately, these signals may have serious signal-to-noise problems due to strong background noise sources. Neutronic-acoustic cross correlation techniques are expected to provide a means of improving the signal-to-noise ratio. This technique can improve the signal-to-noise ratio because the neutronic and acoustic signals due to boiling are highly correlated near the bubble repetition frequency, while the background noise sources are expected to be uncorrelated (or at most weakly correlated). An experiment was designed to show that the neutronic and acoustic noise signals are indeed highly correlated. The experiment consisted of simulating the void and pressure effects of local sodium boiling in the core of a zero-power reactor (ARK). The analysis showed that the neutronic and acoustic noise signals caused by boiling are almost perfectly correlated in a wide frequency band about the bubble repetition frequency. The results of the experiments were generalized to full-scale reactors to compare the inherent effectiveness of the methods which use the neutronic or acoustic signals alone with a hybrid method, which cross correlates the neutronic and acoustic signals. It was concluded that over a zone of the reactor where the void coefficient is sufficiently large (approximately 85 percent the core volume), the cross correlation method can provide a more rapid detection system for a given signal-to-noise ratio. However, where the void coefficient is small, one must probably rely on the acoustic method alone

Neutron detection using a planar array of superheated superconductors

International Nuclear Information System (INIS)

Meagher, G.

1996-01-01

A new thermal neutron detector consisting of an indium/mylar PASS array with a filler of boron powder has been tested successfully. A boron nucleus captures a neutron and the α-particle emitted in this reaction nucleates the transition to the normal state in a neighbouring grain. A PASS with grain radius r=12 μm showed very low response to irradiation by 835 keV γ-rays. The same PASS responded to α-particles with high efficiency, and thermal neutrons were detected with good efficiency and very low background. Thermal neutrons were also counted with an R=25 μm PASS. The use of large granules will allow spatial resolution to a single grain to be obtained and a read-out based on conventional inductive coupling and fast electronics to be utilized. (orig.)

Chlorine detection in fly ash concrete using a portable neutron generator.

Science.gov (United States)

Naqvi, A A; Kalakada, Zameer; Al-Matouq, Faris A; Maslehuddin, M; Al-Amoudi, O S B

2012-08-01

The chlorine concentration in chloride-contaminated FA cement concrete specimens was measured using a portable neutron generator based prompt gamma-ray neutron activation (PGNAA) setup with the neutron generator and the gamma-ray detector placed side-by-side on one side of the concrete sample. The minimum detectable concentration of chlorine in FA cement concrete measured in the present study was comparable with previous results for larger accelerator based PGNAA setup. It shows the successful application of a portable neutron generator in concrete corrosion studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Logic based feature detection on incore neutron spectra

International Nuclear Information System (INIS)

Bende-Farkas, S.; Kiss, S.; Racz, A.

1992-09-01

A methodology is proposed to investigate neutron spectra in such a way which is similar to human thinking. The goal was to save experts from tedious, mechanical tasks of browsing a large amount of signals in order to recognize changes in the underlying mechanisms. The general framework for detecting features of incore neutron spectra with a rulebased methodology is presented. As an example, the meaningful peaks in the APSDs are determined. This method is a part of a wider project to develop a noise diagnostic expert system. (R.P.) 6 refs.; 6 figs.; 1 tab

Personnel neutron dose assessment upgrade: Volume 1, Personnel neutron dosimetry assessment: [Final report

International Nuclear Information System (INIS)

Hadlock, D.E.; Brackenbush, L.W.; Griffith, R.V.; Hankins, D.E.; Parkhurst, M.A.; Stroud, C.M.; Faust, L.G.; Vallario, E.J.

1988-07-01

This report provides guidance on the characteristics, use, and calibration criteria for personnel neutron dosimeters. The report is applicable for neutrons with energies ranging from thermal to less than 20 MeV. Background for general neutron dosimetry requirements is provided, as is relevant federal regulations and other standards. The characteristics of personnel neutron dosimeters are discussed, with particular attention paid to passive neutron dosimetry systems. Two of the systems discussed are used at DOE and DOE-contractor facilities (nuclear track emulsion and thermoluminescent-albedo) and another (the combination TLD/TED) was recently developed. Topics discussed in the field applications of these dosimeters include their theory of operation, their processing, readout, and interpretation, and their advantages and disadvantages for field use. The procedures required for occupational neutron dosimetry are discussed, including radiation monitoring and the wearing of dosimeters, their exchange periods, dose equivalent evaluations, and the documenting of neutron exposures. The coverage of dosimeter testing, maintenance, and calibration includes guidance on the selection of calibration sources, the effects of irradiation geometries, lower limits of detectability, fading, frequency of calibration, spectrometry, and quality control. 49 refs., 6 figs., 8 tabs

Thermal neutron detection by activation of CaSO4:Dy + KBr thermoluminescent phosphors

International Nuclear Information System (INIS)

Gordon, A.M.P.L.; Muccillo, R.

1979-01-01

Thermoluminescence (TL) studies to detect thermal neutrons were performed in cold-pressed CaSO 4 :0,1%Dy + KBr samples. The detection is based on the self-irradiation of the CaSO 4 :Dy TL phosphor by the Br isotopes activated by exposure to a mixed neutron-gamma field. (Author) [pt

Neutron stars

International Nuclear Information System (INIS)

Irvine, J.M.

1978-01-01

The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)

Nuclear and activation characteristics of materials in 14.1-MeV and 2.5-MeV neutron field

International Nuclear Information System (INIS)

Seki, Yasushi; Takeyasu, Yuuichi.

1988-11-01

The nuclear and activation characteristics of various materials and elements of interest in terms of fusion reactor design are calculated and the results are graphically shown. The elements and materials are placed in a simple geometry modelling a blanket and shield of a fusion reactor. The neutrons with 14.1-MeV and 2.5-MeV energy are generated from the region represented as D-T and D-D plasma, respectively. The following activation characteristics after neutron irradiation are shown for each material and element; 1. Time evolution of induced activity, 2. Time evolution of decay heat, 3. Delayed gamma-ray dose distribution, 4. Decay heat distribution. In addition to the above activation characteristics, nuclear characteristics during the neutron irradiation, e.g. neutron energy spectra, neutron and gamma-ray flux distribution, nuclear heating distributions, and neutron and gamma-ray dose rate are also shown. (author)

Suppression background device in neutron detection by a scintillation detector

International Nuclear Information System (INIS)

Degtyarev, A.P.; Kozyr', Yu.E.; Prokopets, G.A.

1980-01-01

A pulse shape discriminator for suppression of cosmic and gamma background as well as for suppression of intrinsic noises of a photomultiplier is described. Identification of signals of background and neutrons is performed by means of comparison of relative intensity of fast and slow components of scintillator luminescence. Basic discriminator flowsheet which contains integrating and differential RC circuits and time-to-amplitude converter is given. The discriminator provides minimum energy of detected neutrons equal to 500 keV when using a FEhU-36 neutron detector with a stilbene crystal [ru

Neutron sources and its dosimetric characteristics; Fuentes de neutrones y sus caracteristicas dosimetricas

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Mercado S, G.A. [Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico); Gallego D, E.; Lorente F, A. [Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal 2, E-28006 Madrid (Spain)

2005-07-01

By means of Monte Carlo methods the spectra of the produced neutrons {sup 252} Cf, {sup 252} Cf/D{sub 2}O, {sup 241} Am Be, {sup 239} Pu Be, {sup 140} La Be, {sup 239} Pu{sup 18}O{sub 2} and {sup 226} Ra Be have been calculated. With the information of the spectrum it was calculated the average energy of the neutrons of each source. By means of the fluence coefficients to dose it was determined, for each one of the studied sources, the fluence factors to dose. The calculated doses were H, H{sup *}(10), H{sub p,sIab} (10, 0{sup 0}), E{sub AP} and E{sub ISO}. During the phase of the calculations the sources were modeled as punctual and their characteristics were determined to 100 cm in the hole. Also, for the case of the sources of {sup 239} Pu Be and {sup 241} Am Be, were carried out calculations modeling the sources with their respective characteristics and the dosimetric properties were determined in a space full with air. The results of this last phase of the calculations were compared with the experimental results obtained for both sources. (Author)

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.

Reference neutron radiations. Part 1: Characteristics and methods of production

International Nuclear Information System (INIS)

2001-01-01

ISO 8529 consists of the following parts, under the general title Reference neutron radiations: Part 1: Characteristics and methods of production; Part 2: Calibration fundamentals of radiation protection devices related to the basic quantities characterizing the radiation field; Part 3: Calibration of area and personal dosimeters and determination of response as a function of energy and angle of incidence. This Part 1. of ISO 8529 specifies the reference neutron radiations, in the energy range from thermal up to 20 MeV, for calibrating neutron-measuring devices used for radiation protection purposes and for determining their response as a function of neutron energy. Reference radiations are given for neutron fluence rates of up to 1x10 9 m 2 s-1 , corresponding, at a neutron energy of 1 MeV, to dose-equivalent rates of up to 100 mSv h -1 . This part of ISO 8529 is concerned only with the methods of producing and characterizing the neutron reference radiations. The procedures for applying these radiations for calibrations are described in ISO 8529-2 and ISO 8529-3. The reference radiations specified are the following: neutrons from radionuclide sources, including neutrons from sources in a moderator; neutrons produced by nuclear reactions with charged particles from accelerators; neutrons from reactors. In view of the methods of production and use of them, these reference radiations are divided, for the purposes of this part of ISO 8529, into the following two separate sections. In clause 4, radionuclide neutron sources with wide spectra are specified for the calibration of neutron measuring devices. These sources should be used by laboratories engaged in the routine calibration of neutron-measuring devices, the particular design of which has already been type tested. In clause 5, accelerator-produced monoenergetic neutrons and reactor-produced neutrons with wide or quasi monoenergetic spectra are specified for determining the response of neutron-measuring devices

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)

Neutron detection devices with 6LiF converter layers

Science.gov (United States)

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

2018-01-01

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 art of a promising lowcost technique, based on commercial solid state silicon detectors coupled with thin neutron converter layers of 6LiF deposited onto carbon fiber substrates. Several configurations were studied with the GEANT4 simulation code, and then calibrated at the PTB Thermal Neutron Calibration Facility. The results show that the measured 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.

Neutron sources and their characteristics

International Nuclear Information System (INIS)

McCall, R.C.; Swanson, W.P.

1979-03-01

The significant sources of photoneutrons within a linear-accelerator treatment head are identified and absolute estimates of neutron production per treatment dose are given for typical components. It is found that the high-Z materials within the treatment head do not significantly alter the neutron fluence but do substantially reduce the average energy of the transmitted spectrum. Reflection of neutrons from the concrete treatment room contribute to the neutron fluence, but not substantially to the patient integral dose, because of a further reduction in average energy. The ratio of maximum fluence to the treatment dose at the same distance is given as a function of electron energy. This ratio rises with energy to an almost constant value of 2.1 x 10 5 neutrons cm -2 rad -1 at electron energies above about 25 MeV. Measured data obtained at a variety of accelerator installations are presented and compared with these calculations. Reasons for apparent deviations are suggested. Absolute depth-dose and depth-dose-equivalent distributions for realistic neutron spectra that occur at therapy installations are calculated, and a rapid falloff with depth is found. The ratio of neutron integral absorbed dose to leakage photon absorbed dose is estimated to be 0.04 and 0.2 for 14 to 25 MeV incident electron energy, respectively. Possible reasons are given for lesser neutron production from betatrons than from linear accelerators. Possible ways in which neutron production can be reduced are discussed

Neutron-based techniques for detection of explosives and drugs

Energy Technology Data Exchange (ETDEWEB)

Kiraly, B.; Olah, L.; Csikai, J. E-mail: csikai@falcon.phys.klte.hu

2001-06-01

Systematic measurements were carried out on the possible use of elastically backscattered Pu-Be neutrons combined with the thermal neutron reflection method for the identification of land mines and illicit drugs via he detection of H, C, N, and O elements as their major constituents. While ur present results show that these methods are capable of indicating the anomalies in bulky materials and observation of the major elements, e termination of the exact atom fractions needs further investigation.

Neutron-based techniques for detection of explosives and drugs

CERN Document Server

Kiraly, B; Csikai, J

2001-01-01

Systematic measurements were carried out on the possible use of elastically backscattered Pu-Be neutrons combined with the thermal neutron reflection method for the identification of land mines and illicit drugs via he detection of H, C, N, and O elements as their major constituents. While ur present results show that these methods are capable of indicating the anomalies in bulky materials and observation of the major elements, e termination of the exact atom fractions needs further investigation.

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.

Neutron Sources for Standard-Based Testing

Energy Technology Data Exchange (ETDEWEB)

Radev, Radoslav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McLean, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-11-10

The DHS TC Standards and the consensus ANSI Standards use ²⁵²Cf as the neutron source for performance testing because its energy spectrum is similar to the ²³⁵U and ²³⁹Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.

Detectable radio flares following gravitational waves from mergers of binary neutron stars.

Science.gov (United States)

Nakar, Ehud; Piran, Tsvi

2011-09-28

Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.

Influence of core model parameters on the characteristics of neutron beams of the research reactor

Directory of Open Access Journals (Sweden)

N. A. Khafizova

2013-12-01

Full Text Available IRT MEPhI reactor is equipped with a number of facilities at horizontal experimental channels (HEC. Knowing of parameters influencing spatio-angular distribution of irradiation fields is essential for each application area. The research for neutron capture therapy (NCT facility at HEC of the reactor was made. Calculation methods have been used to estimate how the reactor core parameters influence neutron beam characteristics at the HEC output. The impact of neutron source model in Monte Carlo calculations by MCNP code on the parameters of neutron and secondary photon field at the output of irradiation beam tubes of research reactor is estimated. The study shows that specifying neutron source with fission reaction rate distribution in SDEF option gives almost the same results as criticality calculation considered the most accurate. Our calculations show that changes of the core operational parameters have insignificant influence on characteristics of neutron beams at HEC output.

Neutron borehole logging correction technique

International Nuclear Information System (INIS)

Goldman, L.H.

1978-01-01

In accordance with an illustrative embodiment of the present invention, a method and apparatus is disclosed for logging earth formations traversed by a borehole in which an earth formation is irradiated with neutrons and gamma radiation produced thereby in the formation and in the borehole is detected. A sleeve or shield for capturing neutrons from the borehole and producing gamma radiation characteristic of that capture is provided to give an indication of the contribution of borehole capture events to the total detected gamma radiation. It is then possible to correct from those borehole effects the total detected gamma radiation and any earth formation parameters determined therefrom

ATLAS-TPX: a two-layer pixel detector setup for neutron detection and radiation field characterization

International Nuclear Information System (INIS)

Bergmann, B.; Caicedo, I.; Pospisil, S.; Vykydal, Z.; Leroy, C.

2016-01-01

A two-layer pixel detector setup (ATLAS-TPX), designed for thermal and fast neutron detection and radiation field characterization is presented. It consists of two segmented silicon detectors (256 × 256 pixels, pixel pitch 55 μm, thicknesses 300 μm and 500 μm) facing each other. To enhance the neutron detection efficiency a set of converter layers is inserted in between these detectors. The pixelation and the two-layer design allow a discrimination of neutrons against γs by pattern recognition and against charged particles by using the coincidence and anticoincidence information. The neutron conversion and detection efficiencies are measured in a thermal neutron field and fast neutron fields with energies up to 600 MeV. A Geant4 simulation model is presented, which is validated against the measured detector responses. The reliability of the coincidence and anticoincidence technique is demonstrated and possible applications of the detector setup are briefly outlined.

Neutron detection and radiography

International Nuclear Information System (INIS)

Bollen, R.H.; Van Esch, R.F.

1975-01-01

An improved method of recording neutron images is described which comprises imagewise irradiating with neutrons an intensifying screen containing a gadolinium compound that fluoresces when struck by x-rays and subjecting the fluorescent light pattern resulting from the impact of the neutrons on the screen onto a photographic material. (auth)

Particle and photon detection for a neutron radiative decay experiment

Energy Technology Data Exchange (ETDEWEB)

Gentile, T.R. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)], E-mail: thomas.gentile@nist.gov; Dewey, M.S.; Mumm, H.P.; Nico, J.S.; Thompson, A.K. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Chupp, T.E. [University of Michigan, Ann Arbor, MI 48109 (United States); Cooper, R.L. [University of Michigan, Ann Arbor, MI 48109 (United States)], E-mail: cooperrl@umich.edu; Fisher, B.M.; Kremsky, I.; Wietfeldt, F.E. [Tulane University, New Orleans, LA 70118 (United States); Kiriluk, K.G.; Beise, E.J. [University of Maryland, College Park, MD 20742 (United States)

2007-08-21

We present the particle and photon detection methods employed in a program to observe neutron radiative beta-decay. The experiment is located at the NG-6 beam line at the National Institute of Standards and Technology Center for Neutron Research. Electrons and protons are guided by a 4.6 T magnetic field and detected by a silicon surface barrier detector. Photons with energies between 15 and 750 keV are registered by a detector consisting of a bismuth germanate scintillator coupled to a large area avalanche photodiode. The photon detector operates at a temperature near 80 K in the bore of a superconducting magnet. We discuss CsI as an alternative scintillator, and avalanche photodiodes for direct detection of photons in the 0.1-10 keV range.

Bismuth- and lithium-loaded plastic scintillators for gamma and neutron detection

International Nuclear Information System (INIS)

Cherepy, Nerine J.; Sanner, Robert D.; Beck, Patrick R.; Swanberg, Erik L.; Tillotson, Thomas M.; Payne, Stephen A.; Hurlbut, Charles R.

2015-01-01

Transparent plastic scintillators based on polyvinyltoluene (PVT) have been fabricated with high loading of bismuth carboxylates for gamma spectroscopy, and with lithium carboxylates for neutron detection. When activated with a combination of standard fluors, 2,5-diphenyloxazole (PPO) and tetraphenylbutadiene (TPB), gamma light yields with 15 wt% bismuth tripivalate of 5000 Ph/MeV are measured. A PVT plastic formulation including 30 wt% lithium pivalate and 30 wt% PPO offers both pulse shape discrimination, and a neutron capture peak at ~400 keVee. In another configuration, a bismuth-loaded PVT plastic is coated with ZnS( 6 Li) paint, permitting simultaneous gamma and neutron detection via pulse shape discrimination with a figure-of-merit of 3.8, while offering gamma spectroscopy with energy resolution of R(662 keV)=15%

NELIS - a Neutron Inspection System for Detection of Illicit Drugs

International Nuclear Information System (INIS)

Barzilov, Alexander P.; Womble, Phillip C.; Vourvopoulos, George

2003-01-01

NELIS (Neutron ELemental Inspection System) is currently being developed to inspect cargo pallets for illicit drugs. NELIS must be used in conjunction with an x-ray imaging system to optimize the inspection capabilities at ports of entry. Pulsed fast-thermal neutron analysis is utilized to measure the major and minor chemical elements in a non-destructive and non-intrusive manner. Fourteen-MeV neutrons produced with a pulsed d-T neutron generator are the interrogating particles. NELIS analyzes the characteristic gamma rays emitted from the object that are produced by nuclear reactions from fast and thermal neutrons. These gamma rays have different energies for each chemical element, and act as their fingerprints. Since the elemental composition of illicit drugs is quite different from that of innocuous materials, drugs hidden in pallets are identified through the comparison of expected and measured elemental composition and ratios. Results of tests of the system will be discussed

Neutron detection performance of silicon carbide and diamond detectors with incomplete charge collection properties

Energy Technology Data Exchange (ETDEWEB)

Hodgson, M., E-mail: michael.hodgson@becq.co.uk [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Lohstroh, A.; Sellin, P. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Thomas, D. [NPL, Teddington TW11 0LW (United Kingdom)

2017-03-01

The benefits of neutron detection and spectroscopy with carbon based, wide band gap, semiconductor detectors have previously been discussed within the literature. However, at the time of writing there are still limitations with these detectors related to availability, cost, size and perceived quality. This study demonstrates that lower quality materials—indicated by lower charge collection efficiency (CCE), poor resolution and polarisation effect—available at wafer scale and lower cost, can fulfil requirements for fast neutron detection and spectroscopy for fluxes over several orders of magnitude, where only coarse energy discrimination is required. In this study, a single crystal diamond detector (D-SC, with 100% CCE), a polycrystalline diamond (D-PC, with ≈4% CCE) and semi-insulating silicon carbide (SiC-SI, with ≈35% CCE) have been compared for alpha and fast neutron performance. All detectors demonstrated alpha induced polarisation effects in the form of a change of both energy peak position and count rate with irradiation time. Despite these operational issues the ability to detect fast neutrons and distinguish neutron energies was observed. This performance was demonstrated over a wide dynamic range (500–40,000 neutrons/s), with neutron induced polarisation being demonstrated in D-PC and SiC-SI at high fluxes.

Investigation on the neutron beam characteristics for boron neutron capture therapy with 3D and 2D transport calculations

International Nuclear Information System (INIS)

Kodeli, I.; Diop, C.M.; Nimal, J.C.

1994-01-01

In the framework of future Boron Neutron Capture Therapy (BNCT) experiments, where cells and animals irradiations are planned at the research reactor of Strasbourg University, the feasibility to obtain a suitable epithermal neutron beam is investigated. The neutron fluence and spectra calculations in the reactor are performed using the 3D Monte Carlo code TRIPOLI-3 and the 2D SN code TWODANT. The preliminary analysis of Al 2 O 3 and Al-Al 2 O 3 filters configurations are carried out in an attempt to optimize the flux characteristics in the beam tube facility. 7 figs., 7 refs

Research and Development of Landmine Detection System by a Compact Fusion Neutron Source

International Nuclear Information System (INIS)

Yoshikawa, Kiyoshi; Masuda, Kai; Toku, Hisayuki; Nagasaki, Kazunobu; Mizutani, Toshiyuki; Takamatsu, Teruhisa; Imoto, Masaki; Yamamoto, Yasushi; Ohnishi, Masami; Osawa, Hodaka; Hotta, Eiki; Kohno, Toshiyuki; Okino, Akitoshi; Watanabe, Masato; Yamauchi, Kunihito; Yuura, Morimasa; Shiroya, Seiji; Misawa, Tsuyoshi; Mori, Takamasa

2005-01-01

Current results are described on the research and development of an advanced anti-personnel landmine detection system by using a compact discharge-type fusion neutron source called IECF (Inertial-Electrostatic Confinement Fusion). Landmines are to be identified through backscattering of neutrons, and specific-energy capture γ-rays by hydrogen and nitrogen atoms in the landmine explosives.For this purpose, improvements in the IECF were made by various methods to achieve a drastic enhancement of neutron yields of more than 10 8 n/s in pulsed operation. This required R and D on the power source, as well as analysis of envisaged detection systems with multi-sensors. The results suggest promising and practical features for humanitarian landmine detection, particularly, in Afghanistan

Development of neutron interrogation techniques for detection of hazardous substances in containers port

International Nuclear Information System (INIS)

D’Amico, N. M. B; Mayer, R.E; Tartaglione, A.

2013-01-01

This work is aimed at contributing to the effort of nations seeking to control international borders movement of dangerous chemical substances and nuclear material, in accordance with a multitude of agreements signed to that purpose. At this stage, we try to identify the signature of pure substances: chlorine (Cl), nitrogen (N), chromium (Cr), mercury (Hg), cadmium (Cd), uranium (U) y arsenic (As) and, later, to detect their presence in simulated large cargo containers. The technique employed in previous and in current work, consists in the detection of prompt and early decay gammas induced by incident thermal neutrons or fast neutrons thermalized in the cargo array. Uranium has also been detected through the counting of fast neutrons originated in induced fissions. (author)

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)

Measuring element for the detection and determination of radiation doses of gamma radiation and neutrons

International Nuclear Information System (INIS)

Jahn, W.; Piesch, E.

1975-01-01

A measuring element detects and proves both gamma and neutron radiation. The element includes a photoluminescent material which stores gamma radiation and particles of arsenic and phosphorus embedded in the photoluminescent material for detecting neutron radiation. (U.S.)

Neutron detection using a current biased kinetic inductance detector

International Nuclear Information System (INIS)

Shishido, Hiroaki; Miyajima, Shigeyuki; Ishida, Takekazu; Narukami, Yoshito; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi; Hidaka, Mutsuo; Fujimaki, Akira

2015-01-01

We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. 10 B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current–temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the order of a few tens of ns, which confirms the high speed operation of our detectors

Development of a hand-held fast neutron survey meter

International Nuclear Information System (INIS)

Yoshida, T.; Tsujimura, N.; Yamano, T.

2011-01-01

A neutron survey meter with a ZnS(Ag) scintillator to measure recoil protons was built. The detection probe weighs ∼2 kg, therefore providing us with true portability. Performance tests exhibited satisfactory neutron dosimetry characteristics in unmoderated or lightly moderated fission neutron fields and in particular work environments at a mixed oxide fuel facility. This new survey meter will augment a routine of neutron monitoring that is inconveniently being carried out by moderator-based neutron survey meters. (authors)

Logic based feature detection on incore neutron spectra

Energy Technology Data Exchange (ETDEWEB)

Racz, A.; Kiss, S.; Bende-Farkas, S. (Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics)

1993-04-01

A general framework for detecting features of incore neutron spectra with a rule-based methodology is presented. As an example, we determine the meaningful peaks in the APSD-s. This work is part of a larger project, aimed at developing a noise diagnostic expert system. (Author).

Active neutron technique for detecting attempted special nuclear material diversion

International Nuclear Information System (INIS)

Smith, G.W.; Rice, L.G. III.

1979-01-01

The identification of special nuclear material (SNM) diversion is necessary if SNM inventory control is to be maintained at nuclear facilities. (Special nuclear materials are defined for this purpose as either 235 U of 239 Pu.) Direct SNM identification by the detection of natural decay or fission radiation is inadequate if the SNM is concealed by appropriate shielding. The active neutron interrogation technique described combines direct SNM identification by delayed fission neutron (DFN) detection with implied SNM detection by the identification of materials capable of shielding SNM from direct detection. This technique is being developed for application in an unattended material/equipment portal through which items such as electronic instruments, packages, tool boxes, etc., will pass. The volume of this portal will be 41-cm wide, 53-cm high and 76-cm deep. The objective of this technique is to identify an attempted diversion of at least 20 grams of SNM with a measurement time of 30 seconds

A study of the cosmic-ray neutron field near interfaces

CERN Document Server

Sheu, R J; Jiang, S H

2002-01-01

This study investigated the characteristics of the cosmic-ray neutron field near air/ground and air/water interfaces with an emphasis on the angular distribution. Two sets of high-efficiency neutron detecting systems were used. The first one, called the Bonner Cylinders, was used for measurements of the energy information. The other one, referred to as the eight-channel neutron detector (8CND), was used to characterize the angular information of the neutron field. The measured results were used to normalize and confirm one-dimensional transport calculations for cosmic-ray neutrons below 20 MeV in the air/ground and air/water media. Annual sea level cosmic-ray neutron doses were then determined based on the obtained characteristics of low-energy cosmic-ray neutrons near interfaces and estimated contribution from high-energy neutrons.

In-Pile Qualification of the Fast-Neutron-Detection-System

Science.gov (United States)

Fourmentel, D.; Villard, J.-F.; Destouches, C.; Geslot, B.; Vermeeren, L.; Schyns, M.

2018-01-01

In order to improve measurement techniques for neutron flux assessment, a unique system for online measurement of fast neutron flux has been developed and recently qualified in-pile by the French Alternative Energies and Atomic Energy Commission (CEA) in cooperation with the Belgian Nuclear Research Centre (SCK•ECEN). The Fast-Neutron-Detection-System (FNDS) has been designed to monitor accurately high-energy neutrons flux (E > 1 MeV) in typical Material Testing Reactor conditions, where overall neutron flux level can be as high as 1015 n.cm-2.s-1 and is generally dominated by thermal neutrons. Moreover, the neutron flux is coupled with a high gamma flux of typically a few 1015 γ.cm-2.s-1, which can be highly disturbing for the online measurement of neutron fluxes. The patented FNDS system is based on two detectors, including a miniature fission chamber with a special fissile material presenting an energy threshold near 1 MeV, which can be 242Pu for MTR conditions. Fission chambers are operated in Campbelling mode for an efficient gamma rejection. FNDS also includes a specific software that processes measurements to compensate online the fissile material depletion and to adjust the sensitivity of the detectors, in order to produce a precise evaluation of both thermal and fast neutron flux even after long term irradiation. FNDS has been validated through a two-step experimental program. A first set of tests was performed at BR2 reactor operated by SCK•CEN in Belgium. Then a second test was recently completed at ISIS reactor operated by CEA in France. FNDS proved its ability to measure online the fast neutron flux with an overall accuracy better than 5%.

Background subtraction system for pulsed neutron logging of earth boreholes

International Nuclear Information System (INIS)

Hertzog, R.C.

1983-01-01

The invention provides a method for determining the characteristics of earth formations surrounding a well borehole comprising the steps of: repetitively irradiating the earth formations surrounding the well bore with relatively short duration pulses of high energy neutrons; detecting during each pulse of high energy neutrons, gamma radiation due to the inelastic scattering of neutrons by materials comprising the earth formations surrounding the borehole and providing information representative thereof; detecting immediately following each such pulse of high energy neutrons, background gamma radiation due to thermal neutron capture and providing information representative thereof; and correcting the inelastic gamma representative information to compensate for said background representative information

Description and performance characteristics for the neutron Coincidence Collar for the verification of reactor fuel assemblies

International Nuclear Information System (INIS)

Menlove, H.O.

1981-08-01

An active neutron interrogation method has been developed for the measurement of 235 U content in fresh fuel assemblies. The neutron Coincidence Collar uses neutron interrogation with an AmLi neutron source and coincidence counting the induced fission reaction neutrons from the 235 U. This manual describes the system components, operation, and performance characteristics. Applications of the Coincidence Collar to PWR and BWR types of reactor fuel assemblies are described

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.

A fast, high light output scintillator for gamma ray and neutron detection. Fifth Semi-Annual Report

International Nuclear Information System (INIS)

Entine, Gerald; Kanai, S.; Shah, M.S.; Leonard Cirignano, M.S.; Jarek Glodo; Van Loef, Edgar V.

2003-01-01

In view of the attractive properties of RbGd2Br7:Ce for gamma-ray and thermal neutron detection, and the lack of larger volume crystals, the goal of the Phase I project was to perform a rigorous investigation of the crystal growth of this exciting material and explore its capabilities for gamma-ray and thermal neutron detection. The Phase I research was very successful. All technical objectives were met and in many cases exceeded expectations. We were able to produce large (>1 cm3) RbGd2Br7:Ce crystals with excellent scintillation properties and demonstrated the possibility to detect thermal neutrons. As far as we are aware, our Phase I experiment was the first to demonstrate thermal neutron detection with RbGd2Br7:Ce. Clearly, the feasibility of the proposed research was adequately proven. The Phase II research builds on the successful results obtained during Phase I. Phase II will initially focus on optimizing the RbGd2Br7:Ce growth process to produce high quality, larger volume RbGd2Br7:Ce crystals. We will continue to use the versatile Bridgman technique. During this process, crystal growth parameters will be adjusted for optimal growth conditions. Our goal is to produce high quality RbGd2Br7:Ce crystals of size 1 inch x 1 inch x 1 inch (∼16 cm3). We will work on packaging aspects that allow efficient light collection and prevent crystal degradation. We will study and measure emission spectra, light yield, scintillation decay, energy and time resolution. The effects of variation in Ce concentration on the scintillation properties of RbGd2Br7:Ce will be examined in detail. Comprehensive gamma-ray spectroscopic and imaging studies will be conducted. Also, optimization of RbGd2Br7:Ce for thermal neutron detection will be addressed. Our initial studies will determine the optimal geometry of the RbGd2Br7:Ce crystals for neutron detection. For thermal neutron detection experiments, we will produce large area, thin samples in order to minimize gamma-ray sensitivity

Development of a modular directional and spectral neutron detection system using solid-state detectors

Energy Technology Data Exchange (ETDEWEB)

Weltz, A., E-mail: weltza3@gmail.com; Torres, B.; McElwain, L.; Dahal, R.; Huang, J.; Bhat, I.; Lu, J.; Danon, Y.

2015-08-21

A detection system using room-temperature, microstructured solid-state thermal neutron detectors with very low leakage current has been developed at Rensselaer Polytechnic Institute (RPI) with the ability to provide positional and spectral information about an unknown neutron source. The Directional and Spectral Neutron Detection System (DSNDS) utilizes a set of small-but-scalable, zero-bias solid-state thermal neutron detectors which have demonstrated high thermal neutron efficiency and adequate gamma insensitivity. The DSNDS can gather spectral information about an unknown neutron source with a relatively small number of detectors, simplifying the detector electronics and minimizing cost; however, the DSNDS is modular in design, providing the capability to increase the detection efficiency and angular resolution. The system used in this paper was comprised of a stack of five high-density polyethylene (HDPE) disks with a thickness of 5 cm and a diameter of 30 cm, the middle disk containing 16 detectors positioned as one internal (moderated) and one external (unmoderated) ring of solid-state neutron detectors. These two detector rings provide the ability to determine the directionality of a neutron source. The system gathers spectral information about a neutron source in two ways: by measuring the relative responses of the internal ring of detectors as well as measuring the ratio of the internal-to-external detector responses. Experiments were performed with variable neutron spectra: a {sup 252}Cf spontaneous fission neutron source which was HDPE moderated, HDPE reflected, lead (Pb) shielded, and bare in order to benchmark the system for spectral sensitivity. Simulations were performed in order to characterize the neutron spectra corresponding to each of the source configurations and showed agreement with experimental measurements. The DSNDS demonstrates the ability to determine the relative angle of the source and the hardness of the neutron spectrum. By using the

Neutron detector

International Nuclear Information System (INIS)

Endo, Hiroshi.

1993-01-01

The device of the present invention detects neutrons in a reactor container under a high temperature and reduces the noise level in an FBR type reactor. That is, the detection section comprises a high heat resistant vessel containing a scintillator therein for detecting neutrons. Neutron signals sent from the detection section are inputted to a neutron measuring section by way of a signal transmission section. The detection section is disposed at the inside of the reactor container. Further, the signal transmission section is connected optically to the detection section. With such a constitution, since the detection section comprising the high temperature resistant vessel is disposed at the inside of the reactor container, neutron fluxes can be detected and measured at high sensitivity even under a high temperature circumstance. Since the signal transmission section is optically connected to the detection section, influence of radiation rays upon transmission of the neutron detection signals can be reduced. Accordingly, the noise level can be kept low. (I.S.)

DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

OpenAIRE

Sunardi, Sunardi; Muryono, Muryono

2010-01-01

Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec).  At this research condition of neutron generator was set at...

Neutron spectra characteristics for the intense neutron source, INS

International Nuclear Information System (INIS)

Battat, M.; Dierckx, R.; Emigh, C.R.

1977-01-01

The Intense Neutron Source, INS, facility is presently under construction at the Los Alamos Scientific Laboratory. Its purpose is to provide a broad base for research work related to the radiation effects produced by 14-MeV neutrons from a D-T burn of a fusion reactor. The INS facility produces a D-T burn-like reaction from the collision of an intense tritium-ion beam with a supersonic jet target of deuterium gas. The reaction produces a typical D-T 14-MeV neutron spectrum. By adding a fission blanket surrounding the D-T ''burn,'' the neutron spectral shape may be tailored to match almost perfectly the anticipated first-wall spectra from presently proposed fusion reactors. With a blanket in place, the total production of neutrons can be as large as 3 x 10 16 n/s and experimental volumes of the order of 1000 cm 3 can be available at flux levels greater than 0.6 x 10 14 n/cm 2 s

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.

Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

Directory of Open Access Journals (Sweden)

Obraztsova O.

2018-01-01

Full Text Available Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV, wide band gap energy (3.27 eV and high thermal conductivity (4.9 W/cm·K, SiC can operate in harsh environment (high temperature, high pressure and high radiation level without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV, higher threshold displacement energy (40-50 eV and thermal conductivity (22 W/cm·K, which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD

Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

Science.gov (United States)

Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

2018-01-01

Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond

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.

Training courses on neutron detection systems on the ISIS research reactor: on-site and through internet training

Energy Technology Data Exchange (ETDEWEB)

Lescop, B.; Badeau, G.; Ivanovic, S.; Foulon, F. [National Institute for Nuclear science and Technology French Atomic Energy and Alternative Energies Commission (CEA), Saclay Research Center, 91191 Gif-sur-Yvette (France)

2015-07-01

modify the settings of the electronic system, such as the high voltage and the discrimination level in order to obtain all the characteristic curves of the detectors. These curves are used to define the right setting of the electronic system and to discuss the expected degradation of the detector signal resulting from the detector damage under the integrated neutron and gamma fluxes. Moreover, in addition to the study of the neutron detection systems itself, the integration of the measurements made by these detection systems in the logic of the safety system of the nuclear reactor is also addressed. Providing the trainees with an extensive overview of each part of the neutron monitoring instrumentation apply to a nuclear reactor, hands-on measurements on the ISIS reactor play a major role in ensuring a practical and comprehensive understanding of the neutron detection system and their integration in the safety system of nuclear reactors. It also gives a solid background for the follow up and the development of the neutron detection systems. In addition to on-reactor training, Internet Reactor Laboratory capability has been implemented on the ISIS reactor in 2014. For the Internet Reactor Laboratory an extensive video conference system has been implemented on ISIS reactor. The system includes 4 cameras and the transmission of the video signal given by the supervision system of the reactor which records and processes the data of the reactor. According to the pedagogic needs during the training courses, the lecturer on the ISIS reactor chooses to broadcast the relevant information at each stage of the course. For example, graph showing the histogram of the counting and current as a function of the time, or the electrical signal observed on the oscilloscope, can be broadcasted trough internet. By interacting through the video conference, the remote classroom is able to ask for changes in the reactor power or settings of the detection systems. They can also ask for the

Training courses on neutron detection systems on the ISIS research reactor: on-site and through internet training

International Nuclear Information System (INIS)

Lescop, B.; Badeau, G.; Ivanovic, S.; Foulon, F.

2015-01-01

settings of the electronic system, such as the high voltage and the discrimination level in order to obtain all the characteristic curves of the detectors. These curves are used to define the right setting of the electronic system and to discuss the expected degradation of the detector signal resulting from the detector damage under the integrated neutron and gamma fluxes. Moreover, in addition to the study of the neutron detection systems itself, the integration of the measurements made by these detection systems in the logic of the safety system of the nuclear reactor is also addressed. Providing the trainees with an extensive overview of each part of the neutron monitoring instrumentation apply to a nuclear reactor, hands-on measurements on the ISIS reactor play a major role in ensuring a practical and comprehensive understanding of the neutron detection system and their integration in the safety system of nuclear reactors. It also gives a solid background for the follow up and the development of the neutron detection systems. In addition to on-reactor training, Internet Reactor Laboratory capability has been implemented on the ISIS reactor in 2014. For the Internet Reactor Laboratory an extensive video conference system has been implemented on ISIS reactor. The system includes 4 cameras and the transmission of the video signal given by the supervision system of the reactor which records and processes the data of the reactor. According to the pedagogic needs during the training courses, the lecturer on the ISIS reactor chooses to broadcast the relevant information at each stage of the course. For example, graph showing the histogram of the counting and current as a function of the time, or the electrical signal observed on the oscilloscope, can be broadcasted trough internet. By interacting through the video conference, the remote classroom is able to ask for changes in the reactor power or settings of the detection systems. They can also ask for the broadcast of some

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.

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...

Final LDRD report : advanced plastic scintillators for neutron detection.

Energy Technology Data Exchange (ETDEWEB)

Vance, Andrew L.; Mascarenhas, Nicholas; O' Bryan, Greg; Mrowka, Stanley

2010-09-01

This report summarizes the results of a one-year, feasibility-scale LDRD project that was conducted with the goal of developing new plastic scintillators capable of pulse shape discrimination (PSD) for neutron detection. Copolymers composed of matrix materials such as poly(methyl methacrylate) (PMMA) and blocks containing trans-stilbene (tSB) as the scintillator component were prepared and tested for gamma/neutron response. Block copolymer synthesis utilizing tSBMA proved unsuccessful so random copolymers containing up to 30% tSB were prepared. These copolymers were found to function as scintillators upon exposure to gamma radiation; however, they did not exhibit PSD when exposed to a neutron source. This project, while falling short of its ultimate goal, demonstrated the possible utility of single-component, undoped plastics as scintillators for applications that do not require PSD.

Neutron detection using a current biased kinetic inductance detector

Energy Technology Data Exchange (ETDEWEB)

Shishido, Hiroaki, E-mail: shishido@pe.osakafu-u.ac.jp; Miyajima, Shigeyuki; Ishida, Takekazu [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Narukami, Yoshito [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi [Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Hidaka, Mutsuo [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Fujimaki, Akira [Department of Quantum Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

2015-12-07

We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. {sup 10}B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current–temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the order of a few tens of ns, which confirms the high speed operation of our detectors.

B{sub 4}C thin films for neutron detection

Energy Technology Data Exchange (ETDEWEB)

Hoeglund, Carina [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); Department of Physics, Chemistry and Biology (IFM), Thin Film Physics Division, Linkoeping University, SE-581 83 Linkoeping (Sweden); Birch, Jens; Jensen, Jens; Hultman, Lars [Department of Physics, Chemistry and Biology (IFM), Thin Film Physics Division, Linkoeping University, SE-581 83 Linkoeping (Sweden); Andersen, Ken; Hall-Wilton, Richard [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); Bigault, Thierry; Buffet, Jean-Claude; Correa, Jonathan; Esch, Patrick van; Guerard, Bruno; Piscitelli, Francesco [Institute Laue Langevin, Rue Jules Horowitz, FR-380 00 Grenoble (France); Khaplanov, Anton [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); Institute Laue Langevin, Rue Jules Horowitz, FR-380 00 Grenoble (France); Vettier, Christian [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); European Synchrotron Radiation Facility, BP 220, FR-380 43 Grenoble Cedex 9 (France); Vollenberg, Wilhelmus [Vacuum, Surfaces and Coatings Group (TE/VSC), CERN, CH-1211 Geneva 23 (Switzerland)

2012-05-15

Due to the very limited availability of {sup 3}He, new kinds of neutron detectors, not based on {sup 3}He, are urgently needed. Here, we present a method to produce thin films of {sup 10}B{sub 4}C, with maximized detection efficiency, intended to be part of a new generation of large area neutron detectors. B{sub 4}C thin films have been deposited onto Al-blade and Si wafer substrates by dc magnetron sputtering from {sup nat}B{sub 4}C and {sup 10}B{sub 4}C targets in an Ar discharge, using an industrial deposition system. The films were characterized with scanning electron microscopy, elastic recoil detection analysis, x-ray reflectivity, and neutron radiography. We show that the film-substrate adhesion and film purity are improved by increased substrate temperature and deposition rate. A deposition rate of 3.8 A/s and substrate temperature of 400 deg. C result in films with a density close to bulk values and good adhesion to film thickness above 3 {mu}m. Boron-10 contents of almost 80 at. % are obtained in 6.3 m{sup 2} of 1 {mu}m thick {sup 10}B{sub 4}C thin films coated on Al-blades. Initial neutron absorption measurements agree with Monte Carlo simulations and show that the layer thickness, number of layers, neutron wavelength, and amount of impurities are determining factors. The study also shows the importance of having uniform layer thicknesses over large areas, which for a full-scale detector could be in total {approx}1000 m{sup 2} of two-side coated Al-blades with {approx}1 {mu}m thick {sup 10}B{sub 4}C films.

Optimization of combined delayed neutron and differential die-away prompt neutron signal detection for characterization of spent nuclear fuel assemblies

International Nuclear Information System (INIS)

Blanc, Pauline; Tobin, Stephen J.; Croft, Stephen; Menlove, Howard O.; Swinhoe, M.; Lee, T.

2010-01-01

The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded multiple laboratories and universities to develop a means to accurately quantify the Plutonium (Pu) mass in spent nuclear fuel assemblies and ways to also detect potential diversion of fuel pins. Delayed Neutron (DN) counting provides a signature somewhat more sensitive to 235 U than Pu while Differential Die-Away (DDA) is complementary in that it has greater sensitivity to Pu. The two methods can, with care, be combined into a single instrument which also provides passive neutron information. Individually the techniques cannot robustly quantify the Pu content but coupled together the information content in the signatures enables Pu quantification separate to the total fissile content. The challenge of merging DN and DDA, prompt neutron (PN) signal, capabilities in the same design is the focus of this paper. Other possibilities also suggest themselves, such as a direct measurement of the reactivity (multiplication) by either the boost in signal obtained during the active interrogation itself or by the extension of the die-away profile. In an early study, conceptual designs have been modeled using a neutron detector comprising fission chambers or 3He proportional counters and a ∼14 MeV neutron Deuterium-Tritium (DT) generator as the interrogation source. Modeling was performed using the radiation transport code Monte Carlo N-Particles eXtended (MCNPX). Building on this foundation, the present paper quantifies the capability of a new design using an array of 3 He detectors together with fission chambers to optimize both DN and PN detections and active characterization, respectively. This new design was created in order to minimize fission in 238 U (a nuisance DN emitter), to use a realistic neutron generator, to reduce the cost and to achieve near spatial interrogation and detection of the DN and PN, important for detection of diversion, all within the constraints of

Angular resolution study of a combined gamma-neutron coded aperture imager for standoff detection

International Nuclear Information System (INIS)

Ayaz-Maierhafer, Birsen; Hayward, Jason P.; Ziock, Klaus P.; Blackston, Matthew A.; Fabris, Lorenzo

2013-01-01

Nuclear threat source observables at standoff distances of tens of meters from mCi class sources include both gamma-rays and neutrons. This work uses simulations to investigate the effects of the angular resolution of a mobile gamma-ray and neutron coded aperture imaging system upon orphan source detection significance and specificity. The design requires maintaining high sensitivity and specificity while keeping the system size as compact as possible to reduce weight, footprint, and cost. A mixture of inorganic and organic scintillators was considered in the detector plane for high sensitivity to both gamma-rays and fast neutrons. For gamma-rays (100 to 2500 keV) and fission spectrum neutrons, angular resolutions of 1–9° and radiation angles of incidence appropriate for mobile search were evaluated. Detection significance for gamma-rays considers those events that contribute to the photopeak of the image pixel corresponding the orphan source location. For detection of fission spectrum neutrons, energy depositions above a set pulse shape discrimination threshold were tallied. The results show that the expected detection significance for the system at an angular resolution of 1° is significantly lower compared to its detection significance an angular resolution of ∼3–4°. An angular resolution of ∼3–4° is recommended both for better detection significance and improved false alarm rate, considering that finer angular resolution does not result in improved background rejection when the coded aperture method is used. Instead, over-pixelating the search space may result in an unacceptably high false alarm rate

Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy

International Nuclear Information System (INIS)

Kapadia, A J; Tourassi, G D; Sharma, A C; Crowell, A S; Kiser, M R; Howell, C R

2008-01-01

Iron overload disorders have been the focus of several quantification studies involving non-invasive imaging modalities. Neutron spectroscopic techniques have demonstrated great potential in detecting iron concentrations within biological tissue. We are developing a neutron spectroscopic technique called neutron stimulated emission computed tomography (NSECT), which has the potential to diagnose iron overload in the liver at clinically acceptable patient dose levels through a non-invasive scan. The technique uses inelastic scatter interactions between atomic nuclei in the sample and incoming fast neutrons to non-invasively determine the concentration of elements in the sample. This paper discusses a non-tomographic application of NSECT investigating the feasibility of detecting elevated iron concentrations in the liver. A model of iron overload in the human body was created using bovine liver tissue housed inside a human torso phantom and was scanned with a 5 MeV pulsed beam using single-position spectroscopy. Spectra were reconstructed and analyzed with algorithms designed specifically for NSECT. Results from spectroscopic quantification indicate that NSECT can currently detect liver iron concentrations of 6 mg g -1 or higher and has the potential to detect lower concentrations by optimizing the acquisition geometry to scan a larger volume of tissue. The experiment described in this paper has two important outcomes: (i) it demonstrates that NSECT has the potential to detect clinically relevant concentrations of iron in the human body through a non-invasive scan and (ii) it provides a comparative standard to guide the design of iron overload phantoms for future NSECT liver iron quantification studies

Characteristics of rotating target neutron source and its use in radiation effects studies

International Nuclear Information System (INIS)

Van Konynenburg, R.A.; Barschall, H.H.; Booth, R.; Wong, C.

1975-07-01

The Rotating Target Neutron Source (RTNS) at Lawrence Livermore Laboratory is currently the most intense source of DT fusion neutrons available for the study of radiation effects in materials. This paper will present a brief description of the machine, outline the history of its development and discuss its performance characteristics and its application to CTR materials research. (U.S.)

Aerial Neutron Detection of Cosmic-Ray Interactions with the Earth's Surface

International Nuclear Information System (INIS)

Richard Maurer

2008-01-01

We have demonstrated the ability to measure the neutron flux produced by the cosmic-ray interaction with nuclei in the ground surface using aerial neutron detection. High energy cosmic-rays (primarily muons with GeV energies) interact with the nuclei in the ground surface and produce energetic neutrons via spallation. At the air-surface interface, the neutrons produced by spallation will either scatter within the surface material, become thermalized and reabsorbed, or be emitted into the air. The mean free path of energetic neutrons in air can be hundreds of feet as opposed to a few feet in dense materials. As such, the flux of neutrons escaping into the air provides a measure of the surface nuclei composition. It has been demonstrated that this effect can be measured at long range using neutron detectors on low flying helicopters. Radiological survey measurements conducted at Government Wash in Las Vegas, Nevada, have shown that the neutron background from the cosmic-soil interactions is repeatable and directly correlated to the geological data. Government Wash has a very unique geology, spanning a wide variety of nuclide mixtures and formations. The results of the preliminary measurements are presented

Advances in associated-particle sealed-tube neutron probe diagnostics for substance detection

International Nuclear Information System (INIS)

Rhodes, E.; Dickerman, C.E.; Frey, M.

1995-01-01

The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) shows potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. Generally no collimators or radiation shielding are needed. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Most recently, inspection applications have been investigated for radioactive waste characterization, presence of cocaine in propane tanks, and uranium and plutonium smuggling. Based on lessons learned with the present APSTNG system, an advanced APSTNG tube (along with improved high voltage supply and control units) is being designed and fabricated that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux

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

Method and apparatus for measuring neutron characteristics of material surrounding a borehole

International Nuclear Information System (INIS)

Hopkinson, E.C.

1983-01-01

This invention relates to methods and apparatus for determining the macroscopic thermal neutron absorption cross section of the formations surrounding a borehole as determined by radiation measurements using optimized measurement intervals. A measurement of the decline of the thermal neutron population in the formation is derived by counting the detected radiation within a first pair of measurement intervals occurring at a fixed time after the neutron burst. A ratio of the two counting rates provides the rate of change over the selected time interval. The counting ratio is converted into a natural logarithm representative of the Sigma calculation

Neutron detection time distributions of multisphere LiI detectors and AB rem meter at a 20 MeV electron linac

International Nuclear Information System (INIS)

Liu, J.C.; Rokni, S.; Vylet, V.; Arora, R.; Semones, E.; Justus, A.

1997-01-01

Neutron detection time distribution is an important factor for the dead-time correction for moderator type neutron detectors used in pulsed radiation fields. Measurements of the neutron detection time distributions of multisphere LiL detectors (2''3'' , 5'', 8'', 10'' and 12'' in diameter) and an AB rem meter were made inside an ANL 20 MeV electron linac room. Calculations of the neutron detection time distributions were also made using Monte Carlo codes. The first step was to calculate the neutron energy spectra at the target and detector positions, using a coupled EGS4-MORSE code with a giant-resonant photoneutron generation scheme. The calculated detector spectrum was found in agreement with the multisphere measurements. Then, neutrons hitting the detector surface were scored as a function of energy and the travel time in the room using MCNP. Finally, the above neutron fluence as a function of energy and travel time was used as the source term, and the neutrons detected by 6 Li or 10 B in the sensor were scored as a function of detection time for each detector using MCNP. The calculations of the detection time distributions agree with the measurements. The results also show that the detection time distributions of detectors with large moderators depend mainly on the moderator thickness and neutron spectrum. However, for small detectors, the neutron travel time in the field is also crucial. Therefore, all four factors (neutron spectrum, neutron travel time in the field, detector moderator thickness and detector response function) may play inter-related roles in the detection time distribution of moderator type detectors. (Author)

Characteristics of GaAs MESFET inverters exposed to high energy neutrons

International Nuclear Information System (INIS)

Bloss, W.L.; Yamada, W.E.; Young, A.M.; Janousek, B.K.

1988-01-01

GaAs MESFET circuits have been exposed to high energy neutrons with fluences ranging from 1x10/sup 14/ n/cm/sup 2/ to 2x10/sup 15/ m/cm/sup 2/. Discrete transistors, inverters, and ring oscillators were characterized at each fluence. While the MESFETs exhibit significant threshold voltage shifts and transconductance and saturation current degradation over this range of neutron fluences, the authors have observed improvement in the DC characteristics of Schottky Diode FET Logic (SDFL) inverters. This unusual result has been successfully simulated using device parameters extracted from FETs damaged by exposure to high energy neutrons. Although the decrease in device transconductance results in an increase in inverter gate delay, as reflected in ring oscillator frequency measurements, the authors conclude that GaAs ICs fabricated from this logic family will remain functional after exposure to extreme neutron fluences. This is a consequence of the observed improvement in inverter noise margin evident in both measured and simulated circuit performance

Extensive Air Showers Detected by Aragats Neutron Monitor

International Nuclear Information System (INIS)

Badalyan, A.; Chilingarian, A.; Hovsepyan, G.; Grigoryan, A.; Khanikyants, Y.; Manukyan, A.; Pokhsraryan, D.; Soghomonyan, S.

2017-01-01

Extensive Air Shower (EAS) duration as registered by the surface particle detectors does not exceed a few tens of nanosecond. However, Neutron monitors containing plenty of absorbing matter can respond to EAS core traversal during 1 ∼ms by registering secondary slow neutrons born by EAS hadrons in the soil, walls of buildings and in the matter of detector itself. Thus, the time distribution of the pulses from the proportional counters of the neutron monitor after EAS propagation extends to ∼l ms, ∼5 orders of magnitude larger than the EAS passing time. The Aragats Neutron Monitor (ArNM) has a special option for the EAS core detection. In general, the dead time of NM is ∼1 ms that provides the one-to-one relation of incident hadrons and detector counts. The pulses generated by the neutrons possibly entering the proportional chamber after the first one will be neglected. In ArNM, we use several “electronic” dead times, and with the shortest one, 400 ns, the detector counts all pulses that enter the proportional chambers. If ArNM one-second time series corresponding to the shortest dead time contain much more signals (a neutron burst) than with l-ms dead time, then we conclude that the EAS core hits the detector. We assume that he distribution of registered burst multiplicities is proportional to the energy of the primary particle. The primary cosmic ray energy spectrum was obtained by the frequency analysis through the counting frequencies of the multiplicities of different magnitudes and relating them to the integral energy spectrum measured by the MAKET array at the same place several years ago. (author)

EDAC, a detection and criticality alarm system. Physical and electronic characteristics (French patent no. 2184399, December 1974)

International Nuclear Information System (INIS)

Prigent, Raymond; Renard, Claude.

1976-10-01

A project of investigations (CRAC project) conducted around 1970 brought new conclusions on accident characteristics. These conclusions were at the origin of a new philosophy of detection that resulted in the development of a detection probe sensitive both to neutrons and gamma with a response representative of the dose received by the exposed individuals. To meet these criteria, the main components of the probe are a plastic and a boron scintillators optically and mechanically connected to a photo-emissive cell, the whole being surrounded with a polyethylene casing. The characteristics of these various elements have been determined experimentally in order to get a balanced response; the chief experimental results are described. The information from the probes are collected in a processing unit with characteristics meeting the critically safety commission specifications [fr

Boiling detection using signals of self-powered neutron detectors and thermocouples

International Nuclear Information System (INIS)

Kozma, R.

1989-01-01

A specially-equipped simulated fuel assembly has been placed into the core of the 2 MW research reactor of the IRI, Delft. In this paper the recent results concerning the detection of coolant boiling in the simulated fuel assembly are introduced. Applying the theory of boiling temperature noise, different stages of boiling, i.e. one-phase flow, subcooled boiling, volume boiling, were identified in the measurements using the low-frequency noise components of the thermocouple signals. It has been ascertained that neutron noise spectra remained unchanged when subcooled boiling appeared, and that they changed reasonably only when developed volume boiling took place in the channels. At certain neutron detector positions neutron spectra did not vary at all, although developed volume boiling occurred at a distance of 3-4 cm from these neutron detectors. This phenomenon was applied in studying the field-of-view of neutron detectors

Investigation and analysis of neutron emission characteristics in Denaplasma focus facility

International Nuclear Information System (INIS)

Goodarzi, Sh.; Amrollahi, R.; Babazadeh, A.; Nasiri, A.

2003-01-01

Since the first experiments with plasma focus facilities in 1960' s. These devices are known as intense sources of neutron when the working gas contains deuterium with a proper density. Most of the emitted neutrons are produced by D-D reactions, but the mechanism of these reactions in not still clear completely. In this paper, the results of experimental investigations of neutron emission characteristics in D ena p lasma focus facility (Filipov type, 90 kJ, 25 kV) over a range of discharge voltages and pressures are presented. Out working gases are D 2 and D 2+%1 Kr, two different conic and flat insert anodes were employed. We have simultaneously measured the total emission in our experiments for analyzing the neutron generation mechanism in this device. We have found the upper and lower pressure limits and the optimum pressure for neutron generation, and we have observed the double pluses structure of neutron signal for the first time in this device. Form the experimental results, it seems that both thermonuclear and no thermonuclear mechanisms are always present in neutron generation, but their contribution in the total yield is strongly dependent on experimental conditions (initial pressure, discharge voltage, gas admixture, etc.). It was found that the range of variation of total neutron yield and neutron emission anisotropy factor for experiments with D + %1 Kr is wider than experiments with D 2, and the best neutron emission results belongs to discharges in D 2 + %1 Kr with a conic insert anode. By employing D 2 + %1 Kr with a conic insert anode, and varying pressure between 0.3-2 torr at a discharge voltage of 16 kV, it can be deduced that in low pressures ( n ∝ I α ρ ∝E α / 2 was found about 3.62 for D 2 + %1 Kr and 3 for D 2

Neutron personal dosimetry: state-of-art

International Nuclear Information System (INIS)

Spurný, František

2005-03-01

State-of-art of the personal neutron dosimetry is presented, analysed and discussed. Particular attention is devoted to the problems of this type of the dosimetry of external exposure for radiation fields at nuclear power plants. A review of general problems of neutron dosimetry is given and the active individual dosimetry methods available and/or in the stage of development are briefly reviewed. Main attention is devoted to the analysis of the methods available for passive individual neutron dosimetry. The characteristics of these dosemeters were studied and are compared: their energy response functions, detection thresholds and the highest detection limits, the linearity of response, the influence of environmental factors, etc. Particular attention is devoted to their behavior in reactor neutron fields. It is concluded that the choice of the neutron personal dosemeter depends largely on the conditions in which the instrument should be used (neutron spectrum, the level of exposure and the exposure rate, etc.). The results obtained with some of these dosemeters during international intercomparisons are also presented. Particular attention is paid to the personal neutron dosimeter developed and routinely used by National Personal Dosimetry Service Ltd. in the Czech Republic. (author)

Detection of fast burst of neutrons in the background of intense electromagnetic pulse

International Nuclear Information System (INIS)

Shyam, Anurag

1999-01-01

There are many experiments, in which fast neutron burst is emitted along with strong electromagnetic pulse. This pulse has frequency spectrum starting from few tens of khz to hard x-rays. Detecting these neutrons bursts require special measurement techniques, which are described. (author)

An investigation on detection and measurement of fusion neutron spectrum and radiation flux in large tokamak

International Nuclear Information System (INIS)

Yang Jinwei; Li Wenzhong; Zhang Wei

2003-01-01

The detection methods, detectors and spectrometers of D-D and D-T fusion neutron have been overviewed in large tokamaks. Some options are proposed for developing new detection systems of fusion neutrons suitable to the HL-2A tokamak. (authors)

Digital-to-analog device for continuous detection of neutron damping decrement in logging

International Nuclear Information System (INIS)

Sokolov, Yu.I.; Zinchenko, A.I.; Rudenko, Eh.L.

1976-01-01

Algorithms are analyzed for a continuous detection of the damping decrement (DD) of the thermal neutron density in time, characterizing absorptive and diffusion properties of a bed; an an automated measuring device has been developed. The design of a digital calculator involving reguired mathematical and logical operations in the DD measurement by the specified algorithms necessitated the use of a system of elements with a diode-transistor RC logic. Following laboratory tests the mock-up of the calculator was subjected to borehole tests as part of the pulsed neutron logging apparatus of the IGN-4 type. A continuous detection of the DD reciprocal with a parallel recording of the differential and integral curves of pulsed neutron-neutron logging has been performed. The borehole tests revealed the efficiency of the new device and the possibility of its use together with the apparatus of the IGN-4 type

Design of a versatile detector for the detection of charged particles, neutrons and gamma rays. Neutron interaction with the matter; Diseno de un detector versatil para la deteccion de particulas cargadas, neutrones y rayos gamma. Interaccion neutronica con la materia

Energy Technology Data Exchange (ETDEWEB)

Perez P, J J [Comision Nacional de Seguridad Nuclear y Salvaguardias, Mexico, D.F. (Mexico)

1991-07-01

The Fostron detector detects charged particles, neutrons and gamma rays with a reasonable discrimination power. Because the typical detectors for neutrons present a great uncertainty in the detection, this work was focused mainly to the neutron detection in presence of gamma radiation. Also there are mentioned the advantages and disadvantages of the Fostron detector.

APSTNG: Neutron interrogation for detection of explosives and drugs and nuclear and CW materials

International Nuclear Information System (INIS)

Rhodes, E.; Peters, C.W.

1993-01-01

A recently developed neutron diagnostic probe system has the potential to satisfy a significant number of van-mobile and fixed-portal requirements for nondestructive detection, including monitoring of contraband explosives, drugs, and weapon materials, and treaty verification of sealed munitions. The probe is based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14-MeV neutron generated from the deuterium-tritium reaction and that detects the alpha-particle associated with each neutron. Gamma-ray spectra of resulting neutron reactions identify nuclides associated with all major chemicals in explosives, drugs, and chemical warfare agents, as well as many pollutants and fissile and fertile special nuclear material. Flight times determined from detection times of the gamma rays and alpha-particles yield a separate coarse tomographic image of each identified nuclide. The APSTNG also forms the basis for a compact fast-neutron transmission imaging system that can be used along with or instead of the emission imaging system. Proof-of-concept experiments have been performed under laboratory conditions for simulated nuclear and chemical warfare munitions and for explosives and drugs. The small and relatively inexpensive APSTNG exhibits high reliability and can be quickly replaced. Surveillance systems based on APSTNG technology can avoid the large physical size, high capital and operating expenses, and reliability problems associated with complex accelerators

A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

Energy Technology Data Exchange (ETDEWEB)

Cester, D., E-mail: davide.cester@gmail.com [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Lunardon, M.; Moretto, S. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Pino, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Sajo-Bohus, L. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Apartado 89000, 1080 A Caracas (Venezuela, Bolivarian Republic of); Stevanato, L.; Bonesso, I.; Turato, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

2016-09-11

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

International Nuclear Information System (INIS)

Cester, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pino, F.; Sajo-Bohus, L.; Stevanato, L.; Bonesso, I.; Turato, F.

2016-01-01

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

Study of a nTHGEM-based thermal neutron detector

Science.gov (United States)

Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

2016-07-01

With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

The sensitivity studies of a landmine explosive detection system based on neutron backscattering using Monte Carlo simulation

Directory of Open Access Journals (Sweden)

Khan Hamda

2017-01-01

Full Text Available This paper carries out a Monte Carlo simulation of a landmine detection system, using the MCNP5 code, for the detection of concealed explosives such as trinitrotoluene and cyclonite. In portable field detectors, the signal strength of backscattered neutrons and gamma rays from thermal neutron activation is sensitive to a number of parameters such as the mass of explosive, depth of concealment, neutron moderation, background soil composition, soil porosity, soil moisture, multiple scattering in the background material, and configuration of the detection system. In this work, a detection system, with BF3 detectors for neutrons and sodium iodide scintillator for g-rays, is modeled to investigate the neutron signal-to-noise ratio and to obtain an empirical formula for the photon production rate Ri(n,γ= SfGfMf(d,m from radiative capture reactions in constituent nuclides of trinitrotoluene. This formula can be used for the efficient landmine detection of explosives in quantities as small as ~200 g of trinitrotoluene concealed at depths down to about 15 cm. The empirical formula can be embedded in a field programmable gate array on a field-portable explosives' sensor for efficient online detection.

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)

Neutronics characteristics of space power reactors

International Nuclear Information System (INIS)

Little, W.; Barner, J.

1986-01-01

The objective of the paper is to describe the neutronic characteristics of a range of possible space reactor designs, and indicate the relative advantages and disadvantages of the various designs. Fuel designs to be considered are cermets (i.e., ceramic particles embedded in a metal matrix) consisting of UO 2 or Nn ceramic particles in matrices of Nb, Mo, Ta, or W. These cermet fuels are compared to a UN pin-type design. UN was selected for the reference fuel material since it has a somewhat higher density than UO 2 (i.e., 14.32 versus 10.96 gm/cc), which allows a lower minimum critical mass for both ceramic and cermet designs

Applications of Monte Carlo technique in the detection of explosives, narcotics and fissile material using neutron sources

International Nuclear Information System (INIS)

Sinha, Amar; Kashyap, Yogesh; Roy, Tushar; Agrawal, Ashish; Sarkar, P.S.; Shukla, Mayank

2009-01-01

The problem of illicit trafficking of explosives, narcotics or fissile materials represents a real challenge to civil security. Neutron based detection systems are being actively explored worldwide as a confirmatory tool for applications in the detection of explosives either hidden inside a vehicle or a cargo container or buried inside soil. The development of a system and its experimental testing is a tedious process and to develop such a system each experimental condition needs to be theoretically simulated. Monte Carlo based methods are used to find an optimized design for such detection system. In order to design such systems, it is necessary to optimize source and detector system for each specific application. The present paper deals with such optimization studies using Monte Carlo technique for tagged neutron based system for explosives and narcotics detection hidden in a cargo and landmine detection using backscatter neutrons. We will also discuss some simulation studies on detection of fissile material and photo-neutron source design for applications on cargo scanning. (author)

Neutron detection using CR-39 and Atomic Force Microscopy (AFM)

International Nuclear Information System (INIS)

Vazquez L, C.; Fragoso, R.; Felix, R.; Golzarri, J.I.; Espinosa, G.; Castillo, F.

2007-01-01

AFM has been applied in many CR-39 track formation analyses. In this paper, the use of AFM in the neutron detection and analysis of the track formation is reported. The irradiation was made with an 1.5 GBq (0.5 Ci) 241 Am-Be neutron source, with and without a polyethylene radiator. The surface analysis was made to the CR-39 fresh material without irradiation, after the irradiation, and after a very short etching time. The results show important differences between the irradiation, with and without polyethylene radiator, and the latent tracks of the neutron in the CR-39 polycarbonate. The development of track formation after very short etching time and pits characterization were measured too using the AFM facilities. (Author)

Method and apparatus for formation logging using position sensitive neutron detectors

International Nuclear Information System (INIS)

Gadken, L.L.

1986-01-01

This patent describes a method for logging earth formations using position sensitive neutron detectors. The method consists of: 1) Irradiation of earth formations in the vicinity of a well borehole with a source of fast neutrons. 2) At four longitudinally spaced distances from the neutron source in the borehole, the epithermal neutron population is detected. Each of the four separate populations is detected in an epithermally sensitive and substantially thermally insensitive portion of the same position sensitive neutron detector. A representative signal from each is then individually generated. 3) First, second, third, and fourth neutron population representative signals are combined. They derive a simultaneous measurement signal. This signal is functionally related to the porosity and also a signal functionally related to a neutron characteristic length of the earth formations in the vicinity of the borehole

High Hydrogen Content Graphene Hydride Compounds & High Cross-Section Cladding Coatings for Fast Neutron Detection

International Nuclear Information System (INIS)

Chandrashekhar, MVS

2017-01-01

The objective is to develop and implement a superior low-cost, large area (potentially >32in), easily deployable, close proximity, harsh environment innovative neutron sensor needed for next generation fuel cycle monitoring. We will exploit recent breakthroughs at the PI's lab on the electrochemistry of epitaxial graphene (EG) formed on commercial SiC wafers, a transformative nanomaterial system with superior radiation detection and durability properties to develop a new paradigm in detection for fast neutrons, a by-product of fission reactors. There are currently few effective detection/monitoring schemes, especially solid-state ones at present. This is essential for monitoring and control of future fuel cycles to make them more efficient and reliable. By exploiting these novel materials, as well as innovative hybrid SiC/EG/Cladding device architectures conceived by the team, will develop low-cost, high performance solutions to fast-neutron detection. Finally, we will also explore 3-terminal device implementations for neutron detectors with built-in electronic gain to further shrink these devices and improve their sensitivity.

Experimental investigation of the neutron physics characteristics of the Dalat Nuclear Research Reactor

Energy Technology Data Exchange (ETDEWEB)

Huy, Ngo Quang; Thong, Ha Van [Nuclear Research Inst., Da Lat (Viet Nam)

1994-10-01

The investigation of the neutron physics characteristics of the Dalat Reactor has obtained the results as follows: 1/ The effective fraction of delayed photoneutrons and the extraneous neutron source left after reactor shut down are measured. 2/ The lowest power levels of critical states of the reactor are determined. 3/The perturbation effect is investigated when a water column or a plexiglass rod is substituted for a fuel element. 4/ The relative axial and radial distributions of the thermal neutrons measured and the geometrical parameters of the core such as the inhomogeneous coefficients, the buckling, the effective height and radius, the extrapolated distances are obtained. 4/ The thermal neutron distributions are measured around the old graphite reflector. (author). 10 refs., 10 figs., 2 tabs.

The Muon-Induced Neutron Indirect-Detection EXperiment. MINIDEX

Energy Technology Data Exchange (ETDEWEB)

Palermo, Matteo

2016-06-06

A new experiment to measure muon-induced neutrons is introduced. The design of the Muon-Induced Neutron Indirect Detection EXperiment, MINIDEX, is presented and its installation and commissioning in the Tuebingen Shallow Underground Laboratory are described. Results from its first data taking period, run I, are presented. Muon-induced neutrons are not only an interesting physics topic by itself, but they are also an important source of background in searches for possible new rare phenomena like neutrinoless double beta decay or directly observable interactions of dark matter. These subjects are of great importance to understand the development of the early universe. Therefore, a new generation of ton-scale experiments which require extremely low background levels is under consideration. Reliable Monte Carlo simulations are needed to design such future experiments and estimate their background levels and sensitivities. The background due to muon-induced neutrons is hard to estimate, because of inconsistencies between different experimental results and discrepancies between measurements and Monte Carlo predictions. Especially for neutron production in high-Z materials, more experimental data and related simulation studies are clearly needed. MINIDEX addresses exactly this subject. Already the first five months of data taking provided valuable data on neutron production, propagation and interaction in lead. A first round of comparisons between MINIDEX data and Monte Carlo predictions are presented. In particular, the predictions of two Monte Carlo packages, based on GEANT4, are compared to the data. The data show an overall 70-100% higher rate of muon-induced events than predicted by the Monte Carlo packages. These packages also predict a faster time evolution of the muon-induced signal than observed in the data. Nevertheless, the time until the signal from the muon-induced events is completely collected was correctly predicted by the Monte Carlos. MINIDEX is foreseen

Neutronic characteristics of coupled moderator proposed in integrated model

International Nuclear Information System (INIS)

Teshigawara, Makoto; Meigo, Shin-ichiro; Sakata, Hideaki; Kai, Tetsuya; Harada, Masahide; Ikeda, Yujiro; Watanabe, Noboru

2001-05-01

A pulsed spallation source for the materials science and the life science is currently developing for its construction in the High Intensity Proton Accelerator Project proposed jointly by the Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK). This report presents the analytical results of the neutronic characteristics of the coupled moderator based on the analytical results obtained by using an integrated model which has established on the extensive neutronic and technical study. Total heat deposition in a hydrogen (H 2 ) moderator working as the main moderator was about 420 W/MW. Maximum nuclear heat density in the H 2 moderator was about 1 W/cm 3 /MW. Also total heat deposition in a premoderator was about 9.2 kW/MW. The heat density of the premoderator was comparable to that of the moderator vessel made of aluminum alloy. The heat density of the premoderator and the moderator vessel is about 1.2-2 times higher than that of the hydrogen moderator. The temperature from 300 K to 400 K of the premoderator did not affect on neutron intensity of the H 2 moderator. This suggested an engineering advantage on the thermal and hydraulic design. 6000 or 7000 type of a aluminum alloy was considered from the viewpoint of the neutron beam transmission. The proton beams scattered by the proton beam window did not affect on the nuclear heating in the H 2 moderator. The heat deposition in the H 2 moderator and the neutron intensity of the H 2 moderator did not depend on the proton beam profile but it did on the distance between the proton beam and the moderator. (author)

Neutron irradiation effects on silicon detectors structure, electrical and mechanical characteristics

International Nuclear Information System (INIS)

Rabinovich, E.; Golan, G.; Axelevich, A.; Inberg, A.; Oksman, M.; Rosenwaks, I.; Lubarsky, G.; Seidman, A.; Croitoru, N.; Rancoita, P.G.; Rattaggi, M.

1999-01-01

Neutron irradiation effects on (p-n) and Schottky-junction silicon detectors were studied. It was shown that neutron interactions with monocrystalline silicon create specific types of microstructure defects with morphology differing according to the level of neutron fluences (Φ). The isolated dislocation loops, formed by interstitial atoms were observed in microstructure images for 10 10 ≤ Φ ≤ 10 12 n/cm 2 . A strong change in the dislocation loops density and a cluster formation was observed for Φ ≥ 10 13 n/cm 2 . A drastic silicon damage was found for fluences over 10 14 n/cm 2 . These fluences created zones enriched with all types of dislocations, covering more than 50 % of the total surface area. A mechanical fragility appeared in that fluence range in a form of microcracks. 10 14 n/cm 2 appears to be a critical value of neutron irradiation because of the radiation damage described above and because the characteristics I f -V f of silicon detectors can be differentiated from those obtained at low fluences. (A.C.)

Detecting neutrons by forward recoil protons at the Energy & Transmutation facility: Detector development and calibration with 14.1-MeV neutrons

Science.gov (United States)

Afanasev, S.; Vishnevskiy, A.; Vishnevskiy, D.; Rogachev, A.; Tyutyunnikov, S.

2017-05-01

As part of the Energy & Transmutation project, we are developing a detector for neutrons with energies in the 10-100 MeV range emitted from the target irradiated by a charged-particle beam. The neutron is detected by measuring the time-of-flight and total kinetic energy of the forward-going recoil proton [1] knocked out at a small angle from a thin layer of plastic scintillator, which has to be selected against an intense background created by γ quanta, scattered neutrons, and charged particles. On the other hand, neutron energy has to be measured over the full range with no extra tuning of the detector operation regime. Initial measurements with a source of 14.1-MeV neutrons are reported.

Techniques of in vivo neutron activation analysis

International Nuclear Information System (INIS)

Chettle, D.R.; Fremlin, J.H.

1984-01-01

This review is dealt with under the following headings, intended to reflect the different factors affecting the measurement sensitivity, starting with the choice of neutron source and proceeding, through the reaction characteristics, to the detection system, the questions of dosimetry and ethical constraints being also discussed: 1) neutron sources, slowing down and interaction processes, energy spectrum and flux uniformity, timing 2) neutron reactions used for in vivo analyses 3) detectors, choice, geometrical considerations and detector shielding 4) data collection and processing 5) interpretation, major elements, absolute or sequential measurements, relationship to other parameters 6) dosimetry, framework for dose levels, biological effects of neutron interactions, neutron doses in practice 7) implications for measurement of calcium, nitrogen and cadmium. (U.K.)

Methematical model of a neutron counting system used for the characteristics control of spontaneously fissioning material

International Nuclear Information System (INIS)

Bessis, J.

1986-09-01

Methods are described for calculating the probabilities, p(m), of detection of m neutrons, inside a split millisecond counting gate, m varying from zero to some units. At the present stage, these methods suppose the source to be very small. Using the generating function concept, they concern both possible modes of the counting system, for opening gates, i.e.: 1) Trigger pulses randomly with regard to the emitted neutrons, 2) Trigger pulses from the detected neutrons themselves. Computed values are finally compared to the measured ones. This comparison seems to be very favourable, since the respective deviations are often lower than 1 % [fr

Neutron capture on nitrogen as a means of detecting explosives

International Nuclear Information System (INIS)

Thompson, M.N.; Rassool, R.P.

1995-01-01

A research prototype was developed on the basis of neutron capture on nitrogen and is demonstrated to be able to detect parcel and letter bombs. Is the gamma radiation that is detected as an indication of the presence of nitrogen, and the probable presence of nitrogen-containing explosive. The conceptual design of the explosive detector and some experimental results are briefly presented. figs., ills

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-03-15

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

Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

Energy Technology Data Exchange (ETDEWEB)

Mahl, Adam [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States); Yemam, Henok A.; Stuntz, John [Department of Chemistry and Geochemistry and the Materials Science Program Colorado School of Mines, Golden, CO 80401 (United States); Remedes, Tyler [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States); Sellinger, Alan [Department of Chemistry and Geochemistry and the Materials Science Program Colorado School of Mines, Golden, CO 80401 (United States); Greife, Uwe, E-mail: ugreife@mines.edu [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States)

2016-04-21

A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B{sub 2}Pin{sub 2}) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% {sup 10}B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1–20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1–15 wt% B{sub 2}Pin{sub 2} were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B{sub 2}Pin{sub 2} concentration, strong {sup 10}B neutron capture signals around 90 keV{sub ee} were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the {sup 10}B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

International Nuclear Information System (INIS)

Mahl, Adam; Yemam, Henok A.; Stuntz, John; Remedes, Tyler; Sellinger, Alan; Greife, Uwe

2016-01-01

A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B_2Pin_2) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% "1"0B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1–20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1–15 wt% B_2Pin_2 were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B_2Pin_2 concentration, strong "1"0B neutron capture signals around 90 keV_e_e were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the "1"0B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

Carbon filter property detection with thermal neutron technique

International Nuclear Information System (INIS)

Deng Zhongbo; Han Jun; Li Wenjie

2003-01-01

The paper discussed the mechanism that the antigas property of the carbon filter will decrease because of its carbon bed absorbing water from the air while the carbon filter is being stored, and introduced the principle and method of detection the amount of water absorption with thermal neutron technique. Because some certain relation between the antigas property of the carbon filter and the amount of water absorption exists, the decrease degree of the carbon filter antigas property can be estimated through the amount of water absorption, offering a practicable facility technical pathway to quickly non-destructively detect the carbon filter antigas property

The Nuclear Car Wash: Neutron interrogation of cargo containers to detect hidden SNM

Science.gov (United States)

Hall, J. M.; Asztalos, S.; Biltoft, P.; Church, J.; Descalle, M.-A.; Luu, T.; Manatt, D.; Mauger, G.; Norman, E.; Petersen, D.; Pruet, J.; Prussin, S.; Slaughter, D.

2007-08-01

LLNL is actively involved in the development of advanced technologies for use in detecting threats in sea-going cargo containers, particularly the presence of hidden special nuclear materials (SNM). The "Nuclear Car Wash" (NCW) project presented here uses a high-energy (En ≈ 3.5-7.0 MeV) neutron probe to scan a container and then takes high-energy (Eγ ⩾ 2.5 MeV), β-delayed γ-rays emitted during the subsequent decay of any short-lived, neutron-induced fission products as a signature of fissionable material. The components of the proposed system (e.g. neutron source, gamma detectors, etc.) will be discussed along with data processing schemes, possible threat detection metrics and potential interference signals. Results from recent laboratory experiments using a prototype system at LLNL will also be presented.

The Nuclear Car Wash: Neutron interrogation of cargo containers to detect hidden SNM

International Nuclear Information System (INIS)

Hall, J.M.; Asztalos, S.; Biltoft, P.; Church, J.; Descalle, M.-A.; Luu, T.; Manatt, D.; Mauger, G.; Norman, E.; Petersen, D.; Pruet, J.; Prussin, S.; Slaughter, D.

2007-01-01

LLNL is actively involved in the development of advanced technologies for use in detecting threats in sea-going cargo containers, particularly the presence of hidden special nuclear materials (SNM). The 'Nuclear Car Wash' (NCW) project presented here uses a high-energy (E n ∼ 3.5-7.0 MeV) neutron probe to scan a container and then takes high-energy (E γ ≥ 2.5 MeV), β-delayed γ-rays emitted during the subsequent decay of any short-lived, neutron-induced fission products as a signature of fissionable material. The components of the proposed system (e.g. neutron source, gamma detectors, etc.) will be discussed along with data processing schemes, possible threat detection metrics and potential interference signals. Results from recent laboratory experiments using a prototype system at LLNL will also be presented

Characteristics of SiC neutron sensor spectrum unfolding process based on Bayesian inference

Energy Technology Data Exchange (ETDEWEB)

Cetnar, Jerzy; Krolikowski, Igor [Faculty of Energy and Fuels AGH - University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Ottaviani, L. [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231 -13397 Marseille Cedex 20 (France); Lyoussi, A. [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France)

2015-07-01

This paper deals with SiC detector signal interpretation in neutron radiation measurements in mixed neutron gamma radiation fields, which is called the detector inverse problem or the spectrum unfolding, and it aims in finding a representation of the primary radiation, based on the measured detector signals. In our novel methodology we resort to Bayesian inference approach. In the developed procedure the resultant spectra is unfolded form detector channels reading, where the estimated neutron fluence in a group structure is obtained with its statistical characteristic comprising of standard deviation and correlation matrix. In the paper we present results of unfolding process for case of D-T neutron source in neutron moderating environment. Discussions of statistical properties of obtained results are presented as well as of the physical meaning of obtained correlation matrix of estimated group fluence. The presented works has been carried out within the I-SMART project, which is part of the KIC InnoEnergy R and D program. (authors)

Neutronic characteristics of linear-assembly breed-and-burn reactors

International Nuclear Information System (INIS)

Petroski, Robert; Forget, Benoit; Forsberg, Charles

2012-01-01

Highlights: ► Simple models used to characterize general behavior of linear-assembly B and B reactors. ► Diffusion theory model developed to explain axial distributions, height vs. reactivity. ► Neutron excess concept reformulated to include linear-assembly B and B reactors. ► Designed model of B and B reactor started using melt-refined B and B reactor used fuel. ► Computed doubling time of fuel cycle requiring no chemical separations. - Abstract: Linear-assembly breed-and-burn (B and B) reactors are B and B reactors that use axially connected assemblies similar to conventional LWR or fast reactor fuel assemblies. Methods for analyzing linear-assembly B and B reactors and their fuel cycles are developed and applied. General neutronic characteristics of linear-assembly B and B reactors are analyzed, including the effects that burnup, shuffling sequence, and radial and axial size have on equilibrium-cycle k-effective. The mechanisms that give rise to a highly peaked axial burnup distribution are explained, and a method for predicting peak burnup vs. k-effective based on infinite-medium depletion calculations is developed. Next, the neutron excess concept from previous studies of B and B reactors is extended to apply to linear-assembly B and B reactors, which allows the amount of starter fuel needed to establish a given equilibrium cycle to be calculated. Several example applications of the neutron excess formulation are given. First, an example model of a linear-assembly B and B reactor is analyzed to find the neutron excess cost of an equilibrium cycle. Second, simple one-dimensional models are used to predict the neutron excess value obtainable from different starter fuel configurations. Finally, these ideas are applied to design a fuel cycle consisting of linear-assembly B and B reactors and fuel recycling via a melt refining process. The neutron excess concept is used to design an appropriate starter fuel configuration made from melt refined fuel, which

Application of neutron/gamma transport codes for the design of explosive detection systems

International Nuclear Information System (INIS)

Elias, E.; Shayer, Z.

1994-01-01

Applications of neutron and gamma transport codes to the design of nuclear techniques for detecting concealed explosives material are discussed. The methodology of integrating radiation transport computations in the development, optimization and analysis phases of these new technologies is discussed. Transport and Monte Carlo codes are used for proof of concepts, guide the system integration, reduce the extend of experimental program and provide insight into the physical problem involved. The paper concentrates on detection techniques based on thermal and fast neutron interactions in the interrogated object. (authors). 6 refs., 1 tab., 5 figs

Detection and identification of explosives and illicit drugs using neutron based techniques

International Nuclear Information System (INIS)

Papp, A.; Csikai, J.; Debrecen University,

2011-01-01

Some methods developed in collaboration between the ATOMKI and IEP for bulk hydrogen analysis and for the detection and identification of illicit drugs are presented. Advantages and limitations of neutron techniques (reflection, transmission, elastic and inelastic scatterings, leakage spectra and angular yields of Be(d,n), Pu-Be, D-D, D-T and 252 Cf neutrons transmitted from thick samples, effects of hidden materials) are discussed. (author)

Neutron-neutron probe for uranium exploration

International Nuclear Information System (INIS)

Smith, R.C.

1979-01-01

A neutron activation probe for assaying the amount of fissionable isotopes in an ore body is described which comprises a casing which is movable through a borehole in the ore body, a neutron source and a number of delayed neutron detectors arranged colinearly in the casing below the neutron source for detecting delayed neutrons

A Monte-Carlo study of landmines detection by neutron backscattering method

International Nuclear Information System (INIS)

Maucec, M.; De Meijer, R.J.

2000-01-01

The use of Monte-Carlo simulations for modelling a simplified landmine detector system with a 252 Cf- neutron source is presented in this contribution. Different aspects and variety of external conditions, affecting the localisation and identification of a buried suspicious object (such as landmine) have been tested. Results of sensitivity calculations confirm that the landmine detection methods, based on the analysis of the backscattered neutron radiation can be applicable in higher density formations, with the mass fraction of present pore-water <15 %. (author)

Characteristics of diallyl phthalate resin as a fission track detector

CERN Document Server

Tsuruta, T

1999-01-01

Diallyl phthalate (DAP) resin plates were irradiated with fission fragments, and then etched in aqueous solution of KOH. Etched tracks were observed and counted by using an optical microscope. The detection efficiency of fission fragments was about 100% for both perpendicular and random incidence. DAP plates were insensitive to alpha particles and fast neutrons. These characteristics are suitable for detecting selected fission fragments, which coexist with alpha particles or fast neutrons. DAP plates are valuable for quantitative analysis of fissionable materials and neutron dosimetry. DAP and allyl diglycol carbonate (CR-39) were formed into copolymers in various ratios. The copolymers showed intermediate characteristics between DAP and CR-39. The fabrication of the copolymers made it possible to control the discrimination level for detection of heavy charged particles.

High Hydrogen Content Graphene Hydride Compounds & High Cross-­ Section Cladding Coatings for Fast Neutron Detection

Energy Technology Data Exchange (ETDEWEB)

Chandrashekhar, MVS [Univ. of South Carolina, Columbia, SC (United States)

2017-06-21

The objective is to develop and implement a superior low-cost, large area (potentially >32in), easily deployable, close proximity, harsh environment innovative neutron sensor needed for next generation fuel cycle monitoring. We will exploit recent breakthroughs at the PI’s lab on the electrochemistry of epitaxial graphene (EG) formed on commercial SiC wafers, a transformative nanomaterial system with superior radiation detection and durability properties to develop a new paradigm in detection for fast neutrons, a by-product of fission reactors. There are currently few effective detection/monitoring schemes, especially solid-state ones at present. This is essential for monitoring and control of future fuel cycles to make them more efficient and reliable. By exploiting these novel materials, as well as innovative hybrid SiC/EG/Cladding device architectures conceived by the team, will develop low-cost, high performance solutions to fast-neutron detection. Finally, we will also explore 3-terminal device implementations for neutron detectors with built-in electronic gain to further shrink these devices and improve their sensitivity.

Calibration of a neutron probe for determining the humidity in deep alluvial soils

International Nuclear Information System (INIS)

Ferrer, A.; Rivero, H.; Lopez, F.; Cantillo, O.

1993-01-01

Preliminary data for the calibration of a neutron probe in deep alluvial soils for determining the humidity are reported. Comparisons of Neutron flow behaviour with the depth of the land are established. A characteristic curve of amount of detected neutrons according to the humidity percentage (from 50 to 100 % of the field humidity) is obtained

Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons; Camara de ionizacao de eletretos: um novo metodo para deteccao e dosimetria de neutrons termicos

Energy Technology Data Exchange (ETDEWEB)

Ghilardi, A J.P.

1988-12-31

An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of {gamma}-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF{sub 3} ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs.

Neutronic characteristics simulation of LMFBR of great size

International Nuclear Information System (INIS)

Kim, Y.C.

1987-09-01

The CONRAD experimental program to be executed on the critical mockup MASURCA in Cadarache and use all the european plutonium stock. The objectives of this program are to reduce the uncertainties on important project parameters such as the reactivity value of control rods, the flux distribution to valid calcul methods and data to use for new LMFBR conception (heterogeneous axial core by example) and to resolve the neutronic control problems for a LMFBR of great size. The present study has permitted to define this program and its physical characteristics [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)

Clustering and correlations at the neutron drip-line

Energy Technology Data Exchange (ETDEWEB)

Orr, N.A.; Marques, F.M

2003-03-01

Some recent experimental studies of clustering and correlations within very neutron-rich light nuclei are reviewed. In particular, the development of the novel probes of neutron-neutron interferometry and Dalitz-plot analyses is presented through the example of the dissociation of the two-neutron halo system {sup 14}Be. The utility of high-energy proton radiative capture is illustrated using a study of the {sup 6}He(p,{gamma}) reaction. A new approach to the production and detection of bound neutron clusters is also described, and the observation of events with the characteristics expected for tetraneutrons ({sup 4}n) liberated in the breakup of {sup 14}Be is discussed. The prospects for future work, including systems beyond the neutron drip-line, are briefly outlined. (authors)

Method and device for optimizing the measurements of the damping characteristics of therman neutrons

International Nuclear Information System (INIS)

Jacobson, L.A.; Johnstone, C.W.

1978-01-01

The borehole probe consists of a pulsed neutron generator and two detectors installed at different distances from the generator. The decay or damping characteristics of the thermal neutrons in a ground formation are measured by picking up indications of the concentration of thermal neutrons in the formation during a set of two measuring intervals offer irradiation. These measuring intervals consist of a sequence of discrete time gates. The time gates are subdivided into groups of progressive periods of time. The time delay between the pulses and the beginning of the sequence is adjusted by means of a selected scale factor value. (DG) [de

Phototransistor response under a neutron fluence

International Nuclear Information System (INIS)

Santos, Luiz A.P.; Barros, Fabio R.; Ursulino, Luciano C.; Silva Junior, Eronides F.; Antonio Filho, Joao

2009-01-01

The purpose of this communication is to show some effects on a bipolar phototransistor after it has been under a neutron fluence. Unlike a transistor, a phototransistor is designed so that the collector has a large area and consequently it has a higher radiation detection probability. Then, it is possible to have a certain number of interactions so that any changes in the internal structure of the phototransistor can be observed after a neutron irradiation. If a phototransistor is under a certain spectra of neutron fluence the interaction depends on the cross section of the either silicon chip or its encapsulation, and recoil protons could be the charged particle responsible for changes in the semiconductor structure. Furthermore, neutron irradiation could give to the device a state of vanishing in its electrical characteristic which can be performed tracing the current versus voltage curve (I x V). The experimental arrangement basically consists of a photonic device, a neutron-gamma radiation source and a Flip-Flop electrometer second generation (EFF-2G). One of the main parameters of evaluation was the phototransistor dark current. In fact, the first results demonstrate that when the phototransistor is neutron irradiated there is a significant variation in its I x V characteristic curve. (author)

Characteristics and calibration of the transmission-type fast neutron moisture meter

International Nuclear Information System (INIS)

Banzai, K.

1984-01-01

With the Transmission-type Fast Neutron Moisture Meter, we did some experiments for calibration and the effective range of fast neutron scattering, and observed soil moisture process before and after making artificial rainfall at a lysimeter filled by decomposed granite. A fast neutron source of this meter is 252 Cf and capacity of 100 μ Ci. The neutron detector is NE-213 liquid scintilator which recovers a little flux of neutron source. For the customary thermal neutron meter, the effective range of neutron scattering is variable by soil moisture values surrounding the observation point, but this fast neutron, insert and transmission-type meter shows soil moisture in small capacity between a source and a detector. Experimental Results; 1) The calibration curve, calculated statistically from the relation of soil moisture and the count ratio in a 200 l drum packed with beads, gravel, sand and Kanto loam, became only one line. The correlation coefficient of this curve was 0.996 and the standard error was 1.94% with volumetric water content. 2) Count ratio started to decrease as observation point approached soil surface from the boundary of 6 cm depth in soil. Volumetric water content increased more than fact with the previous calibration curve. 3) We limited the detectable range to fast neutron, but a little scattering was seen surrounding the soil of a observation point. The effective range of horizontal scattering was a width of 20 cm with the center line connected between a source and a detector, with a circle of 5 cm diameter surrounding the source, and a circle of 10-15 cm diameter surrounding the detector. 4) Soil moisture before and after artificial rainfall was observed with this meter and by the measurement of a 100 cm 3 oven dried sampling vessel. Volumetric water content by the latter measurement, was more variable because sampling points were at a distance from the center of observation site and sampling technique was bad. Otherwise soil moisture values

Associated-particle sealed-tube neutron generators and hodoscopes for NDA applications

International Nuclear Information System (INIS)

Rhodes, E.; Peters, C.W.

1991-01-01

With radioisotope sources, gamma-ray transmission hodoscopes can inspect canisters and railcars to monitor rocket motors, can detect nuclear warheads by their characteristic strong gamma-ray absorption, or can count nuclear warheads inside a missile by low-resolution tomography. Intrinsic gamma-ray radiation from warheads can also be detected in a passive mode. Neutron hodoscopes can use neutron transmission, intrinsic neutron emission, or reactions stimulated by a neutron source, in treaty verification roles. Gamma-ray and neutron hodoscopes can be combined with a recently developed neutron diagnostic probe system, based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14-MeV neutrons, and that uses flight-time to electronically collimate transmitted neutrons and to tomographically image nuclides identified by reaction gamma-rays. Gamma-ray spectra of resulting neutron reactions identify nuclides associated with all major chemicals in chemical warfare agents, explosives, and drugs, as well as many pollutants and fissile and fertile special nuclear material. 5 refs., 12 figs

LISe pixel detector for neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Herrera, Elan; Hamm, Daniel [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Wiggins, Brenden [Technology Development, Y-12 National Security Complex, Oak Ridge, TN (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Milburn, Rob [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Burger, Arnold [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Department of Life and Physical Sciences, Fisk University, Nashville, TN (United States); Bilheux, Hassina [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Santodonato, Louis [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Chvala, Ondrej [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Stowe, Ashley [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Technology Development, Y-12 National Security Complex, Oak Ridge, TN (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Lukosi, Eric, E-mail: elukosi@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States)

2016-10-11

Semiconducting lithium indium diselenide, {sup 6}LiInSe{sub 2} or LISe, has promising characteristics for neutron detection applications. The 95% isotopic enrichment of {sup 6}Li results in a highly efficient thermal neutron-sensitive material. In this study, we report on a proof-of-principle investigation of a semiconducting LISe pixel detector to demonstrate its potential as an efficient neutron imager. The LISe pixel detector had a 4×4 of pixels with a 550 µm pitch on a 5×5×0.56 mm{sup 3} LISe substrate. An experimentally verified spatial resolution of 300 µm was observed utilizing a super-sampling technique.

Contribution to the study of position sensitive detectors with high spatial resolution for thermal neutron detection

International Nuclear Information System (INIS)

Idrissi Fakhr-Eddine, Abdellah.

1978-01-01

With a view to improving the spatial resolution of the localization of thermal neutrons, the work covers four position sensitive detectors: - 800 cell multi-detectors (1 dimension), - linear 'Jeu de Jacquet' detectors (1 dimension) - Multi-detector XYP 128x128 (2 dimensions), - 'Jeu de Jacquet' detector with 2 dimensions. Mention is made of the various position finding methods known so far, as well as the reasons for selecting BF 3 as detector gas. A study is then made of the parameters of the multiwire chamber whose principle will form the basis of most of the position detecting appliances subsequently dealt with. Finally, a description is given of the detection tests of the thermal neutrons in the multiwire chamber depending on the pressure, a parameter that greatly affects the accuracy of the position finding. The single dimension position tests on two kinds of appliance, the 800 cell multi-detector for the wide angle diffraction studies, and the linear 'Jeu de Jacquet' detector designed for small angle diffraction are mentioned. A description is then given of two position appliances with two dimensions; the multi-detector XYP 128x128 and the two dimensional 'Jeu de Jacquet' detector. In the case of this latter detector, only the hoped for characteristics are indicated [fr

Preliminary examination of the applicability of imaging plates to fast neutron radiography

International Nuclear Information System (INIS)

Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

2001-01-01

Fast neutron radiography is an attractive non-destructive inspection technique because of the excellent penetration characteristics of fast neutrons in matter. However, the difficulty of detecting fast neutrons reduces this attractive feature. As an experiment to overcome the difficulty, imaging plates were applied to fast neutron radiography. A simple combination of two sheets of imaging plates and a sheet of polyethylene as a proton emitter was examined with the (fast neutron, thermal neutron and gamma ray) FTG discriminator proposed by Yoneda et al. . The experimental results showed that the method could be applicable to fast neutron radiography with effective discrimination of γ-rays

Simulation of Thermal, Neutronic and Radiation Characteristics in Spent Nuclear Fuel and Radwaste Facilities

International Nuclear Information System (INIS)

Poskas, P.; Bartkus, G.

1999-01-01

The overview of the activities in the Division of Thermo hydro-mechanics related with the assessment of thermal, neutronic and radiation characteristics in spent nuclear fuel and radwaste facilities are performed. Also some new data about radiation characteristics of the RBMK-1500 spent nuclear fuel are presented. (author)

Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

Energy Technology Data Exchange (ETDEWEB)

Dickens, Peter T.; Marcial, José; McCloy, John; McDonald, Benjamin S.; Lynn, Kelvin G.

2017-10-01

In this study, LiAlO2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6 % 6Li, a 10 mm Ø by 10 mm sample of LiAlO2 has a 70.7 % intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.

Radiation damage of pixelated photon detector by neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Isamu [KEK, 1-1 Oho Tsukuba 305-0801 (Japan)], E-mail: isamu.nakamura@kek.jp

2009-10-21

Radiation Damage of Pixelated Photon Detector by neutron irradiation is reported. MPPC, one of PPD or Geiger-mode APD, developed by Hamamatsu Photonics, is planned to be used in many high energy physics experiments. In such experiments radiation damage is a serious issue. A series of neutron irradiation tests is performed at the Reactor YAYOI of the University of Tokyo. MPPCs were irradiated at the reactor up to 10{sup 12}neutron/cm{sup 2}. In this paper, the effect of neutron irradiation on the basic characteristics of PPD including gain, noise rate, photon detection efficiency is presented.

Neutron counting and gamma spectroscopy with PVT detectors

International Nuclear Information System (INIS)

Mitchell, Dean James; Brusseau, Charles A.

2011-01-01

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

Coupled neutronics/thermal-hydraulics and safety characteristics of liquid-fueled molten salt reactors

International Nuclear Information System (INIS)

Qiu, Suizheng; Zhang, Dalin; Liu, Minghao; Liu, Limin; Xu, Rongshuan; Gong, Cheng; Su, Guanghui

2016-01-01

Molten salt reactor (MSR) as one candidate of the Generation IV advanced nuclear power systems is attracted more attention in China due to its top ranked fuel cycle and thorium utilization. The MSRs are characterized by using liquid-fuel, which offers complicated coupling problem of neutronics and thermal hydraulics. In this paper, the fundamental model and numerical method are established to calculate and analyze the safety characteristics for liquid-fuel MSRs. The theories and methodologies are applied to the MOSART concept. The liquid-fuel flow effects on neutronics, reactivity coefficients and three operation parameters' influences at steady state are obtained, which provide the basic information for safety analysis. The unprotected loss of flow transient is calculated, the results of which shows the inherent safety characteristics of MOSART due to its strong negative reactivity feedbacks.

Coupled neutronics/thermal-hydraulics and safety characteristics of liquid-fueled molten salt reactors

Energy Technology Data Exchange (ETDEWEB)

Qiu, Suizheng; Zhang, Dalin; Liu, Minghao; Liu, Limin; Xu, Rongshuan; Gong, Cheng; Su, Guanghui [Xi' an Jiaotong Univ. (China). State Key Laboratory of Multiphase Flow in Power Engineering

2016-05-15

Molten salt reactor (MSR) as one candidate of the Generation IV advanced nuclear power systems is attracted more attention in China due to its top ranked fuel cycle and thorium utilization. The MSRs are characterized by using liquid-fuel, which offers complicated coupling problem of neutronics and thermal hydraulics. In this paper, the fundamental model and numerical method are established to calculate and analyze the safety characteristics for liquid-fuel MSRs. The theories and methodologies are applied to the MOSART concept. The liquid-fuel flow effects on neutronics, reactivity coefficients and three operation parameters' influences at steady state are obtained, which provide the basic information for safety analysis. The unprotected loss of flow transient is calculated, the results of which shows the inherent safety characteristics of MOSART due to its strong negative reactivity feedbacks.

Transparent lithiated polymer films for thermal neutron detection

Energy Technology Data Exchange (ETDEWEB)

Mabe, Andrew N., E-mail: andrew.n.mabe@gmail.com [Department of Chemistry, University of Tennessee, Knoxville, TN 37996 (United States); Auxier, John D. [Department of Chemistry, University of Tennessee, Knoxville, TN 37996 (United States); Urffer, Matthew J. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Penumadu, Dayakar [Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Schweitzer, George K. [Department of Chemistry, University of Tennessee, Knoxville, TN 37996 (United States); Miller, Laurence F. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

2013-09-11

Novel water-soluble {sup 6}Li loaded copolymer scintillation films have been designed and fabricated to detect thermal neutrons. Styrene and maleic anhydride were copolymerized to form an alternating copolymer, then the anhydride functionality was hydrolyzed using {sup 6}Li hydroxide. The resulting poly(styrene-co-lithium maleate) was mixed with salicylic acid as a fluor and cast as a thin film from water. The maximum {sup 6}Li loading obtained that resulted in a transparent film was 4.36% by mass ({sup 6}Li to polymer). The optimum fluorescence output was obtained for 11.7% salicylic acid by mass, presumably in the form of lithium salicylate, resulting in an optimum film containing 3.85% by mass of {sup 6}Li. A facile and robust synthesis method, film fabrication protocol, photoluminescence results, and scintillation responses are reported herein. -- Highlights: • A transparent polymer scintillator containing 3.85 wt% {sup 6}Li has been synthesized. • This class of polymeric thermal neutron scintillation detector is water-soluble. • Salicylic acid, presumably in the form of lithium salicylate, is used as a fluor. • The material emits 373 photons/α ({sup 241}Am) and an average of 139 photons/β ({sup 36}Cl). • The material emits 360 photons per thermal neutron capture event.

Neutron flux monitor

International Nuclear Information System (INIS)

Oda, Naotaka.

1993-01-01

The device of the present invention greatly saves an analog processing section such as an analog filter and an analog processing circuit. That is, the device of the present invention comprises (1) a neutron flux detection means for detecting neutron fluxed in the reactor, (2) a digital filter means for dividing signals corresponding to the detected neutron fluxes into predetermined frequency band regions, (3) a calculation processing means for applying a calculation processing corresponding to the frequency band regions to the neutron flux detection signals divided by the digital filter means. With such a constitution, since the neutron detection signals are processed by the digital filter means, the accuracy is improved and the change for the property of the filter is facilitated. Further, when a neutron flux level is obtained, a calculation processing corresponding to the frequency band region can be conducted without the analog processing circuit. Accordingly, maintenance and accuracy are improved by greatly decreasing the number of parts. Further, since problems inherent to the analog circuit are solved, neutron fluxes are monitored at high reliability. (I.S.)

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

Monte Carlo calculations of the neutron coincidence gate utilisation factor for passive neutron coincidence counting

CERN Document Server

Bourva, L C A

1999-01-01

The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP sup T sup M , has been used to simulate the neutronic characteristics of the on-site laboratory passive neutron coincidence counter to be installed, under Euratom Safeguards Directorate supervision, at the Sellafield reprocessing plant in Cumbria, UK. This detector is part of a series of nondestructive assay instruments to be installed for the accurate determination of the plutonium content of nuclear materials. The present work focuses on one aspect of this task, namely, the accurate calculation of the coincidence gate utilisation factor. This parameter is an important term in the interpretative model used to analyse the passive neutron coincidence count data acquired using pulse train deconvolution electronics based on the shift register technique. It accounts for the limited proportion of neutrons detected within the time interval for which the electronics gate is open. The Monte Carlo code MCF, presented in this work, represents...

Confirmation of identity and detection limit in neutron activation analysis

International Nuclear Information System (INIS)

Yustina Tri Handayani; Slamet Wiyuniati; Tulisna

2010-01-01

Neutron Activation Analysis (NAA) based on neutron capture by nuclides. Of the various possibilities of radionuclides that occur, radionuclides and gamma radiation which provides the identity of the element were analyzed and the best sensitivity should be determined. Confirmation for elements in sediment samples was done theoretically and experimentally. The result of confirmation shows that Al, V, Cr K, Na, Ca and Zn were analyzed based on radionuclides of Al-28, V-52, Cr-51 , K-42, Na-24, Ca-48, Zn-65. Elements of Mg, Mn, Fe, Co were analyzed based on radionuclides of Mg-27, Mn-56, Fe-59, Co-60 through peak which the highest value of combined probability of radiation emission and efficiency. Cu can be analyzed through Cu-64 or Cu-66, but the second is more sensitive. Detection limit is determined at a certain measurement conditions carried out by a laboratory. Detection limit in the NAA is determined based on the Compton continue area by Curie method. The detection limit of Al, V, Ca, Mg, Mn, As, K, Na, Mg, Ce, Co, Cr, Fe, La, Sc, and Zn in sediment samples are 240, 27, 4750, 2600, 21, 3.3 , 75, 1.4, 1.8, 0.5, 2.7, 29, 1, 0.05, and 37 ppm. Analysis of Cu in sediments which concentrations of 98.6 ppm, Cu-66 is not detected. Tests using pure standard solutions of Cu obtained detection limit of 0.12 µg, or 7.9 ppm in samples of 15 mg. In general, the detection limit obtained was higher than the detection limit of the reference, it was caused by the differences in the sample matrix and analytical conditions. (author)

Development of the Very Low Angle Detector (VLAD) for detection of epithermal neutrons at low momentum transfers

International Nuclear Information System (INIS)

Tardocchi, M.; Andreani, C.; Cremonesi, O.; Gorini, G.; Perelli-Cippo, E.; Pietropaolo, A.; Rhodes, N.; Schooneveld, E.; Senesi, R.

2006-01-01

New perspectives for epithermal neutron spectroscopy are opened up by the recent development of new instrumentation for inverse geometry time of flight spectrometers at pulsed neutron sources. One example is the Very Low Angle Detector (VLAD) bank which will be installed as an upgrade of the VESUVIO neutron spectrometer, at the ISIS pulsed neutron source. VLAD is developed for detecting epithermal neutrons in the 1-100 eV energy range at very low scattering angles (l deg. - 5 deg.). VLAD will extend the kinematical region covered by today's neutron scattering experiments to the region of low wave vector transfers ( -1 ) and high energy transfers (>1 eV). Accessing such kinematical region will allow new experimental studies in condensed matter systems. The neutron detection is based on Resonance Detectors (RD), which consist of the combination of a resonance foil used as neutron-to-gamma converter and a photon detector. The results obtained with a prototype VLAD detector confirm the potential of this kind of experiments at scattering angles as low as 2 deg. - 5 deg. GEANT4 simulations are used to address issues, such as detector cross talk, which arise with the construction of compact RD arrays

Detection mechanisms in silicon diodes used as α-particle and thermal neutron detectors

International Nuclear Information System (INIS)

Cerofolini, G.F.; Ferla, G.; Foglio Para, A.

1981-01-01

Some common silicon devices (diodes, RAMs etc.) can be used as α and thermal neutron detectors. An α resolution of approx. equal to 3% can be obtained utilizing p + /n or n + /p diodes with no external bias. Thermal neutrons are detected by means of the reaction 10 B(n,α) 7 Li on the 10 B present in the devices. Neutron efficiency has been substantially improved by implantation of 10 B ions in the p + region of the diodes. Experimental results allow us to clarify the carrier collection mechanisms throughout the device. Some current opinions in the field are contradicted. (orig.)

Neutron dosimetry program at Mound - problems and solutions

International Nuclear Information System (INIS)

Winegardner, M.K.

1991-01-01

The Mound personnel neutron dosimetry program utilizes TLD albedo technology. The neutron dosimeter design incorporates a two-element spectrometer for site-specific neutron quality determination and empirical application of field neutron calibration factors. Design elements feature two Li(6)F (TLD- 600) chips for neutron detection and one Li(7)F (TLD-700) chip for gamma compensation of the TLD- 600 chips. One TLD-600 chip is Cadmium shielded on the front side of the dosimeter, the other is Cadmium shielded from the back side. Tin filters are placed opposite of the Cadmium shield on each of the TLD-600 chips and on both sides of the TLD-700 chip for symmetrically equivalent gamma absorption characteristics. Neutron quality determination is accomplished by the albedo neutron-to- incident thermal neutron response ratio above the Cadmium cutoff. This front Cadmium shielded-to-back Cadmium shielded response ratio, compensated for the presence of gamma radiation, provides the basis for neutron energy calibration via the albedo response curve

Investigation of the neutron detection statistics in fast critical assembly BFS-24-1

International Nuclear Information System (INIS)

Avramov, A.M.; Tyutyunnikov, P.L.; Mikulski, A.T.; Rafalska, E.; Chwaszczewski, S.; Jablonski, K.

1974-01-01

The results of the neutron detection statistics investigation at the fast critical assembly BFS-24-1 are given. The Ross-α measurements were carried out using: digital flash-start unit and 256 channel time analyzer, 10 channel time analyzer, alphameter device. Parallely the measurements using the variable dead time method and zero probability method were performed. The prompt neutron decay constants, the effectiveness of neutron detector and the intensity of external neutron source are determined using the experimental data. The experimental values of prompt neutron decay constant are compared with the calculated ones. The codes used in the calculation are following: one dimensional, diffusion, 26-group code 26-M and EWA-1, one dimensional, multiregion, nonstationary diffusion 3-group code SPECTR, 26-group, diffusion code in buckling approximation, MIXSPECTR. In all codes the 26 group nuclear constants BNAB-26 and BNAB-70 are used. (author)

A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.

Energy Technology Data Exchange (ETDEWEB)

Doyle, Barney Lee (Sandia National Laboratories, Albuquerque, NM); King, Michael; Rossi, Paolo (Sandia National Laboratories, Albuquerque, NM); McDaniel, Floyd Del (Sandia National Laboratories, Albuquerque, NM); Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak (Sandia National Laboratories, Albuquerque, NM); Raber, Thomas N.

2008-12-01

Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

Detection of wood discoloration in a canker fungus-inoculated Japanese cedar by neutron radiography

International Nuclear Information System (INIS)

Yamada, T.; Aoki, Y.; Yamato, M.; Komatsu, M.; Kusumoto, D.; Suzuki, K.; Nakanishi, T.M.

2005-01-01

Neutron radiography (NRG) was applied to trace the development of discolored tissue in the wood of Japanese cedar (Cryptomeria japonica) after being infected with a canker fungus. Japanese cedar seedlings were wound inoculated with a virulent and avirulent isolate of a canker fungus, Guignardia cryptomeriae. Three, 7, 13 and 22 days after the inoculation, the seedlings were irradiated with thermal neutrons. The image on the X-ray film showed that the whiteness in the image corresponded to the water content in the sample. Discolored tissue and surrounding dry zones induced by the fungal inoculation were detected as dark areas, indicating water deficiency with a high resolution. Through image analysis, the dry zones were detected as early as 3 days after inoculation. Neutron images also showed the difference in the size of water deficient parts due to the tissue damage among the treatments. The neutron beam dose used in this experiment had no effect on the growth rate of the fungus on a medium, showing that NRG is an effective method for pathological research of trees. (author)

Detection and identification of unexploded ordnance (UXO) by neutron interrogation

International Nuclear Information System (INIS)

Caffrey, A.J.; Hartwell, J.K.; Krebs, K.M.; McLaughlin, G.D.

1998-01-01

This document reviews the principle of operation and unexploded ordnance (UXO) signatures of the PINS Chemical Assay System, a prompt-gamma-ray neutron activation analysis (PGNAA) for the identification of recovered UXO. Two related low cost methods for buried landmine detection are also suggested. Nuclear methods may compliment existing search techniques to improve the overall probability of detection and to reduce the false positive rate of other technologies. In addition, nuclear methods are a proven method for identification of UXO such as landmines

Fast neutron attenuation measurements for detection of illicit materials

International Nuclear Information System (INIS)

Lee, Hee Seock; Chung, Chin Wha; Guon, Ki Il; Lee, Bo Young; Ko, Seung Kook; Shin, Yong Mu

2002-01-01

Experiments were carried out to develop a novel method using neutron attenuation for the detection of illicit materials. By using pulsed fast neutrons generated from a Bi target bombarded with a 2 GeV electron beam, attenuation spectra of C, N, and O have been measured to study the feasibility of a practical application. The spectral dependence on the material thickness and the geometrical distribution as well as the ability to identify different elements in a layered environment have been studied. For the elements mentioned here, the total cross sections have been obtained from the measured attenuation spectra and compared with ENDF-VI, which showed good agreement. The study confirms that a conventional low energy electron linac can be put into a practical use, and some practical idea is presented

Radiation portal monitor with {sup 10}B+ZnS(Ag) neutron detector performance for the detection of special nuclear materials

Energy Technology Data Exchange (ETDEWEB)

Guzman G, K. A.; Gallego, E.; Lorente, A.; Ibanez F, S. [Universidad Politecnica de Madrid, Departamento de Ingenieria Energetica, ETSI Industriales, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Gonzalez, J. A. [Universidad Politecnica de Madrid, Laboratorio de Ingenieria Nuclear, ETSI Caminos, Canales y Puertos, C. Prof. Aranguren 3, 28040 Madrid (Spain); Mendez, R., E-mail: ingkarenguzman@gmail.com [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 40, 28040 Madrid (Spain)

2016-10-15

In homeland security, neutron detection is used to prevent the smuggling of special nuclear materials. Thermal neutrons are normally detected with {sup 3}He proportional counters, in the radiation portal monitors, Rpms, however due to the {sup 3}He shortage new procedures are being studied. In this work Monte Carlo methods, using the MCNP6 code, have been used to study the neutron detection features of a {sup 10}B+ZnS(Ag) under real conditions inside of a Rpm. The performance for neutron detection was carried out for {sup 252}Cf, {sup 238}U and {sup 239}Pu under different conditions. In order to mimic an actual situation occurring at border areas, a sample of SNM sited inside a vehicle was simulated and the Rpm with {sup 10}B+ZnS(Ag) response was calculated. At 200 cm the {sup 10}B+ZnS(Ag) on Rpm response is close to 2.5 cps-ng {sup 252}Cf, when the {sup 252}Cf neutron source is shielded with 0.5 cm-thick lead and 2.5 cm-thick polyethylene fulfilling the ANSI recommendations. Three different geometries of neutron detectors of {sup 10}B+ZnS(Ag) in a neutron detection system in Rpm were modeled. Therefore, the {sup 10}B+ZnS(Ag) detectors are an innovative and viable replacement for the {sup 3}He detectors in the Rpm. (Author)

The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

International Nuclear Information System (INIS)

Enqvist, Andreas

2008-03-01

One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible sample

The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

Energy Technology Data Exchange (ETDEWEB)

Enqvist, Andreas

2008-03-15

One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible

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)

Field Prototype of the ENEA Neutron Active Interrogation Device for the Detection of Dirty Bombs

Directory of Open Access Journals (Sweden)

Nadia Cherubini

2016-10-01

Full Text Available The Italian National Agency for New Technologies, Energy, and Sustainable Economic Development (ENEA Neutron Active Interrogation (NAI device is a tool designed to improve CBRNE defense. It is designed to uncover radioactive and nuclear threats including those in the form of Improvised Explosive Devices (IEDs, the so-called “dirty bombs”. The NAI device, at its current development stage, allows to detect 6 g of 235U hidden in a package. It is easily transportable, light in weight, and with a real-time response. Its working principle is based on two stages: (1 an “active” stage in which neutrons are emitted by a neutron generator to interact with the item under inspection, and (2 a “passive” stage in which secondary neutrons are detected originating a signal that, once processed, allows recognition of the offence. In particular, a clear indication of the potential threat is obtained by a dedicated software based on the Differential Die-Away Time Analysis method.

Theoretical determination of the neutron detection efficiency of plastic track detectors. Pt. 1

International Nuclear Information System (INIS)

Pretzsch, G.

1982-01-01

A theoretical model to determine the neutron detection efficiency of organic solid state nuclear track detectors without external radiator is described. The model involves the following calculation steps: production of heavy charged particles within the detector volume, characterization of the charged particles by appropriate physical quantities, application of suitable registration criteria, formation of etch pits. The etch pits formed are described by means of a distribution function which is doubly differential in both diameter and depth of the etch pits. The distribution function serves as the input value for the calculation of the detection efficiency. The detection efficiency is defined as the measured effect per neutron fluence. Hence it depends on the evaluation technique considered. The calculation of the distribution function is carried out for cellulose triacetate. The determination of the concrete detection efficiency using the light microscope and light transmission measurements as the evaluation technique will be described in further publications. (orig.)

Performance of an RPM based on Gd-lined plastic scintillator for neutron and gamma detection [ANIMMA--2015-IO-372

Energy Technology Data Exchange (ETDEWEB)

Fanchini, Erica [INFN/ANN and SCINTILLA groups, Isituto Nazionale di Fisica Nucleare - INFN (Italy)

2015-07-01

set-up for dynamic tests of multiple systems according to international standards. The performed measurements utilized radioactive sources with activities selected according to ANSI and IEC standards to test the detector alarm performances in terms of gamma and neutron response, sensitivity to high gamma fields, sensitivity to moderated neutron sources as well as false alarm rates (FAR). In addition, the RPM was tested in challenging configurations exceeding the requirements set by international standards to determine the real limits of the system. The results obtained during these campaigns demonstrated that the system detection efficiency is not only compliant to international standards for its category, but often exceeds them, demonstrating the validity of the chosen technology and of the implemented layout. The positive performance also showed the effectiveness of the SCS and of its functionalities. To further demonstrate the system capabilities, a test in a real-life environment of the RPM is planned to happen in a near future by installing the detectors in a seaport. In this presentation I will give an overview of the RPM characteristics, of its performances as determined in the test campaign mentioned above and of future plans, to demonstrate how this technology can be an effective choice for the realization of {sup 3}He-free RPM detectors. (authors)

A study on measurement of neutrons generated in radiation therapy – Measurement of neurons in CR-39 detection method

International Nuclear Information System (INIS)

Park, Cheol-Soo; Cho, Jae-Hwan; Lee, Hae-Kag; Lee, Sun-Yeob; Jang, Hyon-Chol; Dong, Kyung-Rae; Chung, Woon-Kwan; Jin, Lee; Moon, Deog-Hwan; Lee, Kwang-Sung; Yang, Nam-Oh; Cho, Moo-Seong

2013-01-01

Highlights: ► To measure the neutrons generated in a linear accelerator. ► Both fast neutrons and thermal neutrons produced an increase in the dose of neutrons generated with increasing irradiation dose. ► The generation of neutrons increased when a wedge filter was used. ► When the SRS cone that required a high dose was used, more neutrons were detected. -- Abstract: The CR-39 [diethylene glycol bis-(allylcarbonate)] neuron detection method was used to measure the dose of neutrons generated in X-ray (photon) therapy conducted in a linear accelerator, and to use high-energy photons as part of the clinical applications to examine the problems associated with the dose for patients caused by the generation of neutrons from high-energy photons used for cancer therapy. According to the experimental results, 0.35 mSv, 0.65 mSv 1.82 mSv of fast neutrons on average were generated from 1 Gy, 2 Gy and 5 Gy of photon irradiation, respectively, whereas 0.26 mSv, 0.56 mSv and 1.23 mSv of thermal neutrons were generated. Both fast neutrons and thermal neutrons produced an increase in the dose of neutrons generated with increasing irradiation dose. With in regard to the dose generated within and around the irradiation area of the photon rays, it was confirmed that more neutrons were generated within the irradiation area. A wedge filer was used to measure the generation of neutrons. According to the measurement results, the generation of neutrons increased when a wedge filter was used. When the SRS cone that required a high dose was used, more neutrons were detected than those in the previous experiment. When fast neutrons were used, 2.85 mSv neutrons on average were generated from 5 Gy of photon irradiation. When thermal neutrons were used, 1.37 mSv neutrons on average were generated from 5 Gy of photon irradiation. Overall, approximately 1.6 times and 1.12 times more fast and thermal neutrons, respectively, were generated than in the case of a general treatment with 5 Gy

Material classification by fast neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Buffler, A. E-mail: abuffler@physci.uct.ac.za; Brooks, F.D. E-mail: brooks@physci.uct.ac.za; Allie, M.S.; Bharuth-Ram, K.; Nchodu, M.R

2001-02-01

The scattering of a beam of fast monoenergetic neutrons is used to determine elemental compositions of bulk samples (0.2-0.8 kg) of materials composed from one or more of the elements H, C, N, O, Al, S, Fe and Pb. Scattered neutrons are detected by liquid scintillators placed at forward and at backward angles. Different elements are identified by their characteristic scattering signatures derived either from a combination of time-of-flight and pulse height measurements, or from pulse height measurements alone. Scattering signatures measured for multi-element samples are analysed to determine atom fractions for H, C, N, O and other elements in the sample. Atom fractions determined from scattering signatures are insensitive to neutron interactions in material surrounding the scattering sample, provided the amount of material is not excessive. The atom fraction data are used to classify scattering material into categories including 'explosives', 'illicit drugs' and 'other materials' for the purpose of contraband detection.

CFRMF neutron flux gradient and spectral determinations

International Nuclear Information System (INIS)

Rogers, J.W.; Turk, E.H.; Hogg, C.H.

1976-01-01

Recently more accurate and complete measurements of the flux gradient have been measured by the activation of 235 U and Au samples. Neutron spectrum characteristics were studied by making activation measurements with and without the ends of the CFRMF test region plugged with 10 B. These measurements define the flux gradient to +-1 to 2% and indicate there is no detectable streaming of thermal or resonance neutrons from the ends in the central 30 cm of the CFRMF test region. Measurements of the Cd ratio of Au foil activations were conducted and these results also indicate there is no streaming of thermal and resonance neutrons into the CFRMF test region

Thermal-hydraulic and neutron-physical characteristics of a new SCWR fuel assembly

International Nuclear Information System (INIS)

Liu, X.J.; Cheng, X.

2009-01-01

A new fuel assembly design for a thermal supercritical water cooled reactor (SCWR) core is proposed. Compared to the existing fuel assemblies, the present fuel assembly has two-rows of fuel rods between the moderator channels, to achieve a more uniform moderation for all fuel rod cells, and subsequently, a more uniform radial power distribution. In addition, a neutron-kinetics/thermal-hydraulics coupling method is developed, to analyze the neutron-physical and thermal-hydraulic behavior of the fuel assembly designs. This coupling method is based on the sub-channel analysis code COBRA-IV for thermal-hydraulics and the neutron-kinetics code SKETCH-N for neutron-physics. Both the COBRA-IV code and the SKETCH-N code are accordingly modified. An interface is established for the data transfer between these two codes. This coupling method is applied to both the one-row fuel assemblies (previous design) and the two-row fuel assemblies (present design). The performance of the two types of fuel assemblies is compared. The results show clearly that the two-row fuel assembly has more favorable neutron-physical and thermal-hydraulic characteristics than the one-row fuel assembly. The effect of various parameters on the fuel assembly performance is discussed. The coupling method is proven to be well suitable for further applications to SCWR fuel assembly design analysis

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.

Characteristics of polyethylene-moderated 252Cf neutron sources

International Nuclear Information System (INIS)

Alejnikov, V.E.; Beskrovnaya, L.G.; Florko, B.V.

2000-01-01

Polyethylene-moderated 252 Cf neutron sources were designed to produce neutron reference fields' spectra that simulate the spectra observed in the workplaces within nuclear reactors and accelerators. The paper describes the neutron sources and fields. Neutron spectra were calculated by Monte Carlo method and compared with experimental data

350 keV accelerator-based neutron transmission setup at KFUPM for hydrogen detection

CERN Document Server

Naqvi, A; Maslehuddin, M; Kidwai, S; Nassar, R

2002-01-01

An experimental setup has been developed to determine hydrogen contents of bulk samples using fast neutron transmission technique. Neutrons with 3 MeV energy were produced via D(d, n) reaction. The neutrons transmitted through the sample were detected by a NE213 scintillation detector. Preliminary tests of the setup were carried out using soil samples with different moisture contents. In addition to experimental study, Monte Carlo simulations were carried out to generate calibration curve of the experimental setup. Finally, experimental tests results were compared with the results of Monte Carlo simulations. A good agreement has been obtained between the simulation results and experimental results.

Neutron Detection with a Cryogenic Spectrometer

CERN Document Server

Bell, Z W; Cristy, S S; Lamberti, V E

2003-01-01

Cryogenic calorimeters are used for x-ray detection because of their exquisite energy resolution and have found application in x-ray astronomy, and the search for dark matter. These devices operate by detecting the heat pulse produced by ionization in an absorber cooled to temperatures below 1 K. Such temperatures are needed to lower the absorber's heat capacity to the point that the deposition of even a few eV results in a measurable temperature excursion. Typical absorbers for dark matter measurements are massive Si or Ge crystals, and, with Ge, have achieved a resolution of 650 eV at 10 keV. Chow, et al., report the measurement of the 60 keV emission from sup 2 sup 4 sup 1 Am with 230 eV resolution using a superconducting tin absorber. Cunningham, et al., also using a superconducting tin absorber, have recently reported a four-fold improvement over Chow. With such results being reported from the x- and gamma-ray world it is natural to examine the possibilities for cryogenic neutron spectroscopy. Such a det...

Experimental determination of the neutron detection efficiency for the testing of the results of a measurement of the magnetic neutron form factor at ELSA

International Nuclear Information System (INIS)

Maschke, P.

2001-08-01

A pion production experiment with almost real photons on 1 H has been carried out at the electron stretcher accelerator ELSA to determine the neutron detection efficiency of the large solid angle acceptance nonmagnetic ELAN Time-of-Flight spectrometer. The source of unknown discrepancy between the neutron magnetic form factor values measured at ELSA and MAMI could no longer be attributed to a wrong detection efficiency of the ELSA data. A GEANT Monte Carlo calculation has been adapted to determine the detection efficiency for the ToF spectrometer. The result of this simulation is η Geant =3.1%±0.2% in very good agreement with the experimental value of η Exp =3.2%±0.2%. (orig.)

Simultaneous analysis of qualitative parameters of solid fuel using complex neutron gamma method

International Nuclear Information System (INIS)

Dombrovskij, V.P.; Ajtsev, N.I.; Ryashchikov, V.I.; Frolov, V.K.

1983-01-01

A study was made on complex neutron gamma method for simultaneous analysis of carbon content, ash content and humidity of solid fuel according to gamma radiation of inelastic fast neutron scattering and radiation capture of thermal neutrons. Metrological characteristics of pulse and stationary neutron gamma methods for determination of qualitative solid fuel parameters were analyzed, taking coke breeze as an example. Optimal energy ranges of gamma radiation detection (2-8 MeV) were determined. The advantages of using pulse neutron generator for complex analysis of qualitative parameters of solid fuel in large masses were shown

Neutron, gamma ray, and temperature effects on the electrical characteristics of thyristors

Science.gov (United States)

Frasca, A. J.; Schwarze, G. E.

1992-01-01

Experimental data showing the effects of neutrons, gamma rays, and temperature on the electrical and switching characteristics of phase-control and inverter-type SCR's are presented. The special test fixture built for mounting, heating, and instrumenting the test devices is described. Four SCR's were neutron irradiated at 300 K and four at 365 K for fluences up to 3.2 x 10 exp 13 pn/sq. cm, and eight were gamma irradiated at 300 K only for gamma doses up to 5.1 Mrads. The electrical measurements were made during irradiation and the switching measurements were made only before and after irradiation. Radiation induced crystal defects, resulting primarily from fast neutrons, caused the reduction of minority carrier lifetime through the generation of R-G centers. The reduction in lifetime caused increases in the on-state voltage drop and in the reverse and forward leakage currents, and decreases in the turn-off time.

Neutron, gamma ray, and temperature effects on the electrical characteristics of thyristors

International Nuclear Information System (INIS)

Schwarze, G.E.; Frasca, A.J.

1992-01-01

In this paper, experimental data showing the effects of neutrons, gamma rays, and temperature on the electrical and switching characteristics of phase-control and inverter-type SCRs are presented. The special test fixture built for mounting, heating, and instrumenting the test devices is described. Four SCRs were neutron irradiated at 300 K and four at 365 K for fluences up to 3.2 x 10 13 n/cm 2 , and eight were gamma irradiated at 300 K only for gamma doses up to 5.1 Mrads. The electrical measurements were made during irradiation and the switching measurements were made only before and after irradiation. Radiation induced crystal defects, resulting primarily from fast neutrons, caused the reduction of minority carrier lifetime through the generation of R-G centers. The reduction in lifetime caused increases in the on-state voltage drop and in the reverse and forward leakage currents, and decreases in the turn-off time

Radiation portal monitor with "1"0B+ZnS(Ag) neutron detector performance for the detection of special nuclear materials

International Nuclear Information System (INIS)

Guzman G, K. A.; Gallego, E.; Lorente, A.; Ibanez F, S.; Vega C, H. R.; Gonzalez, J. A.; Mendez, R.

2016-10-01

In homeland security, neutron detection is used to prevent the smuggling of special nuclear materials. Thermal neutrons are normally detected with "3He proportional counters, in the radiation portal monitors, Rpms, however due to the "3He shortage new procedures are being studied. In this work Monte Carlo methods, using the MCNP6 code, have been used to study the neutron detection features of a "1"0B+ZnS(Ag) under real conditions inside of a Rpm. The performance for neutron detection was carried out for "2"5"2Cf, "2"3"8U and "2"3"9Pu under different conditions. In order to mimic an actual situation occurring at border areas, a sample of SNM sited inside a vehicle was simulated and the Rpm with "1"0B+ZnS(Ag) response was calculated. At 200 cm the "1"0B+ZnS(Ag) on Rpm response is close to 2.5 cps-ng "2"5"2Cf, when the "2"5"2Cf neutron source is shielded with 0.5 cm-thick lead and 2.5 cm-thick polyethylene fulfilling the ANSI recommendations. Three different geometries of neutron detectors of "1"0B+ZnS(Ag) in a neutron detection system in Rpm were modeled. Therefore, the "1"0B+ZnS(Ag) detectors are an innovative and viable replacement for the "3He detectors in the Rpm. (Author)

Swelling behavior detection of irradiated U-10Zr alloy fuel using indirect neutron radiography

Energy Technology Data Exchange (ETDEWEB)

Sun, Yong; Huo, He-yong; Wu, Yang [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China); Li, Jiangbo [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Zhou, Wei; Guo, Hai-bing [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China); Li, Hang, E-mail: lihang32@gmail.com [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China); Cao, Chao; Yin, Wei; Wang, Sheng; Liu, Bin; Feng, Qi-jie; Tang, Bin [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China)

2016-11-21

It is hopeful that fusion-fission hybrid energy system will become an effective approach to achieve long-term sustainable development of fission energy. U-10Zr alloy (which means the mass ratio of Zr is 10%) fuel is the key material of subcritical blanket for fusion-fission hybrid energy system which the irradiation performance need to be considered. Indirect neutron radiography is used to detect the irradiated U-10Zr alloy because of the high residual dose in this paper. Different burnup samples (0.1%, 0.3%, 0.5% and 0.7%) have been tested with a special indirect neutron radiography device at CMRR (China Mianyang Research Reactor). The resolution of the device is better than 50 µm and the quantitative analysis of swelling behaviors was carried out. The results show that the swelling behaviors relate well to burnup character which can be detected accurately by indirect neutron radiography.

Electronic neutron sensor based on coincidence detection

International Nuclear Information System (INIS)

Barelaud, B.; Decossas, J.L.; Mokhtari, F.; Vareille, J.C.

1996-01-01

The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of The last symposium on neutron dosimetry which took place in Paris in November 1995 have shown again that it doesn't exist any individual active neutron dosemeter. The state of art on electronic device, the needs of the nuclear power industry in individual neutron monitoring and the new trends of researches were presented. They confirm the relevance of our studies in progress in the C2M team of the University of Limoges. The aim of this work is to realize an individual electronic neutron dosemeter. The device in the progress of being development will operate either as a dosemeter or as ratemeter giving H p (10) and H p (10) either as a spectrometer permitting to characterize the primary neutron beam. (author)

Monte Carlo simulations with MENATE program in order to determine the characteristics of neutron multidetector

International Nuclear Information System (INIS)

Petrascu, M.; Isbasescu, Alina; Constantinescu, A.; Serban, S.; Stoica, I.V.

2004-01-01

The neutron multidetector consists of 81 detectors, made of 4x4x12 cmc BC-400 crystals mounted on XP2972 phototubes. This detector placed in the forward direction at 138 cm from the target, was used to detect the correlated neutrons in the fusion of Li11 halo nuclei with Si targets. To verify the criterion for selecting the true coincidences against cross-talk ( a spurious effect in which the same neutron is registered by two or more detectors) and to establish the optimal distance between adjacent detectors, the program MENATE ( written by P.Desesquelles, IPN - Orsay) was used to generate Monte Carlo neutrons and their interactions in multidetector. The results were analysed with PAW (from CERN Library). (authors)

Impact of nuclear library difference on neutronic characteristics of thorium-loaded light water reactor fuel

International Nuclear Information System (INIS)

Unesaki, H.; Isaka, S.; Nakagome, Y.

2006-01-01

Impact of nuclear library difference on neutronic characteristics of thorium-loaded light water reactor fuel is investigated through cell burnup calculations using SRAC code system. Comparison of k ∞ and nuclide composition was made between the results obtained by JENDL-3.3, ENDF/B-VI.8 and JEFF3.0 for (U, Th)O 2 fuels as well as UO 2 fuels, with special interest on the burnup dependence of the neutronic characteristics. The impact of nuclear data library difference on k ∞ of (U, Th)O 2 fuels was found to be significantly large compared to that of UO 2 fuels. Notable difference was also found in nuclide concentration of TRU nuclides. (authors)

A SrBPO5: Eu2+ phosphor for neutron imaging

International Nuclear Information System (INIS)

Sakasai, K.; Katagiri, M.; Toh, K.; Nakamura, T.

2001-01-01

A SrBPO 5 : Eu 2+ phosphor material has been investigated for neutron imaging. This phosphor showed photostimulated luminescence (PSL) by illumination of 635 nm laser light after X-ray irradiation. The spectral characteristics of the phosphor were similar to those of BaFBr: Eu 2+ , which is a commonly used phosphor of imaging plates. In addition, we found that this phosphor also showed PSL for neutron irradiation. It comes from the fact that it contains atomic boron in base matrix. Therefore, this phosphor can be used for neutron imaging without adding neutron sensitive materials such as Gd in commercially available neutron imaging plates. The PSL intensity and the neutron detection will be increased by using enriched boron instead of natural boron. (author)

Neutron Detection at JET Using Artificial Diamond Detectors

International Nuclear Information System (INIS)

Pillon, M.; Angelone, M.; Lattanzi, D.; Milani, E.; Tucciarone, A.; Verona-Rinati, G.; Popovichev, S.; Murari, A.

2006-01-01

Three CVD diamond detectors are installed and operated at Joint European Torus, Culham laboratory. Diamond detectors are very promising detectors to be used in fusion environment due to their radiation hardness, gamma discrimination properties, fast response and spectroscopy properties. The aim of this work is to test and qualify artificial diamond detectors as neutron counters and spectrometers on a large fusion device. Two of these detectors are polycrystalline CVD diamond films of thickness 30 mm and 40 mm respectively while the third detector is a monocrystalline CVD of 110 mm thickness. The first polycrystalline diamond is covered with 4 mm of LiF 95 % enriched in 6 Li and enclosed inside a polyethylene moderator cap. This detector is used with a standard electronic chain made with a charge preamplifier, shaping amplifier and threshold discriminator. It is used to measure the time-dependent total neutron yield produced by JET plasma and its signal is compared with JET fission chambers. The second polycrystalline diamond is connected with a fast (1 GHz) preamplifier and a threshold discriminator via a long (about 100 m) double screened cable. This detector is used to detect the 14 MeV neutrons produced by triton burn-up using the reaction 12 C (n, α) 9 Be which occurs in diamond and a proper discriminator threshold. The response of this detector is fast and the electronic is far from the high radiation environment. Its signal is used in comparison with JET silicon diodes. The third monocrystalline diamond is also connected using a standard electronic and is used to demonstrate the feasibility of 14 MeV neutron spectrometry at about 3% peak resolution taking advantage of the spectrometer properties of monocrystalline diamonds. The results obtained are presented in this work. (author)

Neutron interrogation system using high gamma ray signature to detect contraband special nuclear materials in cargo

Science.gov (United States)

Slaughter, Dennis R [Oakland, CA; Pohl, Bertram A [Berkeley, CA; Dougan, Arden D [San Ramon, CA; Bernstein, Adam [Palo Alto, CA; Prussin, Stanley G [Kensington, CA; Norman, Eric B [Oakland, CA

2008-04-15

A system for inspecting cargo for the presence of special nuclear material. The cargo is irradiated with neutrons. The neutrons produce fission products in the special nuclear material which generate gamma rays. The gamma rays are detecting indicating the presence of the special nuclear material.

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)

Elemental analysis technique based on detecting gamma-rays from interactions of neutrons with medium

International Nuclear Information System (INIS)

Pospisil, S.; Janout, Z.; Vobecky, M.

1979-01-01

The methods are discussed of carbon content determination in large amounts of material by detecting 4438 keV gamma radiation accompanying inelastic scattering of neutrons from a radionuclide neutron source. Presented are the methodological analysis of the problem, the results of test measurements, and methodological recommendations for the practical application of the method. Test measurements were conducted on fly ash, limestone and brown coal in amounts of approximately 5 kg for each material sample, using an Am-Be neutron source. The determined sensitivity thresholds corresponded to the carbon concentration of 5 to 10% w.w. (S.P.)

Quantitative detection of microscopic lithium distributions with neutrons

Energy Technology Data Exchange (ETDEWEB)

Neri, Giulia; Gernhaeuser, Roman; Lichtinger, Josef; Winkler, Sonja; Seiler, Dominik; Bendel, Michael [Technische Universitaet Muenchen, Physik-Department (Germany); Kunze-Liebhaeuser, Julia; Brumbarov, Jassen; Portenkirchner, Engelbert [Institut fuer Physikalische Chemie, Leopold-Franzens-Universitaet Innsbruck (Austria); Renno, Axel; Rugel, Georg [Helmholtz Zentrum Dresden Rossendorf, Helmholtz-Institut Freiberg fuer Ressourcentechnologie (Germany)

2016-07-01

The importance of lithium in the modern industrial society is continuously increasing. Spatially resolved detection of tritium particles from {sup 6}Li(n,α){sup 3}H nuclear reactions is used to reconstruct microscopic lithium distributions. Samples are exposed to a flux of cold neutrons. Emitted charged particles are detected with a PSD. Introducing a pinhole aperture between target and detector, the experimental setup works like a ''camera obscura'', allowing to perform spatially resolved measurements. Tritium detection analysis was successfully used to reconstruct the lithium content in self-organized TiO{sub 2-x}-C and Si/TiO{sub 2-x}-C nanotubes electrochemically lithiated, for the first time. Titanium dioxide nanotubes are a candidate for a safe anode material in lithium-ion batteries. Also lithium distributions in geological samples, so called ''pathfinder-minerals'' containing lithium, like lepidolite from a pegmatite, were analyzed. With this development we present a new precision method using nuclear physics for material science.

Method and apparatus for measuring neutron characteristics of material surrounding a borehole

International Nuclear Information System (INIS)

Randall, R.R.

1983-01-01

A method for logging the formations surrounding an earth borehole, comprising: pulsedly irradiating said formations with discrete bursts form a source of high energy neutrons; detecting radiations emanating from said irradiated formations at a detector spaced from said source; measuring said detected radiations during first and second time intervals following a burst from said source; generating time-separated electrical pulses indicative of said detected radiations during a third fixed time duration interval following a subsequent burst from said sources; and controlling automatically the starting time of said third measurement interval in accordance with the said measurement from said first and second time intervals

Study by Monte Carlo methods of an explosives detection system made up with a D-D neutron generator and NaI(Tl) gamma detectors.

Science.gov (United States)

Cevallos Robalino, Lenin E; García Fernández, Gonzalo Felipe; Gallego, Eduardo; Guzmán-García, Karen A; Vega-Carrillo, Hector Rene

2018-02-17

Detection of hidden explosives is of utmost importance for homeland security. Several configurations of an Explosives Detection System (EDS) to intercept hidden threats, made up with a Deuterium-Deuterium (D-D) compact neutron generator and NaI (Tl) scintillation detectors, have been evaluated using MCNP6 code. The system's response to various samples of explosives, such as RDX and Ammonium Nitrate, is analysed. The D-D generator is able to produce fast neutrons with 2.5 MeV energy in a maximum yield of 10 10 n/s. It is surrounded by high-density polyethylene to thermalize the fast neutrons and to optimize interactions with the sample inspected, whose emission of gamma rays gives a characteristic spectrum of the elements that constitute it. This procedure allows to determine its chemical composition and to identify the type of substance. The necessary shielding is evaluated to estimate its thicknesses depending on the admissible dose of operation, using lead and polyethylene. The results show that its functionality is promising in the field of national security for explosives inspection. Copyright © 2018 Elsevier Ltd. All rights reserved.

Neutron recognition in the LAND detector for large neutron multiplicity

Energy Technology Data Exchange (ETDEWEB)

Pawlowski, P., E-mail: piotr.pawlowski@ifj.edu.pl [Institute of Nuclear Physics, PAN, Radzikowskiego 152, 31-342 Krakow (Poland); Brzychczyk, J. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Leifels, Y.; Trautmann, W. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Adrich, P. [National Centre for Nuclear Research, PL-00681 Warsaw (Poland); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Aumann, T. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Bacri, C.O. [Institut de Physique Nucleaire, IN2P3-CNRS et Universite, F-91406 Orsay (France); Barczyk, T. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Bassini, R. [Istituto di Scienze Fisiche, Universita degli Studi and INFN, I-20133 Milano (Italy); Bianchin, S. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Boiano, C. [Istituto di Scienze Fisiche, Universita degli Studi and INFN, I-20133 Milano (Italy); Boretzky, K. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Boudard, A. [IRFU/SPhN, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Chbihi, A. [GANIL, CEA et IN2P3-CNRS, F-14076 Caen (France); Cibor, J.; Czech, B. [Institute of Nuclear Physics, PAN, Radzikowskiego 152, 31-342 Krakow (Poland); De Napoli, M. [Dipartimento di Fisica e Astronomia-Universita and INFN-CT and LNS, I-95123 Catania (Italy); and others

2012-12-01

The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment.

Neutron detection using superheated drops. Progress report, 1 May 1981-15 November 1982

International Nuclear Information System (INIS)

Apfel, R.E.

1981-11-01

The goal of this research has been to determine whether neutron detectors based on superheated drops not only have the characteristics desirable for neutron dosimetry (sensitivity and energy response, etc.) but also have the practical attributes (stability and ease of handling) which warrant later commercial development. Initial experiments with five materials (Freons 12, 114, 142B, and isobutane and cis-2-butene) indicate threshold neutron energies ranging from thermal to 5 MeV depending on the material, and an energy response which follows the general shape of the dose equivalent response of the body as set forth by the Commission on Radiological Protection (ICRP). This indicates that one can choose a drop material to meet a wide variety of objectives

Measurement of two-dimensional thermal neutron flux in a water phantom and evaluation of dose distribution characteristics

International Nuclear Information System (INIS)

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Horiguchi, Yoji

2001-03-01

To evaluate nitrogen dose, boron dose and gamma-ray dose occurred by neutron capture reaction of the hydrogen at the medical irradiation, two-dimensional distribution of the thermal neutron flux is very important because these doses are proportional to the thermal neutron distribution. This report describes the measurement of the two-dimensional thermal neutron distribution in a head water phantom by neutron beams of the JRR-4 and evaluation of the dose distribution characteristic. Thermal neutron flux in the phantom was measured by gold wire placed in the spokewise of every 30 degrees in order to avoid the interaction. Distribution of the thermal neutron flux was also calculated using two-dimensional Lagrange's interpolation program (radius, angle direction) developed this time. As a result of the analysis, it was confirmed to become distorted distribution which has annular peak at outside of the void, though improved dose profile of the deep direction was confirmed in the case which the radiation field in the phantom contains void. (author)

Measuring planetary neutron albedo fluxes by remote gamma-ray sensing

International Nuclear Information System (INIS)

Haines, E.L.; Metzger, A.E.

1984-01-01

A remote-sensing γ-ray spectrometer (GRS) is capable of measuring planetary surface composition through the detection of characteristic gamma rays. In addition, the planetary neutron leakage flux may be detected by means of a thin neutron absorber surrounding the γ-ray detector which converts the neutron flux into a γ-ray flux having a unique energy signature. The γ rays representing the neutron flux are observed against interference consisting of cosmic γ rays, planetary continuum and line emission, and a variety of gamma rays arising from cosmic-ray particle interactions with the γ-ray spectrometer and spacecraft (SC). In this paper the amplitudes of planetary and non-planetary neutron fluxes are assessed and their impact on the sensitivity of measurement is calculated for a lunar orbiter mission and a comet nucleus rendezvous mission. For a 100 h observation period from an altitude of 100 km, a GRS on a lunar orbiter can detect a thermal neutron albedo flux as low as 0.002 cm -2 s -1 and measure the expected flux of approx.=0.6 cm -2 s -1 with an uncertainty of 0.001 cm -2 s -1 . A GRS rendezvousing with a comet at a distance equal to the radius of the comet's nucleus, again for a 100 h observation time, should detect a thermal neutron albedo flux at a level of 0.006 cm -2 s -1 and measure the expected flux of approx.=0.4 cm -2 s -1 with an uncertainty of 0.004 cm -2 s -1 . Mapping the planetary neutron flux jointly with the direct detection of H will not only provide a more accurate model for translating observed γ-ray fluxes into concentrations but will also extend the effective sampling depth and should provide a capability for simple stratigraphic modeling of hydrogen. (orig.)

Calculations of accelerator-based neutron sources characteristics

International Nuclear Information System (INIS)

Tertytchnyi, R.G.; Shorin, V.S.

2000-01-01

Accelerator-based quasi-monoenergetic neutron sources (T(p,n), D(d;n), T(d;n) and Li (p,n)-reactions) are widely used in experiments on measuring the interaction cross-sections of fast neutrons with nuclei. The present work represents the code for calculation of the yields and spectra of neutrons generated in (p, n)- and ( d; n)-reactions on some targets of light nuclei (D, T; 7 Li). The peculiarities of the stopping processes of charged particles (with incident energy up to 15 MeV) in multilayer and multicomponent targets are taken into account. The code version is made in terms of the 'SOURCE,' a subroutine for the well-known MCNP code. Some calculation results for the most popular accelerator- based neutron sources are given. (authors)

Parameters affecting temporal resolution of Time Resolved Integrative Optical Neutron Detector (TRION)

International Nuclear Information System (INIS)

Mor, I; Vartsky, D; Bar, D; Feldman, G; Goldberg, M B; Brandis, M; Dangendorf, V; Tittelmeier, K; Bromberger, B; Weierganz, M

2013-01-01

The Time-Resolved Integrative Optical Neutron (TRION) detector was developed for Fast Neutron Resonance Radiography (FNRR), a fast-neutron transmission imaging method that exploits characteristic energy-variations of the total scattering cross-section in the E n = 1–10 MeV range to detect specific elements within a radiographed object. As opposed to classical event-counting time of flight (ECTOF), it integrates the detector signal during a well-defined neutron Time of Flight window corresponding to a pre-selected energy bin, e.g., the energy-interval spanning a cross-section resonance of an element such as C, O and N. The integrative characteristic of the detector permits loss-free operation at very intense, pulsed neutron fluxes, at a cost however, of recorded temporal resolution degradation This work presents a theoretical and experimental evaluation of detector related parameters which affect temporal resolution of the TRION system

Detection of 10B distributions in histological samples by NCAR using thermal and cold neutrons and photoluminiscent imaging plates. New results

International Nuclear Information System (INIS)

Rant, J.; Skvarc, J.; Ilic, R.; Gabel, D.; Bayon, G.; Yanagie, H.; Kobayashi, H.; Lehmann, E.; Kuehne, G.

1999-01-01

The Neutron Capture Autoradiography (NCAR) using various Solid State Nuclear Track Detectors (SSNTDs) is a well established and accurate method to detect and measure the distributions of 10 B in the ppm range on macroscopic and microscopic level in biological samples, such as histological sections of tumours loaded with 10 B compounds used for BNCT (e.g. 1,2). recently a new technique of NCAR using sensitive photoluminescent Imaging Plates (IP) has been proposed to detect 10 B distributions in histological sections (3), exploiting excellent detection properties of IP systems such as very high detection sensitivity and quantum detection efficiency, broad linear response and dynamic range, very small image distortion, reusability of IP and possibilities of digital autoradiography. The advantage of IP-NCAR vs. NCAR with SSNTDs should be the much lower neutron fluence (10 7 10 9 vs. 10 10 10 13 n/cm 2 with SSNTDs), no intermediate chemical treatment (track etching) and direct and fast compuitational handling and evaluation of the digitized autoradiographic image. However, the spatial resolution of the present available IP detection systems is somewhat lower (∼ 0,04 mm) than with SSNTDs (∼ 0,01 mm). Another problem with IP NCAR is rather high sensitivity of IP to all types of ionizing radiations. Therefore the background of direct and induced gamma-rays as well as of epithermal and fast neutrons has to be filtered out of thermal neutron beam to be used for IP-NCAR. To improve the signal/background ratio and to increase the detectibility of 10 B we propose to use clean cold neutron beams for the IP-NCAR of 10 B distributions in histological samples in BNCT experiments (4,5). In the present work the recent results of experiments in IP-NCAR with cold neutrons from the neutron radiographic channel of the ORPHEE reactor in Saclay and with the rather clean thermal neutron beam of the NEUTRA neutron radiography facility of the PSI (Villingen) will be presented. For the

A Monte Carlo Model for Neutron Coincidence Counting with Fast Organic Liquid Scintillation Detectors

International Nuclear Information System (INIS)

Gamage, Kelum A.A.; Joyce, Malcolm J.; Cave, Frank D.

2013-06-01

Neutron coincidence counting is an established, nondestructive method for the qualitative and quantitative analysis of nuclear materials. Several even-numbered nuclei of the actinide isotopes, and especially even-numbered plutonium isotopes, undergo spontaneous fission, resulting in the emission of neutrons which are correlated in time. The characteristics of this i.e. the multiplicity can be used to identify each isotope in question. Similarly, the corresponding characteristics of isotopes that are susceptible to stimulated fission are somewhat isotope-related, and also dependent on the energy of the incident neutron that stimulates the fission event, and this can hence be used to identify and quantify isotopes also. Most of the neutron coincidence counters currently used are based on 3 He gas tubes. In the 3 He-filled gas proportional-counter, the (n, p) reaction is largely responsible for the detection of slow neutrons and hence neutrons have to be slowed down to thermal energies. As a result, moderator and shielding materials are essential components of many systems designed to assess quantities of fissile materials. The use of a moderator, however, extends the die-away time of the detector necessitating a larger coincidence window and, further, 3 He is now in short supply and expensive. In this paper, a simulation based on the Monte Carlo method is described which has been performed using MCNPX 2.6.0, to model the geometry of a sector-shaped liquid scintillation detector in response to coincident neutron events. The detection of neutrons from a mixed-oxide (MOX) fuel pellet using an organic liquid scintillator has been simulated for different thicknesses of scintillators. In this new neutron detector, a layer of lead has been used to reduce the gamma-ray fluence reaching the scintillator. The effect of lead for neutron detection has also been estimated by considering different thicknesses of lead layers. (authors)

Neutron radiographic characteristics of MA-ND type (allyl-diglycol-carbonate) nuclear track detectors

Energy Technology Data Exchange (ETDEWEB)

Ilic, R.; Rant, J.; Humar, M.; Somogyi, G.; Hunyadi, I.

1986-01-01

Neutron radiographic properties of recently developed new nuclear track detectors (MA-ND/..cap alpha.., MA-ND/p and MA-ND/p1), manufactured from allyl diglycol carbonate, were studied. It was found that the quality of radiographic image has an optimum at a removed layer thickness of about 0.8 ..mu..m. The image obtained under this condition is characterized by high detection sensitivity to neutrons (approx. 8.10/sup -3/ tracks/nsub(th) when using B converter) and by excellent inherent unsharpness (approx. 5 ..mu..m) as well as high image contrast (maximum value of net optical density is approx. 1.4).

Experiment of Neutron Generation by Using Prototype D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In Jung; Kim, Suk Kwon; Park, Chang Su; Jung, Nam Suk; Jung, Hwa Dong; Park, Ji Young; Hwang, Yong Seok; Choi, H.D.

2005-01-01

Experiment of neutron generation was performed by using a prototype D-D neutron generator. The characteristics of D-D neutron generation in drive-in target was studied. The increment of neutron yield by increasing ion beam energy was investigated, too

Neutron Dosimetry

International Nuclear Information System (INIS)

Vanhavere, F.

2001-01-01

The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding

An investigation of the neutron die-away time in passive neutron waste assay systems

International Nuclear Information System (INIS)

Baeten, P.; Bruggeman, M.; Carchon, R.

1997-02-01

Neutron coincidence counting applied to the assay of Pu-bearing waste is commonly based on the assumption that the time intervals between detected fission neutrons are distributed according to a mono-exponential function, often called Rossi-alpha distribution. The time constant of this characteristic exponential function is generally referred to as the die-away time of the detector assembly. In fact, the distribution of time intervals is derived from the more fundamental arrival time distribution, which is also assumed to obey a mono-exponential law. In view of the design studies for a neutron counter, the validity of this basic assumption was investigated. Different parameters such as neutron moderation and absorption in the sample and the presence of cadmium-lining were investigated by means of Monte Carlo simulations using the NCNP-code. The simulation results lead to the conclusion that the description of the arrival time function with a mono-exponential function with a sample-independent die-away time is only a first approximations. The mono-exponential decay is perturbed by a second time component related to the detection of neutrons already thermalized in the sample. This thermal component cannot be described by a mono-exponential function, but has a characteristic shape with a fast build-up reaching a maximum followed by a slow decay as a function of the arrival time. The relative contribution of this component strongly depends on the absorption and moderation of the sample matrix. This component cannot be described by a simple analytical expression involving sample related parameters. Hence, no direct useful information can be withdrawn from the arrival time probability function to characterize the waste matrix. The thermal component can be strongly suppressed by the use of cadmium-lining in front of the detector blocks simplifying the mathematical description of the arrival time probability function. Indications of the bias introduced by an inaccurate

Transmission and signal loss in mask designs for a dual neutron and gamma imager applied to mobile standoff detection

International Nuclear Information System (INIS)

Ayaz-Maierhafer, Birsen; Hayward, Jason P.; Ziock, Klaus P.; Blackston, Matthew A.; Fabris, Lorenzo

2013-01-01

In order to design a next-generation, dual neutron and gamma imager for mobile standoff detection which uses coded aperture imaging as its primary detection modality, the following design parameters have been investigated for gamma and neutron radiation incident upon a hybrid, coded mask: (1) transmission through mask elements for various mask materials and thicknesses; and (2) signal attenuation in the mask versus angle of incidence. Each of these parameters directly affects detection significance, as quantified by the signal-to-noise ratio. The hybrid mask consists of two or three layers: organic material for fast neutron attenuation and scattering, Cd for slow neutron absorption (if applied), and one of three of the following photon or photon and slow neutron attenuating materials—Linotype alloy, CLYC, or CZT. In the MCNP model, a line source of gamma rays (100–2500 keV), fast neutrons (1000–10,000 keV) or thermal neutrons was positioned above the hybrid mask. The radiation penetrating the mask was simply tallied at the surface of an ideal detector, which was located below the surface of the last mask layer. The transmission was calculated as the ratio of the particles transmitted through the fixed aperture to the particles passing through the closed mask. In order to determine the performance of the mask considering relative motion between the source and detector, simulations were used to calculate the signal attenuation for incident radiation angles of 0–50°. The results showed that a hybrid mask can be designed to sufficiently reduce both transmission through the mask and signal loss at large angles of incidence, considering both gamma ray and fast neutron radiations. With properly selected material thicknesses, the signal loss of a hybrid mask, which is necessarily thicker than the mask required for either single mode imaging, is not a setback to the system's detection significance

Characteristics of Pyrolytic Graphite as a Neutron Monochromator

International Nuclear Information System (INIS)

Adib, M.; Habib, N.; El-Mesiry, M.S.; Fathallah, M.

2011-01-01

Pyrolytic graphite (PG) has become nearly indispensable in neutron spectroscopy. Since the integrated reflectivity of the monochromatic neutrons from PG crystals cut along its c-axis is high within a wavelength band from 0.1 nm up to .65 nm. The monochromatic features of PG crystal is detailed in terms of the optimum mosaic spread, crystal thickness and reactor moderating temperature for efficient integrated neutron reflectivity within the wavelength band. A computer code Mono-PG has been developed to carry out the required calculations for the PG hexagonal close-packed structure. Calculation shows that, 2 mm thick of PG crystal having 0.30 FWHM on mosaic spread are the optimum parameters of PG crystal as a monochromator at selected neutron wavelength shorter than 2 nm. However, the integrated neutron intensity of 2nd and 3rd orders from thermal reactor flux is even higher than that of the 1st order one at neutron wavelengths longer than 2 nm. While, from cold reactor flux, integrated neutron intensity of the 1st order within the wavelength band from 0.25 up to 0.5 nm is higher than the 2nd and 3rd ones

Nitrogen Detection in Bulk Samples Using a D-D Reaction-Based Portable Neutron Generator

Directory of Open Access Journals (Sweden)

A. A. Naqvi

2013-01-01

Full Text Available Nitrogen concentration was measured via 2.52 MeV nitrogen gamma ray from melamine, caffeine, urea, and disperse orange bulk samples using a newly designed D-D portable neutron generator-based prompt gamma ray setup. Inspite of low flux of thermal neutrons produced by D-D reaction-based portable neutron generator and interference of 2.52 MeV gamma rays from nitrogen in bulk samples with 2.50 MeV gamma ray from bismuth in BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays indicates satisfactory performance of the setup for detection of nitrogen in bulk samples.

A new method for the measurement of the polarization characteristics of ferromagnetic films on ultracold neutrons

International Nuclear Information System (INIS)

Taran, Yu.V.

1985-01-01

A new method has been developed for measuring the polarization characteristics of ferromagnetic films on ultracold neutrons (UCN) by single-, double- and triple-transmission of UCN beam through one and the same film. To realize the method an installation has been proposed consisting of the two UCN storage traps connected with a mirror neutron guide. An investigated film is placed in the slit in the middle of the neutron guide. On both sides of the film a spin-flipper is installed bottle is equiped with three neutron values which permit filling in the bottle with UCN and allow oneto let UCN out to the neutron guide or detector. The neutrons once let out from one bottle into the neutron guide are caught by the other. The film can be moved out of the neutron guide or rotated. By manipulating with spin-flippers and the film one may take the integral polarization parameters of the film: transmission, polarizing and analysing efficiencies, so-called S-factor, which is the fourth independent linear combination of the elements of the square 2x2 transmission matrix of the film. The measurement parameters help to restore the film transmission matrix. Then a comparison is drawn with the theoretical models of UCN depolarization on transmission through a ferromagnetic film

Neutron Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Vanhavere, F

2001-04-01

The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding.

Detection of drugs and explosives using neutron computerized tomography and artificial intelligence techniques

Energy Technology Data Exchange (ETDEWEB)

Ferreira, F.J.O. [Instituto de Engenharia Nuclear, Cidade Universitaria, Rio de Janeiro, CEP 21945-970, Caixa Postal 68550 (Brazil)], E-mail: fferreira@ien.gov.br; Crispim, V.R.; Silva, A.X. [DNC/Poli, PEN COPPE CT, UFRJ Universidade Federal do Rio de Janeiro, CEP 21941-972, Caixa Postal 68509, Rio de Janeiro (Brazil)

2010-06-15

In this study the development of a methodology to detect illicit drugs and plastic explosives is described with the objective of being applied in the realm of public security. For this end, non-destructive assay with neutrons was used and the technique applied was the real time neutron radiography together with computerized tomography. The system is endowed with automatic responses based upon the application of an artificial intelligence technique. In previous tests using real samples, the system proved capable of identifying 97% of the inspected materials.

Detection of drugs and explosives using neutron computerized tomography and artificial intelligence techniques

International Nuclear Information System (INIS)

Ferreira, F.J.O.; Crispim, V.R.; Silva, A.X.

2010-01-01

In this study the development of a methodology to detect illicit drugs and plastic explosives is described with the objective of being applied in the realm of public security. For this end, non-destructive assay with neutrons was used and the technique applied was the real time neutron radiography together with computerized tomography. The system is endowed with automatic responses based upon the application of an artificial intelligence technique. In previous tests using real samples, the system proved capable of identifying 97% of the inspected materials.

Observation of Neutron Skyshine from an Accelerator Based Neutron Source

Energy Technology Data Exchange (ETDEWEB)

Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

2011-12-13

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

Recovery characteristics of neutron-irradiated V-Ti alloys

International Nuclear Information System (INIS)

Leguey, T.; Pareja, R.

2000-01-01

The recovery characteristics of neutron-irradiated pure V and V-Ti alloys with 1.0 and 4.5 at.% Ti have been investigated by positron annihilation spectroscopy. Microvoid formation during irradiation at 320 K is produced in pure V and V-1Ti but not in V-4.5Ti. The results are consistent with a model of swelling inhibition induced by vacancy trapping by solute Ti during irradiation. The temperature dependencies of the parameter S in the range 8-300 K indicate a large dislocation bias for vacancies and solute Ti. This dislocation bias prevents the microvoid nucleation in V-4.5Ti, and the microvoid growth in V-1Ti, when vacancies become mobile during post-irradiation annealing treatments. A characteristic increase of the positron lifetime is found during recovery induced by isochronal annealing. It is attributed to a vacancy accumulation into the lattice of Ti oxides precipitated during cooling down, or at their matrix/precipitate interfaces. These precipitates could be produced by the decomposition of metastable phases of Ti oxides formed during post-irradiation annealing above 1000 K

Phonon characteristics of high Tc superconductors from neutron Doppler broadening measurements

International Nuclear Information System (INIS)

Trela, W.J.; Kwei, G.H.; Lynn, J.E.; Meggers, K.

1994-01-01

Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La 2-x Ba x CuO 4 . Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra

Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

Energy Technology Data Exchange (ETDEWEB)

Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)

1994-12-01

Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

Training courses on the use of neutron detection systems carried out on the ISIS research reactor

International Nuclear Information System (INIS)

Lescop, Bernard; Foulon, Francois

2013-06-01

Training courses on the use of the neutron detection systems for the control of the nuclear reactors are carried out by the National Institute for Nuclear Science using the ISIS research reactor. The study and the comprehension of the operation of these systems are facilitated by the use a research reactor in order to observe the electronic signals in real conditions. Thus, ISIS reactor offers a wide range of neutron fluxes and the level of power can be easily set to any value from zero to nominal power (700 kW). Different kinds of detectors (counters, ionization chambers), which operate in the different modes of detection (pulse, current and Campbelling) can be placed in the periphery of the core for the courses. The electronic signal can be analyzed at each step of the detection process. One goal of the courses is to understand the role of each component of the detection system: detector, cable and each electronic module. A comparison with the nuclear instrumentation used by the instrumentation and control of ISIS reactor is also made. This comparison is very useful to understand the role of the neutron instrumentation in terms of safety, availability, reliability and maintainability. (authors)

Studies on the characteristics of nuclear track spark counting for neutron monitoring

International Nuclear Information System (INIS)

Kawai, H.; Koga, T.; Morishima, H.; Niwa, T.; Nishiwaki, Y.

1979-01-01

The fission-track counting method using polycarbonate foil is known to be very effective for neutron monitoring. The detection system consists of a track detector foil placed in contact with a thin layer of fissile material. When the unit is irradiated with neutrons, fission fragments from the fissile material produce tracks in the foil. The foil is then etched chemically to enlarge the tracks to etch-pits, which are counted by an automatic spark counting method suggested by Cross and Tommasino. Spark counting characteristics of the above system using polycarbonate detector foils of different thicknesses and aluminized polyester sheets having different thicknesses of the aluminium which serves as an electrode, and etch-pit sizes in relation to spark counting have been studied. The results obtained are summarized as follows: 1. A growth in etch-pit sizes was observed for etching times of 10 to 50 minutes with Makrofol KG (10 μm thick) and Panlite foils (18 μm thick). As the etching time increased, the number of etch-pits which appeared as round pits increased and the number which appeared rod-like decreased; 2. Round etch-pits seemed to be easily spark-punched; 3. Major and minor diameters of etch-pits produced by fission fragments from the uranium fissile target were larger than those from the thorium target; 4. As the thickness of the Makrofol KG foil increased, the minor diameters of the etch-pits appeared to become smaller and major diameters larger; 5. The foils that appeared to be best suited for routine use were 10 μm thick Makrofol KG or 6 μm thick Lumirror foils. (author)

Portable Neutron Generator with 9-Section Silicon $\\alpha $-Detector

CERN Document Server

Bystritsky, V M; Kadyshevskij, V G; Khasaev, T O; Kobzev, A P; Presnyakov, Yu K; Rogov,Yu N; Ryzhkov, V I; Sapozhnikov, M G; Sissakian, A N; Slepnev, V M; Zamyatin, N I

2006-01-01

The characteristics of the portable neutron generator with a built-in $\\alpha $-detector are presented. Based on the "tagged" neutron method (TNM) the generator ~is being used for identification of ~the hidden chemical compounds. One of the special features of such generators compared to generators traditionally used and produced in industry is that the generator is a source of monoenergetic "tagged" 14.1 MeV neutrons produced in the binary nuclear reaction $d+t \\to \\alpha $ (3.5 MeV) $+n$ (14.1~MeV). Unambiguous information about the time and direction of the neutron emitted from the target can be obtained by recording an $\\alpha $ particle by the multi-pixel $\\alpha $-detector placed inside the neutron tube. The study of the "tagged" neutron method (TNM) shows that the use of the ($\\alpha $--$\\gamma $) coincidence reduces the gamma background induced by scattered neutrons by a factor of more than 200, which allows the detection and identification of small quantities of explosives, drugs, and toxic agents. T...

Note: Coincidence measurements of 3He and neutrons from a compact D-D neutron generator

Science.gov (United States)

Ji, Q.; Lin, C.-J.; Tindall, C.; Garcia-Sciveres, M.; Schenkel, T.; Ludewigt, B. A.

2017-05-01

Tagging of neutrons (2.45 MeV) with their associated 3He particles from deuterium-deuterium (D-D) fusion reactions has been demonstrated in a compact neutron generator setup enabled by a high brightness, microwave-driven ion source with a high fraction of deuterons. Energy spectra with well separated peaks of the D-D fusion reaction products, 3He, tritons, and protons, were measured with a silicon PIN diode. The neutrons were detected using a liquid scintillator detector with pulse shape discrimination. By correlating the 3He detection events with the neutron detection in time, we demonstrated the tagging of emitted neutrons with 3He particles detected with a Si PIN diode detector mounted inside the neutron generator vacuum vessel.