Intermediate energy neutron fast chopper associated to the pile EL3; Spectrometre mecanique rapide pour neutrons intermediaires associe a la pile EL3

Energy Technology Data Exchange (ETDEWEB)

Julien, J; Netter, F; Martin, R; Rouge, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Arditti, R; Chaffiotte, P [S.E.M. Hispano-Suisa (France)

1958-07-01

The apparatus is a fast chopper placed on a beam issued from the tank of the pile EL3. It is composed of a steel rotor with a rigid vertical axis and eight pairs of slits in the maximum cross-section plane (diameter 48 cm). The originality of the apparatus consists mainly in the driving system by oil turbine, whiclows a more reliable and versatile operation. The spectrometer is running regularly at 15000 r.p.m. In the conditions, the slits (precision of cutting: {+-} 5 microns) release neutron beams with time half-width equal to 1/4 micro-second. Therefore, with a 20 meter flight-path, the resolution power of the fast chopper is about 10 milli-microsecond/metre. All the safety devices are provided to ensure a steady running, without permanent control. The speed of rotation is stabilized to better than {+-} 1/1000 in all the rate range between 6 000 and 15 500 r.p.m. A lead device for moving in and out the sample allows to work with radioactive samples. The apparatus is connected to a hundred 1/4 microsecond channel time-of-flight selector. A thousand channel selector with magnetic memory (Argonne type) will be ready in a few months. (author)Fren. [French] L'appareil est un spectrometre mecanique rapide dispose sur un des faisceaux sortant de la cuve de la pile EL3. Il comprend un rotor d'acier a axe vertical rigide avec huit paires de fentes disposees dans le plan de section maximum (diametre 40 cm). L'originalite de l'appareil tient surtout dans le systeme d'entrainement par turbine a huile, qui assure une grande securite et une grande souplesse de fonctionnement. Le spectrometre tourne a 15000 tours/mn de fa n reguliere. Dans ces conditions, les fentes (executees a {+-} 5 microns pres liberent des faisceaux de neutrons avec une largeur a mi-hauteur en temps de 1/4 de microseconde. Avec une base de parcours de 20 m, le pouvoir de resolution du spectrometre mecanique est donc voisin de 10 millimicroseconde/metre. Tous les dispositifs de securite sont prevus pour

Comparison of accelerator mass spectrometric measurement with liquid scintillation counting measurement for the determination of 14C in environmental samples

International Nuclear Information System (INIS)

Yasuike, Kaeko; Yamada, Yoshimune; Amano, Hikaru

2010-01-01

The concentrations of organically-bound 14 C in tree-ring cellulose of a Japanese Black Pine grown in Shika-machi (37.0 deg. N, 136.8 deg. E) and those of a Japanese Cedar grown in Kanazawa (36.5 deg. N, 136.7 deg. E), Japan, were analyzed for the ring-years from 1989 to 1998 by the accelerator mass spectrometric measurement. The results were compared with those of the same samples analyzed by the liquid scintillation counting measurement to determine the reliability of liquid scintillation counting measurement. An important result of this study is that the sensitivity and reproducibility of accelerator mass spectrometric measurement was almost equal to that of liquid scintillation counting measurement.

Measurement of activation cross sections for quasi-monoenergetic neutron induced reactions of {sup 89}Y

Energy Technology Data Exchange (ETDEWEB)

Zaman, Muhammad; Kim, Guinyun; Kim, Kwangsoo; Nadeem, Muhammad [Kyungpook National University, Department of Physics and Center for High Energy Physics, Daegu (Korea, Republic of); Naik, Haladhara [Kyungpook National University, Department of Physics and Center for High Energy Physics, Daegu (Korea, Republic of); Bhabha Atomic Research Centre, Radiochemistry Division, Mumbai (India); Lee, Manwoo [Dongnam Inst. of Radiological and Medical Sciences, Research Center, Busan (Korea, Republic of)

2017-09-15

The neutron induced cross sections of the {sup 89}Y(n, 2n){sup 88}Y, {sup 89}Y(n, 3n){sup 87}Y and {sup 89}Y(n, 4n){sup 86}Y reactions were measured in the neutron energy range of 15.2 to 37.2 MeV by using an activation and off-line γ-ray spectrometric technique. The quasi-monoenergetic neutrons used for the above reactions are based on a {sup 9}Be(p, n) reaction. Simulations of the neutron spectra from the Be target were done using the MCNPX 2.6.0 program. Theoretical calculations were performed for the {sup 89}Y(n, 2n){sup 88}Y, {sup 89}Y(n, 3n){sup 87}Y and {sup 89}Y(n, 4n){sup 86}Y reaction cross sections using nuclear model code Talys 1.8. The measured and calculated cross sections were compared with the literature data given in EXFOR and the TENDL-2015 data libraries. The present data of the {sup 89}Y(n, xn) reaction were also compared with the similar data of the {sup 89}Y(γ, xn) reaction to examine the effect of the entrance channel parameters as well as the role of projectiles and ejectiles. (orig.)

A measuring generator for testing spectrometric channels

International Nuclear Information System (INIS)

Dinh Sy Hien; Kalinkin, A.I.

1984-01-01

A measuring generator for testing and tuning an amplitude spectrometric channel is described. The device consists of a pseudo random pulse generator, constructed on shifters, a sawtooth wave generator and a shaper of stable amplitude pulses with exponential decay times. The device is made as CAMAC unit width modules and has the following specifications: average pulse repetition rate of pseudo random pulses is 3.1; 25; 50; 100; 200 kHz; peak amplitude of 2 Hz pulse repetition of saw tooth pulses is 6 V; peak amplitude of exponential shape pulses is 5 V. The block-diagram and basic circuits of the device are given

Radioisotopic neutron transmission spectrometry: Quantitative analysis by using partial least-squares method

International Nuclear Information System (INIS)

Kim, Jong-Yun; Choi, Yong Suk; Park, Yong Joon; Jung, Sung-Hee

2009-01-01

Neutron spectrometry, based on the scattering of high energy fast neutrons from a radioisotope and slowing-down by the light hydrogen atoms, is a useful technique for non-destructive, quantitative measurement of hydrogen content because it has a large measuring volume, and is not affected by temperature, pressure, pH value and color. The most common choice for radioisotope neutron source is 252 Cf or 241 Am-Be. In this study, 252 Cf with a neutron flux of 6.3x10 6 n/s has been used as an attractive neutron source because of its high flux neutron and weak radioactivity. Pulse-height neutron spectra have been obtained by using in-house built radioisotopic neutron spectrometric system equipped with 3 He detector and multi-channel analyzer, including a neutron shield. As a preliminary study, polyethylene block (density of ∼0.947 g/cc and area of 40 cmx25 cm) was used for the determination of hydrogen content by using multivariate calibration models, depending on the thickness of the block. Compared with the results obtained from a simple linear calibration model, partial least-squares regression (PLSR) method offered a better performance in a quantitative data analysis. It also revealed that the PLSR method in a neutron spectrometric system can be promising in the real-time, online monitoring of the powder process to determine the content of any type of molecules containing hydrogen nuclei.

Validation of MCNP NPP Activation Simulations for Decommissioning Studies by Analysis of NPP Neutron Activation Foil Measurement Campaigns

Directory of Open Access Journals (Sweden)

Volmert Ben

2016-01-01

Full Text Available In this paper, an overview of the Swiss Nuclear Power Plant (NPP activation methodology is presented and the work towards its validation by in-situ NPP foil irradiation campaigns is outlined. Nuclear Research and consultancy Group (NRG in The Netherlands has been given the task of performing the corresponding neutron metrology. For this purpose, small Aluminium boxes containing a set of circular-shaped neutron activation foils have been prepared. After being irradiated for one complete reactor cycle, the sets have been successfully retrieved, followed by gamma-spectrometric measurements of the individual foils at NRG. Along with the individual activities of the foils, the reaction rates and thermal, intermediate and fast neutron fluence rates at the foil locations have been determined. These determinations include appropriate corrections for gamma self-absorption and neutron self-shielding as well as corresponding measurement uncertainties. The comparison of the NPP Monte Carlo calculations with the results of the foil measurements is done by using an individual generic MCNP model functioning as an interface and allowing the simulation of individual foil activation by predetermined neutron spectra. To summarize, the comparison between calculation and measurement serve as a sound validation of the Swiss NPP activation methodology by demonstrating a satisfying agreement between measurement and calculation. Finally, the validation offers a chance for further improvements of the existing NPP models by ensuing calibration and/or modelling optimizations for key components and structures.

Thermal neutron detectors based on complex oxide crystals

CERN Document Server

Ryzhikov, V; Volkov, V; Chernikov, V; Zelenskaya, O

2002-01-01

The ways of improvement of spectrometric quality of CWO and GSO crystals have been investigated with the aim of their application in thermal neutron detectors based on radiation capture reactions. The efficiency of the neutron detection by these crystals was measured, and the obtained data were compared with the results for sup 6 LiI(Tl) crystals. It is shown that the use of complex oxide crystals and neutron-absorption filters for spectrometry of thermal and resonance neutrons could be a promising method in combination with computer data processing. Numerical calculations are reported for spectra of gamma-quanta due to radiation capture of the neutrons. To compensate for the gamma-background lines, we used a crystal pair of heavy complex oxides with different sensitivity to neutrons.

Measurement of fission cross-section for the {sup 232}Th(n,f){sup 141}Ba reaction induced by neutrons around 14 MeV

Energy Technology Data Exchange (ETDEWEB)

Lan, Chang-Lin; Fang, Kai-Hong [Lanzhou University, School of Nuclear Science and Technology, Lanzhou, Gansu Province (China); Lanzhou University, Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou, Gansu Province (China); Liu, Shuang-Tong; Lv, Tao; Wang, Qiang; Zhang, Zheng-Wei [Lanzhou University, School of Nuclear Science and Technology, Lanzhou, Gansu Province (China); Lai, Cai-Feng [Chinese Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang, Sichuan Province (China)

2016-11-15

The fission cross-section of the {sup 232}Th(n,f){sup 141}Ba reaction induced by neutrons around 14 MeV was measured precisely with the neutron activation and off-line gamma-ray spectrometric technique. Neutron fluence was monitored on-line using the accompanying α-particles from the {sup 3}H({sup 2}H,n){sup 4}He reaction, whereas the neutron energies were measured by the method of cross-section ratios of {sup 90}Zr(n,2n){sup 89}Zr to {sup 93}Nb(n,2n){sup 92m}Nb reactions. The experimentally determined {sup 232}Th(n,f){sup 141}Ba reaction cross-sections were 12.2 ± 0.4 mb at E{sub n} = 14.1 ± 0.3 MeV, 13.0 ± 0.5 mb at E{sub n} = 14.5 ± 0.3 MeV and 13.3 ± 0.5 mb at E{sub n} = 14.7 ± 0.3 MeV, respectively. (orig.)

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

Determination of plutonium-241 half-life by mass spectrometric measurement

International Nuclear Information System (INIS)

Hiyama, Takashi; Wada, Yukio; Onishi, Koichi

1982-01-01

Much data for Pu-241 half-life have been reported, but these values range from 13.8 years to 15.1 years depending on investigators. In order to define the half-life of Pu-241, the half-life was calculated by analyzing the mass spectrometry data obtained in the author's laboratory over the past six years on Plutonium Isotopic Standard Reference Materials prepared at the National Bureau of Standards (NBS). The sample used for this work consisted of SRM-947 and SRM-948 prepared at NBS. Before mass spectrometric analysis, the plutonium aliquot was separated from its Am-241 daughter by anion exchange chromatography, since Am-241 is not distinguished from Pu-241 in the mass spectrometer. 241 Pu/ 239 Pu and 241 Pu/ 240 Pu ratios were calculated from the values of mass spectrometric measurement. From the relation of log N to time, the half-life of Pu-241 was determined, based on the slope using a least squares fit. The half-life of Pu-241 was estimated to be 14.29+-0.15 years. (Yoshitake, I.)

Neutron measuring device

International Nuclear Information System (INIS)

Hatayama, Akiyoshi; Seki, Eiji; Kita, Yoshio; Nishitani, Takeo.

1993-01-01

The device of the present invention concerns measurement for neutrons in a tokamak type thermonuclear device and it can measure total amount of generated neutrons accurately throughout the operation period even if an error is caused in counted values by plasma disruption. That is, the device comprises (1) a means for detecting presence or absence of occurrence of plasma disruption and the time for the initiation of the occurrence, (2) a first data processing means for processing detection signals, (3) a means for detecting neutrons generated in plasmas and (4) a second data processing means for calculating integrated values for the number of neutrons generated from the start to the completion of electric discharge when no disruption occurs and calculating integrated values for the number of generated neutrons from the start of electric discharge to the time at the initiation of occurrence of the disruption when disruption is present. In the thus constituted device, even if an error is caused by frequent occurrence of plasma disruption, total time integrated amount of neutrons generated in the plasmas can be measured accurately. (I.S.)

High-efficient method for spectrometric data real time processing with increased resolution of a measuring channel

International Nuclear Information System (INIS)

Ashkinaze, S.I.; Voronov, V.A.; Nechaev, Yu.I.

1988-01-01

Solution of reduction problem as a mean to increase spectrometric tract resolution when it is realized using the digit-by-digit modified method and special strategy, significantly reducing the time of processing, is considered. The results presented confirm that the complex measurement tract plus microcomputer is equivalent to the use of the tract with a higher resolution, and the use of the digit-by-digit modified method permits to process spectrometric information in real time scale

The measurement of mass spectrometric peak height ratio of helium isotope in trace samples

International Nuclear Information System (INIS)

Sun Mingliang

1989-01-01

An experiment study on the measurement of mass spectrometric peak height ratio of helium isotope in the trace gaseous sample is discussed by using the gas purification line designed by the authors and model VG-5400 static-vacuum noble gas mass spectrometer imported and air helium as a standard. The results show that the amount of He and Ne in natural gas sample is 99% after purification. When the amount of He in Mass Spectrometer is more than 4 x 10 -7 cm 3 STP, it's sensitivity remains stable, about 10 -4 A/cm 3 STP He and the precision of 3 He/ 4 He ratio within the following 17 days is 1.32%. The 'ABA' pattern and experiment condition in the measurement of mass spectrometric peak height ratio of He isotope are presented

Dosimetry Characterization of the Neutron Fields of the Intermediate Temporary Storage of the Trillo Nuclear Power Plant

International Nuclear Information System (INIS)

Campo Blanco, X.

2015-01-01

The Neutron Standards Laboratory of CIEMAT, in collaboration with the Trillo Nuclear Power Plant, has conducted a detailed dosimetric and spectrometric characterization of the neutron fields at the Intermediate Temporary Storage of the Trillo Nuclear Power Plant, as well as the neutron fields of ENSA-DPT spent fuel casks. For neutron measurements, neutron monitors and a Bonner spheres spectrometry system have been used. In addition, a Monte Carlo model of the installation and the cask has been developed and validated.

Measurement of the neutron capture cross-section of 232Th using the neutron activation technique

International Nuclear Information System (INIS)

Naik, H.; Singh, Sarbjit; Goswami, A.; Manchanda, V.K.; Prajapati, P.M.; Surayanarayana, S.V.; Nayak, B.K.; Sharma, S.C.; Jagadeesan, K.C.; Thakare, S.V.; Raj, D.; Ganesan, S.; Mulik, V.K.; Sivashankar, B.S.; Mukherjee, S.

2011-01-01

The 232 Th(n, γ) reaction cross-section at average neutron energies of 3.7±0.3 MeV and 9.85±0.38 MeV from the 7 Li(p, n) reaction has been determined for the first time using activation and off-line γ -ray spectrometric technique. The 232 Th(n, 2n) reaction cross-section at the average neutron energy of 9.85±0.38 MeV has been also determined using the same technique. The experimentally determined 232 Th(n, γ) and 232 Th(n, 2n) reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0 and JEFF-3.1 and were found to be in good agreement. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 232 Th(n, γ) and 232 Th(n, 2n) reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were found to be slightly higher than the experimental data. (orig.)

Determination of the neutron mass; Determinacion de la masa del neutron

Energy Technology Data Exchange (ETDEWEB)

Amador V, P.; Chacon R, A.; Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Vega C, H.R. [Unidad Academica de Estudios Nucleares, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)]. e-mail: paus2281@yahoo.com.mx

2005-07-01

The binding energy of the deuteron was measured and it was determined the neutron mass starting from the nuclear reaction, {sup 1}{sub 0} n + {sup 1}{sub 1} H {yields}{sup 2}{sub 1} D + {gamma}. The produced photon is soon a gamma ray that is emitted when the hydrogen captures a thermal neutron. The photon energy was measured using two spectrometric systems for gamma rays. A system with a detector of NaI(TI) of 3'' x 3'' and the other one with a High-purity Germanium detector. The first detector has a bigger efficiency and a smaller resolution in comparison with the second detector. The energy of the measured photon is the binding energy of the deuteron. With the measurement of the photon energy and the masses of the proton and of the deuterium it was determined the neutron mass. The value of the mass obtained with both systems it was compared with the value reported in the literature. The nuclear reaction was induced in a volume of paraffin that it was bombing with a source {sup 239} PuBe whose activity is of 3.7 x 10{sup 10} Bq. (Author)

Development of ultracold neutron detectors and a polarization analyzing system for the measurement of the neutron electric dipole moment; Developpement de detecteurs de neutrons ultra-froids et d'un systeme d'analyse de polarisation pour la mesure du moment electrique dipolaire du neutron

Energy Technology Data Exchange (ETDEWEB)

Rogel, Gwendal

2009-10-29

This thesis was performed in the context of a project aiming to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute. Two aspects have been studied: The detection and the polarization analysis of ultracold neutrons. Three types of detectors have been tested at the Institut Laue-Langevin (ILL): The Cascade-U (GEM technology), the {sup 3}He gas detector and {sup 6}Li-doped glass scintillators (GS family). Their detection efficiency and their background sensitivity have been measured. The GS10 scintillator is competitive with the {sup 3}He gas detector under the conditions realized with the EDM spectrometer. A GS3/GS20 scintillator stack has enabled to improve the neutron/gamma discrimination. It has been found 20% less efficient than the {sup 3}He gas detector under the EDM spectrometer. The Cascade-U detector has been observed to be 20% less efficient than a 500 microns thick GS10 glass as confirmed by simulations. A new system for simultaneous spin analysis is presented. It consists of two independent detection systems (arms) which are each made of an adiabatic spin flipper, a spin analyzer, and a detector. The arms detect opposite spin components, allowing the simultaneous counting of both neutron spin orientations. A prototype mounted in horizontal configuration has been tested at ILL. The analyzing power of both arms has been measured to be 80%. The transmission of the system without spin analyzers has been found to be 50%. (author) [French] Cette these s'inscrit dans un nouveau projet de mesure du moment dipolaire electrique (EDM) du neutron a l'institut Paul Scherrer. Deux aspects ont ete etudies ici: la detection et l'analyse de polarisation de neutrons ultra-froids. Trois types de detecteurs ont ete testes a l'Institut Laue-Langevin (ILL): le Cascade-U (technologie GEM), le compteur a gaz {sup 3}He et des scintillateurs dopes au {sup 6}Li (type GS). Leur efficacite de detection ainsi que leur sensibilite au bruit de fond ont

Measuring neutron spectra in radiotherapy using the nested neutron spectrometer

Energy Technology Data Exchange (ETDEWEB)

Maglieri, Robert, E-mail: robert.maglieri@mail.mcgill.ca; Evans, Michael; Seuntjens, Jan; Kildea, John [Medical Physics Unit, McGill University, Montreal, Quebec H4A 3J1 (Canada); Licea, Angel [Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5S9 (Canada)

2015-11-15

Purpose: Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers. Methods: The NNS is designed for easy handling and is more practical than the traditional BSS. Operated in current-mode, the problem of pulse pileup due to high dose-rates is overcome by measuring current, similar to an ionization chamber. In a bunker housing a Varian Clinac 21EX, the performance of the NNS was evaluated in terms of reproducibility, linearity, and dose-rate effects. Using a custom maximum-likelihood expectation–maximization algorithm, measured neutron spectra at various locations inside the bunker were then compared to Monte Carlo simulations of an identical setup. In terms of dose, neutron ambient dose equivalents were calculated from the measured spectra and compared to bubble detector neutron dose equivalent measurements. Results: The NNS-measured spectra for neutrons at various locations in a treatment room were found to be consistent with expectations for both relative shape and absolute magnitude. Neutron fluence-rate decreased with distance from the source and the shape of the spectrum changed from a dominant fast neutron peak near the Linac head to a dominant thermal neutron peak in the moderating conditions of the maze. Monte Carlo data and NNS-measured spectra agreed within 30% at all locations except in the maze where the deviation was a maximum of 40%. Neutron ambient dose equivalents calculated from the authors’ measured spectra were consistent (one standard deviation) with bubble detector measurements in the treatment room. Conclusions: The NNS may

NZG 201 portable spectrometric unit

International Nuclear Information System (INIS)

Jursa, P.; Novakova, O.; Slezak, V.

The NZG 201 spectrometric unit is a portable single-channel processing unit supplied from the mains or a battery which allows the qualitative and quantitative measurement of different types of ionizing radiation when connected to a suitable detection unit. The circuit layout and the choice of control elements makes the spectrometric unit suitable for use with scintillation detector units. The spectrometric unit consists of a pulse amplifier, an amplitude pulse analyzer, a pulse counter, a pulse rate counter with an output for a recorder, a high voltage source and a low voltage source. The block diagram is given. All circuits are modular and are mounted on PCB's. The apparatus is built in a steel cabinet with a raised edge which protects the control elements. The linear pulse amplifier has a maximum gain of 1024, the pulse counter has a maximum capacity of 10 6 -1 imp and time resolution better than 0.5 μs. The temperature interval at which the apparatus is operational is 0 to 45 degC, its weight is 12.5 kg and dimensions 36x280x310 mm, energy range O.025 to 2.5 MeV, for 137 Cs the energy resolution is 8 to 10%. The spectrometric unit NZG 2O1 may, with regard to its parameters, number and range of control elements, be used as a universal measuring unit. (J.P.)

Measurement of neutron spectra generated by a 62 AMeV carbon-ion beam on a PMMA phantom using extended range Bonner sphere spectrometers

International Nuclear Information System (INIS)

Bedogni, R.; Amgarou, K.; Domingo, C.; Russo, S.; Cirrone, G.A.P.; Pelliccioni, M.; Esposito, A.; Pola, A.; Introini, M.V.; Gentile, A.

2012-01-01

Neutrons constitute an important component of the radiation environment in hadron therapy accelerators. Their energy distribution may span from thermal up to hundred of MeV. The characterization of these fields in terms of dosimetric or spectrometric quantities is crucial for either the patient protection or the facility design aspects. To date, the Extended Range Bonner Sphere Spectrometer (ERBSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, a measurement campaign was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN-LNS (Laboratori Nazionali del Sud), where a 62 AMeV carbon ion is available. The beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0° and 90° with respect to the beam-line. The ERBSSs of UAB (Universidad Autónoma de Barcelona-Grup de Física de les Radiacions) and INFN (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati) were used to measure the resulting neutron fields. The two ERBSSs use different detectors and sphere diameters, and have been independently calibrated. The FRUIT code was used to unfold the results.

Measurement of neutron spectra generated by a 62 AMeV carbon-ion beam on a PMMA phantom using extended range Bonner sphere spectrometers

Energy Technology Data Exchange (ETDEWEB)

Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Amgarou, K.; Domingo, C. [Grup de Recerca en Radiacions Ionitzants, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Russo, S.; Cirrone, G.A.P. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali dei Sud, Via S. Sofia 62, 95125 Catania (Italy); Pelliccioni, M.; Esposito, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Pola, A.; Introini, M.V. [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Gentile, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy)

2012-07-21

Neutrons constitute an important component of the radiation environment in hadron therapy accelerators. Their energy distribution may span from thermal up to hundred of MeV. The characterization of these fields in terms of dosimetric or spectrometric quantities is crucial for either the patient protection or the facility design aspects. To date, the Extended Range Bonner Sphere Spectrometer (ERBSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, a measurement campaign was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN-LNS (Laboratori Nazionali del Sud), where a 62 AMeV carbon ion is available. The beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0 Degree-Sign and 90 Degree-Sign with respect to the beam-line. The ERBSSs of UAB (Universidad Autonoma de Barcelona-Grup de Fisica de les Radiacions) and INFN (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati) were used to measure the resulting neutron fields. The two ERBSSs use different detectors and sphere diameters, and have been independently calibrated. The FRUIT code was used to unfold the results.

Measurement of neutron spectra generated by a 62 AMeV carbon-ion beam on a PMMA phantom using extended range Bonner sphere spectrometers

Science.gov (United States)

Bedogni, R.; Amgarou, K.; Domingo, C.; Russo, S.; Cirrone, G. A. P.; Pelliccioni, M.; Esposito, A.; Pola, A.; Introini, M. V.; Gentile, A.

2012-07-01

Neutrons constitute an important component of the radiation environment in hadron therapy accelerators. Their energy distribution may span from thermal up to hundred of MeV. The characterization of these fields in terms of dosimetric or spectrometric quantities is crucial for either the patient protection or the facility design aspects. To date, the Extended Range Bonner Sphere Spectrometer (ERBSS) is the only instrument able to simultaneously determine all spectral components in such workplaces. With the aim of providing useful data to the scientific community involved in neutron measurements at hadron therapy facilities, a measurement campaign was carried out at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) of INFN-LNS (Laboratori Nazionali del Sud), where a 62 AMeV carbon ion is available. The beam was directed towards a PMMA phantom, simulating the patient, and two neutron measurement points were established at 0° and 90° with respect to the beam-line. The ERBSSs of UAB (Universidad Autónoma de Barcelona-Grup de Física de les Radiacions) and INFN (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati) were used to measure the resulting neutron fields. The two ERBSSs use different detectors and sphere diameters, and have been independently calibrated. The FRUIT code was used to unfold the results.

The potentials and limitations of using neutron activation analysis data on human hair as a forensic evidence

International Nuclear Information System (INIS)

Pillay, K.K.S.; Kuis, R.L.

1978-01-01

A survey of hair samples from a group of 300 vounteers, involving nearly 12 000 elemental analyses, indicates that while neutron-activation-analysis data have distinct potentials to develop useful forensic evidence, there are several limitations to its routine applications. The multi-elemental analyses of hair-wash samples were done using multiple neutron irradiation and high resolution gamma ray spectrometry. All neutron irradiations were performed in the Penn State TRIGA Reactor at a thermal neutron flux of approximately 10 13 nxcm -2 xs -1 . The gamma-ray spectrometric measurements utilized a 40 cm 3 high resolution Ge(Li) detector. This detector, in association with a software oriented programmable multichannel analyzer with a 12 K core size, was used for gamma ray spectrometric measurements. The data were recorded on computer-compatible magnetic tape. The quantitative measurements of only 22 elements were reported from both the hair samples and the ''hair-wash''. These elements are Ti, I, Br, Mn, Cu, V, Cl, Al, Na, Ca, Se, Hg, Cr, Au, Sb, Ag, Sc, Zn, Co, Fe, and La. In expressing the analytical results of ''hair-wash'' samples, the weight of hair from which the hair-wash originated was used to calculate the results in terms of the weight of hair. (T.G.)

A neutron detector for measurement of total neutron production cross sections

International Nuclear Information System (INIS)

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

1976-01-01

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

Neutron spectrum measurement by TOF

International Nuclear Information System (INIS)

Aizawa, Otohiko

1982-01-01

The TOF experiments by using various facilities are described. The steady neutron spectra in light water which contains non-1/V absorbing materials were measured by the TOF method at a LINAC facility. The results were compared with the calculations based on the Koppel-Haywood model and two others. The leakage neutron spectra from a heavy-water assembly were measured and compared with model calculations. The time-dependent energy spectra in a small graphite assembly were measured. For this measurement, a chopper system was also used. The two-region calculation explains the spectrum just after the neutron burst. The time-dependent spectra in a small Be assembly and in an assembly of coolant-moderator containing hydrogen were also measured. The calculations based on various models are in progress. The TOF experiments at the reactor-chopper facility were carried out for measuring the total cross sections of crystalline moderators, the thermal neutron total cross section of high temperature beryllium, the thermal neutron total cross sections of granular lead and high temperature liquid lead, and the angle-dependent scattering spectra. A pseudo-chopper was designed and constructed. The spectra of the neutron field for medical use were measured by the chopper-TOF system. The thermal neutron total cross sections of Fe, Zr, Nb and Mg were measured, and the results were compared with the calculations by THRUSH and UNCLE-TOM codes. The random-trigger TOF experiments were made by using Cf-252. (Kato, T.)

Determination of the neutron mass

International Nuclear Information System (INIS)

Amador V, P.; Chacon R, A.; Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Vega C, H.R.

2005-01-01

The binding energy of the deuteron was measured and it was determined the neutron mass starting from the nuclear reaction, 1 0 n + 1 1 H → 2 1 D + γ. The produced photon is soon a gamma ray that is emitted when the hydrogen captures a thermal neutron. The photon energy was measured using two spectrometric systems for gamma rays. A system with a detector of NaI(TI) of 3'' x 3'' and the other one with a High-purity Germanium detector. The first detector has a bigger efficiency and a smaller resolution in comparison with the second detector. The energy of the measured photon is the binding energy of the deuteron. With the measurement of the photon energy and the masses of the proton and of the deuterium it was determined the neutron mass. The value of the mass obtained with both systems it was compared with the value reported in the literature. The nuclear reaction was induced in a volume of paraffin that it was bombing with a source 239 PuBe whose activity is of 3.7 x 10 10 Bq. (Author)

Mass Spectrometric Calibration of Controlled Fluoroform Leak Rate Devices Technique and Uncertainty Analysis

CERN Document Server

Balsley, S D; Laduca, C A

2003-01-01

Controlled leak rate devices of fluoroform on the order of 10 sup - sup 8 atm centre dot cc sec sup - sup 1 at 25 C are used to calibrate QC-1 War Reserve neutron tube exhaust stations for leak detection sensitivity. Close-out calibration of these tritium-contaminated devices is provided by the Gas Dynamics and Mass Spectrometry Laboratory, Organization 14406, which is a tritium analytical facility. The mass spectrometric technique used for the measurement is discussed, as is the first principals calculation (pressure, volume, temperature and time). The uncertainty of the measurement is largely driven by contributing factors in the determination of P, V and T. The expanded uncertainty of the leak rate measurement is shown to be 4.42%, with a coverage factor of 3 (k=3).

A neutron detector for measurement of total neutron production cross sections

Energy Technology Data Exchange (ETDEWEB)

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

1976-03-01

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

Neutron measurement techniques for tokamak plasmas

International Nuclear Information System (INIS)

Jarvis, O.N.

1994-01-01

The present article reviews the neutron measurement techniques that are currently being applied to the study of tokamak plasmas. The range of neutron energies of primary interest is limited to narrow bands around 2.5 and 14 MeV, and the variety of measurements that can be made for plasma diagnostic purposes is also restricted. To characterize the plasma as a neutron source, it is necessary only to measure the total neutron emission, the relative neutron emissivity as a function of position throughout the plasma, and the energy spectra of the emitted neutrons. In principle, such measurements might be expected to be relatively easy. That this is not the case is, in part, attributable to practical problems of accessibility to a harsh environment but is mostly a consequence of the time-scale on which the measurements have to be made and of the wide range of neutron emission intensities that have to be covered: for tokamak studies, the time-scale is of the order of 1 to 100 ms and the neutron intensity ranges from 10 12 to 10 19 s -1 . (author)

Measurements of fission cross-sections and of neutron production rates; Mesures de sections efficaces de fission et du nombre de neutrons prompts emis par fission

Energy Technology Data Exchange (ETDEWEB)

Billaud, P; Clair, C; Gaudin, M; Genin, R; Joly, R; Leroy, J L; Michaudon, A; Ouvry, J; Signarbieux, C; Vendryes, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin {sup 10}B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of {sup 235}U. We intend to measure the variation of the neutron induced fission cross section of {sup 235}U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of {sup 235}U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF{sub 3} proportional counters. c) Mean number {nu} of neutrons emitted in neutron induced fission. We measured the value of {nu} for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) {alpha} reaction by means of a 300 kV Cockcroft Walton generator. (author)Fren. [French] a) Mesures de sectionficaces de fission a basse energie. Nous avons mesure et analyse la variation de la section efficace de fission de divers isotopes fissiles pour des neutrons d'energie inferieure a 0,025 eV. Le monochromateur est constitue par un spectrometre a cristal auquel est associe un selecteur mecanique destine a eliminer les diffractions de Bragg d'ordre superieur au premier. Le materiau fissile est contenu dans une chambre a fission sous forme de depots realises par peinture; une chambre d'ionisation a depots minces de B{sub 10

Passive neutron-multiplication measurements

International Nuclear Information System (INIS)

Zolnay, A.S.; Barnett, C.S.; Spracklen, H.P.

1982-01-01

We have developed an instrument to measure neutron multiplication by statistical analysis of the timing of neutrons emitted from fissionable material. This instrument is capable of repeated analysis of the same recorded data with selected algorithms, graphical displays showing statistical properties of the data, and preservation of raw data on disk for future comparisons. In our measurements we have made a comparison of the covariance to mean and Feynman variance to mean analysis algorithms to show that the covariance avoids a bias term and measures directly the effect due to the presence of neutron chains. A spherical assembly of enriched uranium shells and acrylic resin reflector/moderator components used for the measurements is described. Preliminary experimental results of the Feynman variance to mean measurements show the expected correlation with assembly multiplication

Fast neutron spectrometry and dosimetry

International Nuclear Information System (INIS)

Blaize, S.; Ailloud, J.; Mariani, J.; Millot, J.P.

1958-01-01

We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author) [fr

Spectrometric techniques 4

CERN Document Server

Vanasse, George A

2013-01-01

Spectrometric Techniques, Volume IV discusses three widely diversified areas of spectrometric techniques. The book focuses on three spectrometric methods. Chapter 1 discusses the phenomenology and applications of Coherent Anti-Stokes Raman Spectroscopy (CARS), the most commonly used optical technique that exploit the Raman effect. The second chapter is concerned with diffraction gratings and mountings for the Vacuum Ultraviolet Spectral Region. Chapter 3 accounts the uses of mass spectrometry, detectors, types of spectrometers, and ion sources. Physicists and chemists will find the book a go

Fast neutron spectrometry and dosimetry; Spectrometrie et dosimetrie des neutrons rapides

Energy Technology Data Exchange (ETDEWEB)

Blaize, S; Ailloud, J; Mariani, J; Millot, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

We have studied fast neutron spectrometry and dosimetry through the recoil protons they produce in hydrogenated samples. In spectrometric, we used nuclear emulsions, in dosimetric, we used polyethylene coated with zinc sulphide and placed before a photomultiplier. (author)Fren. [French] Nous avons etudie la spectrometrie et la dosimetrie des neutrons rapides en utilisant les protons de recul qu'ils produisent dans une matiere hydrogenee. En spectrometrie, nous avons employe des emulsions nucleaires, en dosimetrie, du polyethylene recouvert de sulfure de zinc place devant un photomultiplicateur. (auteur)

Characterization of the neutron field of the {sup 241}AmBe in a calibration room; Caracterizacion del campo de neutrones del {sup 241} AmBe en una sala para calibracion

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain)] e-mail: rvega@cantera.reduaz.mx

2003-07-01

The field of neutrons produced by an isotopic source of neutrons of {sup 241} Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

Irradiation and gamma-ray spectrometric parameters for 129I neutron-activation analysis

International Nuclear Information System (INIS)

Brauer, F.P.; Strebin, R.S. Jr.; Mitzlaff, W.A.; Kaye, J.H.

1983-09-01

This paper describes the influence of reactor neutron irradiation facilities on low-level 129 I analysis methodology. Three reactors are compared - the HFIR at ORNL, the N-Reactor at Hanford, and a 1-MW research reactor at Washington State University, Pullman, WA. Parameters compared include sensitivity for 129 I and natural iodine and interference effects due to high levels of 127 I in irradiated samples. Selection of detector systems for off-site use at HFIR is discussed. A comparison of neutron activation analysis with other sensitive detection methods for measurement of 129 I is given

Neutron spectrometry and dosimetry using NSDAAN

International Nuclear Information System (INIS)

Martinez B, M. R.; Vega C, H. R.; Ortiz R, J. M.

2009-10-01

The reconstruction of neutron spectra from count rates of a Bonner spheres spectrometric system is performed using various methods such as Monte Carlo methods, the parameterization and iterative methods. The weight of the Bonner spheres spectrometric system, the procedure for the reconstruction of the spectra, the need of an experienced user, the high consumer of time, the need of use a reconstruction code as the BUNKI, SAND, among others, and the resolution of the spectrum are some problems that this system presents. This has motivated the development of complementary procedures such as maximum entropy, genetic algorithms and artificial neural networks. In previous work, has reported a new method called robust design methodology of artificial neural networks, to construct various network topologies capable of solving the problems of neutron spectrometry and dosimetry, however, due to the newness of this technology, be noted that there are not tools to end-user that allow test and validate the designed networks. This paper presents a software for the neutron spectrometry and dosimetry, designed from the information extracted of an artificial neural network designed by robust design methodology of artificial neural networks. This tool has the following characteristics: was designed in a user graphical interface easy to use, requires not knowledge of neural networks or neutron spectrometry by the user; execution speed of the application; unlike the deconvolution codes are not required to select an initial spectrum for the spectrum reconstruction; as an additional element to this tool, besides the spectrum, the calculation is performed simultaneous to H(10), E, H p , s (10,θ) from just counting rates from a Bonner spheres spectrometric system. (author)

Determination of trace elements in Egyptian cane sugar (Deshna Factories) by neutron activation, atomic absorption spectrophotometric and inductively coupled plasma-atomic emission spectrometric analysis

International Nuclear Information System (INIS)

Awadallah, R.M.; Sherif, M.K.; Mohamed, A.E.; Grass, F.

1986-01-01

Multielement instrumental neutron activation (INAA), inductively coupled plasma-atomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses were utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth, respectively. (author)

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.

Neutron energy measurement for practical applications

Science.gov (United States)

Roshan, M. V.; Sadeghi, H.; Ghasabian, M.; Mazandarani, A.

2018-03-01

Industrial demand for neutrons constrains careful energy measurements. Elastic scattering of monoenergetic α -particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with specific energy is obtained by counting the number of α -particles in the corresponding location on the charged particle detector. Monte Carlo simulation and COMSOL Multiphysics5.2 are used to account for one-to-one collision of neutrons with α -particles.

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 spectrometry in the temporary storage of waste of the Jose Cabrera (Zorita)

International Nuclear Information System (INIS)

Domingo, C.; Amgarou, K.

2011-01-01

Radiation controls the temporary storage of waste must ensure that the exterior of the same area is classified as open access. Gamma radiation monitors commonly used ensure that this is the case for this type of radiation. The presence of the neutron field associated with the fission of the fuel and the inherent complexity of the neutron dosimetry, in which information is required to assess spectrometric corresponding dosimetric quantities, has led to this season, first in Spain, measures in containers of waste and spent nuclear fuel in the ATT of the Jose Cabrera.

Neutron measurements as fusion plasma diagnostics

International Nuclear Information System (INIS)

Nishitani, Takeo; Hoek, M.

1993-01-01

Neutron measurements play important roles as the diagnostics of many aspects of the plasma in large tokamak devices such as JT-60U and JET. In the d-d discharges of JT-60U, the most important application of the neutron measurement is the investigation of the fusion performance using fission chambers. The ion velocity distribution function, and the triton slowing down are investigated by the neutron spectrometer and the 14 MeV neutron detector, respectively. TANSY is a combined proton-recoil and neutron time-of flight spectrometer for 14 MeV neutrons to be used during the d-t phase at JET. The detection principle is based on the measurements of the flight time of a scattered initial neutron and the energy of a corresponding recoil proton. The scattering medium is a polyethylene foil. The resolution and efficiency, using a thin foil (0.95 mg/cm 2 ), is 155 keV and 1.4x10 -5 cm 2 , respectively. (author)

Characterization of the neutron field of the 241AmBe in a calibration room

International Nuclear Information System (INIS)

Vega C, H.R.; Gallego, E.; Lorente, A.

2003-01-01

The field of neutrons produced by an isotopic source of neutrons of 241 Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

Determination of iodine to compliment mass spectrometric measurements

International Nuclear Information System (INIS)

Hohorst, F.A.

1994-11-01

The dose of iodine-129 to facility personnel and the general public as a result of past, present, and future activities at DOE sites is of continuing interest, WINCO received about 160 samples annually in a variety of natural matrices, including snow, milk, thyroid tissue, and sagebrush, in which iodine-129 is determined in order to evaluate this dose, Currently, total iodine and the isotopic ratio of iodine-127 to iodine-129 are determined by mass spectrometry. These two measurements determine the concentration of iodine-129 in each sample, These measurements require at least 16 h of mass spectrometer operator time for each sample. A variety of methods are available which concentrate and determine small quantities of iodine. Although useful, these approaches would increase both time and cost. The objective of this effort was to determine total iodine by an alternative method in order to decrease the load on mass spectrometry by 25 to 50%. The preparation of each sample for mass spectrometric analysis involves a common step--collection of iodide on an ion exchange bed. This was the focal point of the effort since the results would be applicable to all samples

Notes on neutron flux measurement

International Nuclear Information System (INIS)

Alcala Ruiz, F.

1984-01-01

The main purpose of this work is to get an useful guide to carry out topical neutron flux measurements. Although the foil activation technique is used in the majority of the cases, other techniques, such as those based on fission chambers and self-powered neutron detectors, are also shown. Special interest is given to the description and application of corrections on the measurement of relative and absolute induced activities by several types of detectors (scintillators, G-M and gas proportional counters). The thermal arid epithermal neutron fluxes, as determined in this work, are conventional or effective (West cots fluxes), which are extensively used by the reactor experimentalists; however, we also give some expressions where they are related to the integrated neutron fluxes, which are used in neutron calculations. (Author) 16 refs

Spectrometry of degraded neutrons with SSNTDs

International Nuclear Information System (INIS)

Gopalani, Deepak; Kumar, S.; Jodha, A.S.; Reddy, A.R.

1993-01-01

Considerable interest has grown during the last decade in the use of solid state nuclear track detectors (SSNTDs) for routine neutron monitoring and dosimetry work. In addition, using these detectors neutron spectrometry has also been undertaken by some investigators. In spectrometry the energy of neutrons was determined either from minor axis of proton tracks observed on the surface of detector or from the use of polyethylene radiators of selected thickness with varying etching time. Using this latter method in the present work fast neutron spectrometry is made. The method involves the measurement of etch induction time, thickness of removed critical layer for constant radiator thickness with varying etching time. Besides a computer programme has been developed for the calculation of neutron sensitivity at different critical removal layers. The degraded neutron spectra of 252 Cf with shield materials of different thickness but of same composition and shield materials of same thickness but of different compositions have been obtained. The study shows that SSNTD films can be used for recording the transmitted neutron spectra from different shield materials. This spectrometric capability added to the technique advantages of SSNTDs such as integrating nature and small size make them important for nuclear engineering applications. (author). 7 refs., 4 figs., 1 tab

Electronic instrumentation system for pulsed neutron measurements

International Nuclear Information System (INIS)

Burda, J.; Igielski, A.; Kowalik, W.

1982-01-01

An essential point of pulsed neutron measurement of thermal neutron parameters for different materials is the registration of the thermal neutron die-away curve after a fast neutron bursts have been injected into the system. An electronic instrumentation system which is successfully applied for pulsed neutron measurements is presented. An important part of the system is the control unit which has been designed and built in the Laboratory of Neutron Parameters of Materials. (author)

Measurement of neutron sensitivity of self powered neutron detectors

International Nuclear Information System (INIS)

Mahant, A.K.; Yeshuraja, V.; Ghodke, Shobha

2005-01-01

Self powered neutron detectors (SPNDs ) will form the part of Reactor Instrumentation in the upcoming 500 MWe power reactors. ECIL has developed Vanadium and Cobalt SPNDs for NPCIL to be used in regulation and protection channels. Experimental determination of neutron sensitivity of the vanadium and cobalt Self Powered Neutron Detectors (SPNDs) was carried out in A-l location of Apsara reactor at BARC. The measurements involved determination of total detector signal, its various components and the thermal neutron flux at the detector location. The paper describes the experimental techniques used to measure various parameters required to evaluate the neutron sensitivity of the SPNDs and also the parameters required to ascertain the integrity of SPNDs. Neutron flux measurement was done by gold foil irradiation technique. The predominant signal component from the vanadium SPND is Ib the current due to activation of the vanadium emitter, it forms about 85% of the total signal. The other components I n,γ due to the capture gamma rays of 52 V and I externalγ produced by the external reactor gamma rays contribute about 10% and 5% respectively to the total signal. Whereas in the cobalt SPND the main signal component is due to the capture gamma rays of 60 Co and accounts for about the 95% of the total signal. Remaining 5% signal is due to external reactor gamma rays. (author)

Neutron spectrometry and dosimetry in the environment and at workplaces

International Nuclear Information System (INIS)

Alevra, A.V.; Klein, H.; Knauf, K.; Wittstock, J.; Wolber, G.

1998-01-01

Results obtained in diverse environments (including workplaces) using both spectrometric and dosimetric instrumentation were compared. The following topics are included: PTB Bonner sphere spectrometers; natural cosmic ray-induced neutron background; neutron fields at the Dukovany nuclear power plant (Czech Republic); neutron fields at the isochronous cyclotron of the German Cancer Research center in Heidelberg; and accuracy of the integral results obtained with Bonner spheres. (P.A.)

ATLAS MDT neutron sensitivity measurement and modeling

International Nuclear Information System (INIS)

Ahlen, S.; Hu, G.; Osborne, D.; Schulz, A.; Shank, J.; Xu, Q.; Zhou, B.

2003-01-01

The sensitivity of the ATLAS precision muon detector element, the Monitored Drift Tube (MDT), to fast neutrons has been measured using a 5.5 MeV Van de Graaff accelerator. The major mechanism of neutron-induced signals in the drift tubes is the elastic collisions between the neutrons and the gas nuclei. The recoil nuclei lose kinetic energy in the gas and produce the signals. By measuring the ATLAS drift tube neutron-induced signal rate and the total neutron flux, the MDT neutron signal sensitivities were determined for different drift gas mixtures and for different neutron beam energies. We also developed a sophisticated simulation model to calculate the neutron-induced signal rate and signal spectrum for ATLAS MDT operation configurations. The calculations agree with the measurements very well. This model can be used to calculate the neutron sensitivities for different gaseous detectors and for neutron energies above those available to this experiment

Neutron fluence measurements

International Nuclear Information System (INIS)

1970-01-01

For research reactor work dealing with such subjects as radiation effects on solids and such disciplines as radiochemistry and radiobiology, the radiation dose or neutron fluence is an essential parameter in evaluating results. Unfortunately it is very difficult to determine. Even when the measurements have been accurate, it is difficult to compare results obtained in different experiments because present methods do not always reflect the dependence of spectra or of different types of radiation on the induced processes. After considering the recommendations of three IAEA Panels, on 'In-pile dosimetry' held in July 1964, on 'Neutron fluence measurements' in October 1965, and on 'In-pile dosimetry' in November 1966, the Agency established a Working Group on Reactor Radiation Measurements. This group consisted of eleven experts from ten different Member States and two staff members of the Agency. In the measurement of energy absorbed by materials from neutrons and gamma rays, there are various reports and reviews scattered throughout the literature. The group, however, considered that the time was ripe for all relevant information to be evaluated and gathered together in the form of a practical guide, with the aim of promoting consistency in the measurement and reporting of reactor radiation. The group arranged for the material to be divided into two manuals, which are expected to be useful both for experienced workers and for beginners

Summary of neutron measurements for the Viking Program

International Nuclear Information System (INIS)

Anderson, M.E.

1975-01-01

The results of neutron measurements for 238 Pu-fueled, 683-W (thermal) capsules fabricated for the Viking Program (Mars Lander) are presented. These results include, for each capsule, the total neutron emission rate and neutron multiplication and, for one capsule, the neutron energy spectrum. A precision long counter was used for the neutron emission rate measurements and a single stilbene crystal for the neutron spectrum measurement. (U.S.)

Neutron energy measurement for practical applications

Indian Academy of Sciences (India)

M V Roshan

2018-02-07

. Elastic scattering of monoenergetic α-particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with ...

Neutron spectrometry in mixed fields: characterisation of the Ra-1- reactor workplace

International Nuclear Information System (INIS)

Gregori, B.; Carelli, J.; Cruzate, J.; Papadopulos, S.

2006-01-01

The characterisation of the neutron spectrum of a workplace is an essential dosimetric tool for improving the assessment of the personal equivalent dose of the workers. In addition, if the operational conditions of the facility are well defined, the set of field spectra obtained may be used as a reference for comparing the performance of different type of neutron detectors. Recently, using a neutron spectrometric system based on a set of moderated spheres with 3 He detector, the characterisation of the neutron spectra in workplaces of the Argentine Reactor No. 1 (R.A. -1) has been carried out. The spectrometric system consists of 12 spheres made of the high density polyethylene d mean δ =0.95 g cm 3 , with diameters between 3'' and 12'' and a proportional counter of 3 He, 4 atm of nominal pressure, Centronic trade mark, located in the centre of the spheres. The neutron response matrix was calculated using the M.C.N.P. -I.V.B. code and E.N.D.F./B-VI library in the energy range between thermal neutron and 100 MeV. The neutron spectrum was unfolded using the M.A.X.E.D. unfolding code. The validation of the spectrometric system was performed at Cea-Cadarache (France) with of 252 Cf, Am Be, and 252 Cf + D 2 O sources. Therefore, in this work, the spectral fluence of the field in the selected points of the facility (R.A.-1) has been presented and the ambient dose equivalent, H *(10), and the personal dose equivalent, Hp(10), have been derived from the neutron fluence, applying ICRP-74 recommended fluence to dose conversion factors. The quantities evaluated have uncertainties less than 15%, which is considered good enough for radiation protection requirements. (authors)

Cosmic-ray neutron simulations and measurements in Taiwan

International Nuclear Information System (INIS)

Chen, Wei-Lin; Jiang, Shiang-Huei; Sheu, Rong-Jiun

2014-01-01

This study used simulations of galactic cosmic ray in the atmosphere to investigate the neutron background environment in Taiwan, emphasising its altitude dependence and spectrum variation near interfaces. The calculated results were analysed and compared with two measurements. The first measurement was a mobile neutron survey from sea level up to 3275 m in altitude conducted using a car-mounted high-sensitivity neutron detector. The second was a previous measured result focusing on the changes in neutron spectra near air/ground and air/water interfaces. The attenuation length of cosmic-ray neutrons in the lower atmosphere was estimated to be 163 g cm -2 in Taiwan. Cosmic-ray neutron spectra vary with altitude and especially near interfaces. The determined spectra near the air/ground and air/water interfaces agree well with measurements for neutrons below 10 MeV. However, the high-energy portion of spectra was observed to be much higher than our previous estimation. Because high-energy neutrons contribute substantially to a dose evaluation, revising the annual sea-level effective dose from cosmic-ray neutrons at ground level in Taiwan to 35 μSv, which corresponds to a neutron flux of 5.30 x 10 -3 n cm -2 s -1 , was suggested. The cosmic-ray neutron background in Taiwan was studied using the FLUKA simulations and field measurements. A new measurement was performed using a car-mounted high-efficiency neutron detector, re-coding real-time neutron counting rates from sea level up to 3275 m. The attenuation of cosmic-ray neutrons in the lower atmosphere exhibited an effective attenuation length of 163 g cm -2 . The calculated neutron counting rates over predicted the measurements by ∼32 %, which leaded to a correction factor for the FLUKA-calculated cosmic-ray neutrons in the lower atmosphere in Taiwan. In addition, a previous measurement regarding neutron spectrum variation near the air/ground and air/water interfaces was re-evaluated. The results showed that the

Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

Science.gov (United States)

Bedogni, Roberto; Esposito, Adolfo; Andreani, Carla; Senesi, Roberto; De Pascale, Maria Pia; Picozza, Piergiorgio; Pietropaolo, Antonino; Gorini, Giuseppe; Frost, Christopher D.; Ansell, Stewart

2009-12-01

One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) [1] ( http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm), a spectrometric characterization was performed on the VESUVIO beamline [2] (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

International Nuclear Information System (INIS)

Bedogni, Roberto; Esposito, Adolfo; Andreani, Carla; Senesi, Roberto; De Pascale, Maria Pia; Picozza, Piergiorgio; Pietropaolo, Antonino; Gorini, Giuseppe; Frost, Christopher D.; Ansell, Stewart

2009-01-01

One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) ((http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm)), a spectrometric characterization was performed on the VESUVIO beamline (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

Energy Technology Data Exchange (ETDEWEB)

Bedogni, Roberto; Esposito, Adolfo [INFN-LNF Via E. Fermi n. 40-00044 Frascati (RM) (Italy); Andreani, Carla [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); Senesi, Roberto, E-mail: roberto.senesi@roma2.infn.i [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); De Pascale, Maria Pia; Picozza, Piergiorgio [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); Pietropaolo, Antonino; Gorini, Giuseppe [CNISM and Universita degli Studi di Milano Bicocca, Dipartimento di Fisica ' G. Occhialini' , Piazza della Scienza 3, 20126 Milano (Italy); Frost, Christopher D. [INFN-LNF Via E. Fermi n. 40-00044 Frascati (RM) (Italy); Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); CNISM and Universita degli Studi di Milano Bicocca, Dipartimento di Fisica ' G. Occhialini' , Piazza della Scienza 3, 20126 Milano (Italy); STFC Rutherford Appleton Laboratory, ISIS Facility, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX (United Kingdom); Ansell, Stewart [STFC Rutherford Appleton Laboratory, ISIS Facility, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX (United Kingdom)

2009-12-21

One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) ((http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm)), a spectrometric characterization was performed on the VESUVIO beamline (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

Neutron flux measurement utilizing Campbell technique

International Nuclear Information System (INIS)

Kropik, M.

2000-01-01

Application of the Campbell technique for the neutron flux measurement is described in the contribution. This technique utilizes the AC component (noise) of a neutron chamber signal rather than a usually used DC component. The Campbell theorem, originally discovered to describe noise behaviour of valves, explains that the root mean square of the AC component of the chamber signal is proportional to the neutron flux (reactor power). The quadratic dependence of the reactor power on the root mean square value usually permits to accomplish the whole current power range of the neutron flux measurement by only one channel. Further advantage of the Campbell technique is that large pulses of the response to neutrons are favoured over small pulses of the response to gamma rays in the ratio of their mean square charge transfer and thus, the Campbell technique provides an excellent gamma rays discrimination in the current operational range of a neutron chamber. The neutron flux measurement channel using state of the art components was designed and put into operation. Its linearity, accuracy, dynamic range, time response and gamma discrimination were tested on the VR-1 nuclear reactor in Prague, and behaviour under high neutron flux (accident conditions) was tested on the TRIGA nuclear reactor in Vienna. (author)

Measurement for skyshine of neutron generated by the K-600 neutron generator

International Nuclear Information System (INIS)

Zhen Huazhi; Li Guisheng; Wu Jingmin; Li Jianping

1988-01-01

The attenuation low of neutron scattering in atmosphere that generated by K-600 neutron generator at IMP was measured in order to evaluate the effect of the neutron generator to surroundings. The attenuation lenth λ = 396m was obtained and this result is in aggreement with the measured data at some laboratories abroad

Measurement of activation cross sections of the {sup 27}Al(n,α){sup 24}Na and {sup 27}Al(n,p){sup 27}Mg reactions with quasi-monoenergetic neutrons

Energy Technology Data Exchange (ETDEWEB)

Zaman, Muhammad; Kim, Guinyun; Kim, Kwangsoo [Kyungpook National Univ., Daegu (Korea, Republic of). Dept. of Physics; Naik, Haladhara [Kyungpook National Univ., Daegu (Korea, Republic of). Dept. of Physics; Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Lee, Young-Ouk; Cho, Young-Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Nuclear Data Center; Lee, Man Woo; Kang, Yeong-Rok [Dongnam Institute of Radiological and Medical Science, Busan (Korea, Republic of). Research Center

2017-10-01

The cross sections of the {sup 27}Al(n,α){sup 24}Na and {sup 27}Al(n,p){sup 27}Mg reactions with the average neutron energies of 15.2, 26.4, and 37.2 MeV were measured using the activation and off-line γ-ray spectrometric technique at the Korean Institute of Radiological and Medical Sciences (KIRAMS), Korea. Quasi-monoenergetic neutrons produced via the {sup 9}Be(p,n) reaction with the proton beam energies of 25, 35, and 45 MeV from the MC50 cyclotron of KIRAMS were used. The present measured values were compared with those from the evaluated nuclear data libraries ENDF/B-VII, TENDL-2015, TALYS 1.8, and from literature. In general, a close agreement with the literature data as well as the evaluated data was found.

Neutron spin echo scattering angle measurement (SESAME)

International Nuclear Information System (INIS)

Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

2005-01-01

We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-μm-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for

Measurement of spectrometric magnet field of EXCHARM setup

International Nuclear Information System (INIS)

Aleev, A.N.; Balandin, V.P.; Bordyukov, A.A.

1998-01-01

The EXCHARM spectrometer is used for studying charm, strange and exotic hadrons. It is located at the neutron 5N channel of U-70 accelerator (Protvino). The EXCHARM dipole magnet has external size 4.486 x 3.196 x 3.058 m 3 with aperture 2.74 x 0.489 m 2 . The field measurement was made by three-component Hall magnetometer on-line computer in measurement region 2.40 x 0.32 x 3.78 m 3 . The apparatus and methods of the field measuring are described. The results of the measurements of the magnetic field are presented. The estimation of the measurement precision is given. (author)

Velocity-space sensitivity of neutron spectrometry measurements

DEFF Research Database (Denmark)

Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.

2015-01-01

Neutron emission spectrometry (NES) measures the energies of neutrons produced in fusion reactions. Here we present velocity-space weight functions for NES and neutron yield measurements. Weight functions show the sensitivity as well as the accessible regions in velocity space for a given range...

Neutron spectra measurements and neutron flux monitoring for radiation damage purposes

International Nuclear Information System (INIS)

Osmera, B.; Petr, J.; Racek, J.; Rumler, C.; Turzik, Z.; Franc, L.; Holman, M.; Hogel, J.; Kovarik, K.; Marik, P.; Vespalec, R.; Albert, D.; Hansen, V.; Vogel, W.

1979-09-01

Neutron spectra were measured for the TR-0, WWR-S and SR-0 experimental reactors using the recoil proton method, 6 Li spectrometry, scintillation spectrometry and activation detectors in a variety of conditions. Neutron fluence was also measured and calculated. (M.S.)

Neutron Measurements At Hanford's Plutonium Finishing Plant

International Nuclear Information System (INIS)

Conrady, Matthew M.; Berg, Randal K.; Scherpelz, Robert I.; Rathbone, Bruce A.

2009-01-01

The Pacific Northwest National Laboratory (PNNL) conducted neutron measurements at Hanford's Plutonium Finishing Plant (PFP). The measurements were performed to evaluate the performance of the Hanford Standard Dosimeter (HSD) and the 8816 TLD component of the Hanford Combination Neutron Dosimeter (HCND) in the neutron fields responsible for worker neutron exposures. For this study, TEPC detectors and multisphere spectrometers were used to measure neutron dose equivalent rate, and multispheres were used to measure average neutron energy. Water-filled phantoms holding Hanford dosimeters were positioned at each measurement location. The phantoms were positioned in the same location where a multisphere measurement was taken and TEPCs were also positioned there. Plant survey meters were also used to measure neutron dose rates at all locations. Three measurement locations were chose near the HC-9B glovebox in room 228A of Building 234-5. The multisphere spectrometers measured average neutron energies in the range of 337 to 555 keV at these locations. Personal dose equivalent, Hp(10)n, as measured by the multisphere and TEPC, ranged from 2.7 to 9.7 mrem/h in the three locations. Effective dose assuming a rotational geometry (EROT) was substantially lower than Hp(10), ranging from 1.3 to 3.6 mrem/h. These values were lower than the reported values from dosimeters exposed on a rotating phantom. Effective dose assuming an AP geometry (EAP) was also substantially lower than Hp(10), ranging from 2.3 to 6.5 mrem/h. These values were lower than the reported values from the dosimeters on slab phantoms. Since the effective dose values were lower than reported values from dosimeters, the dosimeters were shown to be conservative estimates of the protection quantities.

Measurement of fast neutron background in SAGE

International Nuclear Information System (INIS)

Abdurashitov, J.N.; Gavrin, V.N.; Kalikhov, A.V.; Matushko, V.L.; Shikhin, A.A.; Yants, V.E.; Zaborskaia, O.S.

2002-01-01

The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 -7 cm -2 s -1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 ± 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 ± 2.1) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 ± 2.4) x 10 -7 cm -2 s -1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be -7 cm -2 s -1 in 1.0-11.0 MeV energy range

Neutron activation system for spectral measurements of pulsed ion diode neutron production

International Nuclear Information System (INIS)

Hanson, D.L.; Kruse, L.W.

1980-02-01

A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4π required for a spectral measurement with this system is approx. 10 10 n where the neutron yield is predominantly below 4 MeV and approx. 10 8 n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described

Neutron spectrum measurements from a neutron guide tube facility at the ETRR-1 reactor

Energy Technology Data Exchange (ETDEWEB)

Maayouf, R M.A.; El-Sayed, L A.A.; El-Kady, A S.I. [Reactor and Neutron Physics Dept., NRC, Atomic Energy Authority, Cairo (Egypt)

1997-12-31

The present work deals with measurements of the neutron spectrum emitted from a neutron guide tube (NGT) recently installed at one of the ETRR-1 reactor horizontal channels designed to deliver thermal neutrons, free from fast neutrons and gamma ray background, to a fourier reverse-time-of-flight (RTOF) diffractometer. The measurements were performed using a {sup 6} Li glass scintillation detector combined with a multichannel analyzer set at channel width 4 M sec and installed at 3.4 m from a disc Fermi chopper. Also a theoretical model was specially developed for the neutron spectrum calculations. According to the model developed, the spectrum calculated was found to be in good agreement with the measured one. It was found, both from measurements and calculations, that the spectrum emitted from the NGT covers, after transmission through a fourier chopper, neutron wavelengths from 1-4 A adequate for neutron diffraction measurements at D values between 0.71-2.9 A respectively. 6 FIGS.

Physical and microdosimetric studies of neutron beams used in radiobiology

International Nuclear Information System (INIS)

Lavigne, Bernard.

1978-10-01

Microdosimetry is concerned with the energy imparted in microscopic regions irradiated with different radiations. The energy imparted is subject to random fluctuations. The probability distribution may be estimated by measurements or by computing code. The results obtained with a tissue-equivalent proportional counter of Rossi type are compared with those obtained by means of the computer code of DENNIS and EDWARDS. Beams of monoenergetic neutrons of 0.68 MeV, 2.18 MeV, 3.53 MeV, 5.5 MeV and 14.18 MeV, and fission neutrons were used. The computer code requires that neutron spectrum and W, the mean energy expanded in a gas per ion pair formed are determined. The first part of the report thus describes: -spectrometric measurements done with a NE 213 scintillator; -W measurements with a chamber operating alternately as ionization chamber and proportional counter. Results are given for H + , He + , C + , N + and O + ions in argon and tissue-equivalent gas in the energy range 25 keV - 500 keV [fr

Rapid uranium analysis by delayed neutron counting of neutron activated samples

International Nuclear Information System (INIS)

Papadopoulos, N.N.

1985-01-01

The uranium analyzer at the Nuclear Research Center ''Demokritos'' and the delayed neutron method have been used to determine the uranium content in lignite, in chemically enriched samples and in solutions of extractable uranium. The results are compared with data obtained by other methods. In the case of dissolved extractable uranium. The results are in good agreement with X-ray fluorescence data in the range 100 ppm to 2000 ppm while beyond these limits the discrepancies between neutron and spectrophotometric data are observed. The results for lignite samples are in good agreement with gamma spectrometric data. Discrepancies indicate that more extensive intercomparisons are needed to check the reliability of various methods

Car-borne multichannel gamma-ray spectrometric system model CZD-6

International Nuclear Information System (INIS)

Lu Shili; Zhai Yugui; Ma Yanfang; Jiao Cangwen; Zhang Biao

1998-01-01

The car-borne multichannel gamma-ray spectrometric system Mode CZD-6 is composed of a HDY-256 of portable multichannel gamma-ray spectrometer developed by the Beijing Research Institute of Uranium Geology and a large volume scintillation detector. the position for each measurement point is determined by the GPS instrument. Its latitude and longitude, as well as measured 256 channels of γ-spectrometric data are collected by a notebook computer, which can show the 256 channels of spectra for each point during measuring processes. The complete system can be loaded in a field car. This system has been used to environmental radioactive monitoring after calibration by airborne radiometric models in Shijiazhuang, Hebei province. A lot of data confirm that the system works stably and reliably, and is a fast and advanced approach for environmental γ-spectrometric monitoring. It can be used not only to determination of contents of natural radioactive elements in environments, but also to monitoring nuclear pollution and emergency treatment in nuclear accidents significantly

Neutron beam measurement dosimetry

International Nuclear Information System (INIS)

Amaro, C.R.

1995-01-01

This report describes animal dosimetry studies and phantom measurements. During 1994, 12 dogs were irradiated at BMRR as part of a 4 fraction dose tolerance study. The animals were first infused with BSH and irradiated daily for 4 consecutive days. BNL irradiated 2 beagles as part of their dose tolerance study using BPA fructose. In addition, a dog at WSU was irradiated at BMRR after an infusion of BPA fructose. During 1994, the INEL BNCT dosimetry team measured neutron flux and gamma dose profiles in two phantoms exposed to the epithermal neutron beam at the BMRR. These measurements were performed as a preparatory step to the commencement of human clinical trials in progress at the BMRR

Accurate measurements of neutron activation cross sections

International Nuclear Information System (INIS)

Semkova, V.

1999-01-01

The applications of some recent achievements of neutron activation method on high intensity neutron sources are considered from the view point of associated errors of cross sections data for neutron induced reaction. The important corrections in -y-spectrometry insuring precise determination of the induced radioactivity, methods for accurate determination of the energy and flux density of neutrons, produced by different sources, and investigations of deuterium beam composition are considered as factors determining the precision of the experimental data. The influence of the ion beam composition on the mean energy of neutrons has been investigated by measurement of the energy of neutrons induced by different magnetically analysed deuterium ion groups. Zr/Nb method for experimental determination of the neutron energy in the 13-15 MeV energy range allows to measure energy of neutrons from D-T reaction with uncertainty of 50 keV. Flux density spectra from D(d,n) E d = 9.53 MeV and Be(d,n) E d = 9.72 MeV are measured by PHRS and foil activation method. Future applications of the activation method on NG-12 are discussed. (author)

Neutron lifetime measurements with a large gravitational trap for ultracold neutrons

Science.gov (United States)

Serebrov, A. P.; Kolomensky, E. A.; Fomin, A. K.; Krasnoshchekova, I. A.; Vassiljev, A. V.; Prudnikov, D. M.; Shoka, I. V.; Chechkin, A. V.; Chaikovskiy, M. E.; Varlamov, V. E.; Ivanov, S. N.; Pirozhkov, A. N.; Geltenbort, P.; Zimmer, O.; Jenke, T.; Van der Grinten, M.; Tucker, M.

2018-05-01

Neutron lifetime is one of the most important physical constants: it determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. There remains the unsolved problem of a 3.9σ discrepancy between measurements of this lifetime using neutrons in beams and those with stored ultracold neutrons (UCN). In our experiment we measure the lifetime of neutrons trapped by Earth's gravity in an open-topped vessel. Two configurations of the trap geometry are used to change the mean frequency of UCN collisions with the surfaces; this is achieved by plunging an additional surface into the trap without breaking the vacuum. The trap walls are coated with a hydrogen-less fluorine-containing polymer to reduce losses of UCN. The stability of this coating over multiple thermal cycles between 80 and 300 K was tested. At 80 K, the probability of UCN loss due to collisions with the trap walls is just 1.5% of the probability of β decay. The free neutron lifetime is determined by extrapolation to an infinitely large trap with zero collision frequency. The result of these measurements is τn=881.5 ±0 .7stat ±0 .6syst s which is consistent with the conventional value of 880.2 ± 1.0 s presented by the Particle Data Group. Future prospects for this experiment are in further cooling to 10 K, which will lead to an improved accuracy of measurement. In conclusion we present an analysis of currently available data on various measurements of the neutron lifetime.

Workshop on industrial application of neutron diffraction. Stress measurement by neutron diffraction

CERN Document Server

Minakawa, N; Morii, Y; Oyama, Y

2002-01-01

This workshop was planned to make use of the neutron from the reactor and the pulse neutron source JSNS for the industrial world. Especially, this workshop focused on the stress measurement by the neutron diffraction and it was held on the Tokai JAERI from October 15 to 16, 2001. The participant total was 93 and 40 participated from the industrial world. The introduction of the residual stress development of measurement technique by the neutron diffraction method and a research of the measurement of the residual stress such as the nuclear reactor material, the ordinary structure material, the composite material, the quenching steel, the high strength material were presented and discussed in this workshop. Moreover, it was introduced for the industrial world that an internal stress measurement is important for development of new product or an improvement of a manufacturing process. The question from the industrial world about which can be measured the product form, the size, the measurement precision, the reso...

Measurements of neutron flux in the RA reactor

International Nuclear Information System (INIS)

Raisic, N.

1961-12-01

This report includes the following separate parts: Thermal neutron flux in the experimental channels od RA reactor; Epithermal neutron flux in the experimental channels od RA reactor; Fast neutron flux in the experimental channels od RA reactor; Thermal neutron flux in the thermal column and biological experimental channel; Neutronic measurements in the RA reactor cell; Temperature reactivity coefficient of the RA reactor; design of the device for measuring the activity of wire [sr

Neutron flux measurements in PUSPATI Triga Reactor

International Nuclear Information System (INIS)

Gui Ah Auu; Mohamad Amin Sharifuldin Salleh; Mohamad Ali Sufi.

1983-01-01

Neutron flux measurement in the PUSPATI TRIGA Reactor (PTR) was initiated after its commissioning on 28 June 1982. Initial measured thermal neutron flux at the bottom of the rotary specimen rack (rotating) and in-core pneumatic terminus were 3.81E+11 n/cm 2 sec and 1.10E+12n/cm 2 sec respectively at 100KW. Work to complete the neutron flux data are still going on. The cadmium ratio, thermal and epithermal neutron flux are measured in the reactor core, rotary specimen rack, in-core pneumatic terminus and thermal column. Bare and Cadmium covered gold foils and wires are used for the above measurement. The activities of the irradiated gold foils and wires are determined using Ge(Li) and hyperpure germinium detectors. (author)

Measurement of fast neutron background in SAGE

CERN Document Server

Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S

2002-01-01

The spectrometer intended for direct measurements of ultra low fluxes of fast neutrons is described. It is sensitive to neutron fluxes of 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 and lower. The detection efficiency of fast neutrons with simultaneous energy measurement was determined from Monte-Carlo simulation to be equal to 0.11 +- 0.01. The background counting rate in the detector corresponds to a neutron flux of (6.5 +- 2.1) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The natural neutron flux from the surrounding mine rock at the depth of 4700 meters of water equivalent was measured to be (7.3 +- 2.4) x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in the range 1.0-11.0 MeV. The flux of fast neutrons in the SAGE main room was measured to be < 2.3 x 10 sup - sup 7 cm sup - sup 2 s sup - sup 1 in 1.0-11.0 MeV energy range.

Method and apparatus for measuring thermal neutron characteristics

International Nuclear Information System (INIS)

Johnstone, C.W.

1983-01-01

The thermal neutron decay characteristics of an earth formation are measured by detecting indications of the thermal neutron concentration in the formation during a selected set of two measurement intervals following irradiation of the formation with a burst of fast neutrons. These measurement intervals may comprise a sequence of time gates following a delay after the neutron burst. The duration of the neutron bursts, of the delay between the burst and the start of the sequence, and of the individual time gates, may all be adjusted by a common, selected one of a finite number of scale factor values. The set of two measurement intervals is selected from among a number of possible sets as a function of a previously measured value of the decay characteristic. Each measurement interval set is used over only a specific range of decay characteristic values for which it has been determined, in accordance with a previously established relationship between the decay characteristic value and a function of the thermal neutron concentration measurements for the set, to afford enhanced statistical accuracy in the measured value of the decay characteristic. (author)

Measuring thermal neutron characteristics

International Nuclear Information System (INIS)

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

1983-01-01

A method for providing a background-compensated measurement of the level of inducted radiation within an earth formation is claimed. The formation is irradiated with a discrete burst of neutrons and the level of radiation in the formation measured. The level of background radiation is then measured. An average level of both measurements is obtained

Nuclear reactor, fuel assembly and neutron measuring system

International Nuclear Information System (INIS)

Chaki, Masao; Murase, Michio; Zukeran, Atsushi; Moriya, Kimiaki

1998-01-01

The present invention provides a BWR type reactor improved with the efficiency of used fuels and fuel economy by increasing a rated power and reducing exchange fuels. Namely, in a BWR type reactor at present, a thermal limit value is determined by conducting nuclear calculation of the reactor core based on data of reactor flow rate measurement and data of neutron flux measurement. However, since the neutron calculation of the reactor core is based on fuel assemblies while the points for the neutron measurement are present at the outside of the fuel assemblies, errors are caused. A margin including the errors has been used as a thermal limit value during operation. In the present invention, neutron fluxes in the fuel assembly as a base of the nuclear calculation can be measured by the same number of neutron detector tubes, but the number of the measuring points is increased to four times. With such procedures, errors caused by the difference of the neutron calculation and values at neutron measuring points can be reduced. As a result, a margin of the thermal limit value is reduced to increase the degree of freedom of reactor operation. Then, the economical property of the reactor operation can be improved. (N.H.)

Fission neutron output measurements at LANSCE

International Nuclear Information System (INIS)

Nelson, Ronald Owen; Haight, Robert C.; Devlin, Matthew J.; Fotiadis, Nikolaos; Laptev, Alexander; O'Donnell, John M.; Taddeucci, Terry N.; Tovesson, Fredrik; Ullmann, J.L.; Wender, Stephen A.; Bredeweg, T.A.; Jandel, M.; Vieira, D.J.; Wu, Ching-Yen; Becker, J.A.; Stoyer, M.A.; Henderson, R.; Sutton, M.; Belier, Gilbert; Chatillon, A.; Granier, Thierry; Laurent, Benoit; Taieb, Julien

2010-01-01

Accurate data for both physical properties and fission properties of materials are necessary to properly model dynamic fissioning systems. To address the need for accurate data on fission neutron energy spectra, especially at outgoing neutron energies below about 200 keV and at energies above 8 MeV, ongoing work at LANSCE involving collaborators from LANL, LLNL and CEA Bruyeres-le-Chatel is extending the energy range, efficiency and accuracy beyond previous measurements. Initial work in the outgoing neutron energy range from 1 to 7 MeV is consistent with current evaluations and provides a foundation for extended measurements. As part of these efforts, a new fission fragment detector that reduces backgrounds and improves timing has been designed fabricated and tested, and new neutron detectors are being assessed for optimal characteristics. Simulations of experimental designs are in progress to ensure that accuracy goals are met. Results of these measurements will be incorporated into evaluations and data libraries as they become available.

The measurement of neutron and neutron induced photon spectra in fusion reactor related assemblies

CERN Document Server

Unholzer, S; Klein, H; Seidel, K

2002-01-01

The spectral neutron and photon fluence (or flux) measured outside and inside of assemblies related to fusion reactor constructions are basic quantities of fusion neutronics. The comparison of measured spectra with the results of MCNP neutron and photon transport calculations allows a crucial test of evaluated nuclear data as generally used in fusion applications to be carried out. The experiments concern mixed neutron/photon fields with about the same intensity of the two components. An NE-213 scintillation spectrometer, well described by response matrices for both neutrons and photons, is used as proton-recoil and Compton spectrometer. The experiments described here in more detail address the background problematic of two applications, an iron benchmark experiment with an ns-pulsed neutron source and a deep penetration mock-up experiment for the investigation of the ITER in-board shield system. The measured spectral neutron and photon fluences are compared with spectra calculated with the MCNP code on the b...

Reduction of beta-interference in gamma-spectrometric measurements of neutron-irradiated geological material

International Nuclear Information System (INIS)

Garmann, L.B.

1986-01-01

The analytical technique for INAA, when applied to geological materials, is improved by introducing an electromagnetic field between sample and detector. This field lowers the bremsstrahlung background intensity in the gamma-spectrum by reducing the number of beta-particles reaching the detector. Thus precision, accuracy and lower detection limit are improved. The technique was used on alkalisyenite and on meteoritic material, rocks containing high quantities of sodium and iron, respectively. After neutron irradiation, the induced nuclides sup(24)Na and sup(59)Fe are responsible for high bremsstrahlung interference, which under normal analyitical conditions would mask any x-ray or gamma-ray peaks of interest. The technique is easily applied to multielement analysis of geological and biological materials. It can be combined with sophisticated spectrum-treating techniques such as spectrum stripping and spectrum smoothing, or coincidence-anticoincidence circuits. (author)

Measurement channel of neutron flow based on software

International Nuclear Information System (INIS)

Rivero G, T.; Benitez R, J. S.

2008-01-01

The measurement of the thermal power in nuclear reactors is based mainly on the measurement of the neutron flow. The presence of these in the reactor core is associated to neutrons released by the fission reaction of the uranium-235. Once moderate, these neutrons are precursors of new fissions. This process it is known like chain reaction. Thus, the power to which works a nuclear reactor, he is proportional to the number of produced fissions and as these depend on released neutrons, also the power is proportional to the number of present neutrons. The measurement of the thermal power in a reactor is realized with called instruments nuclear channels. To low power (level source), these channels measure the individual counts of detected neutrons, whereas to a medium and high power, they measure the electrical current or fluctuation of the same one that generate the fission neutrons in ionization chambers especially designed to detect neutrons. For the case of TRIGA reactors, the measurement channels of neutron flow use discreet digital electronic technology makes some decades already. Recently new technological tools have arisen that allow developing new versions of nuclear channels of simple form and compacts. The present work consists of the development of a nuclear channel for TRIGA reactors based on the use of the correlated signal of a fission chamber for ample interval. This new measurement channel uses a data acquisition card of high speed and the data processing by software that to the being installed in a computer is created a virtual instrument, with what spreads in real time, in graphic and understandable form for the operator, the power indication to which it operates the nuclear reactor. This system when being based on software, offers a major versatility to realize changes in the signal processing and power monitoring algorithms. The experimental tests of neutronic power measurement show a reliable performance through seven decades of power, with a

Spectrometric techniques 3

CERN Document Server

Vanasse, George A

2013-01-01

Spectrometric Techniques, Volume III presents the applications of spectrometric techniques to atmospheric and space studies. This book reviews the spectral data processing and analysis techniques that are of broad applicability.Organized into five chapters, this volume begins with an overview of the instrumentation used for obtaining field data. This text then reviews the contribution that space-borne spectroscopy in the thermal IR has made to the understanding of the planets. Other chapters consider the instruments that have recorded the planetary emission spectra. This book discusses as well

Fission neutron spectra measurements at LANSCE - Status and plans

International Nuclear Information System (INIS)

Haight, R. C.; Noda, S.; Nelson, R. O.; O'Donnell, J. M.; Devlin, M.; Chatillon, A.; Granier, T.; Taiebb, J.; Laurent, B.; Belier, G.; Becker, J. A.; Wu, C. Y.

2010-01-01

A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of 235 U, 238 U, 237 Np and 239 Pu. The range of outgoing energies measured so far is from 0.7 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date are summarized in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including measurements of fission neutrons below 0.7 MeV and improvements in the data above 8 MeV. (authors)

In-core neutron flux measurements at PARR using self powered neutron detector

International Nuclear Information System (INIS)

Hussain, A.; Ansari, S.A.

1989-10-01

This report describes experimental reactor physics measure ments at PARR using the in-core neutron detectors. Rhodium self powered neutron detectors (SPND) were used in the PARR core and several measurements were made aimed at detector calibration, response time determination and neutron flux measurements. The detectors were calibrated at low power using gold foils and full power by the thermal channel. Based on this calibration it was observed that the detector response remains almost linear throughout the power range. The self powered detectors were used for on-line determination of absolute neutron flux in the core as well as the spatial distribution of neutron flux or reactor power. The experimental, axial and horizontal flux mapping results at certain locations in the core are presented. The total response time of rhodium detector was experimentally determined to be about 5 minutes, which agree well with the theoretical results. Because of longer response time of SPND of the detectors it is not possible to use them in the reactor protection system. (author). 10 figs

Quasi-elastic measurements using neutron spin flippers

International Nuclear Information System (INIS)

Bleuel, M.; Fitzsimmons, M.R.; Lal, J.

2008-01-01

A method for low-resolution quasi-elastic measurements using commonly available components on a polarized neutron beam reflectometer is demonstrated. By amplitude modulation of the current in a neutron spin flipper placed between the neutron beam polarizer and polarization analyzer, the intensity of the neutron beam illuminating a sample is similarly modulated (or chopped). We show that the intensity contrast between subsequent chopped pulses is dramatically reduced by a sample that changes neutron velocity

Measurements of {sup 237}Np secondary neutron spectra

Energy Technology Data Exchange (ETDEWEB)

Kornilov, N.V.

1997-03-01

The activities carried out during the first year of the project are summarized. The main problems for Np spectra measurements arise from high intrinsic gamma-ray activity of the sample and admixture of the oxygen and iron nuclei. The inelastically scattered neutrons and the fission neutrons spectra for {sup 237}Np were measured by time-of-flight spectrometer of the IPPE at incident neutron energies {approx_equal}1.5 MeV, and {approx_equal}0.5 MeV. A solid tritium target and a Li-metallic target were used as neutron sources. The neutron scattering on C sample (C(n,n) standard reaction) was measured to normalize the Np data. The experimental data should be simulated by Monte Carlo method to correct the experimental data for oxygen and iron admixture as well as for multiple scattering of the neutrons in the sample. Therefore the response function of the spectrometer, and the neutron energy distribution from the source were investigated in detail. (author)

Neutron fluence measurement in nuclear facilities

International Nuclear Information System (INIS)

Camacho L, M.E.

1997-01-01

The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant 'Laguna Verde'. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the 'Centro de Metrologia de Radiaciones Ionizantes' of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author)

Radiochemical Means of Investigating Delayed Neutron Precursors

International Nuclear Information System (INIS)

Marmol, P. del

1968-01-01

Fast radiochemical methods used now for the determination of delayed neutron precursors are classified and reviewed: precipitations, solvent extractions, range experiments, milking, gas sweeping, isotopic and ion exchange, hot atom reactions and diffusion loss. Advantages and limitations of irradiation systems with respect to fast separations are discussed: external beams which allow faster separations only have low neutron fluxes, internal beams which are mostly fit for gaseous reactions; and rabbits for solution irradiations. Future prospects of radiochemical procedures are presented; among these, studies should be mostly oriented towards gaseous reactions which offer possibilities of isolating very short-lived delayed neutron precursors. Chemical procedures for delayed neutron precursor detection are compared with mass spectrometric and isotope separator techniques; it is concluded that the methods are complementary. (author)

Radiochemical Means of Investigating Delayed Neutron Precursors

International Nuclear Information System (INIS)

Marmol, P. del

1968-01-01

Fast radiochemical methods used now for the determination of delayed neutron precursors are classified and reviewed: precipitations, solvent extractions, range experiments, milking, gas sweeping, isotopic and ion exchange, hot-atom reactions and diffusion loss. Advantages and limitations of irradiation systems with respect to fast separations are discussed: external beams which allow faster separations only have low neutron fluxes, internal beams which are mostly fit for gaseous reactions; and rabbits for solution irradiations. Future prospects of radiochemical procedures are presented; among these, studies should be mostly oriented towards gaseous reactions which offer possibilities of isolating very short-lived delayed neutron precursors. Chemical procedures for delayed neutron precursor detection are compared with mass spectrometric and isotope-separator techniques; it is concluded that the methods are complementary. (author)

Spectrometric assembly for portable installations

International Nuclear Information System (INIS)

Kluger, A.; Popescu, C.

1997-01-01

The components of the portable spectrometric assembly are: - the detecting probe with Na I(Tl) crystal and air-tight case of industrial type; - a microcomputer; - a unit of analogical processing of the signal from the detecting probe; - a single-channel analyzer with adjustable threshold; - commands and display module; - a source of high voltage; - an electrical supply battery. The device uses the method of gamma photons detection in energetic windows. Through theoretical and experimental studies carried out during the prototype development phase, the superiority of this method has been proved as compared with the installations which make use of the classical principle of photon integral detection. The achieved prototype has a basic program enabling the setting of all working parameters (measuring time, discriminating thresholds, discriminators operating conditions, etc.). Through the included interface RS232 it is possible to transmit the data to a more powerful computer in order to continually process the results. The spectrometric assembly, realized on the basis of micro-computers, can be used in a wide range of applications: measurement of thickness and erosion of walls and tubes, measurement of level in closed containers, of soil density, etc. The adjustment for specific application is performed only through a program modification. (authors)

An improved fast neutron radiography quantitative measurement method

International Nuclear Information System (INIS)

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

2004-01-01

The validity of a fast neutron radiography quantification method, the Σ-scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the Σ-scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the Σ-scaling method could be successfully adopted for quantitative measurements in fast neutron radiography

Measurement of actinide neutron cross sections

International Nuclear Information System (INIS)

Firestone, Richard B.; Nitsche, Heino; Leung, Ka-Ngo; Perry, DaleL.; English, Gerald

2003-01-01

The maintenance of strong scientific expertise is critical to the U.S. nuclear attribution community. It is particularly important to train students in actinide chemistry and physics. Neutron cross-section data are vital components to strategies for detecting explosives and fissile materials, and these measurements require expertise in chemical separations, actinide target preparation, nuclear spectroscopy, and analytical chemistry. At the University of California, Berkeley and the Lawrence Berkeley National Laboratory we have trained students in actinide chemistry for many years. LBNL is a leader in nuclear data and has published the Table of Isotopes for over 60 years. Recently, LBNL led an international collaboration to measure thermal neutron capture radiative cross sections and prepared the Evaluated Gamma-ray Activation File (EGAF) in collaboration with the IAEA. This file of 35, 000 prompt and delayed gamma ray cross-sections for all elements from Z=1-92 is essential for the neutron interrogation of nuclear materials. LBNL has also developed new, high flux neutron generators and recently opened a 1010 n/s D+D neutron generator experimental facility

Measurement of natural background neutron

CERN Document Server

Li Jain, Ping; Tang Jin Hua; Tang, E S; Xie Yan Fong

1982-01-01

A high sensitive neutron monitor is described. It has an approximate counting rate of 20 cpm for natural background neutrons. The pulse amplitude resolution, sensitivity and direction dependence of the monitor were determined. This monitor has been used for natural background measurement in Beijing area. The yearly average dose is given and compared with the results of KEK and CERN.

Benchmark referencing of neutron dosimetry measurements

International Nuclear Information System (INIS)

Eisenhauer, C.M.; Grundl, J.A.; Gilliam, D.M.; McGarry, E.D.; Spiegel, V.

1980-01-01

The concept of benchmark referencing involves interpretation of dosimetry measurements in applied neutron fields in terms of similar measurements in benchmark fields whose neutron spectra and intensity are well known. The main advantage of benchmark referencing is that it minimizes or eliminates many types of experimental uncertainties such as those associated with absolute detection efficiencies and cross sections. In this paper we consider the cavity external to the pressure vessel of a power reactor as an example of an applied field. The pressure vessel cavity is an accessible location for exploratory dosimetry measurements aimed at understanding embrittlement of pressure vessel steel. Comparisons with calculated predictions of neutron fluence and spectra in the cavity provide a valuable check of the computational methods used to estimate pressure vessel safety margins for pressure vessel lifetimes

Application of neutron backscatter techniques to level measurement problems

International Nuclear Information System (INIS)

Leonardi-Cattolica, A.M.; McMillan, D.H.; Telfer, A.; Griffin, L.H.; Hunt, R.H.

1982-01-01

We have designed and built portable level detectors and fixed level monitors based on neutron scattering and detection principles. The main components of these devices, which we call neutron backscatter gauges, are a neutron emitting radioisotope, a neutron detector, and a ratemeter. The gauge is a good detector for hydrogen but is much less sensitive to most other materials. This allows level measurements of hydrogen bearing materials, such as hydrocarbons, to be made through the walls of metal vessels. Measurements can be made conveniently through steel walls which are a few inches thick. We have used neutron backscatter gauges in a wide variety of level measurement applications encountered in the petrochemical industry. In a number of cases, the neutron techniques have proven to be superior to conventional level measurement methods, including gamma ray methods

Application of instrumental neutron activation analysis of uranium in burn-up measurements using. gamma. -ray spectrometric method

Energy Technology Data Exchange (ETDEWEB)

Chao, H E; Lu, W D

1975-12-01

In uranium burnup measurements, the amount of uranium in the irradiated sample needs to be determined, and the application of instrumental neutron activation analysis for this purpose is investigated. The method uses the gamma-ray activities of /sup 239/Np and some short-lived fission products of half-lives no longer than a few days to determine the quantities of /sup 238/U and /sup 235/U respectively. The advantages of the method include: (1) the amounts of both /sup 235/U and /sup 238/U of the sample can be simultaneously determined with good accuracy, (2) the same sample may be used to determine both the fission numbers and the amount of uranium remaining simultaneously or one after another, thus the exact amount of the sample is not necessarily known, (3) since the amount of the sample needed for the determination is usually small, i.e., about 10 ..mu..g, it should be easily handled even for high-level burnup samples. The error of the method is about 3 percent for a single measurement. The burnup values measured for an irradiated natural uranium sample from three aliquots using several fission products are in good agreement. The effective cross section for /sup 235/U deduced from the burnup and the integrated flux from a cobalt monitor is found to be 589 +- 19 barn which is in agreement with the literature value of 577 +- 1 barn.

Secondary standard neutron detector for measuring total reaction cross sections

International Nuclear Information System (INIS)

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

1975-01-01

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

Procedure for measurement of anisotropy factor for neutron sources

International Nuclear Information System (INIS)

Creazolla, Prycylla Gomes

2017-01-01

Radioisotope neutron sources allow the production of reference fields for calibration of neutron detectors for radiation protection and analysis purposes. When the emission rate of these sources is isotropic, no correction is necessary. However, variations in source encapsulation and in the radioactive material concentration produce differences in its neutron emission rate, relative to the source axis, this effect is called anisotropy. In this study, is describe a procedure for measuring the anisotropy factor of neutron sources performed in the Laboratório de Metrologia de Neutrons (LN) using a Precision Long Counter (PLC) detector. A measurement procedure that takes into account the anisotropy factor of neutron sources contributes to solve some issues, particularly with respect to the high uncertainties associated with neutron dosimetry. Thus, a bibliographical review was carried out based on international standards and technical regulations specific to the area of neutron fields, and were later reproduced in practice by means of the procedure for measuring the anisotropy factor in neutron sources of the LN. The anisotropy factor is determined as a function of the angle of 90° in relation to the cylindrical axis of the source. This angle is more important due to its high use in measurements and also of its higher neutron emission rate if compared with other angles. (author)

Measurement of neutron total cross-sections for {sup nat}Dy at Pohang Neutron Facility

Energy Technology Data Exchange (ETDEWEB)

Shin, S. G.; Kye, Y. U.; Shvetsov, Valery; Cho, M. H. [POSTECH, Pohang (Korea, Republic of); Namkung, W.; Cho, M. H. [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Kim, G. N. [Kyungpook National Univ., Daegu (Korea, Republic of); Lee, M. W. [Dongnam Inst. of radiological and Medical Science, Busan (Korea, Republic of)

2013-05-15

There are few measurements for Dy below 100 eV. Moreover, there exist discrepancies among the measurements. In the present work, the total neutron cross-sections for {sup nat}Dy were measured by using the time-of-flight (TOF) method at the Pohang Neutron Facility (PNF). The PNF consists of an electron linac, a water-cooled Ta target, and an 11-m-long TOF path. The characteristics of PNF are described elsewhere. We also briefly discuss the future plan to verify our experimental result. We have measured the total neutron cross-sections of {sup nat}Dy in the neutron energy region from 0.1 eV to 100 eV with the TOF method at the Po hang Neutron Facility. The present result is in good agreement with the previous data and the evaluated data in ENDF/B-VI. We would like to get resonance parameters by using SAMMY or REFIT codes.

The theoretical study of full spectrum analysis method for airborne gamma-ray spectrometric data

International Nuclear Information System (INIS)

Ni Weichong

2011-01-01

Spectra of airborne gamma-ray spectrometry was found to be the synthesis of spectral components of radioelement sources by analyzing the constitution of radioactive sources for airborne gamma-ray spectrometric survey and establishing the models of gamma-ray measurement. The mathematical equation for analysising airborne gamma-ray full spectrometric data can be expressed into matrix and related expansions were developed for the mineral resources exploration, environmental radiation measurement, nuclear emergency monitoring, and so on. Theoretical study showed that the atmospheric radon could be directly computed by airborne gamma-ray spectrometric data with full spectrum analysis without the use of the accessional upward-looking detectors. (authors)

Development of Optical Fiber Detector for Measurement of Fast Neutron

International Nuclear Information System (INIS)

YAGI, Takahiro; KAWAGUCHI, Shinichi; MISAWA, Tsuyoshi; PYEON, Cheol Ho; UNESAKI, Hironobu; SHIROYA, Seiji; OKAJIMA, Shigeaki; TANI, Kazuhiro

2008-01-01

Measurement of fast neutron flux is important for investigation of characteristic of fast reactors. In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO 2 as converter material because 232 Th makes fission reaction with fast neutrons. The place where 232 Th can be used is limited by regulations because 232 Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without 232 Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons. (authors)

Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

Science.gov (United States)

Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velázquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttilä, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

2015-05-01

Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g (r ) inferred from neutron scattering measurements of the differential cross section d/σ d Ω from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. We describe our measurements and compare them with previous work.

Thermal neutron albedo measurements for multilithic reflectors

International Nuclear Information System (INIS)

Mehboob, Khurram; Ahmed, Raheel; Ali, Majid; Tabassam, Uzma

2013-01-01

Highlights: • Measurement of thermal neuron albedo for multilithic reflectors. • Modeling of experiments in MATLAB. • Comparison of numerical calculated and experimental values. • Study of thermal neutron albedo in different multilayered shielding. - Abstract: An experimental measurement of the thermal neutron (0.025 eV) albedo (αth) has been carried out for multilithic shielding by using Am–Be neutron source and BF 3 detector. The measured saturation value for the thermal albedo of paraffin wax has been found to be 0.734 ± 0.020, which is in close agreement to the corresponding value 0.83 quoted in the literature. The thermal neutron albedo has been measured for the multilayered shielding in copper–wood, copper–aluminum, wood–paraffin and paraffin–iron combinations in horizontal geometric configurations. Modeling and numerical simulation have been carried out by developing a MATLAB code which solves the diffusion equation in order to calculate the experimental results. Good agreement has been found between the numerical calculated and experimental results. The uncertainties in the measurements have also been calculated based on error propagation of the underlying Poisson distribution

Measurements of neutron intensity from liquid deuterium moderator of the cold neutron source of KUR

International Nuclear Information System (INIS)

Kawai, Takeshi; Ebisawa, Toru; Akiyoshi, Tsunekazu; Tasaki, Seiji

1990-01-01

The neutron spectra from the liquid deuterium moderator of the cold neutron source of KUR were measured by the time of flight (TOF) method similar to the previous measurements for the liquid hydrogen moderator. The cold neutron gain factor is found to be about 20 ∼ 28 times for the wavelength longer than 6 A. Cold neutron intensities from the liquid deuterium moderator and from the liquid hydrogen moderator are compared and discussed. (author)

Neutronic spectrometry measurements in sodium

International Nuclear Information System (INIS)

Perlini, G.; Acerbis, S.

1987-01-01

Measurements were made of neutronic penetration in sodium, which could serve as a reference and as a benchmark for computer codes. The model employed consisted of an assembly of 7 containers full of sodium for a total of 10 tons and a useful length of almost 4 metres. Measurements were performed at various depths along the central axis of the structure with proton recoil proportional counters. The energy band explored was between 100 and 650 keV. Here we report not only the original spectra of the impulses but also the neutronic spectra found by unfolding with the SPEC-4 code

Lithium-based neutron detectors

International Nuclear Information System (INIS)

Yursova, L.

1977-01-01

The problems of using scintillation lithium-based detectors (LiJ(Eu) and 6 LiJ(Eu)), as well as lithium glasses for neutron detection are described. As compared with the glasses the LiJ(Eu) monocrystal possesses substantially higher energy resolution, its luminescence yield is considerably higher (in some cases ten fold), its application makes possible gamma radiation discrimination with the energy approximately four times higher and its higher specific mass ensures better efficiency of gamma radiation counting. The only 6 LiJ(Eu) drawback is its high hydroscopicity as well as its possibility to be used only in a limited temperature range (maximum temperature +35 deg C). The lithium glass can be used (with the exception of spectrometric measurements and radiation mixed regions measurement) with more than 1 MeV gamma radiation energy in a wide temperature range, in agressive, corroding and acid media

Absolute measurement of neutron fluxes inside the reactor core

International Nuclear Information System (INIS)

Ajdacic, S. V.

1964-10-01

The subject of this work is the development and study of two methods of neutron measurements in nuclear reactors, the new method of high neutron flux measurements and the Li 6 -semiconductor neutron spectrometer. This work is presented in four sections: Section I. The introduction explains the need for neutron measurements in reactors. A critical survey is given of the existing methods of high neutron flux measurement and methods of fast neutron spectrum determination. Section II. Theoretical basis of the work of semiconductor counters and their most important characteristics are given. Section III. The main point of this section is in presenting the basis of the new method which the author developed, i.e., the long-tube method, and the results obtained by it, with particular emphasis on absolute measurement of high neutron fluxes. Advantages and limitations of this method are discussed in details at the end of this section. Section IV. A comparison of the existing semiconductor neutron spectrometers is made and their advantages and shortcomings underlined. A critical analysis of the obtained results with the Li 6 -semiconductor spectrometer with plane geometry is given. A new type of Li 6 -semiconductor spectrometer is described, its characteristics experimentally determined, and a comparison of it with a classical Li 6 -spectrometer made (author)

Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

International Nuclear Information System (INIS)

Kluson, J.; Jansky, B.

2009-01-01

Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

International Nuclear Information System (INIS)

Kluson, J.; Jansky, B.

2008-01-01

Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

Slow neutron mapping technique for level interface measurement

Science.gov (United States)

Zain, R. M.; Ithnin, H.; Razali, A. M.; Yusof, N. H. M.; Mustapha, I.; Yahya, R.; Othman, N.; Rahman, M. F. A.

2017-01-01

Modern industrial plant operations often require accurate level measurement of process liquids in production and storage vessels. A variety of advanced level indicators are commercially available to meet the demand, but these may not suit specific need of situations. The neutron backscatter technique is exceptionally useful for occasional and routine determination, particularly in situations such as pressure vessel with wall thickness up to 10 cm, toxic and corrosive chemical in sealed containers, liquid petroleum gas storage vessels. In level measurement, high energy neutrons from 241Am-Be radioactive source are beamed onto a vessel. Fast neutrons are slowed down mostly by collision with hydrogen atoms of material inside the vessel. Parts of thermal neutron are bounced back towards the source. By placing a thermal detector next to the source, these backscatter neutrons can be measured. The number of backscattered neutrons is directly proportional to the concentration of the hydrogen atoms in front of the neutron detector. As the source and detector moved by the matrix around the side of the vessel, interfaces can be determined as long as it involves a change in hydrogen atom concentration. This paper presents the slow neutron mapping technique to indicate level interface of a test vessel.

Automatic control unit for neutron transmission measurements

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Abdel-Kawy, A.; Eid, Y.; Ashry, A.; Mostafa, M.; Hamouda, I. (Atomic Energy Establishment, Inshas (Egypt). Reactor and Neutron Physics Dept.)

1981-01-01

An automatic transistorized unit has been designed to control the neutron transmission measurements carried out using the time-of-flight spectrometer. The function of the automatic unit is to control the measurements of the neutron counting rate distribution transmitted through a sample at a selected channel group of the time analyzer for a certain preadjusted time period. At the end of this time, the unit removes the sample out of the neutron beam, selects a second equal channel group of the time analyzer and provides the measurement of the neutron counting rate distribution for the same time period as in the case with the sample on. Such a measuring cycle can be repeated as much as the experiment requires. At the end of these cycles the stored information can be immediately obtained through the analyzer read out unit. It is found that the time of removing the sample out of the neutron beam or returning it back does not exceed 20 seconds instead of the five minutes required in case of manual operation. The most important advantages of using such an automatic unit are saving about 20 percent of the reactor operating time avoidng unnecessary radiation exposure of the experimentalists.

Measurements of neutron radiation in aircraft

International Nuclear Information System (INIS)

Vukovic, B.; Poje, M.; Varga, M.; Radolic, V.; Miklavcic, I.; Faj, D.; Stanic, D.; Planinic, J.

2010-01-01

Radiation environment is a complex mixture of charged particles of the solar and galactic origin, as well as of secondary particles created in an interaction of galactic cosmic particles with the nuclei of the Earth's atmosphere. A radiation field at aircraft altitude consists of different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. In order to measure a neutron component of the cosmic radiation, we investigated a few combinations of a track etch detector (CR-39, LR-115) with a plastic converter or boron foil. Detector calibration was performed on neutrons coming from the nuclear reactor, as well as in the CERN-EU high-energy Reference Field (CERF) facility. From November 2007 to September 2008, the neutron dose equivalent was measured by the track detectors during five aircraft flights, in the north geographical latitude from 21 o to 58 o ; the respective average dose rate, determined by using the D-4 detector (CR-39/B), was H n =5.9 μSv/h. The photon dose rate, measured by the electronic dosimeter RAD-60 SE, had the average value of H f =1.4 μSv/h.

Measurements of neutron radiation in aircraft

Energy Technology Data Exchange (ETDEWEB)

Vukovic, B.; Poje, M.; Varga, M.; Radolic, V.; Miklavcic, I. [Department of Physics, University of Osijek, Osijek, P.O. Box 125 (Croatia); Faj, D. [Clinical Hospital Osijek (Croatia); Stanic, D. [Department of Physics, University of Osijek, Osijek, P.O. Box 125 (Croatia); Planinic, J., E-mail: planinic@ffos.h [Department of Physics, University of Osijek, Osijek, P.O. Box 125 (Croatia)

2010-12-15

Radiation environment is a complex mixture of charged particles of the solar and galactic origin, as well as of secondary particles created in an interaction of galactic cosmic particles with the nuclei of the Earth's atmosphere. A radiation field at aircraft altitude consists of different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. In order to measure a neutron component of the cosmic radiation, we investigated a few combinations of a track etch detector (CR-39, LR-115) with a plastic converter or boron foil. Detector calibration was performed on neutrons coming from the nuclear reactor, as well as in the CERN-EU high-energy Reference Field (CERF) facility. From November 2007 to September 2008, the neutron dose equivalent was measured by the track detectors during five aircraft flights, in the north geographical latitude from 21{sup o} to 58{sup o}; the respective average dose rate, determined by using the D-4 detector (CR-39/B), was H{sub n}=5.9 {mu}Sv/h. The photon dose rate, measured by the electronic dosimeter RAD-60 SE, had the average value of H{sub f}=1.4 {mu}Sv/h.

Thermal neutron flux measurements using neutron-electron converters; Mesure de flux de neutrons thermiques avec des convertisseurs neutrons electrons

Energy Technology Data Exchange (ETDEWEB)

Le Meur, R; Lecomte, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

The operation of neutron-electron converters designed for measuring thermal neutron fluxes is examined. The principle is to produce short lived isotopes emitting beta particles, by activation, and to measure their activity not by extracting them from the reactor, but directly in the reactor using the emitted electrons to deflect the needle of a galvanometer placed outside the flux. After a theoretical study, the results of the measurements are presented; particular attention is paid to a new type of converter characterized by a layer structure. The converters are very useful for obtaining flux distributions with more than 10{sup 7} neutrons cm{sup -2}*sec{sup -1}. They work satisfactorily in pressurized carbon dioxide at 400 Celsius degrees. Some points still have to be cleared up however concerning interfering currents in the detectors and the behaviour of the dielectrics under irradiation. (authors) [French] On examine le fonctionnement de convertisseurs neutrons electrons destines a des mesures de flux de neutrons thermiques. Le principe est de former par activation des isotopes a periodes courtes et a emission beta et de mesurer leur activite non pas en les sortant du reacteur, mais directement en pile, utilisant les electrons emis pour faire devier l'aiguille d'un galvanometre place hors flux. Apres une etude theorique, on indique des resultats de mesures obtenus, en insistant particulierement sur un nouveau type de convertisseur, caracterise par sa structure stratifiee. Les convertisseurs sont tres interessants pour tracer, des cartes de flux a partir de 10{sup 7} neutrons cm{sup -2}*s{sup -1}. Ils sont utilisables pour des flux de 10{sup 14} neutrons cm{sup -2}*s{sup -1}. Ils fonctionnent correctement dans du gaz carbonique sous pression a 400 C. Des points restent cependant a eclaircir concernant les courants parasites dans les detecteurs et le comportement des dielectriques pendant leur irradiation. (auteur)

Interpretation of Spectrometric Measurements of Active Geostationary Satellites

Science.gov (United States)

Bedard, D.; Wade, G.

2014-09-01

Over 5000 visible near-infrared (VNIR) spectrometric measurements of active geostationary satellites have been collected with the National Research Council (NRC) 1.8m Plaskett telescope located at the Dominion Astrophysical Observatory (DAO) in Victoria, Canada. The objective of this ongoing experiment is to study how reflectance spectroscopy can be used to reliably identify specific material types on the surface of artificial Earth-orbiting objects. Active geostationary satellites were selected as the main subjects for this experiment since their orientation is stable and can be estimated to a high-level of confidence throughout a night of observation. Furthermore, for most geostationary satellites, there is a wide variety of sources that can provide some level of information as to their external surface composition. Notwithstanding the high number of measurements that have been collected to date, it was assumed that the experimenters would have a much greater success rate in material identification given the choice experimental subjects. To date, only the presence of aluminum has been confidently identified in some of the reflectance spectra that have been collected. Two additional material types, namely photovoltaic cells and polyimide film, the first layer of multi-layer insulation (MLI), have also been possibly identified. However uncertainties in the reduced spectral measurements prevent any definitive conclusion with respect to these materials at this time. The surprising lack of results with respect to material identification have forced the experimenters to use other data interpretation methods to characterize the spectral scattering characteristics of the studied satellites. The results from this study have already led to improvements in the ways that reflectance spectra from spacecraft are collected and analysed. Equally important, the data interpretation techniques elaborated over the course of this experiment will also serve to increase the body of

Measurement of epithermal neutrons by a coherent demodulation technique

CERN Document Server

Horiuchi, N; Takahashi, H; Kobayashi, H; Harasawa, S

2000-01-01

Epithermal neutrons have been measured using a neutron dosimeter via a coherent demodulation technique. This dosimeter consists of CsI(Tl)-photodiode scintillation detectors, four of which are coupled to neutron-gamma converting foils of various sizes. Neutron-gamma converting foils of In, Au and Co materials were used, each of which has a large capture cross section which peaks in the epithermal neutron energy region. The type of foil was selected according to the material properties that best correspond to the energy of the epithermal neutrons to be measured. In addition, the proposed technique was applied using Au-foils in order to measure the Cd ratio. The validity of the proposed technique was examined using an sup 2 sup 4 sup 1 Am-Be source placed in a testing stack of polyethylene blocks, and the results were compared with the theoretical values calculated by the Monte Carlo calculation. Finally, the dosimeter was applied for measuring epithermal neutrons and the Cd ratio in an experimental beam-tube o...

Fission neutron spectra measurements at LANSCE - status and plans

International Nuclear Information System (INIS)

Haight, Robert C.; Noda, Shusaku; Nelson, Ronald O.; O' Donnell, John M.; Devlin, Matt; Chatillon, Audrey; Granier, Thierry; Taieb, Julien; Laurent, Benoit; Belier, Gilbert; Becker, John A.; Wu, Ching-Yen

2009-01-01

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

A measurement of the absolute neutron beam polarization produced by an optically pumped 3He neutron spin filter

International Nuclear Information System (INIS)

Rich, D.R.; Bowman, J.D.; Crawford, B.E.; Delheij, P.P.J.; Espy, M.A.; Haseyama, T.; Jones, G.; Keith, C.D.; Knudson, J.; Leuschner, M.B.; Masaike, A.; Masuda, Y.; Matsuda, Y.; Penttilae, S.I.; Pomeroy, V.R.; Smith, D.A.; Snow, W.M.; Szymanski, J.J.; Stephenson, S.L.; Thompson, A.K.; Yuan, V.

2002-01-01

The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized 3 He spin filter and a relative transmission measurement technique. 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method

A spectrometrical method to measure the deuterium content in 2H-enriched water

International Nuclear Information System (INIS)

Dumke, I.

1980-04-01

A test method and spectrometer has been developed for emission-spectrometrical measurement of the deuterium content in water enriched with deuterium. The water sample is melted into a previously evacuated glas tube and a gas discharge is excited in vapour over the cooled sample to adjust to a low vapour pressure with high frequency. The intensities of the H(α) and D(α) lines appearing in the spectrum determine the D-content. Both lines were resolved by a Fabry-Perot interferometer and geometrically separated fed to two photodetectors. The remaining spectrum is filtered off. Following electronic calculation of the signals, the measured value is indicated which has to be corrected by a standard curve. The relative measuring accuracy is about +-1% for enrichments of over 1% D and less than +-5% in the region of 0.3-1% D. The detection limit is about 0.03% D (sample amount: 50 μl, average of 5 samples). (orig./HP) [de

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

Energy Technology Data Exchange (ETDEWEB)

Cecilia, A.; Baccaro, S.; Cemmi, A. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Colli, V.; Gambarini, G. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy); Rosi, G. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Scolari, L. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy)

2004-07-01

A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF{sub 2}:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH{sub 3}CH(NH{sub 2})COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. (authors)

Measurements of fission cross-sections and of neutron production rates

International Nuclear Information System (INIS)

Billaud, P.; Clair, C.; Gaudin, M.; Genin, R.; Joly, R.; Leroy, J.L.; Michaudon, A.; Ouvry, J.; Signarbieux, C.; Vendryes, G.

1958-01-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin 10 B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of 235 U. We intend to measure the variation of the neutron induced fission cross section of 235 U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of 235 U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF 3 proportional counters. c) Mean number ν of neutrons emitted in neutron induced fission. We measured the value of ν for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) α reaction by means of a 300 kV Cockcroft Walton generator. (author) [fr

Assay of fissionable isotopes in aqueous solution by pulsed neutron interrogation

International Nuclear Information System (INIS)

Campbell, P.; Gardy, E.M.; Boase, D.G.

1978-04-01

Non-destructive assay of uranium-235 and thorium-232 in aqueous nitric acid solutions has been accomplished by irradiation with pulses of neutrons from a 14-MeV Cockcroft-Walton neutron generator, and counting of the delayed neutrons emitted from the fissions induced. Design of the delayed neutron detector assemblies is described, together with the neutron pulse timing and counting systems. The effects of irradiation time, counting time, neutron moderation, detector design and sample geometry on the delayed neutron response from uranium-235 and 238 and thorium-232 are discussed. By using polyethylene to moderate the interrogating neutrons, solutions can be analyzed for both uranium-235 and thorium. Comparative analyses with chemical and γ-spectrometric methods show good agreement. The neutron method is rapid and is shown to be unaffected by the presence in solution of impurities such as iron, nickel, chromium, and aluminum. With the experimental equipment described, detection limits of 0.6 mg of 235 U and 9 mg of 232 Th in a sample volume of 25 mL have been achieved. Analyses of highly radioactive samples may be done easily since the measurements are not affected by the presence of large amounts of βγ radiation. Samples can be enclosed in small lead-shielded flasks during analysis to protect the analyst. The potential of the technique to on-line analysis applications is explored briefly. (author)

Radioactive waste reality as revealed by neutron measurements

International Nuclear Information System (INIS)

Schultz, F.J.

1995-01-01

To comprehend certain aspects of the contents of a radioactive waste container is not a trivial matter, especially if one is not allowed to open the container and peer inside. One of the suite of tools available to a practioner in the art of nondestructive assay is based upon neutron measurements. Neutrons, both naturally occuring and induced, are penertrating radiations that can be detected external to the waste container. The practioner should be skilled in applying the proper technique(s) to selected waste types. Available techniques include active and passive neutron measurements, each with their own strengths and weaknesses. The waste material itself can compromise the assay results by occluding a portion of the mass of fissile material present, or by multiplying the number of neutrons produced by a spontaneously fissioning mass. This paper will discuss the difficult, but albeit necessary marriage, between radiioactive waste types and alternative neutron measurement techniques

Absolute measurement of neutron fluxes inside the reactor core

Energy Technology Data Exchange (ETDEWEB)

Ajdacic, S V [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1964-10-15

The subject of this work is the development and study of two methods of neutron measurements in nuclear reactors, the new method of high neutron flux measurements and the Li{sup 6}-semiconductor neutron spectrometer. This work is presented in four sections: Section I. The introduction explains the need for neutron measurements in reactors. A critical survey is given of the existing methods of high neutron flux measurement and methods of fast neutron spectrum determination. Section II. Theoretical basis of the work of semiconductor counters and their most important characteristics are given. Section III. The main point of this section is in presenting the basis of the new method which the author developed, i.e., the long-tube method, and the results obtained by it, with particular emphasis on absolute measurement of high neutron fluxes. Advantages and limitations of this method are discussed in details at the end of this section. Section IV. A comparison of the existing semiconductor neutron spectrometers is made and their advantages and shortcomings underlined. A critical analysis of the obtained results with the Li{sup 6}-semiconductor spectrometer with plane geometry is given. A new type of Li{sup 6}-semiconductor spectrometer is described, its characteristics experimentally determined, and a comparison of it with a classical Li{sup 6}-spectrometer made (author)

Neutron capture cross section measurements: case of lutetium isotopes

International Nuclear Information System (INIS)

Roig, O.; Meot, V.; Belier, G.

2011-01-01

The neutron radiative capture is a nuclear reaction that occurs in the presence of neutrons on all isotopes and on a wide energy range. The neutron capture range on Lutetium isotopes, presented here, illustrates the variety of measurements leading to the determination of cross sections. These measurements provide valuable fundamental data needed for the stockpile stewardship program, as well as for nuclear astrophysics and nuclear structure. Measurements, made in France or in United-States, involving complex detectors associated with very rare targets have significantly improved the international databases and validated models of nuclear reactions. We present results concerning the measurement of neutron radiative capture on Lu 173 , Lu 175 , Lu 176 and Lu 177m , the measurement of the probability of gamma emission in the substitution reaction Yb 174 (He 3 ,pγ)Lu 176 . The measurement of neutron cross sections on Lu 177m have permitted to highlight the process of super-elastic scattering

Measured and evaluated neutron cross sections of elemental bismuth

International Nuclear Information System (INIS)

Smith, A.; Guenther, P.; Smith, D.; Whalen, J.; Howerton, R.

1980-04-01

Neutron total cross sections of elemental bismuth are measured with broad resolution from 1.2 to 4.5 MeV to accuracies of approx. = 1%. Neutron-differential-elastic-scattering cross sections of bismuth are measured from 1.5 to 4.0 MeV at incident neutron energy intervals of approx.< 0.2 MeV over the scattered-neutron angular range approx. = 20 to 160 deg. Differential neutron cross sections for the excitation of observed states in bismuth at 895 +- 12, 1606 +- 14, 2590 +- 15, 2762 +- 29, 3022 +- 21, and 3144 +- 15 keV are determined at incident neutron energies up to 4.0 MeV. An optical-statistical model is deduced from the measured values. This model, the present experimental results, and information available elsewhere in the literature are used to construct a comprehensive evaluated nuclear data file for elemental bismuth in the ENDF format. The evaluated file is particularly suited to the neutronic needs of the fusion-fission hybrid designer. 87 references, 10 figures, 6 tables

Neutron spectrum measurement using rise-time discrimination method

International Nuclear Information System (INIS)

Luo Zhiping; Suzuki, C.; Kosako, T.; Ma Jizeng

2009-01-01

PSD method can be used to measure the fast neutron spectrum in n/γ mixed field. A set of assemblies for measuring the pulse height distribution of neutrons is built up,based on a large volume NE213 liquid scintillator and standard NIM circuits,through the rise-time discrimination method. After that,the response matrix is calculated using Monte Carlo method. The energy calibration of the pulse height distribution is accomplished using 60 Co radioisotope. The neutron spectrum of the mono-energetic accelerator neutron source is achieved by unfolding process. Suggestions for further improvement of the system are presented at last. (authors)

First delayed neutron emission measurements at ALTO with the neutron detector TETRA

International Nuclear Information System (INIS)

Testov, D.; Ancelin, S.; Bettane, J.; Ibrahim, F.; Kolos, K.; Mavilla, G.; Niikura, M.; Verney, D.; Wilson, J.; Kuznetsova, E.; Penionzhkevich, Yu.; Smirnov, V.; Sokol, E.

2013-01-01

Beta-decay properties are among the easiest and, therefore, the first ones to be measured to study new neutron-rich isotopes. Eventually, a very small number of nuclei could be sufficient to estimate their lifetime and neutron emission probability. With the new radioactive beam facilities which have been commissioned recently (or will be constructed shortly) new areas of neutron-rich isotopes will become reachable. To study beta-decay properties of such nuclei at IPN (Orsay) in the framework of collaboration with JINR (Dubna), a new experimental setup including the neutron detector of high efficiency TETRA was developed and commissioned

Inventory verification measurements using neutron multiplicity counting

International Nuclear Information System (INIS)

Ensslin, N.; Foster, L.A.; Harker, W.C.; Krick, M.S.; Langner, D.G.

1998-01-01

This paper describes a series of neutron multiplicity measurements of large plutonium samples at the Los Alamos Plutonium Facility. The measurements were corrected for bias caused by neutron energy spectrum shifts and nonuniform multiplication, and are compared with calorimetry/isotopics. The results show that multiplicity counting can increase measurement throughput and yield good verification results for some inventory categories. The authors provide recommendations on the future application of the technique to inventory verification

Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source

International Nuclear Information System (INIS)

Hollas, C.L.; Goulding, C.A.; Myers, W.L.

1999-01-01

A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using 3 He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations

Pulsed neutron generator for mass flow measurement using the pulsed neutron activation technique

International Nuclear Information System (INIS)

Rochau, G.E.; Hornsby, D.R.; Mareda, J.F.; Riggan, W.C.

1980-01-01

A high-output, transportable neutron generator has been developed to measure mass flow velocities in reactor safety tests using the Pulsed Neutron Activation (PNA) Technique. The PNA generator produces >10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. The Millisecond Pulse (MSP) Neutron Tube, developed for this application, has an expected operational life of 1000 pulses, and it limits the generator pulse repetition rate to 12 pulses/minute. A semiconductor neutron detector is included in the generator package to monitor the neutron output. The control unit, which can be operated manually or remotely, also contains a digital display with a BCD output for the neutron monitor information. The digital logic of the unit controls the safety interlocks and rejects transient signals which could accidently fire the generator

A Novel Detector for High Neutron Flux Measurements

International Nuclear Information System (INIS)

Singo, T. D.; Wyngaardt, S. M.; Papka, P.; Dobson, R. T.

2010-01-01

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

Unfolding neutron spectra with BS-TLD system using genetic algorithms

Energy Technology Data Exchange (ETDEWEB)

Santos, Joelan A.L., E-mail: jasantos@cnen.gov.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Silva, Everton R. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Informatica; Ferreira, Tiago A.E. [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Estatistica e Informatica; Fonseca, Evaldo S. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Vilela, Eudice C., E-mail: ecvilela@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

2011-07-01

Due to the variability of neutron spectrum within the same environment, it is essential that the spectral distribution as function of energy to be characterized. To perform this task, the neutron spectrometer has a primary role in determining the neutron flux ({Phi}{sub E}(E)). Precise information allows radiological quantities establishment related to that spectrum but it is necessary, however, a series of steps with a spectrometric system that can cover a large interval of energy and whose answer is isotropic. The most widely used for accomplishing this task is the spectrometric Bonner spheres system. One of the biggest problems related to neutron spectrometry is the process of data analysis, known as unfolding. Most of the work undertaken to implement new techniques of this process, using data obtained with the scintillator {sup 6}LiI(I). However, characteristics related to the dead time make it not be so effective when used in high flow neutron fields. An alternative to this problem is the use of thermoluminescent detectors (TLD), but the codes used do not provide a more specific response matrix to unfolding the information obtained through these materials, which makes the development of a specific response matrix important to adequately characterize the response obtained by them. This paper proposes using a technique of artificial intelligence called genetic algorithm, which uses bio-inspired mathematical models and through the implementation of a specific matrix to unfolding data obtained from a combination of TLDs embedded in a system of Bonner spheres, such as thermal neutron detectors, to characterize the neutron spectrum as a function of energy. The results obtained with this method were in accordance with reference spectra, thus enables of this technique to unfolding neutrons spectra with BS-TLD system. (author)

Unfolding neutron spectra with BS-TLD system using genetic algorithms

International Nuclear Information System (INIS)

Santos, Joelan A.L.; Silva, Everton R.; Vilela, Eudice C.

2011-01-01

Due to the variability of neutron spectrum within the same environment, it is essential that the spectral distribution as function of energy to be characterized. To perform this task, the neutron spectrometer has a primary role in determining the neutron flux (Φ E (E)). Precise information allows radiological quantities establishment related to that spectrum but it is necessary, however, a series of steps with a spectrometric system that can cover a large interval of energy and whose answer is isotropic. The most widely used for accomplishing this task is the spectrometric Bonner spheres system. One of the biggest problems related to neutron spectrometry is the process of data analysis, known as unfolding. Most of the work undertaken to implement new techniques of this process, using data obtained with the scintillator 6 LiI(I). However, characteristics related to the dead time make it not be so effective when used in high flow neutron fields. An alternative to this problem is the use of thermoluminescent detectors (TLD), but the codes used do not provide a more specific response matrix to unfolding the information obtained through these materials, which makes the development of a specific response matrix important to adequately characterize the response obtained by them. This paper proposes using a technique of artificial intelligence called genetic algorithm, which uses bio-inspired mathematical models and through the implementation of a specific matrix to unfolding data obtained from a combination of TLDs embedded in a system of Bonner spheres, such as thermal neutron detectors, to characterize the neutron spectrum as a function of energy. The results obtained with this method were in accordance with reference spectra, thus enables of this technique to unfolding neutrons spectra with BS-TLD system. (author)

Neutron measurements at BRIT/BARC medical cyclotron facility of RMC, Parel

International Nuclear Information System (INIS)

Sathian, Deepa; Sathian, V.; Phandnis, U.V.; Soni, P.S.; Mohite, D.Y.

2005-01-01

Neutron leakage and its long distance propagation in the atmosphere from the intense neutron facilities such as high energy accelerators like Cyclotron are very important for the shielding design of the facilities and resulting dose reduction to nearby population, because of strong penetrability of high energy neutrons. The neutron interaction cross sections are highly energy dependent, so different methods are adopted for measuring different energy neutrons. The method also depends on the amount of neutron fluence rate expected at the location. When the fluence rate is very high, the foil activation is the best method for the measurement of neutron fluence rate. In foil activation technique an inactive material is activated by neutrons and the activity is measured and correlated to the neutron fluence rate. In this paper, neutron fluence rate measurement using different activation foils at medical cyclotron room of Radiation Medicine Centre (RMC) is discussed. (author)

Calibration of neutron yield activation measurements at JET using MCNP and furnace neutron transport codes

International Nuclear Information System (INIS)

Pillon, M.; Martone, M.; Verschuur, K.A.; Jarvis, O.N.; Kaellne, J.

1989-01-01

Neutron transport calculations have been performed using fluence ray tracing (FURNACE code) and Monte Carlo particle trajectory sampling methods (MCNP code) in order to determine the neutron fluence and energy distributions at different locations in the JET tokamak. These calculations were used to calibrate the activation measurements used in the determination of the absolute fusion neutron yields from the JET plasma. We present here the neutron activation response coefficients calculated for three different materials. Comparison of the MCNP and FURNACE results helps identify the sources of error in these neutron transport calculations. The accuracy of these calculations was tested by comparing the total 2.5 MeV neutron yields derived from the activation measurements with those obtained with calibrated fission chambers; agreement at the ±15% level was demonstrate. (orig.)

Definition and production of calibration standard neutron sources for radiation protection device calibration

International Nuclear Information System (INIS)

De Matos, E.

1987-01-01

To improve the characterization of radioprotection devices performances, it would be advisable to calibrate these devices in neutron spectra which are nearly like those met in practice (nuclear reactors, plutonium technology laboratories...). The purpose of this work is, in a first time, to choose the nature and the dimensions of the different shields used to achieve broad typical neutron spectra extending to lower energies from a 14.8 MeV neutron beam. The second step is the evaluation of spectral distribution and calculation of associated dosimetric quantities. For that, several spectrometric techniques are employed: on one hand, activation detectors and Bonner spheres method named rough spectrometry; on the other hand, an accurate spectrometry which uses recoil proton counters. The dosimetric quantities, especially the value of kerma deduced from these spectra must be in good agreement with those measured with a tissue equivalent ionization chamber [fr

Measured neutron beam line shielding effectiveness of several iron/polyethylene configurations

International Nuclear Information System (INIS)

Legate, G.L.; Howe, M.L.; Mundis, R.L.

1988-01-01

Neutron and gamma-ray leakage measurements were taken at various stages of shield construction of neutron flight path 5 (the Lash-up flight path) at LANSCE, to compare the relative effectiveness of several configurations. Dose equivalent rates were determined for three categories: ''low-energy neutrons'', below 20 MeV; ''high- energy neutrons'', above 20 MeV; and gamma rays, as measured by hand-held survey instruments. The low energy neutrons were measured by activation of an indium foil in a paraffin-filled cadmium canister, sized to be generally insensitive above 20 MeV. High-energy neutrons were measured by (n,2n) production of Carbon 11 in a plastic scintillator with a 20-MeV threshold. Thermal neutrons were not measured at the shield-leakage test points. Room-scattered neutrons were observed by Albatross IV detector readings, which were taken beside the shield as a measure of variation of room background as the shield configuration changed. 1 fig., 1 tab

Neutron yield measurements on a TMX endplug

International Nuclear Information System (INIS)

Slaughter, D.R.

1980-01-01

Neutron yield measurements were made on the east endplug of TMX using a calibrated recoil proton counter. The detector consists of a liquid scintillator (NE 213) with a pulse shape discrimination property that allows for identifying photon and neutron interactions. An energy threshold is established to suppress the response to scattered neutrons with energies lower than 1 to 2 MeV. Results indicate there are typical neutron yields of 2 to 3 x 10 11 n/s during a 25-ms discharge with 200 A of 20-keV neutral beam injection into the endplug

Neutron transmission measurements of poly and pyrolytic graphite crystals

Science.gov (United States)

Adib, M.; Abbas, Y.; Abdel-Kawy, A.; Ashry, A.; Kilany, M.; Kenawy, M. A.

The total neutron cross-section measurements of polycrystalline graphite have been carried out in a neutron wavelength from 0.04 to 0.78 nm. This work also presents the neutron transmission measurements of pyrolytic graphite (PG) crystal in a neutron wavelength band from 0.03 to 0.50 nm, at different orientations of the PG crystal with regard to the beam direction. The measurements were performed using three time-of-flight (TOF) spectrometers installed in front of three of the ET-RR-1 reactor horizontal channels. The average value of the coherent scattering amplitude for polycrystalline graphite was calculated and found to be bcoh = (6.61 ± 0.07) fm. The behaviour of neutron transmission through the PG crystal, while oriented at different angles with regard to the beam direction, shows dips at neutron wavelengths corresponding to the reflections from (hkl) planes of hexagonal graphite structure. The positions of the observed dips are found to be in good agreement with the calculated ones. It was also found that a 40 mm thick PG crystal is quite enough to reduce the second-order contamination of the neutron beam from 2.81 to 0.04, assuming that the incident neutrons have a Maxwell distribution with neutron gas temperature 330 K.

Neutron transmission measurements of poly and pyrolytic graphite crystals

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.; Kilany, M.

1989-01-01

The total neutron cross-section measurements of polycrystalline graphite have been carried out in a neutron wavelength from 0.04 to 0.78 nm. This work also presents the neutron transmission measurements of pyrolytic graphite (PG) crystal in a neutron wavelength band from 0.03 to 0.50 nm, at different orientations of the PG crystal with regard to the beam direction. The measurements were performed using three time-of-flight (TOF) spectrometers installed in front of three of the ET-RR-1 reactor horizontal channels. The average value of the coherent scattering amplitude for polycrystalline graphite was calculated and found to be b coh = (6.61 ± 0.07) fm. The behaviour of neutron transmission through the PG crystal, while orientated at different angles with regard to the beam direction, shows dips at neutron wavelengths corresponding to the reflections from (hk1) planes of hexagonal graphite structure. The positions of the observed dips are found to be in good agreement with the calculated ones. It was also found that a 40 mm thick PG crystal is quite enough to reduce the second-order contamination of the neutron beam from 2.81 to 0.04, assuming that the incident neutrons have a Maxwell distribution with neutron gas temperature 330 K. (author)

Calibration of quantitative neutron radiography method for moisture measurement

International Nuclear Information System (INIS)

Nemec, T.; Jeraj, R.

1999-01-01

Quantitative measurements of moisture and hydrogenous matter in building materials by neutron radiography (NR) are regularly performed at TRIGA Mark II research of 'Jozef Stefan' Institute in Ljubljana. Calibration of quantitative method is performed using standard brick samples with known moisture content and also with a secondary standard, plexiglas step wedge. In general, the contribution of scattered neutrons to the neutron image is not determined explicitly what introduces an error to the measured signal. Influence of scattered neutrons is significant in regions with high gradients of moisture concentrations, where the build up of scattered neutrons causes distortion of the moisture concentration profile. In this paper detailed analysis of validity of our calibration method for different geometrical parameters is presented. The error in the measured hydrogen concentration is evaluated by an experiment and compared with results obtained by Monte Carlo calculation with computer code MCNP 4B. Optimal conditions are determined for quantitative moisture measurements in order to minimize the error due to scattered neutrons. The method is tested on concrete samples with high moisture content.(author)

Determination of Magnesium in Needle Biopsy Samples of Muscle Tissue by Means of Neutron Activation Analysis

Energy Technology Data Exchange (ETDEWEB)

Brune, D; Sjoeberg, H E

1964-07-15

Magnesium has been determined by means of neutron-activation analysis in needle biopsy samples of the order of magnitude 1 mg dry weight. The procedure applied was to extract the Mg-27 activity from irradiated muscle tissue with concentrated hydrochloric acid followed by a fast hydroxide precipitation and gamma-spectrometric measurements. The Mg activity was recovered in the muscle tissue samples to (97 {+-} 2) per cent. The sensitivity for the magnesium determination is estimated as 0.3 {mu}g.

Measurement of neutron captured cross-sections in 1-2 MeV

Energy Technology Data Exchange (ETDEWEB)

Kim, Gi Dong; Kim, Young Sek; Kim, Jun Kon; Yang, Tae Keun [Korea Institutes of Geoscience and Mineral Resources, Taejeon (Korea)

2001-04-01

The measurement of neutron captured reaction cross sections was performed to build the infra system for the production of nuclear data. MeV neutrons were produced with TiT target and {sup 3}T(p,n){sup 3}He reaction. The characteristics of TiT thin film was analyzed with ERD-TOF and RBS. The results was published at Journal of the Korea Physical Society (SCI registration). The energy, the energy spread and the flux of the produced neutron were measured. The neutron excitation functions of {sup 12}C and {sup 16}O were obtained to confirm the neutron energy and neutron energy spread. The neutron energy spread found to be 1.3 % at the neutron energy of 2.077 MeV. The {sup 197}Au(n,{gamma}) reaction was performed to obtain the nerutron flux. The maximum neutron flux found to be 1 x 10{sup 8} neutrons/sec at the neutron energy of 2 MeV. The absolute efficiency of liquid scintillation detector was obtained in the neutron energy of 1 - 2 MeV. The fast neutron total reaction cross sections of Cu, Fe, and Au were measured with sample in-out method. Also the neutron captured reaction cross sections of {sup 63}Cu were measured with fast neutron activation method. The measurement of neutron total reaction cross sections and the neutron captured reaction cross sections with fast neutrons were first tried in Korea. The beam pulsing system was investigated and the code of calculating the deposition spectrums for primary gamma rays was made to have little errors at nuclear data. 25 refs., 28 figs., 14 tabs. (Author)

Passive detectors for neutron fluence measurement

International Nuclear Information System (INIS)

Holt, P.D.

1985-01-01

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

Earth formation porosity log using measurement of neutron energy spectrum

International Nuclear Information System (INIS)

1981-01-01

Methods and apparatus are described for measuring the porosity of subsurface earth formations in the vicinity of a well borehole by means of neutron well logging techniques. All the commercial techniques for measuring porosity currently available are not as accurate as desirable due to variations in the borehole wall diameter, in the borehole fluids (e.g. with chlorine content) in the casings of the borehole etc. This invention seeks to improve accuracy by using a measurement of the epithermal neutron population at one detector and the fast neutron population at a second detector, spaced approximately the same distance from a neutron source. The latter can be detected either by a fast neutron detector or indirectly by an inelastic gamma ray detector. Background correction can be made, and special detectors used, to discriminate against the detection of thermal neutrons or their resultant capture gamma rays. These fluctuations affect the measurement of thermal neutron populations. (U.K.)

Measurement of thermal neutron capture cross section

International Nuclear Information System (INIS)

Huang Xiaolong; Han Xiaogang; Yu Weixiang; Lu Hanlin; Zhao Wenrong

2001-01-01

The thermal neutron capture cross sections of 71 Ga(n, γ) 72 Ga, 94 Zr(n, γ) 95 Zr and 191 Ir(n, γ) 192 Ir m1+g,m2 reactions were measured by using activation method and compared with other measured data. Meanwhile the half-life of 72 Ga was also measured. The samples were irradiated with the neutron in the thermal column of heavy water reactor of China Institute of Atomic Energy. The activities of the reaction products were measured by well-calibrated Ge(Li) detector

Neutron background measurements in the underground laboratory of Modane

International Nuclear Information System (INIS)

Chazal, V.; Chambon, B.; De Jesus, M.; Drain, D.; Pastor, C.; Vagneron, L.; Brissot, R.; Cavaignac, J.F.; Stutz, A.; Giraud-Heraud, Y.

1997-07-01

Measurements of the background neutron environment, at a depth of 1780 m (4800 mWe) in the Underground Laboratory of Modane (L.S.M) are reported. Using a 6 Li liquid scintillator, the energy spectrum of the fast neutron flux has been determined. Monte-Carlo calculations of the (α,n) and spontaneous fission processes in the surrounding rock has been performed and compared to the experimental result. In addition, using two 3 He neutron counters, the thermal neutron flux has been measured. (author)

Neutron flux measurements in C-9 capsule pressure tube

International Nuclear Information System (INIS)

Barbos, D.; Roth, C. S.; Gugiu, D.; Preda, M.

2001-01-01

C-9 capsule is a fuel testing facility in which the testing consists of a daily cycle ranging between the limits 100% power to 50% power. C-9 in-pile section with sample holder an instrumentation are introduced in G-9 and G-10 experimental channels. The experimental fuel channel has a maximum value when the in-pile section (pressure tube) is in G-9 channel and minimum value in G-10 channel. In this paper the main goals are determination or measurements of: - axial thermal neutron flux distribution in C-9 pressure tube both in G-9 and G-10 channel; - ratio of maximum neutron flux value in G-9 and the same value in G-9 channel and the same value in G-10 channel; - neutron flux-spectrum. On the basis of axial neutron flux distribution measurements, the experimental fuel element in sample holder position in set. Both axial neutron flux distribution of thermal neutrons and neutron flux-spectrum were performed using multi- foil activation technique. Activation rates were obtained by absolute measurements of the induced activity using gamma spectroscopy methods. To determine the axial thermal neutron flux distribution in G-9 and G-10, Cu 100% wire was irradiated at the reactor power of 2 MW. Ratio between the two maximum values, in G-9 and G-10 channels, is 2.55. Multi-foil activation method was used for neutron flux spectrum measurements. The neutron spectra and flux were obtained from reaction rate measurements by means of SAND 2 code. To obtain gamma-ray spectra, a HPGe detector connected to a multichannel analyzer was used. The spectrometer is absolute efficiency calibrated. The foils were irradiated at 2 MW reactor power in previously determined maximum flux position resulted from wire measurements. This reaction rates were normalized for 10 MW reactor power. Neutron self shielding corrections for the activation foils were applied. The self-shielding corrections are computed using Monte Carlo simulation methods. The measured integral flux is 1.1·10 14 n/cm 2 s

Prospects for a new cold neutron beam measurement of the neutron lifetime

Energy Technology Data Exchange (ETDEWEB)

Dewey, M., E-mail: mdewey@nist.go [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Coakley, K., E-mail: kevin.coakley@nist.go [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Gilliam, D., E-mail: david.gilliam@nist.go [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Greene, G., E-mail: greenegl@ornl.go [Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Lab, Building 6010, Oak Ridge, TN 37831 (United States); Laptev, A., E-mail: alaptev@nist.go [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Nico, J., E-mail: jnico@nist.go [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Snow, W., E-mail: wsnow@indiana.ed [Indiana University/IUCF, Bloomington, IN 47408 (United States); Wietfeldt, F., E-mail: few@tulane.ed [Tulane University, New Orleans, LA 70118 (United States); Yue, A., E-mail: ayue@nist.go [Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States)

2009-12-11

In the most accurate cold neutron beam determination of the neutron lifetime based on the absolute counting of decay protons, the largest uncertainty was attributed to the absolute determination of the capture flux of the cold neutron beam. Currently an experimental effort is underway at the National Institute of Standards and Technology (NIST) that will significantly reduce this contribution to the uncertainty in the lifetime determination. The next largest source of uncertainty is the determination of the absolute count rate of decay protons, which contributes to the experimental uncertainty approximately at the 1 s level. Experience with the recent neutron radiative decay experiment, which used the neutron lifetime apparatus, has provided valuable insights into ways to reduce other uncertainties. In addition, the cold neutron fluence rate at NIST is presently 1.5 times greater than in the 2003 measurement, and there is the prospect for a significantly higher rate with the new guide hall expansion. This paper discusses an approach for achieving a determination of the neutron lifetime with an accuracy of approximately 1 s.

Recent high-accuracy measurements of the 1S0 neutron-neutron scattering length

International Nuclear Information System (INIS)

Howell, C.R.; Chen, Q.; Gonzalez Trotter, D.E.; Salinas, F.; Crowell, A.S.; Roper, C.D.; Tornow, W.; Walter, R.L.; Carman, T.S.; Hussein, A.; Gibbs, W.R.; Gibson, B.F.; Morris, C.; Obst, A.; Sterbenz, S.; Whitton, M.; Mertens, G.; Moore, C.F.; Whiteley, C.R.; Pasyuk, E.; Slaus, I.; Tang, H.; Zhou, Z.; Gloeckle, W.; Witala, H.

2000-01-01

This paper reports two recent high-accuracy determinations of the 1 S 0 neutron-neutron scattering length, a nn . One was done at the Los Alamos National Laboratory using the π - d capture reaction to produce two neutrons with low relative momentum. The neutron-deuteron (nd) breakup reaction was used in other measurement, which was conducted at the Triangle Universities Nuclear Laboratory. The results from the two determinations were consistent with each other and with previous values obtained using the π - d capture reaction. The value obtained from the nd breakup measurements is a nn = -18.7 ± 0.1 (statistical) ± 0.6 (systematic) fm, and the value from the π - d capture experiment is a nn = -18.50 ± 0.05 ± 0.53 fm. The recommended value is a nn = -18.5 ± 0.3 fm. (author)

ATW neutron spectrum measurements at LAMPF

Energy Technology Data Exchange (ETDEWEB)

Butler, G.W.; Littleton, P.E.; Morgan, G.L. [Los Alamos National Laboratory, NM (United States)] [and others

1995-10-01

Accelerator transmutation of waste (ATW) is a proposal to use a high flux of accelerator-produced thermalized neutrons to transmute both fission product and higher actinide commercial nuclear waste into stable or short-lived radioactive species in order to avoid long-term storage of nuclear waste. At LAMPF the authors recently performed experiments that were designed to measure the spectrum of neutrons produced per incident proton for full-scale proposed ATW targets of lead and lithium. The neutrons produced in such targets have a spectrum of energies that extends up to the energy of the incident proton beam, but the distribution peaks between 1 and 5 MeV. Transmutation reactions and fission of actinides are most efficient when the neutron energy is below a few eV, so the target must be surrounded by a non-absorbing material (blanket) to produce additional neutrons and reduce the energy of high energy neutrons without loss. The experiments with the lead target, 25 cm diameter by 40 cm long, were conducted with 800 MeV protons, while those with the lithium target, 25 cm diameter by 175 cm long, were conducted with 400 MeV protons. The blanket in both sets of experiments was a 60 cm diameter by 200 cm long annulus of lead that surrounded the target. Surrounding the blanket was a steel water tank with dimensions of 250 cm diameter by 300 cm long that simulated the transmutation region. A small sample pipe penetrated the length of the lead blanket and other sample pipes penetrated the length of the water tank at different radii from the beam axis so that the neutron spectra at different locations could be measured by foil activation. After irradiation the activated foil sets were extracted and counted with calibrated high resolution germanium gamma ray detectors at the Los Alamos nuclear chemistry counting facility.

Non-dispersive method for measuring longitudinal neutron coherence length using high frequency cold neutron pulser

International Nuclear Information System (INIS)

Kawai, T.; Tasaki, S.; Ebisawa, T.; Hino, M.; Yamazaki, D.; Achiwa, N.

1999-01-01

Complete text of publication follows. A non-dispersive method is proposed for measuring the longitudinal coherence length of a neutron using a high frequency cold neutron pulser (hf-CNP) placed between two multilayer spin splitters (MSS) which composes the cold neutron spin interferometer. Two spin eigenstates of a neutron polarized x-y plane are split non-dispersively and longitudinally in time by the hf-CNP which could reflect two components alternatively in time. The reduction of the visibility of interference fringes after being superposed by the second MSS is measured as a function of the frequency of the pulser by TOF method. From the zero visibility point obtained by extrapolation one could obtain the longitudinal coherence length of the neutron. (author)

Optimising polarised neutron scattering measurements--XYZ and polarimetry analysis

International Nuclear Information System (INIS)

Cussen, L.D.; Goossens, D.J.

2002-01-01

The analytic optimisation of neutron scattering measurements made using XYZ polarisation analysis and neutron polarimetry techniques is discussed. Expressions for the 'quality factor' and the optimum division of counting time for the XYZ technique are presented. For neutron polarimetry the optimisation is identified as analogous to that for measuring the flipping ratio and reference is made to the results already in the literature

Optimising polarised neutron scattering measurements--XYZ and polarimetry analysis

CERN Document Server

Cussen, L D

2002-01-01

The analytic optimisation of neutron scattering measurements made using XYZ polarisation analysis and neutron polarimetry techniques is discussed. Expressions for the 'quality factor' and the optimum division of counting time for the XYZ technique are presented. For neutron polarimetry the optimisation is identified as analogous to that for measuring the flipping ratio and reference is made to the results already in the literature.

Neutron cross section measurements at ORELA

International Nuclear Information System (INIS)

Dabbs, J.W.T.

1979-01-01

ORELA (Oak Ridge Electron Linear Accelerator) has been for the last decade the most powerful and useful pulsed neutron time-of-flight facility in the world, particularly in the broad midrange of neutron energies (10 eV to 1 MeV). This position will be enhanced with the addition of a pulse narrowing prebuncher, recently installed and now under test. Neutron capture, fission, scattering, and total cross sections are measured by members of the Physics and Engineering Physics Divisions of ORNL, and by numerous guests and visitors. Several fundamental and applied measurements are described, with some emphasis on instrumentation used. The facility comprises the accelerator and its target(s), 10 evacuated neutron flight paths having 18 measurement stations at flight path distances 8.9 to 200 meters, and a complex 4-computer data acquisition system capable of handling some 17,000 32-bit events/s from a total of 12 data input ports. The system provides a total of 2.08 x 10 6 words of data storage on 3 fast disk units. In addition, a dedicated PDP-10 timesharing system with a 250-megabyte disk system and 4 PDP-15 graphic display satellites permits on-site data reduction and analysis. More than 10 man-years of application software development supports the system, which is used directly by individual experiments. 12 figures, 1 table

A technique of measuring neutron spectrum

International Nuclear Information System (INIS)

Sarkar, P.K.; Kirthi, K.N.; Ganguly, A.K.

1975-01-01

Plastic scintillators have been used to measure fast neutron spectrum from various sources. Gamma background discrimination has been done by selecting thin scintillators and thereby achieving near 100% transmission of Compton-edge electrons. The measured distribution has been unfolded by using an iterative least square technique. This gives minimum variance and maximum likelihood estimate with error minimised. Smoothening of the observed distribution has been done by Fourier and time series analyses. The method developed is applicable in principle for the determination of spectra of high energy neutrons ranging from 1 MeV to 70 MeV and beyond. However, practical application of the method is limited by the non-availability of cross-section data for various neutron induced reactions with carbon and hydrogen present in the polymerised polystyrene scintillator. This procedure has been adopted in the present work for spectral determination up to 14 MeV neutrons using the published value of reaction and scattering cross-sections. The spectra of Po-Be, Pu-Be, Am-Be and Ra-Be arrived at agree well with the published spectra obtained by other methods. Spectrum from spontaneous fission of Cf-252 have also been measured and fitted to the expression N(E)=Esup(1/2)exp(-E/T). The fitted parameter T and spectral details agree well with those in published literature

Internal strain measurement using pulsed neutron diffraction at LANSCE

International Nuclear Information System (INIS)

Goldstone, J.A.; Bourke, M.A.M.; Shi, N.

1994-01-01

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction in the only technique that can make nondestructive measurements in the interior of components. By recording the change in crystalline lattice spacings, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all lattice reflections are recorded in each measurement, which allows for easy examination of heterogeneous materials such as metal matrix composites. Measurements made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) demonstrate the potential at pulsed sources for in-situ stress measurements at ambient and elevated temperatures

Activation method for measurement of neutron spectrum parameters

International Nuclear Information System (INIS)

Efimov, B.V.; Demidov, A.M.; Ionov, V.S.; Konjaev, S.I.; Marin, S.V.; Bryzgalov, V.I.

2007-01-01

Experimental researches of spectrum parameters of neutrons at nuclear installations RRC KI are submitted. The installations have different designs of the cores, reflector, parameters and types of fuel elements. Measurements were carried out with use of the technique developed in RRC KI for irradiation resonance detectors UKD. The arrangement of detectors in the cores ensured possibility of measurement of neutron spectra with distinguished values of parameters. The spectrum parameters which are introduced by parametrical representation of a neutrons spectrum in the form corresponding to formalism Westcott. On experimental data were determinate absolute values of density neutron flux (DNF) in thermal and epithermal area of a spectrum (F t , f epi ), empirical dependence of temperature of neutron gas (Tn) on parameter of a rigidity of a spectrum (z), density neutron flux in transitional energy area of the spectrum. Dependences of spectral indexes of nuclides (UDy/UX), included in UKD, from a rigidity z and-or temperatures of neutron gas Tn are obtained.B Tools of mathematical processing of results are used for activation data and estimation of parameters of a spectrum (F t , f epi , z, Tn, UDy/UX). In the paper are presented some results of researches of neutron spectrum parameters of the nuclear installations (Authors)

Characterization of the γ background in epithermal neutron scattering measurements at pulsed neutron sources

International Nuclear Information System (INIS)

Pietropaolo, A.; Tardocchi, M.; Schooneveld, E.M.; Senesi, R.

2006-01-01

This paper reports the characterization of the different components of the γ background in epithermal neutron scattering experiments at pulsed neutron sources. The measurements were performed on the VESUVIO spectrometer at ISIS spallation neutron source. These measurements, carried out with a high purity germanium detector, aim to provide detailed information for the investigation of the effect of the γ energy discrimination on the signal-to-background ratio. It is shown that the γ background is produced by different sources that can be identified with their relative time structure and relative weight

Measurement of radiation skyshine with D-T neutron source

Energy Technology Data Exchange (ETDEWEB)

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

2003-09-01

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

Neutron cross section measurement using the Oak Ridge Electron Linear Accelerator

International Nuclear Information System (INIS)

Winters, R.R.

1991-08-01

This report discusses: argon-40 -- neutron reaction total cross sections from 6.9 kev to 50 kev; The maxwellian averaged neutron capture cross section of oxygen-16; r-matrix parameter analysis of the lead-208 -- neutron reaction cross section measurement; r-matrix parameter analysis of the ORELA neutron transmission zirconium-90 low energy measurement; porting computer codes from the HP9000 to the IBM RISC/6000;and measurements of neutron reactions with strontium-88, zirconium-90, and calcium-40

Studies of neutron measurement methods for fusion plasma diagnostics

International Nuclear Information System (INIS)

Beimer, K.H.

1986-03-01

This thesis comprises several studies mainly devoted to neutron measurement systems for plasma diagnostics at JET (Joint European Torus). An in situ calibration of the U-235 fission chamber detectors located at JET is presented. These detectors are used for measuring the neutron yield from the thermonuclear reactions in the plasma. The energy spectrum of the neutrons from the reactions D(d,n) 3 He has been studied by means of a 3 He spectrometer. Especially, it was found that by measuring the width of the full energy peak in the response spectrum of the 3 He-spectrometer, the deuterium distribution in the deuterium targets used can be estimated. In order to measure different neutron energies it is necessary to obtain a detailed knowledge of the response of the spectrometer. Therefore, the response function to monoenergetic neutrons in the energy range 130-3030 keV was experimentally determined. Some work has been related to a design study of a 14 MeV spectrometer for neutron diagnostics. It is a combined proton-recoil and time-of-flight spectrometer for high resolution measurements. The main parts of it are the collimator, the scattering foil, and the detectors for the recoil protons and the scattered neutrons. The influence of proton straggling in the foil on the resolution and efficiency of the spectrometer has been studied. Furthermore, a three dimensional Monte Carlo code has been written and used for the design of the collimator. (author)

Neutron spectrometry measurements in iron

International Nuclear Information System (INIS)

Perlini, G.; Acerbis, S.; Carter, M.

1988-01-01

A compact structure was prepared for use in making measurements of neutron penetration in iron which could serve as reference data and as a check for computer codes. About 30 iron plates were put together giving a useful overall length of 130 cm. At various depths along the central axis of the iron block, measurements were made with liquid scintillator spectrometers and proton recoil proportional counters. The energy band explored was between 14 KeV and 10 MeV. Here we report the original spectra of the impulses and the neutron spectra found by the NE213 code based on the differential method and by unfolding with the SPEC4 code for liquid scintillation counters and proton recoil spectrometers, respectively. 12 figs., 60 tabs., 6 refs

One procedure for determination of the neutron flux in the nuclear reactor fuel

International Nuclear Information System (INIS)

Bulovic, V.; Krtil, J.; Maksimovic, Z.; Martinc, R.

1979-09-01

Possibility of determination of the neutron flux in the fuel of a heavy water reactor has been examined. In determination of the flux an iterative procedure was used to compare calculated and measured contents of several fission products. The former contents were determined by calculation of the burning process balance and the latter by non-destructive gamma-spectrometric analysis of fuel. The obtained results prove the possibility of such determination of not only the average value of the flux but also of the change of its intensity during utilization of fuel (author) [sr

Development of SiC Neutron Detector Assembly to Measure the Neutron Flux of the Reactor Core

Energy Technology Data Exchange (ETDEWEB)

Park, Se Hwan; Park, June Sic; Shin, Hee Sung; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Yong Kyun [Hanyang University, Seoul (Korea, Republic of)

2012-05-15

At present, the conventional detector to measure the neutron at harsh environment is a Self Powered Neutron Detector (SPND). Rhodium(Rh)-103 is in the SPND. When neutron is incident on the Rhodium, the neutron capture reaction occurs, and the Rh-103 is converted to Rh-104. The Rh-104 is decayed to Pd-104 by {beta}-decay, and electrons are generated as the decay products. Because of the half life of Rh-104, approximately 5 minutes are required for the SPND output to reach the equilibrium condition. Therefore the on-line monitoring of the nuclear reactor state is limited if the neutron flux in the reactor core is monitored with the SPND. Silicon carbide (SiC) has the possibility to be developed as neutron detector at harsh environment, because the SiC can be operative at high temperature and high neutron flux conditions. Previously, the basic operation properties of the SiC detector were studied. Also, the radiation response of the SiC detector was studied at high neutron and gamma dose rate. The measurement results for an ex-core neutron flux monitor or a neutron flux monitor of the spent fuel were published. The SiC detector was also developed as neutron detector to measure the fissile material with active interrogation method. However, the studies about the development of SiC detector are still limited. In the present work, the radiation damage effect of the SiC detector was studied. The detector structure was determined based on the study, and a neutron detector assembly was made with the SiC detectors. The neutron and gamma-ray response of the detector assembly is presented in this paper. The detector assembly was positioned in the HANARO research reactor core, the performance test was done. The preliminary results are also included in this paper

The neutron production rate measurement of an indigenously developed compact D-D neutron generator

Directory of Open Access Journals (Sweden)

Das Basanta Kumar

2013-01-01

Full Text Available One electrostatic accelerator based compact neutron generator was developed. The deuterium ions generated by the ion source were accelerated by one accelerating gap after the extraction from the ion source and bombarded to a target. Two different types of targets, the drive - in titanium target and the deuteriated titanium target were used. The neutron generator was operated at the ion source discharge potential at +Ve 1 kV that generates the deuterium ion current of 200 mA at the target while accelerated through a negative potential of 80 kV in the vacuum at 1.3×10-2 Pa filled with deuterium gas. A comparative study for the neutron yield with both the targets was carried out. The neutron flux measurement was done by the bubble detectors purchased from Bubble Technology Industries. The number of bubbles formed in the detector is the direct measurement of the total energy deposited in the detector. By counting the number of bubbles the total dose was estimated. With the help of the ICRP-74 neutron flux to dose equivalent rate conversion factors and the solid angle covered by the detector, the total neutron flux was calculated. In this presentation the operation of the generator, neutron detection by bubble detector and estimation of neutron flux has been discussed.

Temperature measurement with neutrons

International Nuclear Information System (INIS)

Bizard, G.; Durand, D.; Lecolley, J.F.; Lefebvres, F.; Marques, M.; Peter, J.; Tamain, B.

1998-01-01

The results presented in this report were obtained from the information provided by charged products. Another alternative consists in detecting the neutrons abundantly emitted particularly by heavy nuclei. The residue channel was studied in the 40 Ar + 197 Au at 60 MeV/nucleon by means of the neutron multidetector DEMON. The evolution of the multiplicity of neutrons emitted backwards in the framework of the heavy nucleus forwardly detected as a function of the residue velocity by a silicon detector, placed at 8 degrees and at 24.5 cm from target, agrees with the expected results i.e. an increase with the residue velocity hence with the collision violence. For the same detector the first measurements show similarly a linear increase of the apparent temperature of 4.0 to around 6.5 MeV for residue velocities varying from 0.5 to 1.3 cm/ns and masses ranging from 140 to 160 uma. This first results of the analysis show therefore a good behaviour of the assembly and especially of the couple DeMoN-SyReP

Measurements and calculations of neutron spectra and neutron dose distribution in human phantoms

International Nuclear Information System (INIS)

Palfalvi, J.

1984-11-01

The measurement and calculation of the radiation field around and in a phantom, with regard to the neutron component and the contaminating gamma radiation, are essential for radiation protection and radiotherapy purposes. The final report includes the development of the simple detector system, automized detector measuring facilities and a computerized evaluating system. The results of the depth dose and neutron spectra experiments and calculations in a human phantom are given

Spectrometric properties of crystals for low-energy x-ray diagnostics

International Nuclear Information System (INIS)

Barrus, D.m.; Blake, R.L.; Felthauser, H.; Fenimore, E.E.

1981-01-01

Quantitative diagnostics of fusion and astrophysical plasmas require knowledge of crystal spectrometric properties. To provide more reliable and versatile diagnostics of plasma conditions, increasingly accurate knowledge of crystal spectrometric properties is becoming necessary. A summary is presented of the following accurately measured parameters for the crystals KAP, RbAP, TlAP, NH 4 AP, NaAP, ADP, and EDDT: the interplanar spacing of atoms; the angle correction for normal and anomalous dispersion that is required for application of the Bragg formula; the thermal expansion coefficient near room temperature for commonly used planes; and the integrated coefficient of reflection

Influence of neutron scattering and source extent on the measurement of neutron energy spectra at ASDEX

International Nuclear Information System (INIS)

Huebner, K.; Baetzner, R.; Roos, M.; Robouch, B.V.; Ingrosso, L.; Wurz, H.

1987-08-01

The problem of nuclear emulsion measurements at ASDEX is considered. Besides the application of the VINIA-3DAMC software, this needs a description of the plasma neutron source, a model of the ASDEX structure, and calculation of the response of the nuclear emulsion to the incoming spectral neutron fluence. The latter is essential for comparing the numerical results with measurements at ASDEX. To treat this part, the NEPMC software was developed. The aim of the present work is to demonstrate the feasibility, reliability and usefulness of the method. Therefore simplified treatments for the ASDEX model, the plasma neutron source and the track statistics in the NEPMC software were used. Such calculations are of interest not only for nuclear emulsion measurements as well as any other neutron diagnostics, but also for all problems of neutron shielding for other diagnostics. (orig./GG)

Measurement of neutron spectra through composed material block bombarded with D-T neutrons

Energy Technology Data Exchange (ETDEWEB)

Zhu, T.H. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, P.O. BOX 919-213, Mian yang 621900 (China)], E-mail: zhutonghua@yahoo.com.cn; Liu, R.; Lu, X.X.; Jiang, L.; Wen, Z.W.; Wang, M.; Lin, J.F. [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, P.O. BOX 919-213, Mian yang 621900 (China)

2009-12-15

A 2-dimensional composed material assembly made of the iron and hydric block has been established. The neutron spectra from the assembly bombarded with 14-MeV neutrons at neutron generator have been obtained using the proton recoil technique with a stillbene detector. The detector positions were selected at the 60 deg., 120 deg., 180 deg. on the surface of the iron spherical shell. The background neutron spectra consisted of background and room return radiation were subtracted with combination of methods of experimental shielding and MCNP calculation. The uncertainty of results was 6.3-7.4%. The experiment results were analyzed and simulated by MCNP code and two data library. The difference is integral neutron flux (background neutron subtracted) of measured results greater than calculations with maximum of 21.2% in the range of 1-16 MeV.

Soil-Carbon Measurement System Based on Inelastic Neutron Scattering

International Nuclear Information System (INIS)

Orion, I.; Wielopolski, L.

2002-01-01

Increase in the atmospheric CO 2 is associated with concurrent increase in the amount of carbon sequestered in the soil. For better understanding of the carbon cycle it is imperative to establish a better and extensive database of the carbon concentrations in various soil types, in order to develop improved models for changes in the global climate. Non-invasive soil carbon measurement is based on Inelastic Neutron Scattering (INS). This method has been used successfully to measure total body carbon in human beings. The system consists of a pulsed neutron generator that is based on D-T reaction, which produces 14 MeV neutrons, a neutron flux monitoring detector and a couple of large NaI(Tl), 6'' diameter by 6'' high, spectrometers [4]. The threshold energy for INS reaction in carbon is 4.8 MeV. Following INS of 14 MeV neutrons in carbon 4.44 MeV photons are emitted and counted during a gate pulse period of 10 μsec. The repetition rate of the neutron generator is 104 pulses per sec. The gamma spectra are acquired only during the neutron generator gate pulses. The INS method for soil carbon content measurements provides a non-destructive, non-invasive tool, which can be optimized in order to develop a system for in field measurements

Novel fast-neutron activation counter for high repetition rate measurements

International Nuclear Information System (INIS)

Mahmood, S.; Springham, S. V.; Zhang, T.; Rawat, R. S.; Tan, T. L.; Krishnan, M.; Beg, F. N.; Lee, S.; Schmidt, H.; Lee, P.

2006-01-01

A fast-neutron beryllium activation counter has been constructed for neutron measurements on a high repetition rate deuterium plasma focus. Beryllium activation is especially suitable for measurements of DD neutron yields. The cross section for the relevant reaction, 9 Be(n,α) 6 He, results in a maximum sensitivity at the characteristic energy of the DD neutrons (∼2.5 MeV) and practically no sensitivity to neutrons with energies 6 He enabled the shot-to-shot neutron yield from the plasma focus to be measured for repetition rates from 0.2 to 3 Hz (and for a range of deuterium gas pressures). With careful analysis, the shot-to-shot yield can be measured up to a maximum repetition rate of 3 Hz, beyond which the pileup of counts from the previous shots reduces the accuracy of the measurements to an unacceptable level. This new beryllium activation counter has been cross-checked against an indium activation counter to obtain absolute neutron yields. At a charging voltage of 12.5 kV (bank energy of 2.2 kJ), the average neutron yield was found to be (7.9±0.7)x10 7 per shot (standard deviation of 4x10 7 ). It was found that activation of the plasma focus construction materials (especially aluminum) must be taken into account

Measurements of the energy spectrum of backscattered fast neutrons

International Nuclear Information System (INIS)

Segal, Y.

1976-03-01

Experimental measurements have been made of the energy spectra of neutrons transmitted through slabs of iron, lead and perspex for incident neutron energies of 0.5, 1.0, 1.5 and 1.8 MeV. The neutron energy measurements were made using a He-3 spectrometer. The dependence of the neutrons energy spectrum as a function of scattering thickness was determined. The neutrons source used was a 3MeV Van de Graaff accelerator with a tritium target using the H 3 (p,n) He 3 reaction. The results obtained by the investigator on energy dependence of transmitted neutrons as a function of thickness of scattering material were compared, where possible, with the results obtained by other workers. The comparisons indicated good agreement. The experiment's results are compared with MORSE Monte Carlo calculated values. It is worthwhile to note that direct comparison between measured cross section values and the recommended ones are very far from satisfactory. In almost all cases the calculated spectrum is harder than the experimental one, a situation common to the penetrating and the back-scattered flux

A proposed method of measuring the electric-dipole moment of the neutron by ultracold neutron interferometry

International Nuclear Information System (INIS)

Freedman, M.S.; Peshkin, M.; Ringo, G.R.; Dombeck, T.W.

1989-08-01

The use of an ultracold neutron interferometer incorporating an electrostatic accelerator having a strong electric field gradient to accelerate neutrons by their possible electric dipole moment is proposed as a method of measuring the neutron electric dipole moment. The method appears to have the possibility of extending the sensitivity of the measurement by several orders of magnitude, perhaps to 10 -30 e-cm. 9 refs., 3 figs

Some neutron measurements with simulated ING targets

Energy Technology Data Exchange (ETDEWEB)

Walker, J

1966-07-01

Thermal neutron fluxes in the vicinity of a simulated Intense Neutron Generator target have been measured using Mn and Au foils, and a small BF{sub 3} detector. The target was a Pb cylinder either 4-inch or 8-inch in diameter with a 1.2 g Ra-Be neutron source at its centre. This was centrally mounted in a 5' diam. x 5' high tank which was filled with either H{sub 2}O or D{sub 2}O moderator. Various gaps and absorbing annuli were placed around the target, and air-filled aluminum 'beam tubes' were mounted radially or tangentially from the target to simulate typical ING conditions. The measured thermal neutron fluxes were less than calculated at all radii. The single-age computation clearly gives large errors at large radii, but the multi-energy approach seems to give a useful indication of the thermal flux distribution in spite of the extreme simplicity of the model. The fall in measured fluxes at small radii in both D{sub 2}O and H{sub 2}O is most likely caused by absorption in the target material which is not allowed for in the computational model. (author)

Some neutron measurements with simulated ING targets

International Nuclear Information System (INIS)

Walker, J.

1966-01-01

Thermal neutron fluxes in the vicinity of a simulated Intense Neutron Generator target have been measured using Mn and Au foils, and a small BF 3 detector. The target was a Pb cylinder either 4-inch or 8-inch in diameter with a 1.2 g Ra-Be neutron source at its centre. This was centrally mounted in a 5' diam. x 5' high tank which was filled with either H 2 O or D 2 O moderator. Various gaps and absorbing annuli were placed around the target, and air-filled aluminum 'beam tubes' were mounted radially or tangentially from the target to simulate typical ING conditions. The measured thermal neutron fluxes were less than calculated at all radii. The single-age computation clearly gives large errors at large radii, but the multi-energy approach seems to give a useful indication of the thermal flux distribution in spite of the extreme simplicity of the model. The fall in measured fluxes at small radii in both D 2 O and H 2 O is most likely caused by absorption in the target material which is not allowed for in the computational model. (author)

Space resolved measurements of neutrons and ion emission on plasma focus

International Nuclear Information System (INIS)

Jaeger, U.

1980-05-01

This report describes space-resolved measurements of neutrons and of accelerated charged particles, emitted by a plasmafocus-device. The neutron source has been measured with one and two-dimensional paraffin collimators. The space resolution is 5 mm along the axis and the radius, with a time resolution of 10 ns. In order to make quantitative statements about the neutron yield, neutron-scattering, absorption and nuclear reactions were taken into account. Part of the neutron measurements are carried out together with time and space resolved measurements of the electron density to study possible correlations between nsub(e) and Ysub(n). The following results about the neutron measurement were obtained: The neutron emission reaches its maximum between 40 and 60 ns after the maximum compression. The emission region is limited to a well defined range of 0 50 ns it has been observed a broadening of the emission region in + z-direction. The emission profiles in lower and in higher pressure regimes are almost the same. (orig./HT) [de

Measurements of fast neutron-induced fission data of Np-237

Energy Technology Data Exchange (ETDEWEB)

Win, Than; Saito, Keiichiro; Baba, Mamoru; Iwasaki, Tomohiko; Ibaraki, Masanobu; Miura, Takako; Sanami, Toshiya; Nauchi, Yasushi; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1998-03-01

We have performed the following measurements for {sup 237}Np using the 4.5 MV Dynamitron accelerator of Tohoku University as the pulsed neutron source: (1) Prompt fission neutron spectrum for 0.62 MeV incident neutrons, and (2) Neutron-Induced fission cross-section between 10 and 100 keV. The prompt fission neutron spectrum was measured using TOF method with a heavily shielded NE213 scintillation detector. The Maxwellian temperature T{sub m} derived is 1.28 MeV, which is lower than that of 1.38 MeV in JENDL-3.2. The fission cross sections were measured between 10 - 100 keV. The results are between JENDL-3.2 and ENDF/B-VI. (author)

Influence of instrument design on neutron lifetime measurements

International Nuclear Information System (INIS)

Youmans, A.H.; Hopkinson, E.C.

1975-01-01

Commercially available logging services provide a measurement of the lifetime of thermal neutrons in formations adjacent to a borehole. This lifetime provides a measure of the macroscopic thermal neutron-capture cross-section Σ of the formation, which in turn is functionally related to the abundance and constituency of the rock matrix and contained fluids. Because the measurement is extremely sensitive to an abundance of trace elements like boron and gadolinium, it is very difficult to find rock formations with an accurately known value of Σ, which is required for the accuracy of the measuring system to be experimentally tested. Various theoretical studies published suggest that errors in the determination of Σ may occur because of the influence of borehole parameters and the effects of neutron diffusion. Experimental results are reported that demonstrate that the design of the instrument is crucial to the validity of any theoretical treatment of the subject. The influence of neutron diffusion and borehole effects can be overcome by optimal selection of spacing and shielding parameters

Measurement of neutron-production double-differential cross sections for continuous neutron-incidence reaction up to 100 MeV

International Nuclear Information System (INIS)

Kunieda, Satoshi; Watanabe, Takehito; Shigyo, Nobuhiro; Ishibashi, Kenji; Satoh, Daiki; Nakamura, Takashi; Haight, Robert C.

2004-01-01

The inclusive measurements of neutron-incident neutron-production double-differential cross sections in intermediate energy range is now being carried out. Spallation neutrons are used as incident particles. As a part of this, the experiment was performed by using of NE213 liquid organic scintillators to detect outgoing-neutrons. Incident-neutron energy was determined by time-of-flight technique, and outgoing-neutron energy spectrum was derived by unfolding light-output spectrum of NE213 with response functions calculated by SCINFUL-R. Preliminary cross sections were obtained up to about 100 MeV, and were compared with calculations by the GNASH code. It is hoped to get pure measurements by using measured response functions for our detectors used in this study. (author)

Thai Research Reactor (TRR-1/M1) Neutron Beam Measurements

International Nuclear Information System (INIS)

Ratanatongchai, Wichian

2009-07-01

Full text: Neutron beam tube of neutron radiography facility at Thai Research Reactor (TRR-1/M1) Thailand Institute of Nuclear Technology (public organization) is a divergent beam. The rectangular open-end of the beam tube is 16 cm x 17 cm while the inner-end is closed to the reactor core. The neutron beam size was measured using 20 cm x 40 cm neutron imaging plate. The measurement at the position 100 cm from the end of the collimator has shown that the beam size was 18.2 cm x 19.0 cm. Gamma ray in neutron the beam was also measured by the identical position using industrial X ray film. The area of gamma ray was 27.8 cm x 31.1 cm with the highest intensity found to be along the neutron beam circumference

Influence of target-scattered neutrons on cross-section measurements

International Nuclear Information System (INIS)

Lesiecki, H.; Cosack, M.; Siebert, B.R.L.

1985-01-01

Monoenergetic neutrons produced with accelerators are usually accompanied by degraded and secondary neutrons which arise from reactions of source neutrons in the material of the target construction. A Monte Carlo code was written which takes into account the kinematics and the angular source strength of the neutron producing reaction and the interactions of the neutrons with the material in the immediate vicinity of their production. The calculation of the spectral distribution of the neutron fluence is compared with the result of a time-of-flight measurement. (author)

Simulation of Light Collection for Neutron Electrical Dipole Moment measurement

Science.gov (United States)

Ji, Pan; nEDM Collaboration

2017-09-01

nEDM (Neutron Electrical Dipole moment) measurement addresses a critical topic in particle physics and Standard Model, that is CPT violation in neutron electrical dipole moment if detected in which the Time reversal violation is connected to the matter/antimatter imparity of the universe. The neutron electric dipole moment was first measured in 1950 by Smith, Purcell, and Ramsey at the Oak Ridge Reactor - the first intense neutron source. This measurement showed that the neutron was very nearly round (to better than one part in a million). The goal of the nEDM experiment is to further improve the precision of this measurement by another factor of 100. The signal from the experiment is detected by collecting the photons generated when neutron beams were captured by liquid helium 3. The Geant4 simulation project that I participate simulates the process of light collection to improve the design for higher capture efficiency. The simulated geometry includes light source, reflector, wavelength shifting fibers, wavelength shifting TPB and acrylic as in real experiment. The UV photons exiting from Helium go through two wavelength-shifting processes in TPB and fibers to be finally captured. Oak Ridge National Laboratory Neutron Electric Dipole Moment measurement project.

Measurements of anomalous neutron transport in bulk graphite

International Nuclear Information System (INIS)

Bowman, C.D.; Smith, G.A.; Vogelaar, B.; Howell, C.R.; Bilpuch, E.G.; Tornow, W.

2003-01-01

The neutron absorption of bulk granular graphite has been measured in a classical exponential diffusion experiment. Our first measurements of April 2002 implementing both exponential decay and pulsed die-away experiments and using the TUNL pulsed accelerator at Duke University as a neutron source indicated a capture cross section for graphite a striking factor of three lower than the measured value for carbon of 3.4 millibarns. Therefore a new exponential experiment with an improved geometry enabling greater accuracy has been performed giving an apparent cross section for carbon in the form of bulk granular graphite of less than 0.5 millibarns. This result confirms our first result and is also consistent with less than one part per million of boron in our graphite. The bulk density of the graphite is 1.02 compared with the actual particle density of 1.60 indicating a packing fraction of 0.64 or a void fraction of 0.36. We suspect that the apparent suppression of absorption in bulk graphite may be associated with the strong coherent diffraction of neutrons that dominates neutron transport in graphite. Coherent diffraction has never been taken into account in graphite reactor design and no neutron transport code including general use codes such as MCNP incorporate diffraction effects even though diffraction dominates many practical thermal neutron transport problems. (orig.)

Measurements of anomalous neutron transport in bulk graphite

Energy Technology Data Exchange (ETDEWEB)

Bowman, C.D.; Smith, G.A. [ADNA Corp., Los Alamos, NM (United States); Vogelaar, B. [Virginia Tech., Blacksburg, VA (United States); Howell, C.R.; Bilpuch, E.G.; Tornow, W. [Triangle Univ. Nuclear Lab., Duke Univ., Durham, NC (United States)

2003-07-01

The neutron absorption of bulk granular graphite has been measured in a classical exponential diffusion experiment. Our first measurements of April 2002 implementing both exponential decay and pulsed die-away experiments and using the TUNL pulsed accelerator at Duke University as a neutron source indicated a capture cross section for graphite a striking factor of three lower than the measured value for carbon of 3.4 millibarns. Therefore a new exponential experiment with an improved geometry enabling greater accuracy has been performed giving an apparent cross section for carbon in the form of bulk granular graphite of less than 0.5 millibarns. This result confirms our first result and is also consistent with less than one part per million of boron in our graphite. The bulk density of the graphite is 1.02 compared with the actual particle density of 1.60 indicating a packing fraction of 0.64 or a void fraction of 0.36. We suspect that the apparent suppression of absorption in bulk graphite may be associated with the strong coherent diffraction of neutrons that dominates neutron transport in graphite. Coherent diffraction has never been taken into account in graphite reactor design and no neutron transport code including general use codes such as MCNP incorporate diffraction effects even though diffraction dominates many practical thermal neutron transport problems. (orig.)

Neutron nuclear data measurements for criticality safety

Directory of Open Access Journals (Sweden)

Guber Klaus

2017-01-01

Full Text Available To support the US Department of Energy Nuclear Criticality Safety Program, neutron-induced cross section experiments were performed at the Geel Electron Linear Accelerator of the Joint Research Center Site Geel, European Union. Neutron capture and transmission measurements were carried out using metallic natural cerium and vanadium samples. Together with existing data, the measured data will be used for a new evaluation and will be submitted with covariances to the ENDF/B nuclear data library.

Procedures for measurement of anisotropy factor of neutron sources

International Nuclear Information System (INIS)

Creazolla, P.G.; Camargo, A.; Astuto, A.; Silva, F.; Pereira, W.W.

2017-01-01

Radioisotope sources of neutrons allow the production of reference fields for calibration of neutron measurement devices for radioprotection and analysis purposes. When the emission rate of these sources is isotropic, no correction is necessary. However, variations in the source capsule material and variations in the concentration of the emitting material may produce differences in its neutron emission rate relative to the source axis, this effect is called anisotropy. A proposed procedure for measuring the anisotropy factor of the sources belonging to the IRD/LNMRI/LN Neutron Metrology Laboratory using a Precision Long Counter (PLC) detector will be presented

Neutron spectrometry with Bonner spheres for area monitoring in particle accelerators

International Nuclear Information System (INIS)

Bedogni, R.

2011-01-01

Selecting the instruments to determine the operational quantities in the neutron fields produced by particle accelerators involves a combination of aspects, which is peculiar to these environments: the energy distribution of the neutron field, the continuous or pulsed time structure of the beam, the presence of other radiations to which the neutron instruments could have significant response and the large variability in the dose rate, which can be observed when moving from areas near the beam line to free-access areas. The use of spectrometric techniques in support of traditional instruments is highly recommended to improve the accuracy of dosimetric evaluations. The multi-sphere or Bonner Sphere Spectrometer (BSS) is certainly the most used device, due to characteristics such as the wide energy range, large variety of active and passive detectors suited for different workplaces, good photon discrimination and the simple signal management. Disadvantages are the poor energy resolution, weight and need to sequentially irradiate the spheres, leading to usually long measurement sessions. Moreover, complex unfolding analyses are needed to obtain the neutron spectra. This work is an overview of the BSS for area monitoring in particle accelerators. (authors)

Neutron Larmor diffraction measurements for materials science

International Nuclear Information System (INIS)

Repper, J.; Keller, T.; Hofmann, M.; Krempaszky, C.; Petry, W.; Werner, E.

2010-01-01

Neutron Larmor diffraction (LD) is a high-resolution diffraction technique based on the Larmor precession of polarized neutrons. In contrast to conventional diffraction, LD does not depend on the accurate measurement of Bragg angles, and thus the resolution is independent of the beam collimation and monochromaticity. At present, a relative resolution for the determination of the crystal lattice spacing d of Δd/d∼10 -6 is achieved, i.e. at least one order of magnitude superior to conventional neutron or X-ray techniques. This work is a first step to explore the application of LD to high-resolution problems in the analysis of residual stresses, where both the accurate measurement of absolute d values and the possibility of measuring type II and III stresses may provide additional information beyond those accessible by conventional diffraction techniques. Data obtained from Inconel 718 samples are presented.

Neutron Larmor diffraction measurements for materials science

Energy Technology Data Exchange (ETDEWEB)

Repper, J., E-mail: julia_repper@web.de [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Keller, T. [Max-Planck-Institut fuer Festkoerperforschung, 70569 Stuttgart (Germany)] [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Hofmann, M. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Krempaszky, C. [Christian-Doppler-Labor fuer Werkstoffmechanik von Hochleistungslegierungen, TU Muenchen, 85747 Garching (Germany); Petry, W. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Werner, E. [Lehrstuhl fuer Werkstoffkunde und Werkstoffmechanik, TU Muenchen, 85747 Garching (Germany)

2010-05-15

Neutron Larmor diffraction (LD) is a high-resolution diffraction technique based on the Larmor precession of polarized neutrons. In contrast to conventional diffraction, LD does not depend on the accurate measurement of Bragg angles, and thus the resolution is independent of the beam collimation and monochromaticity. At present, a relative resolution for the determination of the crystal lattice spacing d of {Delta}d/d{approx}10{sup -6} is achieved, i.e. at least one order of magnitude superior to conventional neutron or X-ray techniques. This work is a first step to explore the application of LD to high-resolution problems in the analysis of residual stresses, where both the accurate measurement of absolute d values and the possibility of measuring type II and III stresses may provide additional information beyond those accessible by conventional diffraction techniques. Data obtained from Inconel 718 samples are presented.

Neutron activation analysis of high purity tellurium

International Nuclear Information System (INIS)

Gil'bert, Eh.N.; Verevkin, G.V.; Obrazovskij, E.G.; Shatskaya, S.S.

1980-01-01

A scheme of neutron activation analysis of high purity tellurium is developed. Weighed amount of Te (0.5 g) is irradiated for 20-40 hr in the flux of 2x10 13 neutron/(cm 2 xs). After decomposition of the sample impurities of gold and palladium are determined by the extraction with organic sulphides. Tellurium separation from the remaining impurities is carried out by the extraction with monothiobenzoic acid from weakly acidic HCl solutions in the presence of iodide-ions, suppressing silver extraction. Remaining impurity elements in the refined product are determined γ-spectrometrically. The method allows to determine 34 impurities with determination limits 10 -6 -10 -11 g

Neutron fluence measurement in nuclear facilities.; Medicion de flujos de neutrones en instalaciones nucleares.

Energy Technology Data Exchange (ETDEWEB)

Camacho L, M E

1997-12-01

The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant `Laguna Verde`. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the `Centro de Metrologia de Radiaciones Ionizantes` of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author).

Kalman filter analysis of delayed neutron nondestructive assay measurements

International Nuclear Information System (INIS)

Aumeier, S. E.

1998-01-01

The ability to nondestructively determine the presence and quantity of fissile and fertile nuclei in various matrices is important in several nuclear applications including international and domestics safeguards, radioactive waste characterization and nuclear facility operations. Material irradiation followed by delayed neutron counting is a well known and useful nondestructive assay technique used to determine the fissile-effective content of assay samples. Previous studies have demonstrated the feasibility of using Kalman filters to unfold individual isotopic contributions to delayed neutron measurements resulting from the assay of mixes of uranium and plutonium isotopes. However, the studies in question used simulated measurement data and idealized parameters. We present the results of the Kalman filter analysis of several measurements of U/Pu mixes taken using Argonne National Laboratory's delayed neutron nondestructive assay device. The results demonstrate the use of Kalman filters as a signal processing tool to determine the fissile and fertile isotopic content of an assay sample from the aggregate delayed neutron response following neutron irradiation

The Karlsruhe Neutron Transmission Experiment (KANT): Spherical shell transmission measurements with 14 MeV neutrons on beryllium

International Nuclear Information System (INIS)

Moellendorff, U. von; Fischer, U.; Giese, H.; Kappler, F.; Tayama, R.; Wiegner, E.; Klein, H.; Alevra, A.

1996-01-01

This is a set of viewgraphs (no additional text) of a presentation on spherical shell transmission measurements with 14 MeV neutrons on beryllium; the cross for 9 Be(n,2n)2α for the energy range between threshold (1.85 MeV) and 20 MeV neutron energy is measured and the measurement is compared with the literature. Also, neutron leakage multiplication in spherical Be shells with various thicknesses are presented. Figs, tabs

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

International Nuclear Information System (INIS)

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

1983-08-01

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

Thermal neutron flux measurement using self-powered neutron detector (SPND) at out-core locations of TRIGA PUSPATI Reactor (RTP)

Science.gov (United States)

Ali, Nur Syazwani Mohd; Hamzah, Khaidzir; Mohamad Idris, Faridah; Hairie Rabir, Mohamad

2018-01-01

The thermal neutron flux measurement has been conducted at the out-core location using self-powered neutron detectors (SPNDs). This work represents the first attempt to study SPNDs as neutron flux sensor for developing the fault detection system (FDS) focusing on neutron flux parameters. The study was conducted to test the reliability of the SPND’s signal by measuring the neutron flux through the interaction between neutrons and emitter materials of the SPNDs. Three SPNDs were used to measure the flux at four different radial locations which located at the fission chamber cylinder, 10cm above graphite reflector, between graphite reflector and tank liner and fuel rack. The measurements were conducted at 750 kW reactor power. The outputs from SPNDs were collected through data acquisition system and were corrected to obtain the actual neutron flux due to delayed responses from SPNDs. The measurements showed that thermal neutron flux between fission chamber location near to the tank liner and fuel rack were between 5.18 × 1011 nv to 8.45 × 109 nv. The average thermal neutron flux showed a good agreement with those from previous studies that has been made using simulation at the same core configuration at the nearest irradiation facilities with detector locations.

Guidelines on calibration of neutron measuring devices

International Nuclear Information System (INIS)

Burger, G.

1988-01-01

The International Atomic Energy Agency and the World Health Organization have agreed to establish an IAEA/WHO Network of Secondary Standard Dosimetry Laboratories (SSDLs) in order to improve accuracy in applied radiation dosimetry throughout the world. These SSDLs must be equipped with, and maintain, secondary standard instruments, which have been calibrated against primary standards, and must be nominated by their governments for membership of the network. The majority of the existing SSDLs were established primarily to work with photon radiation (X-rays and gamma rays). Neutron sources are, however, increasingly being applied in industrial processes, research, nuclear power development and radiation biology and medicine. Thus, it is desirable that the SSDLs in countries using neutron sources on a regular basis should also fulfil the minimum requirements to calibrate neutron measuring devices. It is the primary purpose of this handbook to provide guidance on calibration of instruments for radiation protection. A calibration laboratory should also be in a position to calibrate instrumentation being used for the measurement of kerma and absorbed dose and their corresponding rates. This calibration is generally done with photons. In addition, since each neutron field is usually contaminated by photons produced in the source or by scatter in the surrounding media, neutron protection instrumentation has to be tested with respect to its intrinsic photon response. The laboratory will therefore need to possess equipment for photon calibration. This publication deals primarily with methods of applying radioactive neutron sources for calibration of instrumentation, and gives an indication of the space, manpower and facilities needed to fulfil the minimum requirements of a calibration laboratory for neutron work. It is intended to serve as a guide for centres about to start on neutron dosimetry standardization and calibration. 94 refs, 8 figs, 12 tabs

Measurements with the new PHE neutron survey instrument

International Nuclear Information System (INIS)

Eakins, J.S.; Tanner, R.J.; Hager, L.G.

2014-01-01

A novel design of survey instrument has been developed to accurately estimate ambient dose equivalent from neutrons with energies in the range from thermal to 20 MeV. The device features moderating and attenuating layers to ease measurement of fast and intermediate energy neutrons, combined with guides that channel low-energy neutrons to the single, central detector. A prototype of this device has been constructed and exposed to a set of calibration fields: the resulting measured responses are presented and discussed here, and compared against Monte Carlo data. A simple simulated workplace neutron field has also been developed to test the device. Measured response data have been determined for a prototype design of neutron survey instrument, using facilities at PHE and NPL. In general, the results demonstrated good directional invariance and agreed well with data obtained by Monte Carlo modelling, raising confidence in the accuracy of the response characteristics expected for the device. A simple simulated workplace field has also been developed and characterised, and the performance of the device assessed in it: agreement between measured and modelled results suggests that the device would behave as anticipated in real workplace fields. These performances will be investigated further in the future, as the design makes the transition from a research prototype to a commercially available instrument. (authors)

Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

Science.gov (United States)

Bhatia, C.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rundberg, R. S.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

2014-09-01

A program has been initiated to measure the energy dependence of selected high-yield fission products used in the analysis of nuclear test data. We present out initial work of neutron activation using a dual-fission chamber with quasi-monoenergetic neutrons and gamma-counting method. Quasi-monoenergetic neutrons of energies from 0.5 to 15 MeV using the TUNL 10 MV FM tandem to provide high-precision and self-consistent measurements of fission product yields (FPY). The final FPY results will be coupled with theoretical analysis to provide a more fundamental understanding of the fission process. To accomplish this goal, we have developed and tested a set of dual-fission ionization chambers to provide an accurate determination of the number of fissions occurring in a thick target located in the middle plane of the chamber assembly. Details of the fission chamber and its performance are presented along with neutron beam production and characterization. Also presented are studies on the background issues associated with room-return and off-energy neutron production. We show that the off-energy neutron contribution can be significant, but correctable, while room-return neutron background levels contribute less than <1% to the fission signal.

Ultra Low Level Environmental Neutron Measurements Using Superheated Droplet Detectors

Energy Technology Data Exchange (ETDEWEB)

Fernandes, A.C. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Estrada Nacional 10 - km 139.7, 2695-066 Bobadela LRS (Portugal); Centro de Fisica Nuclear, Universidade de Lisboa. Av. Prof. Gama Pinto, 2, 1649- 003 Lisboa (Portugal); Felizardo, M.; Girard, T.A.; Kling, A.; Ramos, A.R. [Centro de Fisica Nuclear, Universidade de Lisboa. Av. Prof. Gama Pinto, 2, 1649- 003 Lisboa (Portugal); Marques, J.G.; Prudencio, M.I.; Marques, R.; Carvalho, F.P. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Estrada Nacional 10 - km 139.7, 2695-066 Bobadela LRS (Portugal)

2015-07-01

Through the application of superheated droplet detectors (SDDs), the SIMPLE project for the direct search for dark matter (DM) reached the most restrictive limits on the spin-dependent sector to date. The experiment is based on the detection of recoils following WIMP-nuclei interaction, mimicking those from neutron scattering. The thermodynamic operation conditions yield the SDDs intrinsically insensitive to radiations with linear energy transfer below ∼150 keVμm{sup -1} such as photons, electrons, muons and neutrons with energies below ∼40 keV. Underground facilities are increasingly employed for measurements in a low-level radiation background (DM search, gamma-spectroscopy, intrinsic soft-error rate measurements, etc.), where the rock overburden shields against cosmic radiation. In this environment the SDDs are sensitive only to α-particles and neutrons naturally emitted from the surrounding materials. Recently developed signal analysis techniques allow discrimination between neutron and α-induced signals. SDDs are therefore a promising instrument for low-level neutron and α measurements, namely environmental neutron measurements and α-contamination assays. In this work neutron measurements performed in the challenging conditions of the latest SIMPLE experiment (1500 mwe depth with 50-75 cm water shield) are reported. The results are compared with those obtained by detailed Monte Carlo simulations of the neutron background induced by {sup 238}U and {sup 232}Th traces in the facility, shielding and detector materials. Calculations of the neutron energy distribution yield the following neutron fluence rates (in 10{sup -8} cm{sup -2}s{sup -1}): thermal (<0.5 eV): 2.5; epithermal (0.5 eV-100 keV): 2.2; fast (>1 MeV): 3.9. Signal rates were derived using standard cross sections and codes routinely employed in reactor dosimetry. The measured and calculated neutron count rates per unit of active mass were 0.15 ct/kgd and 0.33 ct/kg-d respectively. As the major

Measurements for the energy calibration of the TANSY neutron detectors

International Nuclear Information System (INIS)

Drozdowicz, K.; Hoek, M.; Aronsson, D.

1990-05-01

The report describes measurements performed for the energy calibration of the TANSY neutron detectors (two arrays of 16 detectors each one). The calibration procedure determines four calibration parameters for each detector. Results of the calibration measurements are given and test measurements are presented. A relation of the neutron detector calibration parameters to producer's data for the photomulipliers is analysed. Also the tests necessary during normal operation of the TANSY neutron spectrometer are elaborated (passive and active tests). A method how to quickly get the calibration parameters for a spare detector in an array of the neutron detectors is included

Poster - 25: Neutron Spectral Measurements around a Scanning Proton Beam

Energy Technology Data Exchange (ETDEWEB)

Kildea, John; Enger, Shirin; Maglieri, Robert; Mirzakhanian, Lalageh; Dahlgren, Christina Vallhagen; Dubeau, Jacques; Witharana, Sanjeeva [Medical Physics Unit, McGill University Health Centre, Medical Physics Unit, McGill University, Medical Physics Unit, McGill University, Medical Physics Unit, McGill University, Skandion Clinic, Detec Inc., Gatineau, Quebec, Detec Inc., Gatineau, Quebec (Canada)

2016-08-15

We describe the measurements of neutron spectra that we undertook around a scanning proton beam at the Skandion proton therapy clinic in Uppsala, Sweden. Measurements were undertaken using an extended energy range Nested Neutron Spectrometer (NNS, Detec Inc., Gatineau, QC) operated in pulsed and current mode. Spectra were measured as a function of location in the treatment room and for various Bragg peak depths. Our preliminary unfolded data clearly show the direct, evaporation and thermal neutron peaks and we can show the effect on the neutron spectrum of a water phantom in the primary proton beam.

Measurement of the neutron fraction event-by-event in DREAM

International Nuclear Information System (INIS)

Hauptman, John; Akchurin, N; Bedeschi, F; Carosi, R; Incagli, M; Cardini, A; Ciapetti, G; Lacava, F; Pinci, D; Ferrari, R; Gaudio, G; Franchino, S; Fraternali, M; Livan, M; Negri, A; Hauptman, J; Lee, S; La Rotonda, L; Meoni, E; Policicchio, A

2011-01-01

We have measured the neutron fraction event-by-event in beam test data taken at CERN by the DREAM collaboration. I will review these measurements in the context of the importance of neutrons to future high-precision calorimetry, and bring together the data from SPACAL, the GLD compensating calorimeter, and DREAM to estimate the impact neutron fraction measurements will make on hadronic energy resolution in dual-readout calorimeters.

Measurement of neutron spectra for photonuclear reaction with linearly polarized photons

Directory of Open Access Journals (Sweden)

Kirihara Yoichi

2017-01-01

Full Text Available Spectra of neutrons produced by a photonuclear reaction from a 197Au target were measured using 16.95 MeV linearly and circularly polarized photon beams at NewSUBARU-BL01 using a time-of-flight method. The difference in the neutron spectra between the cases of a linearly and circularly polarized photon was measured. The difference in the neutron yield increased with the neutron energy and was approximately threefold at the maximum neutron energy. In a direction perpendicular to that of the linear polarization, the neutron yields decreased as the neutron energy increased.

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

International Nuclear Information System (INIS)

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

1979-01-01

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

NEUTRON SPECTRUM MEASUREMENTS USING MULTIPLE THRESHOLD DETECTORS

Energy Technology Data Exchange (ETDEWEB)

Gerken, William W.; Duffey, Dick

1963-11-15

From American Nuclear Society Meeting, New York, Nov. 1963. The use of threshold detectors, which simultaneously undergo reactions with thermal neutrons and two or more fast neutron threshold reactions, was applied to measurements of the neutron spectrum in a reactor. A number of different materials were irradiated to determine the most practical ones for use as multiple threshold detectors. These results, as well as counting techniques and corrections, are presented. Some materials used include aluminum, alloys of Al -Ni, aluminum-- nickel oxides, and magesium orthophosphates. (auth)

Spatially resolved remote measurement of temperature by neutron resonance absorption

Energy Technology Data Exchange (ETDEWEB)

Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Kockelmann, W.; Pooley, D.E. [STFC, Rutherford Appleton Laboratory, ISIS Facility, Didcot OX11 0QX (United Kingdom); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Road, Sturbridge, MA 01566 (United States)

2015-12-11

Deep penetration of neutrons into most engineering materials enables non-destructive studies of their bulk properties. The existence of sharp resonances in neutron absorption spectra enables isotopically-resolved imaging of elements present in a sample, as demonstrated by previous studies. At the same time the Doppler broadening of resonance peaks provides a method of remote measurement of temperature distributions within the same sample. This technique can be implemented at a pulsed neutron source with a short initial pulse allowing for the measurement of the energy of each registered neutron by the time of flight technique. A neutron counting detector with relatively high timing and spatial resolution is used to demonstrate the possibility to obtain temperature distributions across a 100 µm Ta foil with ~millimeter spatial resolution. Moreover, a neutron transmission measurement over a wide energy range can provide spatially resolved sample information such as temperature, elemental composition and microstructure properties simultaneously.

Measurement of photoneutron spectrum at Pohang Neutron Facility

Energy Technology Data Exchange (ETDEWEB)

Kim, G.N.; Kovalchuk, V.; Lee, Y.S.; Skoy, V.; Cho, M.H.; Ko, I.S.; Namkung, W. [POSTECH, Pohang Accelerator Laboratory, Pohang, Kyungbuk (Korea)

2001-03-01

Pohang Neutron Facility, which is the pulsed neutron facility based on the 100-MeV electron linear accelerator, was constructed for nuclear data production in Korea. The Pohang Neutron Facility consists of an electron linear accelerator, a water-cooled Ta target with a water moderator and a time-of-flight path with an 11 m length. The neutron energy spectra are measured for different water levels inside the moderator and compared with the MCNP calculation. The optimum size of the water moderator is determined on the base of this result. The time dependent spectra of neutrons in the water moderator are investigated with the MCNP calculation. (author)

The neutron utilization and promotion program of TRR-II research reactor project in Taiwan

International Nuclear Information System (INIS)

Gone, J.K.; Huang, Y.H.

2001-01-01

The objective of the Taiwan research reactor system improvement and utilization promotion project is to reconstruct the old Taiwan research reactor (TRR), which was operated by the Institute of Nuclear Energy Research (INER) between 1973 and 1988, into a multi-purpose medium flux research reactor (TRR-II). The project started in 1998, and the new reactor is scheduled to have its first critical in June of 2006. The estimated maximum unperturbed thermal neutron flux (E 14 n/cm 2 sec, and it is about one order of magnitude higher than other operating research reactors in Taiwan. The new reactor will equip with secondary neutron sources to provide neutrons with different energies, which will be an essential tool for advanced material researches in Taiwan. One of the major tasks of TRR-II project is to promote domestic utilization of neutrons generated at TRR-II. The traditional uses of neutrons in fuel/material research, trace element analysis, and isotope production has been carried out at INER for many years. On the other hand, it is obvious that promotions of neutron spectrometric technique will be a major challenge for the project team. The limited neutron flux from operating research reactors had discouraged domestic users in developing neutron spectrometric technique for many years, and only few researchers in Taiwan are experienced in using spectrometers. It is important for the project team to encourage domestic researchers to use neutron spectrometers provided by TRR-II as a tool for their future researches in various fields. This paper describes the current status of TRR-II neutron utilization and promotion program. The current status and future plans for important issues such as staff recruiting, personnel training, international collaboration, and promotion strategy will be described. (orig.)

Time-of-flight neutron spectra measurements in Zenith

Energy Technology Data Exchange (ETDEWEB)

Barclay, F R; Coates, M S; Diment, K M; Durrani, S A; Gayther, D B; Poole, M J; Reed, D L

1962-01-15

Neutron spectra in the second core loading of ZENITH have been measured using a neutron chopper. Spectra at two positions in the reactore core were obtained over a range of temperatures extending to 650 deg C.

Measurements of fast neutrons by bubble detectors

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-03

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

Stress measurement by neutron diffraction method. Standard method using angular dispersion method and trial of using neutron IP

International Nuclear Information System (INIS)

Sasaki, Toshihiko; Takago, Shigeki

2016-01-01

This paper outlined a stress measurement method using neutrons, and introduced the application examples to stress measurement for metal-based composite materials. In the angular dispersion type measurement using a steady-state reactor type neutron source, the white beams taken out from a nuclear reactor are monochromatized (wavelength λ is a constant value) with a single crystal monochromator and utilized. As an example of measurement, there was the case as follows: the stress of a sintered material which has been put to practical use as valve seat part for automobiles was measured by the neutron method, and the deformation behavior during load was studied. This study performed neutron diffraction measurement using a residual stress analyzer (RESA: Diffractometer for Residual Stress Analysis) installed at JAEA's experimental reactor JRR-3. As a result, it was found that the stress state of the sintered composite material of Fe-Cr and TiN can be predicted with a micromechanics model. A neutron diffraction ring can be obtained using a neutron image plate (IP), where fine powder of gadolinium (Gd) was incorporated into IP for X-rays, and it can be used as an IP reader in the same way as the case of X-rays. A report has been introduced on the examination results of the highly accurate stress measurement by applying the cos α method devised for X-ray stress measurement to neutron diffraction ring. (A.O.)

Comparison of Thermal Neutron Flux Measured by Uranium 235 Fission Chamber and Rhodium Self-Powered Neutron Detector in MTR

International Nuclear Information System (INIS)

Fourmentel, D.; Filliatre, P.; Barbot, L.; Villard, J.-F.; Lyoussi, A.; Geslot, B.; Malo, J.-Y.; Carcreff, H.; Reynard-Carette, C.

2013-06-01

Thermal neutron flux is one of the most important nuclear parameter to be measured on-line in Material Testing Reactors (MTRs). In particular two types of sensors with different physical operating principles are commonly used: self-powered neutron detectors (SPND) and fission chambers with uranium 235 coating. This work aims to compare on one hand the thermal neutron flux evaluation given by these two types of sensors and on the other hand to compare these evaluations with activation dosimeter measurements, which are considered as the reference for absolute neutron flux assessment. This study was conducted in an irradiation experiment, called CARMEN-1, performed during 2012 in OSIRIS reactor (CEA Saclay - France). The CARMEN-1 experiment aims to improve the neutron and photon flux and nuclear heating measurements in MTRs. In this paper we focus on the thermal neutron flux measurements performed in CARMEN-1 experiment. The use of fission chambers to measure the absolute thermal neutron flux in MTRs is not very usual. An innovative calibration method for fission chambers operated in Campbell mode has been developed at the CEA Cadarache (France) and tested for the first time in the CARMEN-1 experiment. The results of these measurements are discussed, with the objective to measure with the best accuracy the thermal neutron flux in the future Jules Horowitz Reactor. (authors)

Neutron measurement by transportable spectrometer

International Nuclear Information System (INIS)

Anon.

1990-01-01

Two levels of neutron spectrometry are in regular use at nuclear power plants: some techniques used in the laboratory produce detailed spectra but require specialist operators, while simple instruments used by non-specialists to measure the neutron dose-rate to operators provide little spectral information. The standard portable instruments are therefore of no use when anomalous readings are obtained which require further investigation. AEA Technology at Winfrith has developed a Transportable Neutron Spectrometer (TNS) which is designed to produce reasonable spectra in routine use by staff with no specialist skill in spectroscopy, and high-quality spectra in the hands of skilled staff. The TNS provides a level of information intermediate between those currently available, and is also designed to solve the problem of imperfect dose response which is common in portable dosimeters. The TNS system consists of a power supply, a probe and a signal processing and data acquisition unit. (author)

A New Approach to Measuring the Neutron Decay Correlations with Cold Neutrons at LANSCE

International Nuclear Information System (INIS)

Wilburn, W.S.; Bowman, J.D.; Greene, G.L.; Jones, G.L.; Kapustinsky, J.S.; Penttila, S.I.

1999-01-01

Precision measurements of the neutron beta-decay correlations A, B, a, and b provide important tests of the standard model of electroweak interactions: a test of the unitarity of the first row of the CKM matrix, a search for new weak interactions, a test of the theory of nuclear beta decays, and a test of the conserved-vector-current hypothesis. The authors are designing an experiment at the LANSCE short-pulse spallation source to measure all four correlations to an order of magnitude better accuracy than the existing measurements. The accuracy of the previous measurements was limited by systematics. The design of the proposed experiment makes use of the pulsed nature of the LANSCE source to reduce systematic errors associated with the measurement of the neutron polarization as well as other systematic errors. In addition, the authors are developing silicon strip detectors for detecting both the proton and electron from the neutron decay

Neutron spatial distribution measurement with 6Li-contained thermoluminescent sheets

International Nuclear Information System (INIS)

Konnai, A.; Odano, N.; Sawamura, H.; Ozasa, N.; Ishikawa, Y.

2006-01-01

We have been developing a thermoluminescent (TL) sheet for photon dosimetry (TL sheet) with thermoluminescent material of LiF:Mg, Cu, P and a co-polymer of ethylene and tetrafluoroethylene. For the purpose of a development of simple method for neutron spatial distribution measurement, TL sheet for neutron detection (NTL sheet) is made by adding 94.7% enriched 6 LiF to TL sheet. TL material in TL sheet is directly excited by ionizing radiation whereas, in the case of neutron detection, TL material in NTL sheet is indirectly excited by neutron capture reaction. That is neutron distribution can be obtained with TL caused by α particle from 6 Li(n, α) 3 H reaction. Responses of NTL sheets to neutrons were examined at the neutron beam irradiation facility for Boron Neutron Capture Therapy (BNCT) in JRR-4 research reactor in Japan Atomic Energy Agency. TL and NTL sheets were exposed to striped and roundly distributed neutron fields. Attenuations of neutron flux in air and water were also observed using NTL sheets. TL sheets were also exposed on the same conditions and compared with NTL sheets. TL intensity ratios of NTL sheet to TL sheet were consistent with the calculated value from 6 Li content. Thermal neutron attenuation observed by NTL sheet also corresponded with the result measured by Au wire radioactivation and TLD chips, which were currently used in BNCT at JRR-4. These results were analyzed with by Monte Carlo simulation. The present results indicated that NTL sheet is applicable to measurement of neutron spatial distribution. (author)

Neutron diffraction measurements at the INES diffractometer using a neutron radiative capture based counting technique

Energy Technology Data Exchange (ETDEWEB)

Festa, G. [Centro NAST, Universita degli Studi di Roma Tor Vergata, Roma (Italy); Pietropaolo, A., E-mail: antonino.pietropaolo@roma2.infn.it [Centro NAST, Universita degli Studi di Roma Tor Vergata, Roma (Italy); Grazzi, F.; Barzagli, E. [CNR-ISC Firenze (Italy); Scherillo, A. [CNR-ISC Firenze (Italy); ISIS facility Rutherford Appleton Laboratory (United Kingdom); Schooneveld, E.M. [ISIS facility Rutherford Appleton Laboratory (United Kingdom)

2011-10-21

The global shortage of {sup 3}He gas is an issue to be addressed in neutron detection. In the context of the research and development activity related to the replacement of {sup 3}He for neutron counting systems, neutron diffraction measurements performed on the INES beam line at the ISIS pulsed spallation neutron source are presented. For these measurements two different neutron counting devices have been used: a 20 bar pressure squashed {sup 3}He tube and a Yttrium-Aluminum-Perovskite scintillation detector. The scintillation detector was coupled to a cadmium sheet that registers the prompt radiative capture gamma rays generated by the (n,{gamma}) nuclear reactions occurring in cadmium. The assessment of the scintillator based counting system was done by performing a Rietveld refinement analysis on the diffraction pattern from an ancient Japanese blade and comparing the results with those obtained by a {sup 3}He tube placed at the same angular position. The results obtained demonstrate the considerable potential of the proposed counting approach based on the radiative capture gamma rays at spallation neutron sources.

Spectrometric control of radionuclides production parameters

International Nuclear Information System (INIS)

Zhuk, I.; Potarenko, A.; Yarochevich, O.; Hluboky, N.; Kerko, P.; Bogdanov, V.; Dyatel, N.

2006-01-01

Full text: A radioactive preparations and sources are widely used all over the world for scientific, industrial and medical purposes. These preparations in Belarus are planned to produce by the Joint Belarussian-Russian Closed Joint Stock Company 'Isotope technologies' (CJSC IT). The company was created in 1998 by two leading scientific centers-SSI 'Joint Institute of Power and Nuclear Research-Sosny' the National Academy of Sciences of Belarus and the State Center of Science of the Russian Federation 'Scientific research institute of nuclear reactors'. One of the mainstream directions in CJSC IT activities is production of radioactive preparations for the industrial and scientific application (such as 133 Ba, 109 Cd, 63 Ni, 60 Co) and for the medical purposes (such as 19 '2Ir, 60 Co). All radioactive preparations have a good export potential and adequate to modern technical and consumer requirements. X-γ spectrometric analysis of considered radioactive sources is one of the basic methods for quality control of radioactive sources. At present, we are developing x-γ spectrometric support of purification process from contaminating radionuclides of 109 Cd -γ preparation and 63 Ni - β preparation. Work on x-γ spectrometric quality control of 133 Ba preparation is carried out. The description of the used equipment is given. Techniques of contaminating radionuclides determination (contents ∼10 - '6 from activity of the basic radionuclide) are presented. Problems of the choice of geometry of measurements of sources with activity about 10 7 -10 9 Bq and possible sources of errors are discussed. (author)

D-D neutron energy-spectra measurements in Alcator C

International Nuclear Information System (INIS)

Pappas, D.S.; Wysocki, F.J.; Furnstahl, R.J.

1982-08-01

Measurements of energy spectra of neutrons produced during high density (anti n/sub e/ > 2 x 10 14 cm -3 ) deuterium discharges have been performed using a proton-recoil (NE 213) spectrometer. A two foot section of light pipe (coupling the scintillator and photomultiplier) was used to extend the scintillator into a diagnostic viewing port to maximize the neutron detection efficiency while not imposing excessive magnetic shielding requirements. A derivative unfolding technique was used to deduce the energy spectra. The results showed a well defined peak at 2.5 MeV which was consistent with earlier neutron flux measurements on Alcator C that indicated the neutrons were of thermonuclear origin

Activation measurements of fast neutron radiative capture for 139La

International Nuclear Information System (INIS)

Luo, Junhua; Han, Jiuning; Liu, Rong; Jiang, Li; Liu, Zhenlai; Sun, Guihua; Ge, Suhong

2013-01-01

The neutron capture cross section of the neutron magic isotope 139 La has been measured relative to that of 27 Al by means of the activation method. The fast neutrons were produced via the 3 H(d,n) 4 He reaction on Pd-300 neutron generator. The natural high-purity La 2 O 3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The new values for E n =13.5±0.2, 14.1±0.2, and 14.8±0.2 MeV are found to be 1.30±0.08, 1.15±0.08 and 0.99±0.07 mb, respectively. Results were discussed and compared with some corresponding values found in the literature. - Highlights: ► D–T neutron source was used to measure cross sections using activation method. ► 27 Al(n,α) 24 Na was used as the monitor for the measurement. ► The cross sections for the (n,γ) reactions on neutron magic isotope 139 La have been measured. ► The data for 139 La(n,γ) 140 La reaction are presented. ► The results were compared with previous data and with evaluation data

Measurement of neutron diffusion length in heavy concrete

International Nuclear Information System (INIS)

Krejci, D.

2007-04-01

Using an aluminium sampler filled with heavy concrete the neutron diffusion length was determined, measuring thermal and fast neutrons over the whole beam hole with various threshold detectors using gold samples. These calculations should describe the neutron distribution in the whole concrete shield of the reactor and contribute to the investigation of the activation of the concrete shield using reactor parameters like operating time, power and neutron flux. Instrumentation, activation and positioning of the samples in the beam hole of the TRIGA Mark II reactor are described. (nevyjel)

Neutron cross section measurements for the Fast Breeder Program

International Nuclear Information System (INIS)

Block, R.C.

1979-06-01

This research was concerned with the measurement of neutron cross sections of importance to the Fast Breeder Reactor. The capture and total cross sections of fission products ( 101 102 104 Ru, 143 145 Nd, 149 Sm, 95 97 Mo, Cs, Pr, Pd, 107 Pd, 99 Tc) and tag gases (Kr, 78 80 Kr) were measured up to 100 keV. Filtered neutron beams were used to measure the capture cross section of 238 U (with an Fe filter) and the total cross section of Na (with a Na filter). A radioactive neutron capture detector was developed. A list of publications is included

Spectral distribution measurements of neutrons in paraffin borax mixtures

International Nuclear Information System (INIS)

El-Khatib, A.M.; Gaber, M.; Abou El-Khier, M.A.

1987-01-01

Neutron fluxes from a compact D-T neutron source has been measured in paraffin-borax mixtures by using activation foil detectors with successive threshold energies. The absorbed doses, backscattering coefficients and build-up factors were determined as well. The contribution of thermal and intermediate neutron dose is much lower, compared to that of fast neutrons. Among the used mediums, paraffin loaded with 4% borax concentration was found to be the best absorbing medium against neutrons at near depths within the blocks, while at a depth around 12 cm the neutron absorption (or scattering) is independent on the type of the used medium. (author)

Device for measuring neutron-flux distribution density

International Nuclear Information System (INIS)

Rozenbljum, N.D.; Mitelman, M.G.; Kononovich, A.A.; Kirsanov, V.S.; Zagadkin, V.A.

1977-01-01

An arrangement is described for measuring the distribution of neutron flux density over the height of a nuclear reactor core and which may be used for monitoring energy release or for detecting deviations of neutron flux from an optimal level so that subsequent balance can be achieved. It avoids mutual interference of detectors. Full constructional details are given. (UK)

Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

Energy Technology Data Exchange (ETDEWEB)

Ma, Jian [State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen 361102 (China); Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States); Sengupta, Mrinal K. [Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States); Thermo Fisher Scientific, Dionex Products, 445 Lakeside Drive, Sunnyvale, CA, 94085 (United States); Yuan, Dongxing [State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen 361102 (China); Dasgupta, Purnendu K., E-mail: Dasgupta@uta.edu [Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States)

2014-06-01

Highlights: • Compilation of principal official documents and major review articles, including the toxicology and chemistry of As. • Review of non-atomic spectrometric methods for speciation and detection of arsenic in aqueous samples (2005–2013) of the performance of field-usable methods. - Abstract: Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been

Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

International Nuclear Information System (INIS)

Ma, Jian; Sengupta, Mrinal K.; Yuan, Dongxing; Dasgupta, Purnendu K.

2014-01-01

Highlights: • Compilation of principal official documents and major review articles, including the toxicology and chemistry of As. • Review of non-atomic spectrometric methods for speciation and detection of arsenic in aqueous samples (2005–2013) of the performance of field-usable methods. - Abstract: Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been

Neutron stress measurement of W-fiber reinforced Cu composite

International Nuclear Information System (INIS)

Nishida, M.; Hanabusa, T.; Ikeuchi, Y.; Minakawa, N.

2003-01-01

Stress measurement methods using neutron and X-ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite. Surface stresses were measured by X-ray stress measurement with the sin 2 ψ method. Furthermore, the sin 2 ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Neutron-Activation Analysis of Biological Material with High Radiation Levels

Energy Technology Data Exchange (ETDEWEB)

Samsahl, K

1966-09-15

A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min.

Neutron-Activation Analysis of Biological Material with High Radiation Levels

International Nuclear Information System (INIS)

Samsahl, K.

1966-09-01

A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min

Ship Effect Measurements With Fiber Optic Neutron Detector

International Nuclear Information System (INIS)

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

2010-01-01

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

Training of reverse propagation neural networks applied to neutron dosimetry; Entrenamiento de redes neuronales de propagacion inversa aplicadas a la dosimetria de neutrones

Energy Technology Data Exchange (ETDEWEB)

Hernandez P, C. F.; Martinez B, M. R.; Leon P, A. A.; Espinoza G, J. G.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas, Zac. (Mexico); Mendez V, R. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 22, 28040 Madrid (Spain); Gallego, E. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, ETSI Industriales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); De Sousa L, M. A. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

Neutron dosimetry is of great importance in radiation protection as aims to provide dosimetric quantities to assess the magnitude of detrimental health effects due to exposure of neutron radiation. To quantify detriment to health is necessary to evaluate the dose received by the occupationally exposed personnel using different detection systems called dosimeters, which have very dependent responses to the energy distribution of neutrons. The neutron detection is a much more complex problem than the detection of charged particles, since it does not carry an electric charge, does not cause direct ionization and has a greater penetration power giving the possibility of interacting with matter in a different way. Because of this, various neutron detection systems have been developed, among which the Bonner spheres spectrometric system stands out due to the advantages that possesses, such as a wide range of energy, high sensitivity and easy operation. However, once obtained the counting rates, the problem lies in the neutron spectrum deconvolution, necessary for the calculation of the doses, using different mathematical methods such as Monte Carlo, maximum entropy, iterative methods among others, which present various difficulties that have motivated the development of new technologies. Nowadays, methods based on artificial intelligence technologies are being used to perform neutron dosimetry, mainly using the theory of artificial neural networks. In these new methods the need for spectrum reconstruction can be eliminated for the calculation of the doses. In this work an artificial neural network or reverse propagation was trained for the calculation of 15 equivalent doses from the counting rates of the Bonner spheres spectrometric system using a set of 7 spheres, one of 2 spheres and two of a single sphere of different sizes, testing different error values until finding the most appropriate. The optimum network topology was obtained through the robust design

Data reduction for a high-throughput neutron activation analysis system

International Nuclear Information System (INIS)

Bowman, W.W.

1979-01-01

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

Workplace testing of the new single sphere neutron spectrometer based on Dysprosium activation foils (Dy-SSS)

International Nuclear Information System (INIS)

Bedogni, R.; Gómez-Ros, J.M.; Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Pérez, L.; Angelone, M.; Tana, L.

2012-01-01

A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).

Workplace testing of the new single sphere neutron spectrometer based on Dysprosium activation foils (Dy-SSS)

Science.gov (United States)

Bedogni, R.; Gómez-Ros, J. M.; Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Pérez, L.; Angelone, M.; Tana, L.

2012-08-01

A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).

Workplace testing of the new single sphere neutron spectrometer based on Dysprosium activation foils (Dy-SSS)

Energy Technology Data Exchange (ETDEWEB)

Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN-LNF (Frascati National Laboratories), Via E. Fermi n. 40-00044 Frascati (Italy); Gomez-Ros, J.M. [INFN-LNF (Frascati National Laboratories), Via E. Fermi n. 40-00044 Frascati (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Perez, L. [INFN-LNF (Frascati National Laboratories), Via E. Fermi n. 40-00044 Frascati (Italy); Angelone, M. [ENEA C.R. Frascati, C.P. 65, 00044 Frascati (Italy); Tana, L. [A.O. Universitaria Pisana-Ospedale S. Chiara, Via Bonanno Pisano, Pisa (Italy)

2012-08-21

A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).

Lifetime measurement of prompt neutrons using the neutronic noise analysis

International Nuclear Information System (INIS)

Ortiz Servin, J.J.

1992-01-01

The purpose of this work is to estimate the life of the prompt neutrons, i, of a nuclear reactor utilizing the neutron noise analysis. This technique carry to development of mathematical model that is valid for lower powers reactor. The equation resulting convey to the observation about power spectrum behaviour respect to the frecquency. In this case, the reactor in study is the Triga Mark III of Nuclear Center of Mexico that it was provided of fission chambers for register the neutron fluxes. These fluxes was digitized and storage in computer disc as signals dependents of time, for later apply the Fourier Transformation and obtain the spectras. The spectras measured to different reactor powers were adjusted to the development equation before, using the method of square minimum and so estimate the parameter i. The analysis of results throw a value of 22.73 +/- 0.92 μs. On the other hand, the calculate value to the resolve the kinetic equation of reactor defer in lower than 4 % about the estimate. Of this, it concludes that the model utilized is trusty with a good mistake margin, moreover of that the technique of Neutron Noise analysis demonstrate be competitive (Author)

Measurement of the lunar neutron density profile

International Nuclear Information System (INIS)

Woolum, D.S.; Burnett, D.S.; Furst, M.; Weiss, J.R.

1975-01-01

An in situ measurement of the lunar neutron density from 20 to 400 g cm -2 depth below the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment (LNPE) using particle tracks produced by the 10 B (n,α) 7 Li reaction. Both the absolute magnitude and the depth profile of the neutron density are in good agreement with theoretical calculations by Lingenfelter, Canfield, and Hampel. However, relatively small deviations between experiment and theory in the effect of Cd absorption on the neutron density and in the relative 149 Sm to 157 Gd capture rates reported previously (Russ et al., 1972) imply that the true lunar 157 Gd capture rate is about one half of that calculated theoretically. (Auth.)

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

Measurement of the neutron lifetime by counting trapped protons

International Nuclear Information System (INIS)

Byrne, J.; Dawber, P.G.; Spain, J.A.; Williams, A.P.; Dewey, M.S.; Gilliam, D.M.; Greene, G.L.; Lamaze, G.P.; Scott, R.D.; Pauwels, J.; Eykens, R.; Lamberty, A.

1990-01-01

The neutron lifetime τ n has been measured by counting decay protons stored in a Penning trap whose magnetic axis coincided with a neutron-beam axis. The result of the measurement is τ n =893.6±5.3 s, which agrees well with the value predicted by precise measurements of the β-decay asymmetry parameter A and the standard model

An alternative method for the measurement of neutron flux

Indian Academy of Sciences (India)

A simple and easy method for measuring the neutron flux is presented. This paper deals with the experimental verification of neutron dose rate–flux relationship for a non-dissipative medium. Though the neutron flux cannot be obtained from the dose rate in a dissipative medium, experimental result shows that for ...

Fast neutron measurements with 7Li and 6Li enriched CLYC scintillators

International Nuclear Information System (INIS)

Giaz, A.; Blasi, N.; Boiano, C.; Brambilla, S.; Camera, F.; Cattadori, C.; Ceruti, S.; Gramegna, F.; Marchi, T.; Mattei, I.; Mentana, A.; Million, B.; Pellegri, L.; Rebai, M.; Riboldi, S.; Salamida, F.; Tardocchi, M.

2016-01-01

The recently developed Cs 2 LiYCl 6 :Ce (CLYC) crystals are interesting scintillation detectors not only for their gamma energy resolution (<5% at 662 keV) but also for their capability to identify and measure the energy of both gamma rays and fast/thermal neutrons. The thermal neutrons were detected by the 6 Li(n,α)t reaction while for the fast neutrons the 35 Cl(n,p) 35 S and 35 Cl(n,α) 32 P neutron-capture reactions were exploited. The energy of the outgoing proton or α particle scales linearly with the incident neutron energy. The kinetic energy of the fast neutrons can be measured using both the Time Of Flight (TOF) technique and using the CLYC energy signal. In this work, the response to monochromatic fast neutrons (1.9–3.8 MeV) of two CLYC 1″×1″ crystals was measured using both the TOF and the energy signal. The observables were combined to identify fast neutrons, to subtract the thermal neutron background and to identify different fast neutron-capture reactions on 35 Cl, in other words to understand if the detected particle is an α or a proton. We performed a dedicated measurement at the CN accelerator facility of the INFN Legnaro National Laboratories (Italy), where the fast neutrons were produced by impinging a proton beam (4.5, 5.0 and 5.5 MeV) on a 7 LiF target. We tested a CLYC detector 6 Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7 Li-enriched at more than 99%, which is suitable for fast neutron measurements.

Fast and thermal neutron intensity measurements at the KFUPM PGNAA setup

CERN Document Server

Al-Jarallah, M I; Fazal-Ur-Rehman; Abu-Jarad, F A

2002-01-01

Fast and thermal neutron intensity distributions have been measured at an accelerator based prompt gamma ray neutron activation analysis (PGNAA) setup. The setup is built at the 350 keV accelerator laboratory of King Fahd University of Petroleum and Minerals (KFUPM). The setup is mainly designed to carry out PGNAA elemental analysis via thermal neutron capture. In this study relative intensity of fast and thermal neutrons was measured as a function of the PGNAA moderator assembly parameters using nuclear track detectors (NTDs). The relative intensity of the neutrons was measured inside the sample region as a function of front moderator thickness as well as sample length. Measurements were carried out at the KFUPM 350 keV accelerator using 2.8 MeV pulsed neutron beam from D(d,n) reaction. The pulsed deuteron beam with 5 ns pulse width and 30 kHz frequency was used to produce neutrons. Experimental results were compared with results of Monte Carlo design calculations of the PGNAA setup. A good agreement has bee...

Fast and thermal neutron intensity measurements at the KFUPM PGNAA setup

Energy Technology Data Exchange (ETDEWEB)

Al-Jarallah, M.I.; Naqvi, A.A. E-mail: aanaqvi@kfupm.edu.sa; Fazal-ur-Rehman; Abu-jarad, F

2002-10-01

Fast and thermal neutron intensity distributions have been measured at an accelerator based prompt gamma ray neutron activation analysis (PGNAA) setup. The setup is built at the 350 keV accelerator laboratory of King Fahd University of Petroleum and Minerals (KFUPM). The setup is mainly designed to carry out PGNAA elemental analysis via thermal neutron capture. In this study relative intensity of fast and thermal neutrons was measured as a function of the PGNAA moderator assembly parameters using nuclear track detectors (NTDs). The relative intensity of the neutrons was measured inside the sample region as a function of front moderator thickness as well as sample length. Measurements were carried out at the KFUPM 350 keV accelerator using 2.8 MeV pulsed neutron beam from D(d,n) reaction. The pulsed deuteron beam with 5 ns pulse width and 30 kHz frequency was used to produce neutrons. Experimental results were compared with results of Monte Carlo design calculations of the PGNAA setup. A good agreement has been found between the experimental results and the calculations.

Neutron spectrometric evaluations in the Argentine research reactor RA-1

International Nuclear Information System (INIS)

Kunst, J.J.; Papadopulos, S.B.; Gregori, B.N.; Cruzate, J.A.

1998-01-01

Full text: The determination of the quantities dose equivalent H * (10) and personal dose equivalent Hp(10) in mixed field (n,γ) needs the knowledge of the related spectrum. In order to fulfill this aim spectrometer system has been built based on the combination of polyethylene spheres of different diameters (Bonner Spheres System-BSS) and a He 3 proportional counter detector sensitive to thermal neutrons. The detector is located in the geometrical centre of each of the spheres and has an associated electronics with a charge preamplifier, an amplifier and a multichannel system that allows the outgoing spectrum analysis. In order to determine the neutron spectrum a deconvolution method is applied based on the LOUHI82 code. In this work are shown the spectra and the related values of H * (10) that have been got in five places of the reactor and in the command room with the BSS. (author) [es

Measurement and analysis of neutron flux spectra in a neutronics mock-up of the HCLL test blanket module

International Nuclear Information System (INIS)

Klix, A.; Batistoni, P.; Boettger, R.; Lebrun-Grandie, D.; Fischer, U.; Henniger, J.; Leichtle, D.; Villari, R.

2010-01-01

Fast neutron and gamma-ray flux spectra and time-of-arrival spectra of slow neutrons have been measured in a neutronics mock-up of the European Helium-Cooled Lithium-Lead Test Blanket Module with the aim to validate nuclear cross-section data. The mock-up was irradiated with fusion peak neutrons from the DT neutron generator of the Technical University of Dresden. A well characterized cylindrical NE-213 scintillator was inserted into two positions in the LiPb/EUROFER assembly. Pulse height spectra from neutrons and gamma-rays were recorded from the NE-213 output. The spectra were then unfolded with experimentally obtained response matrices of the NE-213 detector. Time-of-arrival spectra of slow neutrons were measured with a 3 He counter placed in the mock-up, and the neutron generator was operated in pulsed mode. Monte Carlo calculations using the MCNP code and nuclear cross-section data from the JEFF-3.1.1 and FENDL-2.1 libraries were performed and the results are compared with the experimental results. A good agreement of measurement and calculation was found with some deviations in certain energy intervals.

Use of a high repetition rate neutron generator for in vivo body composition measurements via neutron inelastic scattering

International Nuclear Information System (INIS)

Kehayias, J.J.; Ellis, K.J.; Cohn, S.H.; Weinlein, J.H.

1986-01-01

A small D-T neutron generator with a high pulse rate is used for the in vivo measurement of body carbon, oxygen and hydrogen. The core of the neutron generator is a 13 cm-long Zetatron tube pulsed at a rate of 10 kHz delivering 10 3 to 10 4 neutrons per pulse. A target-current feedback system regulates the source of the accelerator to assure constant neutron output. Carbon is measured by detecting the 4.44 MeV γ-rays from inelastic scattering. The short half-life of the 4.44 MeV state of carbon requires detection of the γ-rays during the 10 μs neutron pulse. Generators with low pulsing rate were found inappropriate for carbon measurements because of their low duty-cycle (high neutron output during the pulse). In vivo measurements were performed with normal volunteers using a scanning bed facility for a dose less than 25 mrem. This technique offers medical as well as general bulk analysis applications. 8 refs., 5 figs

Development of time projection chamber for precise neutron lifetime measurement using pulsed cold neutron beams

Energy Technology Data Exchange (ETDEWEB)

Arimoto, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Higashi, N. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Igarashi, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Iwashita, Y. [Institute for Chemical Research, Kyoto University, Kyoto (Japan); Ino, T. [High Energy Accelerator Research Organization, Ibaraki (Japan); Katayama, R. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Kitaguchi, M. [Kobayashi-Maskawa Institute, Nagoya University, Aichi (Japan); Kitahara, R. [Graduate School of Science, Kyoto University, Kyoto (Japan); Matsumura, H.; Mishima, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); Nagakura, N.; Oide, H. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Otono, H., E-mail: otono@phys.kyushu-u.ac.jp [Research Centre for Advanced Particle Physics, Kyushu University, Fukuoka (Japan); Sakakibara, R. [Department of Physics, Nagoya University, Aichi (Japan); Shima, T. [Research Center for Nuclear Physics, Osaka University, Osaka (Japan); Shimizu, H.M.; Sugino, T. [Department of Physics, Nagoya University, Aichi (Japan); Sumi, N. [Faculty of Sciences, Kyushu University, Fukuoka (Japan); Sumino, H. [Department of Basic Science, University of Tokyo, Tokyo (Japan); Taketani, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); and others

2015-11-01

A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with {sup 6}Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.

Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

International Nuclear Information System (INIS)

Andriashin, A.V.; Devkin, B.V.; Lychagin, A.A.; Minko, J.V.; Mironov, A.N.; Nesterenko, V.S.; Sztaricskai, T.; Petoe, G.; Vasvary, L.

1986-01-01

A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra from (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (Auth.)

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

International Nuclear Information System (INIS)

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

1991-10-01

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

Actinide neutron-induced fission cross section measurements at LANSCE

Energy Technology Data Exchange (ETDEWEB)

Tovesson, Fredrik K [Los Alamos National Laboratory; Laptev, Alexander B [Los Alamos National Laboratory; Hill, Tony S [INL

2010-01-01

Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the {sup 235}U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, {sup 239-242}Pu and {sup 243}Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.

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

International Nuclear Information System (INIS)

Menlove, H.O.

2005-01-01

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

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.

Neutron energy response measurement of scintillation detectors

International Nuclear Information System (INIS)

Yang Hongqiong; Peng Taiping; Yang Jianlun; Tang Zhengyuan; Yang Gaozhao; Li Linbo; Hu Mengchun; Wang Zhentong; Zhang Jianhua; Li Zhongbao; Wang Lizong

2004-01-01

Neutron sensitivities of detectors composed of plastic scintillator ST401, ST1422, ST1423 and phyotomultiplier tube in primary energy range of fission neutron are calibrated by direct current. The energy response curve of the detectors is obtained in this experiment. The experimental result has been compared with the theoretical calculation and they are in agreement within measuring uncertainty. (authors)

Residual stress measurement using the pulsed neutron source at LANSCE

International Nuclear Information System (INIS)

Bourke, M.A.M.; Goldstone, J.A.; Holden, T.M.

1991-01-01

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all the lattice reflections are recorded in each measurement which allows anisotropic effects to be studied. Measurements made at the Manuel Lujan Jr Neutron Scattering Centre (LANSCE) demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 15 refs., 7 figs

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

Science.gov (United States)

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

2012-10-01

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

Absolute measurements of neutron cross sections. Progress report

International Nuclear Information System (INIS)

1984-11-01

In the photoneutron laboratory, we have completed a major refurbishing of experimental facilities and begun work on measurements of the capture cross section in thorium and U-238. In the 14 MeV neutron experimental bay, work continues on the measurement of 14 MeV neutron induced reactions of interest as standards or because of their technological importance. First results have been obtained over the past year, and we are extending these measurements along the lines outlined in our proposal of a year ago

Measurement of fast neutron spectra. 1-2

International Nuclear Information System (INIS)

Kimura, Itsuro

1976-01-01

The present status of the techniques for the measurement of fast neutron spectra is reviewed with particular attention to the recent activities in Japan. The first section of this report defines the energy range of fast neutrons, and various techniques are classified into four groups. In the following sections, recent development in each group is reviewed. The first part is the integral method represented mainly by the activation method. The variation of this method is shortly reviewed, and some results of the spectrum measurement for JRR-4 (a thermal research reactor) and YAYOI (a fast neutron source reactor) are presented together with the results of computed spectra. The second part is the method of proton recoil. The improvement of a proportional counter by Ichimori is shortly reviewed. The use of liquid scintillator is also discussed together with the experimental and computational results of YAYOI benchmark spectra of fast neutrons transmitted through the layers of iron. The utilization of n-α or n-p reaction as a sandwitch counter is discussed in the third part. Measured and calculated spectra in the FCA (a fast critical assembly) core are presented as examples. The method of time-of-flight is discussed in the fourth part. Recent developments in Japan such as the method with a double-scintillation counter are shortly presented together with its block diagram. (Aoki, K.)

Method for simultaneous measurement of borehole and formation neutron decay-times

International Nuclear Information System (INIS)

Smith, H.D.; Arnold, D.M.

1982-01-01

A method is described of making in situ measurements of the thermal neutron decay time of earth formations in the vicinity of a wellbore. The borehole and earth formations are irradiated, with pulsed fast neutrons and, during the interval between neutron pulses, capture gamma radiation is measured in at least four, non-overlapping, contiguous time intervals. Count-rates representative of thermal neutron populations in the borehole and the formations are made during each of the time intervals. A background radiation measurement for correcting the count-rates is preferably also periodically made. The count-rates are combined to derive simultaneously the formation and borehole neutron lifetime components which are recorded as a function of borehole depth. (author)

Study of calculated and measured time dependent delayed neutron yields

International Nuclear Information System (INIS)

Waldo, R.W.

1980-05-01

Time-dependent delayed neutron emission is of interest in reactor design, reactor dynamics, and nuclear physics studies. The delayed neutrons from neutron-induced fission of 232 U, 237 Np, 238 Pu, 241 Am, /sup 242m/Am, 245 Cm, and 249 Cf were studied for the first time. The delayed neutron emission from 232 Th, 233 U, 235 U, 238 U, 239 Pu, 241 Pu, and 242 Pu were measured as well. The data were used to develop an empirical expression for the total delayed neutron yield. The expression gives accurate results for a large variety of nuclides from 232 Th to 252 Cf. The data measuring the decay of delayed neutrons with time were used to derive another empirical expression predicting the delayed neutron emission with time. It was found that nuclides with similar mass-to-charge ratios have similar decay patterns. Thus the relative decay pattern of one nuclide can be established by any measured nuclide with a similar mass-to-charge ratio. A simple fission product yield model was developed and applied to delayed neutron precursors. It accurately predicts observed yield and decay characteristics. In conclusion, it is possible to not only estimate the total delayed neutron yield for a given nuclide but the time-dependent nature of the delayed neutrons as well. Reactors utilizing recycled fuel or burning actinides are likely to have inventories of fissioning nuclides that have not been studied until now. The delayed neutrons from these nuclides can now be incorporated so that their influence on the stability and control of reactors can be delineated. 8 figures, 39 tables

Multicomponent activation detector measurements of reactor neutron spectra

International Nuclear Information System (INIS)

Sandberg, J.; Aarnio, P. A.; Routti, J. T.

1984-01-01

Information on the neutron flux is required in many applications of research reactors, such as activation analysis or radiation damage measurements. Flux spectrum measurements are commonly carried out with activation foils. The reaction types used are threshold reactions in the fast energy region, resonance reactions in the intermediate region and neutron capture reactions with l/v-cross section in the thermal region. It has been shown that it is possible to combine several detector elements into homogeneous multicomponent detectors. The activities of all detector reaction products can be determined with a single gamma spectrum measurement. The multicomponent principle sets some restrictions on the choice of detector reactions, for example, each product nuclide may be produced in one reaction only. Separate multicomponent threshold and resonance detectors were designed for the fast and intermediate regions, respectively. The detectors were fabricated in polyethylene irradiation capsules or quartz glass ampoules, and they were irradiated in a cadmium cover. The detectors were succesfully used in the irradiation ring and in the core of a Triga reactor. The intermediate and fast neutron spectrum was unfolded with the least-squares unfolding program LOUHI. According to the preliminary results multicomponent activation detectors might constitute a convenient means for carrying out routine neutron spectrum measurements in research reactors. (orig.)

Measurements of DT and DD neutron yields by neutron activation on TFTR

International Nuclear Information System (INIS)

Barnes, C.W.; Larson, A.R.; LeMunyan, G.

1994-01-01

A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 10 12 to over 10 18 , and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants. and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions on aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the ±9% (one-sigma,) accuracy of the measurements: also agreeing are yields from silicon foils using the ACTL library cross-section. While the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the 115 In(n,n) 115m In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments

Measurements of DT and DD neutron yields by neutron activation on TFTR

International Nuclear Information System (INIS)

Barnes, C.W.; Larson, A.R.; LeMunyan, G.

1995-03-01

A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 10 12 to over 10 18 , and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants, and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions on aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the ±9% (one-sigma) accuracy of the measurements; also agreeing are yields from silicon foils using the ACTL library cross-section, while the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the 115 In(n.n') 115m In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments

Fast neutron measurements at the nELBE time-of-flight facility

Directory of Open Access Journals (Sweden)

Junghansa A. R.

2015-01-01

Full Text Available The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

Filtered thermal neutron captured cross sections measurements and decay heat calculations

International Nuclear Information System (INIS)

Pham Ngoc Son; Vuong Huu Tan

2015-01-01

Recently, a pure thermal neutron beam has been developed for neutron capture measurements based on the horizontal channel No.2 of the research reactor at the Nuclear Research Institute, Dalat. The original reactor neutron spectrum is transmitted through an optimal composition of Bi and Si single crystals for delivering a thermal neutron beam with Cadmium ratio (R ed ) of 420 and neutron flux (Φ th ) of 1.6*10 6 n/cm 2 .s. This thermal neutron beam has been applied for measurements of capture cross sections for nuclide of 51 V, by the activation method relative to the standard reaction 197 Au(n,γ) 198 Au. In addition to the activities of neutron capture cross sections measurements, the study on nuclear decay heat calculations has been also considered to be developed at the Institute. Some results on calculation procedure and decay heat values calculated with update nuclear database for 235 U are introduced in this report. (author)

Liquid metal flow measurement by neutron radiography

International Nuclear Information System (INIS)

Takenaka, N.; Ono, A.; Matsubayashi, M.; Tsuruno, A.

1996-01-01

Visualization of a liquid metal flow and image processing methods to measure the vector field are carried out by real-time neutron radiography. The JRR-3M real-time thermal neutron radiography facility in the Japan Atomic Energy Research Institute was used. Lead-bismuth eutectic was used as a working fluid. Particles made from a gold-cadmium intermetallic compound (AuCd 3 ) were used as the tracer for the visualization. The flow vector field was obtained by image processing methods. It was shown that the liquid metal flow vector field was obtainable by real-time neutron radiography when the attenuation of neutron rays due to the liquid metal was less than l/e and the particle size of the tracer was larger than one image element size digitized for the image processing. (orig.)

Neutron spectrum measurement in D + Be reaction

CERN Document Server

Abbasi-Davani, F; Aslani, G R; Etaati, G R; Koohi-Fayegh, R

2002-01-01

In this project the neutron spectra from the reaction of deuteron on beryllium nuclei is measured. The energies of deuterons were 7, 10, 13 and 15 MeV, and these measurements are performed at 10,30 and 50 degrees relative to the beam of deuterons. The detector used is 76 by 76 mm right circular cylinder of N E-213 liquid scintillator. The zero crossing technique is used for gamma discrimination. For the elimination of the background radiation, a Polyethylene block, 40 cm in thickness, with inserted cadmium sheets, and a lead block, 5 cm in thickness, were used. In order to obtain the background radiation spectrum, the latter blocks were placed between the target and the detector to eliminate neutron and gamma radiations reaching the detector directly. sup F ORIST sup c ode is used to unfold the neutron spectra from the measured pulse high t spectra and sup O 5S sup a nd sup R ESPMG sup c odes are used to obtain the detector response matrix.

Review of procedures involving separation and preconcentration for the determination of cadmium using spectrometric techniques

International Nuclear Information System (INIS)

Ferreira, Sergio L.C.; Andrade, Jailson B. de; Korn, Maria das Gracas A.; Pereira, Madson de G.; Lemos, Valfredo A.; Santos, Walter N.L. dos; Rodrigues, Frederico de Medeiros; Souza, Anderson S.; Ferreira, Hadla S.; Silva, Erik G.P. da

2007-01-01

Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. This review covers separation and preconcentration procedures, such as electrochemical deposition, precipitation, coprecipitation, solid phase extraction, liquid-liquid extraction (LLE) and cloud point extraction (CPE), and consider the features of the their application with several spectrometric techniques

Time-of-flight spectrometer for the measurement of gamma correlated neutron spectra

International Nuclear Information System (INIS)

Andryashin, A.V.; Devlein, B.V.; Lychagin, A.A.; Minko, Y.V.; Mironov, A.N.; Nesterenko, V.S.

1986-01-01

A time-of-flight spectrometer for the measurement of gamma correlated neutron spectra form (n,xnγ) reactions is described. The operation and the main parameters are discussed. The resolution in the neutron channel is 2.2 ns/m at the 150 keV neutron energy threshold. A simultaneous measurement of the time-of-flight and amplitude distributions makes it possible to study gamma correlated neutron spectra as well as the prompt gamma spectra in coincidence with selected energy neutrons. In order to test the spectrometer, measurements of the neutron spectrum in coincidence with the 846 keV gamma line of 56 Fe were carried out at an incident neutron energy of 14.1 MeV. (author). 3 figs., 6 refs

Active-interrogation measurements of fast neutrons from induced fission in low-enriched uranium

International Nuclear Information System (INIS)

Dolan, J.L.; Marcath, M.J.; Flaska, M.; Pozzi, S.A.; Chichester, D.L.; Tomanin, A.; Peerani, P.

2014-01-01

A detection system was designed with MCNPX-PoliMi to measure induced-fission neutrons from U-235 and U-238 using active interrogation. Measurements were then performed with this system at the Joint Research Centre in Ispra, Italy on low-enriched uranium samples. Liquid scintillators measured induced fission neutrons to characterize the samples in terms of their uranium mass and enrichment. Results are presented to investigate and support the use of organic liquid scintillators with active interrogation techniques to characterize uranium containing materials. -- Highlights: • We studied low-enriched uranium using active-interrogation experiments including a deuterium–tritium neutron generator and an americium–lithium isotopic neutron source. • Liquid scintillators measured induced-fission neutrons from the active-interrogation methods. • Fast-neutron (DT) and thermal-neutron (Am–Li) interrogation resulted in the measurement of trends in uranium mass and 235 U enrichment respectively. • MCNPX-PoliMi, the Monte Carlo transport code, simulated the measured induced-fission neutron trends in the liquid scintillators

Active-interrogation measurements of fast neutrons from induced fission in low-enriched uranium

Energy Technology Data Exchange (ETDEWEB)

Dolan, J.L., E-mail: jldolan@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Marcath, M.J.; Flaska, M.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Chichester, D.L. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Tomanin, A.; Peerani, P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, Ispra (Italy)

2014-02-21

A detection system was designed with MCNPX-PoliMi to measure induced-fission neutrons from U-235 and U-238 using active interrogation. Measurements were then performed with this system at the Joint Research Centre in Ispra, Italy on low-enriched uranium samples. Liquid scintillators measured induced fission neutrons to characterize the samples in terms of their uranium mass and enrichment. Results are presented to investigate and support the use of organic liquid scintillators with active interrogation techniques to characterize uranium containing materials. -- Highlights: • We studied low-enriched uranium using active-interrogation experiments including a deuterium–tritium neutron generator and an americium–lithium isotopic neutron source. • Liquid scintillators measured induced-fission neutrons from the active-interrogation methods. • Fast-neutron (DT) and thermal-neutron (Am–Li) interrogation resulted in the measurement of trends in uranium mass and {sup 235}U enrichment respectively. • MCNPX-PoliMi, the Monte Carlo transport code, simulated the measured induced-fission neutron trends in the liquid scintillators.

Measurements of the neutron yield from a coaxial gun plasma

International Nuclear Information System (INIS)

Zolototrubov, I.M.; Krasnikov, A.A.; Kurishchenko, A.M.; Novikov, Yu.M.; Poryatuj, V.S.; Tolstolutskij, A.G.

1977-01-01

Neutron yield from deuterium plasma produced by a pulse coaxial accelerator was measured. The maximum neutron yield with 5 kj stored in a condenser battery is 3x10 6 neutron/pulse. The basis of the method of measuring neutron yield from the plasma was through the induced activity. It was shown that application of even a small uniform longitudinal magnetic field (up to 1 kOe) on the accelerator decreases several times the neutron yield. It is also shown that a small amount of stored discharge energy can produce high-temperature plasma at the output of pulse coaxial accelerator in the absense of the direct magnetic field. It is supposed that the reason for the reduction of neutron yield level in the case of applying the magnetic field is decreasing plasma density because of increasing the bunch cross-section

Measurement of uranium and plutonium in solid waste by passive photon or neutron counting and isotopic neutron source interrogation

Energy Technology Data Exchange (ETDEWEB)

Crane, T.W.

1980-03-01

A summary of the status and applicability of nondestructive assay (NDA) techniques for the measurement of uranium and plutonium in 55-gal barrels of solid waste is reported. The NDA techniques reviewed include passive gamma-ray and x-ray counting with scintillator, solid state, and proportional gas photon detectors, passive neutron counting, and active neutron interrogation with neutron and gamma-ray counting. The active neutron interrogation methods are limited to those employing isotopic neutron sources. Three generic neutron sources (alpha-n, photoneutron, and /sup 252/Cf) are considered. The neutron detectors reviewed for both prompt and delayed fission neutron detection with the above sources include thermal (/sup 3/He, /sup 10/BF/sub 3/) and recoil (/sup 4/He, CH/sub 4/) proportional gas detectors and liquid and plastic scintillator detectors. The instrument found to be best suited for low-level measurements (< 10 nCi/g) is the /sup 252/Cf Shuffler. The measurement technique consists of passive neutron counting followed by cyclic activation using a /sup 252/Cf source and delayed neutron counting with the source withdrawn. It is recommended that a waste assay station composed of a /sup 252/Cf Shuffler, a gamma-ray scanner, and a screening station be tested and evaluated at a nuclear waste site. 34 figures, 15 tables.

Integral measurements of neutron production in spallation targets

International Nuclear Information System (INIS)

Frehaut, J.; Deneuville, D.; Ledoux, X.; Lochard, J.P.; Longuet, J.L.; Petibon, E.; Alrick, K.; Bownan, D.; Cverna, F.; King, N.S.P.; Morgan, G.L.; Greene, G.; Hanson, A.; Snead, L.; Thompson, R.; Ward, T.

1998-01-01

Measurements of neutron production for thick iron, tungsten and lead targets of different diameter prototypic for spallation systems have been made at SATURNE in an incident proton energy range from 400 MeV to 2 GeV. TIERCE code system calculations are in good agreement with experiment for iron and large diameter tungsten and lead targets. They overestimate the measured neutron production for tungsten and lead targets for diameter ≤20 cm. (author)

A remote control neutron cone scanner and measurement of the d(T,n) α neutron cone

International Nuclear Information System (INIS)

Suwanakachorn, D.; Vilaithong, T.; Vilaithong, C.; Boonyawan, D.; Chimooy, T.; Sornphorm, P.; Hoyce, G.; Pairsuwan, W.; Singkarat, S.

1988-01-01

We have measured the neutron cone associated with alpha particles from the d(T,n)α reaction by using a remote-control cone scanner. This scanner has two principal parts. The first part is the neutron detector scanner which can move the detector in the horizontal and vertical axis using to stepping-motors. The neutron detector can be moved in 0.5 cm increments over the whole rage of 30 cm. The second part is the remote-control electronic circuit using digital ICs. The rotation of stepping-motors is controlled by pulse signals from this circuit and the position of the detector is known by counting the number of pulses. The position of the neutron detector is indicated directly on a 3 digit display at the control panel. The method of measuring the neutron cone by the Time-of-Flight technique is also described

Neutron leakage measurements from a medical linear accelerator

International Nuclear Information System (INIS)

Palta, J.R.; Hogstrom, K.R.; Tannanonta, C.

1984-01-01

The McCall method has been used to measure neutron leakage from the Mevatron 77, 18- and 15-MV photon beams. Gold foil activation has been used employing a beta counting technique for the 18-MV beam and a gamma counting technique for both the 18- and 15-MV beam. The two counting techniques were used to evaluate their relative merit. The measurements were made at various locations in the patient-treatment plane for different field sizes. The results show that the thermal-neutron dose equivalent contributes only about 1%--2% of the total neutron dose equivalent. At 100 cm, the neutron dose equivalent for the 18-MV beam is approximately six times that of the 15-MV beam, slightly exceeding the 0.1% of the useful beam criteria used by some of the regulatory agencies. In light of the uncertainty in fluence to dose equivalent conversion factors, the increased dose equivalent above 0.1% is insignificant

Energy corrections in pulsed neutron measurements for cylindrical geometry

International Nuclear Information System (INIS)

Drozdowicz, K.; Woznicka, U.

1982-01-01

A solution of the thermal neutron diffusion equation for a two-region concentric cylindrical system, with a constant neutron flux in the inner medium assumed, is given. The velocity-averaged dynamic parameters for thermal neutrons are used in the method. The corrections due to the diffusion cooling are introduced into the dynamic material buckling and into the velocity distribution of the thermal neutron flux. Detailed relations obtained for a hydrogenous moderator are given. Results of the measurements of the thermal neutron macroscopic absorption cross-sections for the samples in the two-region cylindrical systems are presented. (author)

Training of reverse propagation neural networks applied to neutron dosimetry

International Nuclear Information System (INIS)

Hernandez P, C. F.; Martinez B, M. R.; Leon P, A. A.; Espinoza G, J. G.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, M.; Vega C, H. R.; Mendez V, R.; Gallego, E.; De Sousa L, M. A.

2016-10-01

Neutron dosimetry is of great importance in radiation protection as aims to provide dosimetric quantities to assess the magnitude of detrimental health effects due to exposure of neutron radiation. To quantify detriment to health is necessary to evaluate the dose received by the occupationally exposed personnel using different detection systems called dosimeters, which have very dependent responses to the energy distribution of neutrons. The neutron detection is a much more complex problem than the detection of charged particles, since it does not carry an electric charge, does not cause direct ionization and has a greater penetration power giving the possibility of interacting with matter in a different way. Because of this, various neutron detection systems have been developed, among which the Bonner spheres spectrometric system stands out due to the advantages that possesses, such as a wide range of energy, high sensitivity and easy operation. However, once obtained the counting rates, the problem lies in the neutron spectrum deconvolution, necessary for the calculation of the doses, using different mathematical methods such as Monte Carlo, maximum entropy, iterative methods among others, which present various difficulties that have motivated the development of new technologies. Nowadays, methods based on artificial intelligence technologies are being used to perform neutron dosimetry, mainly using the theory of artificial neural networks. In these new methods the need for spectrum reconstruction can be eliminated for the calculation of the doses. In this work an artificial neural network or reverse propagation was trained for the calculation of 15 equivalent doses from the counting rates of the Bonner spheres spectrometric system using a set of 7 spheres, one of 2 spheres and two of a single sphere of different sizes, testing different error values until finding the most appropriate. The optimum network topology was obtained through the robust design

Measurement and simulation of thermal neutron flux distribution in the RTP core

Science.gov (United States)

Rabir, Mohamad Hairie B.; Jalal Bayar, Abi Muttaqin B.; Hamzah, Na'im Syauqi B.; Mustafa, Muhammad Khairul Ariff B.; Karim, Julia Bt. Abdul; Zin, Muhammad Rawi B. Mohamed; Ismail, Yahya B.; Hussain, Mohd Huzair B.; Mat Husin, Mat Zin B.; Dan, Roslan B. Md; Ismail, Ahmad Razali B.; Husain, Nurfazila Bt.; Jalil Khan, Zareen Khan B. Abdul; Yakin, Shaiful Rizaide B. Mohd; Saad, Mohamad Fauzi B.; Masood, Zarina Bt.

2018-01-01

The in-core thermal neutron flux distribution was determined using measurement and simulation methods for the Malaysian’s PUSPATI TRIGA Reactor (RTP). In this work, online thermal neutron flux measurement using Self Powered Neutron Detector (SPND) has been performed to verify and validate the computational methods for neutron flux calculation in RTP calculations. The experimental results were used as a validation to the calculations performed with Monte Carlo code MCNP. The detail in-core neutron flux distributions were estimated using MCNP mesh tally method. The neutron flux mapping obtained revealed the heterogeneous configuration of the core. Based on the measurement and simulation, the thermal flux profile peaked at the centre of the core and gradually decreased towards the outer side of the core. The results show a good agreement (relatively) between calculation and measurement where both show the same radial thermal flux profile inside the core: MCNP model over estimation with maximum discrepancy around 20% higher compared to SPND measurement. As our model also predicts well the neutron flux distribution in the core it can be used for the characterization of the full core, that is neutron flux and spectra calculation, dose rate calculations, reaction rate calculations, etc.

Simulated and measured neutron/gamma light output distribution for poly-energetic neutron/gamma sources

Science.gov (United States)

Hosseini, S. A.; Zangian, M.; Aghabozorgi, S.

2018-03-01

In the present paper, the light output distribution due to poly-energetic neutron/gamma (neutron or gamma) source was calculated using the developed MCNPX-ESUT-PE (MCNPX-Energy engineering of Sharif University of Technology-Poly Energetic version) computational code. The simulation of light output distribution includes the modeling of the particle transport, the calculation of scintillation photons induced by charged particles, simulation of the scintillation photon transport and considering the light resolution obtained from the experiment. The developed computational code is able to simulate the light output distribution due to any neutron/gamma source. In the experimental step of the present study, the neutron-gamma discrimination based on the light output distribution was performed using the zero crossing method. As a case study, 241Am-9Be source was considered and the simulated and measured neutron/gamma light output distributions were compared. There is an acceptable agreement between the discriminated neutron/gamma light output distributions obtained from the simulation and experiment.

Mobile spectrometric laboratory

International Nuclear Information System (INIS)

Isajenko, K.A.; Lipinski, P.

2002-01-01

The article presents the Mobile Spectrometric Laboratory used by Central Laboratory for Radiological Protection since year 2000. The equipment installed in the Mobile Laboratory and its uses is described. The results of international exercises and intercalibrations, in which the Laboratory participated are presented. (author)

Neutrons field in the neutronic measurements room of the Polytechnic University of Madrid

International Nuclear Information System (INIS)

Vega C, H. R.; Gallego, E.; Lorente, A.; Rubio O, I. P.

2010-09-01

Through of measurements and calculations of a Monte Carlo series has been characterized the neutronic field of the neutronic measurements room of Nuclear Engineering Department of the Polytechnic University of Madrid. The measurements were realized with the Bonner Spheres Spectrometer that allowed establish the spectra on the new stainless steel panel and at different distances measured regarding the source. The values of the speed of environmental equivalent dose were measured with an area monitor Bert hold Lb 6411. Through of Monte Carlo methods was built a detailed model of the room with the panel and the spectra were calculated and, with these the values of the environmental equivalent dose were obtained using the conversion coefficients of the ICRP 74 and the Bert hold Lb 6411 response. The calculated values were compared with those measured and was consistency among the results. (Author)

Activation measurements for thermal neutrons. Part E. 36Cl measurements in Germany

International Nuclear Information System (INIS)

Ruehm, Werner; Huber, Thomas; Nolte, Eckehart; Kato, Kazuo; Egbert, Stephen D.

2005-01-01

The long-lived radioisotope 36 Cl (half-life: 301,000 years) was measured in bomb-exposed granite and concrete samples from Hiroshima, and in granite samples not exposed to A-bomb neutrons, by means of accelerator mass spectrometry (AMS). For those samples exposed to A-bomb neutrons, measured 36 Cl/Cl ratios as a function of distance to the epicenter were compared with calculated ratios based on the new dosimetry system DS02. (J.P.N.)

Neutron and gamma dose and spectra measurements on the Little Boy replica

International Nuclear Information System (INIS)

Hoots, S.; Wadsworth, D.

1984-01-01

The radiation-measurement team of the Weapons Engineering Division at Lawrence Livermore National Laboratory (LLNL) measured neutron and gamma dose and spectra on the Little Boy replica at Los Alamos National Laboratory (LANL) in April 1983. This assembly is a replica of the gun-type atomic bomb exploded over Hiroshima in 1945. These measurements support the National Academy of Sciences Program to reassess the radiation doses due to atomic bomb explosions in Japan. Specifically, the following types of information were important: neutron spectra as a function of geometry, gamma to neutron dose ratios out to 1.5 km, and neutron attenuation in the atmosphere. We measured neutron and gamma dose/fission from close-in to a kilometer out, and neutron and gamma spectra at 90 and 30 0 close-in. This paper describes these measurements and the results. 12 references, 13 figures, 5 tables

Neutron capture and (n,2n) measurements on {sup 241}Am

Energy Technology Data Exchange (ETDEWEB)

Vieira, D.J.; Jandel, M.; Bredeweg, T.A.; Bond, E.M.; Clement, R.R.; Couture, A.; Haight, R.C.; O' Donnell, J.M.; Reifarth, R.; Rundberg, R.S.; Ullmann, J.L.; Wilhelmy, J.B.; Wouters, J.M. [Los Alamos National Laboratory, NM (United States); Tonchev, A.P.; Hutcheson, A.; Angell, C.T.; Crowell, A.S.; Fallin, B.; Hammond, S.; Howell, C.R.; Karowowski, H.J.; Kelley, J.H.; Pedroni, R.; Tornow, W. [Triangle Univ. Nuclear Laboratory, Durham, NC (United States); Macri, R.A.; Agvaanluvsan, U.; Becker, J.A.; Dashdorj, D.; Stoyer, M.A.; Wu, C.Y. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

2008-07-01

We report on a set of neutron-induced reaction measurements on {sup 241}Am which are important for nuclear forensics and advanced nuclear reactor design. Neutron capture measurements have been performed on the DANCE detector array at the Los Alamos Neutron Scattering Center (LANSCE). In general, good agreement is found with the most recent data evaluations up to an incident neutron energy of about 300 keV where background limits the measurement. Using mono-energetic neutrons produced in the {sup 2}H(d,n){sup 3}He reaction at the Triangle Universities Nuclear Laboratory (TUNL), we have measured the {sup 241}Am(n,2n) excitation function from 7.6 to 14.5 MeV using the activation method. Good agreement is found with previous measurements, with the exception of the three data points reported by Perdikakis et al. around 11 MeV, where we obtain a much lower cross section that is more consistent with theoretical estimates. (authors)

Experiment for water-flow measurement by pulsed-neutron activation

International Nuclear Information System (INIS)

Drozdowicz, K.

1994-08-01

An experiment is presented which constitutes a feasibility study for applying the neutron activation method for measurement of the water mass transport in pipings, e.g. in nuclear power stations. The fast neutron generator has been used as a pulsed-neutron activation source for oxygen in water which circulated in a closed system. The γ radiation of the nitrogen product isotope has been measured by the scintillation detectors placed in two positions at the piping. The two time distributions of the pulses have been recorded by a multiscaler (a software design based on CAMAC). The water flow velocity has been estimated from the peak-to-peak time distance. The tests have been performed under different experimental conditions (the neutron pulse duration, the time channel width, the water flow velocity) to define the stability, reproducibility and reliability of the measurement. The detailed results are presented in tables and in time distribution plots. The method has been found useful for the application considered. 4 refs, 17 figs, 5 tabs

Activation measurements for thermal neutrons. Part F. 36Cl measurements in Japan

International Nuclear Information System (INIS)

Nagashima, Yasuo; Seki, Riki; Matsuhiro, Takeshi; Takahashi, Tsutomu; Sasa, Kimikazu; Usui, Toshihide; Sueki, Keisuke

2005-01-01

The development of the accelerator mass spectrometry (AMS) system at the Tandem Accelerator Center of the University of Tsukuba was started in 1995, using the university's own molecular pilot beam technique. Presently, it is the only facility in Japan used to measure 36 Cl (Nagashima et al. 2000). The sensitivity of the 36 Cl AMS system is around 10 -14 36 Cl/Cl atom ratio, which is enough to measure the natural level of the 36 Cl/Cl ratio. The system is characterized by long-term stability, enabling high-quality, continuous measurements over many hours. Our AMS system was used to measure 36 Cl produced in soil by neutrons released into the environment at the time of the JCO criticality accident in Tokai-mura in 1999 (Seki et al. 2003). At the beginning of 2001, our group joined the collaborative efforts to investigate and clarify the discrepancy observed between measurements and calculations of neutron activities induced by the atomic bombings in Hiroshima and Nagasaki. Using our AMS system, 36 Cl was measured in granite samples from Hiroshima exposed to atomic-bomb neutrons and in distant, unexposed samples. (author)

Technological advances in cosmogenic neutron detectors for measuring soil water content

Science.gov (United States)

Zreda, M. G.; Schrön, M.; Köhli, M.

2017-12-01

The cosmic-ray neutron probe is used for measuring area-average soil water content at the hectometer scale. Early work showed a simple exponential decrease with distance of the instrument's sensitivity and a footprint 300 m in radius. Recent research suggested a much higher sensitivity to local neutrons and reduced footprint. We show results confirming the high sensitivity to local neutrons, describe two ways to reduce local and increase far-field effects, and propose ways of measuring neutrons at different spatial scales. Measurements with moderated detectors across a 10-m-wide creek and a 2-m-wide water tank show a decrease by 30% and 20%, respectively, of neutron intensity over water compared to that over land nearby. These results mean that the detector is sensitive to meter-scale heterogeneities of water content. This sensitivity can be reduced by rising the detector or by shielding it from local neutrons. The effect of local water distributions on the measured neutron intensity decreases with height. In the water tank experiment it disappeared almost completely at the height of 2 m, leading to the conjecture that the height roughly equal to the horizontal scale of heterogeneity would eliminate the sensitivity. This may or may not be practical. Shielding the detector below by a hydrogenous material removes a substantial fraction of the local neutrons. The shielded detector has a reduced count rate, reduced sensitivity to local neutrons and increased sensitivity to neutrons farther afield, and a larger footprint. Such a detector could be preferable to the current cosmogenic-neutron probe under heterogeneous soil water conditions. The shielding experiments also inspired the development of a local-area neutron detector. It has hydrogenous neutron shields on all sides except the bottom, substantially blocking the neutrons coming from afar, while allowing the neutrons coming directly from below. Its footprint is equal to its physical dimension when the detector is

Neutron flux measurement by mobile detectors

International Nuclear Information System (INIS)

Verchain, M.

1987-01-01

Various incore instrumentation systems and their technological evolution are first reviewed. Then, for 1300 MWe PWR nuclear power plant, temperature and neutron flux measurement are described. Mobile fission chambers, with their large measuring range and accurate location allow a good knowledge of the core. Other incore measures are possible because of flux detector thimble tubes inserted in the reactor core [fr

Energetic ion diagnostics using neutron flux measurements during pellet injection

International Nuclear Information System (INIS)

Heidbrink, W.W.

1986-01-01

Neutron measurements during injection of deuterium pellets into deuterium plasmas on the Tokamak Fusion Test Reactor (TFTR) indicate that the fractional increase in neutron emission about 0.5 msec after pellet injection is proportional to the fraction of beam-plasma reactions to total fusion reactions in the unperturbed plasma. These observations suggest three diagnostic applications of neutron measurements during pellet injection: (1) measurement of the beam-plasma reaction rate in deuterium plasmas for use in determining the fusion Q in an equivalent deuterium-tritium plasma, (2) measurement of the radial profile of energetic beam ions by varying the pellet size and velocity, and (3) measurement of the ''temperature'' of ions accelerated during wave heating. 18 refs., 3 figs

Monte Carlo Simulation of the Time-Of-Flight Technique for the Measurement of Neutron Cross-section in the Pohang Neutron Facility

Energy Technology Data Exchange (ETDEWEB)

An, So Hyun; Lee, Young Ouk; Lee, Cheol Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Young Seok [National Fusion Research Institute, Daejeon (Korea, Republic of)

2007-10-15

It is essential that neutron cross sections are measured precisely for many areas of research and technique. In Korea, these experiments have been performed in the Pohang Neutron Facility (PNF) with the pulsed neutron facility based on the 100 MeV electron linear accelerator. In PNF, the neutron energy spectra have been measured for different water levels inside the moderator and compared with the results of the MCNPX calculation. The optimum size of the water moderator has been determined on the base of these results. In this study, Monte Carlo simulations for the TOF technique were performed and neutron spectra of neutrons were calculated to predict the measurements.

Void fraction measurements using neutron radiography

International Nuclear Information System (INIS)

Glickstein, S.S.; Vance, W.H.; Joo, H.

1992-01-01

Real-time neutron radiography is being evaluated for studying the dynamic behavior of two phase flow and for measuring void fraction in vertical and inclined water ducts. This technique provides a unique means of visualizing the behavior of fluid flow inside thick metal enclosures. To simulate vapor conditions encountered in a fluid flow duct, an air-water flow system was constructed. Air was injected into the bottom of the duct at flow rates up to 0.47 I/s (1 cfm). The water flow rate was varied between 0--3.78 I/m (0--1 gpm). The experiments were performed at the Pennsylvania State University nuclear reactor facility using a real-time neutron radiography camera. With a thermal neutron flux on the order of 10 6 n/cm 2 /s directed through the thin duct dimension, the dynamic behavior of the air bubbles was clearly visible through 5 cm (2 in.) thick aluminum support plates placed on both sides of the duct wall. Image analysis techniques were employed to extract void fractions from the data which was recorded on videotape. This consisted of time averaging 256 video frames and measuring the gray level distribution throughout the region. The distribution of the measured void fraction across the duct was determined for various air/water mixtures. Details of the results of experiments for a variety of air and water flow conditions are presented

Measurements of neutron and gamma ray streaming through a duct, (2), (3)

International Nuclear Information System (INIS)

Hashikura, Hiroyuki; Fukumoto, Hideshi; Akiyama, Masatsugu; Oka, Yoshiaki; An, Shigehiro

1982-03-01

Measurements of neutron and gamma ray streaming through a duct measurements of and a cavity in concrete shields were measured in the fast neutron source reactor YAYOI of the University of Tokyo. The neutron spectra measured by a NE213 scintillator and proton recoil counters were compared with the calculations using Monte Carlo code, MORSE-CG. The agreements between the experiments and the calculations were generally satisfactory. The attenuations of neutron and gamma ray in the cavity and the duct were studied in the three experimental configurations. (author)

Searching plutonium from a travelling vehicle by neutron measurements

International Nuclear Information System (INIS)

Rosenstock, W.; Koeble, T.; Hilger, P.; Engelen, J.

2001-01-01

For the search and detection of concealed nuclear material and neutron sources we have equipped a conventional car with a neutron measurement system. It consists of six neutron slab counters on each side. Each slab counter has a size of approx. 25x50x9 cm 3 and contains 6 He-3 tubes embedded in polyethylene covered by stainless steel. The active length of the tubes is 33 cm and the diameter 2.54 cm. The efficiency of all six slab counters on each side is 0.66 % for the detection of Cf-252 fission neutrons emitted from a point source in a distance of 100 cm from the center of the detectors. The complete system is mounted in a square steel rod assembly so that it can be fixed in most vehicles easily. Between the racks for the detectors we have fastened a voltage converter and the electronics. A view of this system installed into a car is shown. The pulses of the six modules on each side are summed passively and each side is analyzed separately. The results can be displayed on a handheld PC in the front of the car or in case of a covered search the data can be stored in a non-volatile memory in the electronics. For a clear location these data will be synchronized with a GPS signal. A measurement performed with a car equipped with this neutron detection system is shown. We placed a small neutron source (Cf-252) two meters away from the driving way of the car. The neutron intensity corresponds to less than 10 g reactor plutonium with a burn up of 30 GWd/t. The results show a very clear signal on the right side whereas the signal from the left row of the detector modules is only slightly above background. In addition we have performed measurements in practical operation. The typical neutron background was 10 cps on the test site. A neutron source (Cf-252) was hidden inside a house in the ground floor approx. I m above the floor. The neutron intensity of this source was 1.86 10 5 n/s (in 4π). This corresponds to about 530 g reactor plutonium (burn up of 30 GWd/t) or even

Filtered thermal neutron captured cross-sections measurements and decay heat calculations

International Nuclear Information System (INIS)

Son, Pham Ngoc; Tan, Vuong Huu

2014-01-01

Recently, a pure thermal neutron beam has been developed for neutron capture measurements based on the horizontal channel No.2 of the research reactor at the Nuclear Research Institute, Dalat. The original reactor neutron spectrum is transmitted through an optimal composition of Bi and Si single crystals for delivering a thermal neutron beam with Cadmium ratio (R cd ) of 420 and neutron flux (Φ th ) of 1.6x10 6 n/cm 2 .s. This thermal neutron beam has been applied for measurements of capture cross-sections for nuclide of 51 V, 55 Mn, 180 Hf and 186 W by the activation method relative to the standard reaction 197 Au(n,g) 198 Au. In addition to the activities of neutron capture cross-sections measurements, the study on nuclear decay heat calculations has been also considered to be developed at the Institute. Some results on calculation procedure and decay heat values calculated with update nuclear database for 235 U, 238 U, 239 Pu and 232 Th are introduced in this report. (author)

Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process. Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

Energy Technology Data Exchange (ETDEWEB)

Atanasov, Dinko

2016-07-06

Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton-to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium ({sup 129-131}Cd) and caesium ({sup 132,146-148}Cs) isotopes. Measurements were done at the on-line radioactive ion-beam facility ISOLDE by using the four-trap mass spectrometer ISOLTRAP. The cadmium isotopes are key nuclides for the synthesis of stable isotopes around the mass peak A = 130 in the Solar System abundance.

Neutron temperature measurements in a cryogenic hydrogenous moderator

International Nuclear Information System (INIS)

Ball, R.M.; Hoovler, G.S.; Lewis, R.H.

1995-01-01

Benchmarkings of neutronic calculations are most successful when there is a direct correlation between a measurement and an analytic result. In the thermal neutron energy region, the fluence rate as a function of moderator temperature and position within the moderator is an area of potential correlation. The measurement can be done by activating natural lutetium. The two isotopes of the element lutetium have widely different cross sections and permit the discrimination of flux shape and energy distributions at different reactor conditions. The 175 Lu has a 1/v dependence in the thermal energy region, and 176 Lu has a resonance structure that approximates a constant cross section in the same region. The saturation activation of the two isotopes has been measured in an insulated moderator container at the center of a thermal heterogeneous reactor designed for space nuclear propulsion. The measurements were made in a hydrogenous (polyethylene) moderator at three temperatures (83, 184, and 297 K) and five locations within the moderator. Simultaneously, the reactivity effect of the change in the moderator temperature was determined to be positive with an increase in temperature. The plot of activation shows the variation in neutron fluence rate and current with temperature and explains the positive reactivity coefficient. A neutron temperature can be inferred from a postulated Maxwell-Boltzmann distribution and compared with Monte Carlo or other calculations

Portable instrument for measuring neutron energy spectra and neutron dose in a mixed n-γ field

International Nuclear Information System (INIS)

Daniels, C. J.; Silberberg, J. L.

1980-01-01

A portable high-speed neutron spectrometer consists of an organic scintillator, a true zero-crossing pulse shape discriminator, a 1 MHZ conversion-rate multichannel analyzer, an 8-bit microcomputer, and appropriate displays. The device can be used to measure neutron energy spectra and kerma rate in intense n- gamma radiation fields in which the neutron energy is from 5 to 15 MEV

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

Energy Technology Data Exchange (ETDEWEB)

Mattingly, John K.

2009-11-01

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

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

International Nuclear Information System (INIS)

Mattingly, John K.

2009-01-01

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

Optimising neutron polarizers--measuring the flipping ratio and related quantities

CERN Document Server

Goossens, D J

2002-01-01

The continuing development of gaseous spin polarized sup 3 He transmission filters for use as neutron polarizers makes the choice of optimum thickness for these filters an important consideration. The 'quality factors' derived for the optimisation of transmission filters for particular measurements are general to all neutron polarizers. In this work optimisation conditions for neutron polarizers are derived and discussed for the family of studies related to measuring the flipping ratio from samples. The application of the optimisation conditions to sup 3 He transmission filters and other types of neutron polarizers is discussed. Absolute comparisons are made between the effectiveness of different types of polarizers for this sort of work.

Fissile materials in solution concentration measured by active neutron interrogation

International Nuclear Information System (INIS)

Romeyer Dherbey, J.; Passard, Ch.; Cloue, J.; Bignan, G.

1993-01-01

The use of the active neutron interrogation to measure the concentration of plutonium contained in flow solutions is particularly interesting for fuel reprocessing plants. Indeed, this method gives a signal which is in a direct relation with the fissile materials concentration. Moreover, it is less sensitive to the gamma dose rate than the other nondestructive methods. Two measure methods have been evolved in CEA. Their principles are given into details in this work. The first one consists to detect fission delayed neutrons induced by a 252 Cf source. In the second one fission prompt neutrons induced by a neutron generator of 14 MeV are detected. (O.M.)

Neutron dosimetry in EDF experimental surveillance programme for VVER-440 nuclear power plants

International Nuclear Information System (INIS)

Brumovsky, M.; Erben, O.; Novosad, P.; Zerola, L.; Hogel, J.; Trollat, C.

2001-01-01

Fourteen chains containing experimental surveillance material specimens of the VVER 440/213 nuclear power reactor pressure vessels were irradiated in the surveillance channels of the Nuclear Power Plant Dukovany in the Czech Republic. The irradiation periods were one, two or three cycles. The chains contained different number and types of containers, the omitted ones were replaced by chain elements. All of the containers were instrumented with wire neutron fluence detectors, some of the containers in the chain had spectrometric sets of neutron fluence monitors. For the absolute fluence values evaluation it was taken into account time history of the reactor power and local changes of the neutron flux along the reactor core height, correction factors due to the orientation of monitors with respect to the reactor core centre. Unfolding programs SAND-II or BASA-CF were used. The relative axial fluence distribution was obtained from the O-wire measurements. Neutron fluence values above 0.5 MeV energy and above 1.0 MeV energy in the container axis on the axial positions of the sample centres and fluence values in the geometric centre of the samples was calculated making use the exponential attenuation model of the incident neutron beam. Received fast neutron fluence values can be used as reference values to all VVER-440 type 213 nuclear power plant reactors. (author)

Simultaneous measurement of fission fragments and prompt neutrons for thermal neutron-induced fission of U-235

Energy Technology Data Exchange (ETDEWEB)

Nishio, Katsuhisa; Yamamoto, Hideki; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

1997-03-01

Simultaneous measurement of fission fragments and prompt neutrons following the thermal neutron induced fission of U-235 has been performed in order to obtain the neutron multiplicity (v) and its emission energy ({eta}) against the specified mass (m{sup *}) and the total kinetic energy (TKE). The obtained value of -dv/dTKE(m{sup *}) showed a saw-tooth distribution. The average neutron energy <{eta}>(m{sup *}) had a distribution with a reflection symmetry around the half mass division. The measurement also gave the level density parameters of the specified fragment, a(m{sup *}), and this parameters showed a saw-tooth trend too. The analysis by a phenomenological description of this parameters including the shell and collective effects suggested the existence of a collective motion of the fission fragments. (author)

Photoneutron spectrum measured with Bonner Spheres in Planetary method mode

Energy Technology Data Exchange (ETDEWEB)

Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)

2012-10-15

We measured the spectrum of photoneutrons at 100 cm isocenter linear accelerator (Linac) Varian ix operating at 15 MV Bremsstrahlung mode. In this process was used a radiation field of 20 x 20 cm{sup 2} at a depth of 5 cm in a solid water phantom with dimensions of 30 x 30 x 15 cm{sup 3}. The measurement was performed with a system using it Bonner Spheres spectrometric method Planetary mode. As neutron detector of the spectrometer is used thermoluminescent dosimeters pairs of type 600 and 700. (Author)

Photoneutron spectrum measured with Bonner Spheres in Planetary method mode

International Nuclear Information System (INIS)

Benites R, J.; Vega C, H. R.; Velazquez F, J.

2012-10-01

We measured the spectrum of photoneutrons at 100 cm isocenter linear accelerator (Linac) Varian ix operating at 15 MV Bremsstrahlung mode. In this process was used a radiation field of 20 x 20 cm 2 at a depth of 5 cm in a solid water phantom with dimensions of 30 x 30 x 15 cm 3 . The measurement was performed with a system using it Bonner Spheres spectrometric method Planetary mode. As neutron detector of the spectrometer is used thermoluminescent dosimeters pairs of type 600 and 700. (Author)

A measurement of the neutron lifetime by counting trapped protons

CERN Document Server

Snow, W M; Dewey, M S; Fei, X; Gilliam, D M; Greene, G L; Nico, J S; Wietfeldt, F E

2000-01-01

A measurement of the neutron lifetime tau sub n performed by trapping and counting decay protons from in-beam neutron decays in a Penning trap is in progress at the National Institute of Standards and Technology (NIST). A description of the measurement technique, the status of the data analysis, and prospects for improvements in the measurement are discussed.

Study on measurement technique contrast of 14 MeV neutron fluence

International Nuclear Information System (INIS)

Jiang Li; Hu Jun; Wen Dezhi

2005-10-01

The stability and repetition of the associated-particle method to measure DT neutron fluence was tested. The neutron activation iron method was contrasted with the associated-particle method, the preparatory experiment was done. The neutron fluence measured with associated-particle method was contrasted with neutron activation Al method, the Al activated foil was measured with 4πβ (PC)-γ coincidence standard device. The contrast result's standard deviation of the two method was less than the expand uncertainty of the associated-particle method. Therein, the uncertainty of the associated-particle method is 1.6%, the uncertainty of the activation Al method is 1.8%. (authors)

A new computation tool for neutron spectrometry and dosimetry; Una nueva herramiento de computo para la espectrometria y dosimetria de neutrones

Energy Technology Data Exchange (ETDEWEB)

Martinez B, M. R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Av. Ramon Lopez Velarde No. 801, Col. Centro, Zacatecas (Mexico)], e-mail: mrosariomb@yahoo.com.mx

2009-10-15

By using the integrated accounts of spectrometric system of Bonner spheres is possible to reconstruct the neutron spectrum using various methods such as: Monte Carlo, the parameterization and iterative methods. The response matrix, counting rates and neutron spectrum are intimately related through the integral-differential of Fredholm of first type. however, the weight of Bonner spheres system, the procedure of spectra reconstruction, the need of a expert user, the high time consumption, the need to use a reconstruction code (BUNKI, SAND, among others) and the spectrum resolution, are some of problems that this system presents. The above difficulties have motivated the development of complementary procedures such as maximum entropy, genetic algorithms and artificial neural networks. In recent years, using neural network technology has become an alternative procedure in the nuclear science research area, considering a replacement for classical techniques used for years. In previous works, was used a new method called robust design methodology of artificial neural networks, to construct various network topologies capable of solving the problems of neutron spectrometry and dosimetry, however noted that not exist tools for end-user that allow test and validate the designed networks. This paper presents the development of a software for neutronic spectrometry and dosimetry, based on information extracted from an artificial neural network designed in previous work, through the robust design methodology of artificial neural networks with the following characteristics: was designed in a user graphical interface easy to use, speed on the application execution, unlike other deconvolution codes, not is necessary to select and initial spectrum for spectrum reconstruction, as an additional element to this tool, besides spectrum, the calculation is performed simultaneous of 13 equivalent dose from just counting rates from a spectrometric system of Bonner spheres. (Author)

Measurement of leakage neutron spectra for Tungsten with D-T neutrons and validation of evaluated nuclear data

International Nuclear Information System (INIS)

Zhang, S.; Chen, Z.; Nie, Y.; Wada, R.; Ruan, X.; Han, R.; Liu, X.; Lin, W.; Liu, J.; Shi, F.; Ren, P.; Tian, G.; Luo, F.; Ren, J.; Bao, J.

2015-01-01

Highlights: • Evaluated data for Tungsten are validated by integral experiment. • Leakage neutron spectra from the irradiation of D-T neutrons on Tungsten are measured at 60° and 120° by using a time-of-flight method. • The measured results are compared to the MCNP-4C calculated ones with evaluated data of the different libraries. - Abstract: Integral neutronics experiments have been investigated at Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS) in order to validate evaluated nuclear data related to the design of Chinese Initiative Accelerator Driven Systems (CIADS). In the present paper, the accuracy of evaluated nuclear data for Tungsten has been examined by comparing measured leakage neutron spectra with calculated ones. Leakage neutron spectra from the irradiation of D-T neutrons on Tungsten slab sample were experimentally measured at 60° and 120° by using a time-of-flight method. Theoretical calculations are carried out by Monte Carlo neutron transport code MCNP-4C with evaluated nuclear data of the ADS-2.0, ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0 and CENDL-3.1 libraries. From the comparisons, it is found that the calculations with ADS-2.0 and ENDF/B-VII.1 give good agreements with the experiments in the whole energy regions at 60°, while a large discrepancy is observed at 120° in the elastic scattering peak, caused by a slight difference in the oscillation pattern of the elastic angular distribution at angles larger than 20°. However, the calculated spectra using data from ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries showed larger discrepancies with the measured ones, especially around 8.5–13.5 MeV. Further studies are presented for these disagreements

Measurements of double-differential neutron emission cross sections of Nb and Bi for 11.5 MeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Ibaraki, Masanobu; Matsuyama, Shigeo; Soda, Daisuke; Baba, Mamoru; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1997-03-01

Double-differential neutron emission cross sections (DDXs) of Nb and Bi have been measured for 11.5MeV neutrons using the {sup 15N}(d,n){sup 16}O quasi-monoenergetic neutron source at Tohoku University 4.5MV Dynamitron facility. For En`>6MeV, DDXs were measured by the conventional TOF method (single-TOF:S-TOF). For En`<6MeV, where the S-TOF spectra were distorted by the background neutrons, we adopted a double-TOF method (D-TOF). By applying D-TOF method, we obtained DDXs down to 1MeV. (author)

Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

Energy Technology Data Exchange (ETDEWEB)

Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

1998-03-01

The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

Neutron-capture cross-section measurement for 163Dy In the neutron energy range from 15 to 75 keV

International Nuclear Information System (INIS)

Kim, Hyun Duk; Jung, Eui Jung; Ahn, Jung Keun; Lee, Dae Won; Kim, Guin Yun; Ro, Tae Ik; Min, Young Ki; Igashira, Masayuki; Ohsaki, Toshiro; Mizuno, Satoshi

2002-01-01

The neutron-capture cross-section of 163 Dy were measured in the neutron energy range from 15 to 75 keV at the 3-MV Pelletron accelerator of the Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology. Pulsed neutrons were produced from the 7 Li(p,n) 7 Be reaction by bombarding a metallic lithium target with the 1.903-MeV proton beam. The incident neutron spectra were measured by means of a neutron time-of-flight method with a 6 Li-glass detector. Capture γ-rays were detected with a large anti-Compton NaI(Tl) spectrometer. A pulse-height weighting technique was applied to the capture γ-ray pulse-height spectra to obtain capture yields. The neutron capture cross-section were determined relative to the standard capture cross-sections of 197 Au. The present results were compared with the previous measurements and the evaluated values of ENDF/B-VI

Ship Effect Neutron Measurements And Impacts On Low-Background Experiments

Energy Technology Data Exchange (ETDEWEB)

Aguayo Navarrete, Estanislao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2013-10-01

The primary particles entering the upper atmosphere as cosmic rays create showers in the atmosphere that include a broad spectrum of secondary neutrons, muons and protons. These cosmic-ray secondaries interact with materials at the surface of the Earth, yielding prompt backgrounds in radiation detection systems, as well as inducing long-lived activities through spallation events, dominated by the higher-energy neutron secondaries. For historical reasons, the multiple neutrons produced in spallation cascade events are referred to as “ship effect” neutrons. Quantifying the background from cosmic ray induced activities is important to low-background experiments, such as neutrino-less double beta decay. Since direct measurements of the effects of shielding on the cosmic-ray neutron spectrum are not available, Monte Carlo modeling is used to compute such effects. However, there are large uncertainties (orders of magnitude) in the possible cross-section libraries and the cosmic-ray neutron spectrum for the energy range needed in such calculations. The measurements reported here were initiated to validate results from Monte Carlo models through experimental measurements in order to provide some confidence in the model results. The results indicate that the models provide the correct trends of neutron production with increasing density, but there is substantial disagreement between the model and experimental results for the lower-density materials of Al, Fe and Cu.

Energetic ion diagnostics using neutron flux measurements during pellet injection

Energy Technology Data Exchange (ETDEWEB)

Heidbrink, W.W.

1986-01-01

Neutron measurements during injection of deuterium pellets into deuterium plasmas on the Tokamak Fusion Test Reactor (TFTR) indicate that the fractional increase in neutron emission about 0.5 msec after pellet injection is proportional to the fraction of beam-plasma reactions to total fusion reactions in the unperturbed plasma. These observations suggest three diagnostic applications of neutron measurements during pellet injection: (1) measurement of the beam-plasma reaction rate in deuterium plasmas for use in determining the fusion Q in an equivalent deuterium-tritium plasma, (2) measurement of the radial profile of energetic beam ions by varying the pellet size and velocity, and (3) measurement of the ''temperature'' of ions accelerated during wave heating. 18 refs., 3 figs.

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Scattering length measurements from radiative pion capture and neutron-deuteron breakup

International Nuclear Information System (INIS)

Gibson, B.F.; Tornow, W.; Carman, T.S.

1997-07-01

The neutron-neutron and neutron-proton 1 S 0 scattering lengths a nn and a np , respectively, were determined simultaneously from the neutron-deuteron breakup reaction. Their comparison with the recommended values obtained from two body reactions gives a measure of the importance of three-nucleon force effects in the three-nucleon continuum. In order to check on the result obtained for a nn from the two-body π - -d capture reaction, a new measurement was performed at LANL. Preliminary results of the three experiments are given

A fission ionization detector for neutron flux measurements at a spallation source

Energy Technology Data Exchange (ETDEWEB)

Wender, S.A. (Los Alamos National Lab., Los Alamos, NM (United States)); Balestrini, S. (Los Alamos National Lab., Los Alamos, NM (United States)); Brown, A. (Los Alamos National Lab., Los Alamos, NM (United States)); Haight, R.C. (Los Alamos National Lab., Los Alamos, NM (United States)); Laymon, C.M. (Los Alamos National Lab., Los Alamos, NM (United States)); Lee, T.M. (Los Alamos National Lab., Los Alamos, NM (United States)); Lisowski, P.W. (Los Alamos National Lab., Los Alamos, NM (United States)); McCorkle, W. (Los Alamos National Lab., Los Alamos, NM (United States)); Nelson, R.O. (Los Alamos National Lab., Los Alamos, NM (United States)); Parker, W. (Los Alamos National Lab., Los Alamos, NM (United States)); Hill, N.W. (Oak Ridge National Lab., Oak Ridge, TN (United States))

1993-11-15

The construction of a neutron flux monitor that can measure absolute neutron intensities in the neutron energy range from below 1 MeV to over 500 MeV is described. The detector consists of an ionization chamber with several thin deposits of fissionable material. The ionization chamber is thin enough that it does not significantly affect the neutron beam and may be left in the neutron flight path during experimental measurements to continuously monitor the beam flux. The use of this monitor at the continuous-energy spallation neutron source at the WNR target area at LAMPF is described. (orig.)

A fission ionization detector for neutron flux measurements at a spallation source

International Nuclear Information System (INIS)

Wender, S.A.; Balestrini, S.; Brown, A.; Haight, R.C.; Laymon, C.M.; Lee, T.M.; Lisowski, P.W.; McCorkle, W.; Nelson, R.O.; Parker, W.; Hill, N.W.

1993-01-01

The construction of a neutron flux monitor that can measure absolute neutron intensities in the neutron energy range from below 1 MeV to over 500 MeV is described. The detector consists of an ionization chamber with several thin deposits of fissionable material. The ionization chamber is thin enough that it does not significantly affect the neutron beam and may be left in the neutron flight path during experimental measurements to continuously monitor the beam flux. The use of this monitor at the continuous-energy spallation neutron source at the WNR target area at LAMPF is described. (orig.)

Measurements of prompt gamma-rays from fast-neutron induced fission with the LICORNE directional neutron source

CERN Document Server

Wilson, J N; Halipre, P; Oberstedt, S; Oberstedt, A

2014-01-01

At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of $^7$Li is exploited to produce quasi-monoenergetic neutrons between 0.5 - 4 MeV using the p($^7$Li,$^7$Be)n inverse reaction. The available fluxes of up to 7 × 10$^7$ neutrons/second/steradian for the thickest hydrogen-rich targets are comparable to similar installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013. Some preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fas...

Burn-up measurements coupling gamma spectrometry and neutron measurement

Energy Technology Data Exchange (ETDEWEB)

Toubon, H.; Pin, P. [AREVA/CANBERRA, 1 rue des Herons, 78182 St Quentin-en-Yvelines Cedex (France); Lebrun, A. [IAEA, Wagramer Strasse 5, PO Box 100, Vienna (Austria); Oriol, L.; Saurel, N. [CEA Cadarache, 13108 Saint Paul Lez Durance Cedex (France); Gain, T. [AREVA/COGEMA Reprocessing Business Unit, La Hague, 50444 Beaumont Hague Cedex (France)

2006-07-01

The need to apply for burn-up credit arises with the increase of the initial enrichment of nuclear fuel. When burn-up credit is used in criticality safety studies, it is often necessary to confirm it by measurement. For the last 10 years, CANBERRA has manufactured the PYTHON system for such measurements. However, the method used in the PYTHON itself uses certain reactor data to arrive at burn-up estimates. Based on R and D led by CEA and COGEMA in the framework of burn-up measurement for burn-up credit and safeguards applications, CANBERRA is developing the next generation of burn-up measurement device. This new product, named SMOPY, is able to measure burn-up of any kind of irradiated fuel assembly with a combination of gamma spectrometry and passive neutron measurements. The measurement data is used as input to the CESAR depletion code, which has been developed and qualified by CEA and COGEMA for burn-up credit determinations. In this paper, we explain the complementary nature of the gamma and neutron measurements. In addition, we draw on our previous experience from PYTHON system and from COGEMA La Hague to show what types of evaluations are required to qualify the SMOPY system, to estimate its uncertainties, and to detect discrepancies in the fuel data given by the reactor plant to characterize the irradiated fuel assembly. (authors)

Burn-up measurements coupling gamma spectrometry and neutron measurement

International Nuclear Information System (INIS)

Toubon, H.; Pin, P.; Lebrun, A.; Oriol, L.; Saurel, N.; Gain, T.

2006-01-01

The need to apply for burn-up credit arises with the increase of the initial enrichment of nuclear fuel. When burn-up credit is used in criticality safety studies, it is often necessary to confirm it by measurement. For the last 10 years, CANBERRA has manufactured the PYTHON system for such measurements. However, the method used in the PYTHON itself uses certain reactor data to arrive at burn-up estimates. Based on R and D led by CEA and COGEMA in the framework of burn-up measurement for burn-up credit and safeguards applications, CANBERRA is developing the next generation of burn-up measurement device. This new product, named SMOPY, is able to measure burn-up of any kind of irradiated fuel assembly with a combination of gamma spectrometry and passive neutron measurements. The measurement data is used as input to the CESAR depletion code, which has been developed and qualified by CEA and COGEMA for burn-up credit determinations. In this paper, we explain the complementary nature of the gamma and neutron measurements. In addition, we draw on our previous experience from PYTHON system and from COGEMA La Hague to show what types of evaluations are required to qualify the SMOPY system, to estimate its uncertainties, and to detect discrepancies in the fuel data given by the reactor plant to characterize the irradiated fuel assembly. (authors)

Interpretation of active neutron measurements by the heterogeneous theory

International Nuclear Information System (INIS)

Birkhoff, G.; Depraz, J.; Descieux, J.P.

1979-01-01

In this paper are presented results from a study on the application of the heterogeneous method for the interpretation of active neutron measurements. The considered apparatus consists out of a cylindrical lead pile, which is provided with two axial channels: a central channel incorporates an antimony beryllium photoneutron source and an excentric channel serves for the insertion of the sample to be assayed for fissionable materials contents. The mathematical model of this apparatus is the heterogeneous group diffusion theory. Sample and source channel are described by multigroup monopolar and dipolar sources and sinks. Monopolar sources take account of neutron production within energy group and in-scatter from upper groups. Monopolar sinks represent neutron removal by absorption within energy group and outscatter to lower groups. Dipol sources describe radial streaming of neutrons across the sample channel. Multigroup diffusion theory is applied throughout the lead pile. The strengths of the monopolar and dipolar sources and sinks are determined by linear extrapolation distances of azimuthal mean and first harmonic flux values at the channels' surface. In an experiment we may measure the neutrons leaking out of the lead pile and linear extrapolation distances at the channels' surface. Such informations are utilized for interpretation in terms of fission neutron source strengh and mean neutron flux values in the sample. In this paper we summarized the theoretical work in course

International key comparison of neutron fluence measurements in mono-energetic neutron fields: C.C.R.I.(3)-K10

Energy Technology Data Exchange (ETDEWEB)

Chen, J.; Wang, Z.; Rong, C. [China Institute of Atomic Energy (CIAE), Beijing, People' s Republic of China (China); Lovestam, G.; Plompen, A.; Puglisi, N. [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Geel (Belgium); Gilliam, D.M.; Eisenhauer, C.M.; Nico, J.S.; Dewey, M.S. [National Institute of Standards and Technology (NIST), Gaithersburg (United States); Kudo, K.; Uritani, A.; Harano, H.; Takeda, N. [National Metrology Institute of Japan (NMIJ), Tsukuba (Japan); Thomas, D.J.; Roberts, N.J.; Bennett, A.; Kolkowski, P. [National Physical Laboratory (NPL), Teddington (United Kingdom); Moisseev, N.N.; Kharitonov, I.A. [Mendeleyev Institute for Metrology (VNIIM), St Petersburg (Russian Federation); Guldbakke, S.; Klein, H.; Nolte, R.; Schlegel, D. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)

2007-12-15

C.C.R.I. Section III (neutron measurements) conducted a unique key comparison of neutron fluence measurements in mono-energetic neutron fields. In contrast to former comparisons, here the fluence measurements were performed with the participants' instruments in the same neutron fields at the P.T.B. accelerator facility. Seven laboratories- the C.I.A.E. (China), I.R.M.M. (E.C.), N.M.I.J. (Japan), N.I.S.T. (USA), N.P.L. (UK), P.T.B. (Germany) and the V.N.I.I.M. (Russia)-employed their primary standard reference methods or transfer instruments carefully calibrated against their primary standards, to determine the fluence of 0.144 MeV, 1.2 MeV, 5.0 MeV and 14.8 MeV neutrons and reported calibration coefficients for a selected neutron monitor and each neutron energy with a detailed uncertainty budget for the measurements. The key comparison reference values (K.C.R.V.) were finally evaluated as the weighted mean values of the neutron fluence at 1 m distance from the target in vacuum per neutron monitor count. The uncertainties of each K.C.R.V. amounted to about 1%. The degree of equivalence (D.o.E.), defined as the deviation of the result reported by the laboratories for each energy from the corresponding K.C.R.V., and the associated expanded uncertainty are also reported. The deviations between the results of two laboratories each with the corresponding expanded uncertainties complete the documentation of the degrees of equivalence. (authors)

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.)

Measurements of fusion neutron yields by neutron activation technique: Uncertainty due to the uncertainty on activation cross-sections

Energy Technology Data Exchange (ETDEWEB)

Stankunas, Gediminas, E-mail: gediminas.stankunas@lei.lt [Lithuanian Energy Institute, Laboratory of Nuclear Installation Safety, Breslaujos str. 3, LT-44403 Kaunas (Lithuania); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Batistoni, Paola [ENEA, Via E. Fermi, 45, 00044 Frascati, Rome (Italy); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sjöstrand, Henrik; Conroy, Sean [Department of Physics and Astronomy, Uppsala University, PO Box 516, SE-75120 Uppsala (Sweden); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2015-07-11

The neutron activation technique is routinely used in fusion experiments to measure the neutron yields. This paper investigates the uncertainty on these measurements as due to the uncertainties on dosimetry and activation reactions. For this purpose, activation cross-sections were taken from the International Reactor Dosimetry and Fusion File (IRDFF-v1.05) in 640 groups ENDF-6 format for several reactions of interest for both 2.5 and 14 MeV neutrons. Activation coefficients (reaction rates) have been calculated using the neutron flux spectra at JET vacuum vessel, both for DD and DT plasmas, calculated by MCNP in the required 640-energy group format. The related uncertainties for the JET neutron spectra are evaluated as well using the covariance data available in the library. These uncertainties are in general small, but not negligible when high accuracy is required in the determination of the fusion neutron yields.

A set-up for measuring neutron cross sections and radiation multiplicity from neutron-nucleus interaction

International Nuclear Information System (INIS)

Georgiev, G.P.; Ermakov, V.A.; Grigor'ev, Yu.V.

1988-01-01

A multiplicity detector of the ''Romashka'' type has been used on the 500 m flight part of the IBR-30 pulsed reactor. The detector consists of 16 independent sections with NaJ(Tl) crystals with a total volume of 36 liters. The geometric efficiency of single-ray detection is ∼ 80%. The gamma-ray to neutron detection efficiency ratio is ≥600 for neutrons with energies below 200 keV. This detector allows one to perform neutron capture and fission cross section measurements and to study gamma-ray multiplicity and resonance selfabsorption effects in the 20 eV-200keV neutron energy range

Measurement of neutron production by 500 MeV proton beam

International Nuclear Information System (INIS)

Hirayama, Hideo; Ban, Shuichi

1981-01-01

Measurement of high energy neutrons is difficult, because the cross section data are scarce, the cross section at high energy is usually small, and the monoenergetic neutrons are hardly obtained. At the National Laboratory for High Energy Physics (KEK), various threshold detectors have been used for high energy neutron measurement. A carbon detector is a standard detector for high energy neutrons, since the cross section of the C 12 (n, 2n) C 11 reaction is almost constant at higher energy than 20 MeV, and the data have been well known. The half-life of the product (C 11 ) is about 20 min, and other activities with longer half-life than 1 min are restricted to Be 7 and C 11 . As a carbon detector, a plastic scintillator is used, and the neutron spectra observed at the Booster Beam Dump Room of KEK are presented. The results of measurements were compared with the calculated results using a Monte Carlo code made at KEK. Agreement between both results was good. (Kato, T.)

The fluence research of filter material for fast neutron fluence measurement

International Nuclear Information System (INIS)

Tang Xiding

2010-01-01

When the fast neutron fluence is measured by radioactivation techniques in the nuclear reactor the fast neutron is also filtered a little by the thermal neutron filter material, and if the filter material thickness increase the filtered fast neutron increases therewith. For fast neutron fluenc measurement, there are only cadmium, boron and gadolinium three elements filtering fluence can be calculated ordinarily. In order to calculate the filtered fast neutron fluence of the all elements in the filter material, the many total cross sections of nuclides had checked out from nuclear cross section data library, converted them into the same energy group structure, then element's total cross section, compound's total cross section and multilayer filters' total cross section had calculated from these total cross sections with same energy group structure, a new cross section data library can be obtained lastly through merging these cross sections into the old cross section data library used for neutron fluence measurement. The calculation analysis indicates that the results of the unit 2 surveillance capsule U of DAYA Bay NPP and the unit 1 surveillance capsule A of the Second Nuclear Power Plant of Qinshan by considering the all elements subtracting iron are smaller about 1.5% and 2.6% respectively than the ones only to consider cadmium, boron. The old measured results accord with the new values under the measurement uncertainty, are reliable. The new results are more accuracy. (authors)

Measurement and Analysis of Neutron Leakage Spectra from Pb and LBE Cylinders with D-T Neutrons

Science.gov (United States)

Chen, Size; Gan, Leting; Li, Taosheng; Han, Yuncheng; Liu, Chao; Jiang, Jieqiong; Wu, Yican

2017-09-01

For validating the current evaluated neutron data libraries, neutron leakage spectra from lead and lead bismuth eutectic (LBE) cylinders have been measured using an intense D-T pulsed neutron source with time-of-flight (TOF) method by Institute of Nuclear Energy Safety Technology (INEST), Chinese Academy of Sciences (CAS). The measured leakage spectra have been compared with the calculated ones using Super Monte Carlo Simulation Program for Nuclear and Radiation Process (SuperMC) with the evaluated pointwise data of lead and bismuth processed from ENDF/B-VII.1, JEFF-3.1 and JENDL-4.0 libraries. This work shows that calculations of the three libraries are all generally consistent with the lead experimental result. For LBE experiment, the JEFF-3.1 and JENDL-4.0 calculations both agree well with the measurement. However, the result of ENDF/B-VII.1 fails to fit with the measured data, especially in the energy range of 5.5 and 7 MeV with difference more than 80%. Through sensitivity analysis with partial cross sections of 209Bi in ENDF/B-VII.1 and JEFF, the difference between the measurement and the ENDF/B-VII.1 calculation in LBE experiment is found due to the neutron data of 209Bi.

Neutron measurement in 12,13C+ 27Al system using CR-39 detectors and neutron rem meter

International Nuclear Information System (INIS)

Sahoo, G.S.; Tripathy, S.P.; Shanbhag, A.A.; Sunil, C.; Joshi, D.S.; Sarkar, P.K.

2011-01-01

In this work, neutron measurements carried out for the interaction of 60 and 67.5 MeV 12 C, 57.3 and 65 MeV 13 C ions with thick aluminium target by using CR-39 detectors and neutron rem meter is reported. Both the detector systems were irradiated at different angles viz. 0 deg, 30 deg, 60 deg, 90 deg with respect to the beam direction. The normalized track density measurements (tracks/cm 2 /projectile at 1m) in CR-39 detectors were correlated with the normalized dose equivalent values (μSv/projectile at 1m) obtained using the neutron rem meter. The track density was found to be more in case of 13 C than 12 C. However in all the cases, the track density per incident projectile was found to decrease as the angle with respect to beam direction increases, indicating non-isotropic nature of neutron emission. The ratio between measured dose equivalent in rem meter to the measured track densities in CR-39 detectors was found to be 2.8±0.2, which remains constant irrespective of the change in angle from beam direction as well as neutron spectrum, indicating a flat dose response of CR-39 detectors. (author)

Neutron dose measurements with the GSI ball at high energy accelerators

International Nuclear Information System (INIS)

Fehrenbacher, G.; Gutermuth, F.; Radon, T.; Kozlova, E.

2005-01-01

Full text: At high energy particle accelerators the production of neutron radiation dominates radiation protection. For the radiation survey at accelerators there is a need for reliable detection systems (passive radiation monitors), which can measure the dose for a wide range of neutron energies independently on the beam pulse structure of the produced radiation. In this work a passive neutron dosemeter for the measurement of the ambient dose equivalent is presented. The dosemeter is suitable for measurements of the emerging neutron radiation at accelerators for the whole energy range up to about 10 GeV. The dosemeter consists of a polyethylene sphere, TL elements (pairs of TLD600/700) and an additional lead layer (PE/Pb) in neutron fields at high energy accelerators is investigated in this work. Results of dose measurements which were performed in realistic neutron fields at the high energy accelerator SPS at CERN (CERF facility) and in Cave A at the heavy ion synchrotron SIS at GSI are presented. The results of these measurements are compared with the expected dose values from the neutron spectra determined for the measurement positions at CERF and in Cave A (FLUKA) and with the dosemeter response derived by the calculated response functions (FLUKA) folded with the neutron spectra. The comparisons show that the additional lead layer in the PE/Pb-sphere improves significantly the response of the dosemeter. The response of the PE/Pb-sphere is 40 to 50 % higher at CERF and Cave A in comparison to the bare PE-sphere. At CERF the dose values of the PE/Pb-sphere is about 25 % lower than the expected dose value, whilst for Cave A, a rather good agreement was found (2 % deviation). (author)

Mass spectrometric detection of radiocarbon for dating applications

Energy Technology Data Exchange (ETDEWEB)

Synal, H.-A., E-mail: synal@phys.ethz.ch [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland); Schulze-Koenig, T.; Seiler, M.; Suter, M.; Wacker, L. [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland)

2013-01-15

Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV {sup 14}C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

Mass spectrometric detection of radiocarbon for dating applications

International Nuclear Information System (INIS)

Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

2013-01-01

Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14 C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

Mass spectrometric detection of radiocarbon for dating applications

Science.gov (United States)

Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

2013-01-01

Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

Neutron measurements in the core and blankets of the reactor Rapsodie

International Nuclear Information System (INIS)

Gourdon, J.; Edeline, J.C.

1968-01-01

Beside a brief general discussion, the report contains all the core and blanket neutronic measurements. It covers successively the methods, the measurements themselves and the results. The later concern: spectral indexes, axial and radial fission rates, activation foil measurements and neutronic power determination. (authors) [fr

Optimization of the architecture of a neural network in neutron spectrometry to reduce the number of Bonner spheres; Optimizacion de la arquitectura de una red neuronal en espectrometria de neutrones para reducer el numero de esferas Bonner

Energy Technology Data Exchange (ETDEWEB)

Leon P, A. A.; Martinez B, M. R.; Hernandez P, C. F.; Espinoza G, J. G.; Castaneda M, V. H.; Solis S, L. O.; Castaneda M, R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Av. Ramon Lopez Velarde 801, Col. Centro, 98000 Zacatecas, Zac. (Mexico); Mendez V, R. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 22, 28040 Madrid (Spain); Gallego, E. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, ETSI Industriales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); De Sousa L, M. A. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

The neutron spectrometry is an experimental process for determining the energy distribution called the Spectrum. Among the methods available for neutron spectrometry, one can mention the Bonner Sphere Spectrometric System as one of the most used, consisting of a detector placed in the center of a set of polyethylene spheres whose diameters range from 2 to 18 inches, however has some disadvantages such as the long periods of time to perform the measurements, the weight and the spheres number that vary according to the system. From this, alternative methods such as artificial neural networks are proposed. For this project neural networks of reverse propagation were used with the methodology of robust design of artificial neural networks, with the aid of a computational tool that maximizes the performance, making the time used for the training s of the network is the smallest possible and thus gets the orthogonal fixes quickly to determine the best network topology. The counting rates of a spectrometric system with 7 spheres, 2 spheres and one sphere of 5 and 8 inches were used. This methodology seeks to reduce the work used as in the spectrometric system formed by a greater number of spheres, since to enter less data in the counting rates to obtain the spectra with 60 energy levels saves time and space, because at having a smaller number of spheres its portability is easier to move from one place to another, for this we performed several experiments with different errors until we reached the optimal error so that the topology of the network was appropriate and find the best design parameters. A statistical software JMP was also used to obtain the best topologies and thus to retrain obtaining its best and worst spectra, in order to determine if the reduction is possible. (Author)

Measurements of fusion neutron multiplication in spherical beryllium shells

International Nuclear Information System (INIS)

Giese, H.; Kappler, F.; Tayama, R.; Moellendorff, U. von; Alevra, A.; Klein, H.

1996-01-01

New results of spherical-shell transmission measurements with 14-MeV neutrons on pure beryllium shells up to 17 cm thick are reported. The spectral flux above 3 MeV was measured using a liquid scintillation detector. At 17 cm thickness, also the total neutron multiplication was measured using a Bonner sphere system. The results agree well with calculations using beryllium nuclear data from the EFF-1 or the ENDF/B-Vi library. (author). 23 refs, 4 figs, 1 tab

Utilization of neutrons in nuclear data measurements and bulk sample analysis

International Nuclear Information System (INIS)

Jonah, S. A.

1995-01-01

Experimental investigations were carried out with neutrons in the fields of neutron data measurements and bulk sample analysis based on the interactions of neutron interactions required in the investigations together with some salient features of the sources employed are enumerated. Excitation cross section curves and isomeric cross section ratio of 58 Ni(n,p) 58 Co m , g reaction over the neutron energy range of between 5 and 15 MeV were determined using the activation analysis technique in combination with high-resolution gamma spectroscopy. Characteristics of the incident neutrons produced via the D-T reaction of a neutron generator and D-D reaction of a cyclotron were determined experimentally to account for the contributing effects of background neutrons especially in the 5-13 MeV neutron energy range where existing data are scanty and rather discrepant. The measured data agree well with calculated data using nuclear models but deviate significantly from the recommended data based on existing literature data. The measured δ act and δ m /δ g data made it possible to determine the cross section curve for 58 Ni(n,p) 58 Co m reaction. Furthermore the flux density distributions of thermal and primary fast neutrons in different configurations of bulk samples consisting of water, graphite and coal together with the attenuation characteristics were determined by the activation analysis and pulse height response spectrometry techniques. From the results obtained, an experimental geometry has been proposed for on-line elemental analysis of coal and other minerals. Similarly the total hydrogen content and 0+C/H atomic ratio in household and motor oils as well as crude oil samples of different origins were measured by an improved experimental arrangement based on the thermal neutron reflection technique. A detection limit of 0.12 w % was obtained for hydrogen indicating the possible adaptation of this technique for quality control of petroleum products

Magnetic field devices for neutron spin transport and manipulation in precise neutron spin rotation measurements

Energy Technology Data Exchange (ETDEWEB)

Maldonado-Velázquez, M. [Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, 04510 (Mexico); Barrón-Palos, L., E-mail: libertad@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 (Mexico); Crawford, C. [University of Kentucky, Lexington, KY 40506 (United States); Snow, W.M. [Indiana University, Bloomington, IN 47405 (United States)

2017-05-11

The neutron spin is a critical degree of freedom for many precision measurements using low-energy neutrons. Fundamental symmetries and interactions can be studied using polarized neutrons. Parity-violation (PV) in the hadronic weak interaction and the search for exotic forces that depend on the relative spin and velocity, are two questions of fundamental physics that can be studied via the neutron spin rotations that arise from the interaction of polarized cold neutrons and unpolarized matter. The Neutron Spin Rotation (NSR) collaboration developed a neutron polarimeter, capable of determining neutron spin rotations of the order of 10{sup −7} rad per meter of traversed material. This paper describes two key components of the NSR apparatus, responsible for the transport and manipulation of the spin of the neutrons before and after the target region, which is surrounded by magnetic shielding and where residual magnetic fields need to be below 100 μG. These magnetic field devices, called input and output coils, provide the magnetic field for adiabatic transport of the neutron spin in the regions outside the magnetic shielding while producing a sharp nonadiabatic transition of the neutron spin when entering/exiting the low-magnetic-field region. In addition, the coils are self contained, forcing the return magnetic flux into a compact region of space to minimize fringe fields outside. The design of the input and output coils is based on the magnetic scalar potential method.

FRUIT: An operational tool for multisphere neutron spectrometry in workplaces

International Nuclear Information System (INIS)

Bedogni, Roberto; Domingo, Carles; Esposito, Adolfo; Fernandez, Francisco

2007-01-01

FRUIT (Frascati Unfolding Interactive Tool) is an unfolding code for Bonner sphere spectrometers (BSS) developed, under the Labview environment, at the INFN-Frascati National Laboratory. It models a generic neutron spectrum as the superposition of up to four components (thermal, epithermal, fast and high energy), fully defined by up to seven positive parameters. Different physical models are available to unfold the sphere counts, covering the majority of the neutron spectra encountered in workplaces. The iterative algorithm uses Monte Carlo methods to vary the parameters and derive the final spectrum as limit of a succession of spectra fulfilling the established convergence criteria. Uncertainties on the final results are evaluated taking into consideration the different sources of uncertainty affecting the input data. Relevant features of FRUIT are (1) a high level of interactivity, allowing the user to follow the convergence process, (2) the possibility to modify the convergence tolerances during the run, allowing a rapid achievement of meaningful solutions and (3) the reduced dependence of the results from the initial hypothesis. This provides a useful instrument for spectrometric measurements in workplaces, where detailed a priori information is usually unavailable. This paper describes the characteristics of the code and presents the results of performance tests over a significant variety of reference and workplace neutron spectra ranging from thermal up to hundreds MeV neutrons

Neutron measurements at nuclear power reactors [55

CERN Document Server

Scherpelz, R I

2002-01-01

Staff from the Pacific Northwest National Laboratory (operated by Battelle Memorial Institute), have performed neutron measurements at a number of commercial nuclear power plants in the United States. Neutron radiation fields at light water reactor (LWR) power plants are typically characterized by low-energy distributions due to the presence of large amounts of scattering material such as water and concrete. These low-energy distributions make it difficult to accurately monitor personnel exposures, since most survey meters and dosimeters are calibrated to higher-energy fields such as those produced by bare or D sub 2 O-moderated sup 2 sup 5 sup 2 Cf sources. Commercial plants typically use thermoluminescent dosimeters in an albedo configuration for personnel dosimetry and survey meters based on a thermal-neutron detector inside a cylindrical or spherical moderator for dose rate assessment, so their methods of routine monitoring are highly dependent on the energy of the neutron fields. Battelle has participate...

Neutron measuring instruments for radiation protection

International Nuclear Information System (INIS)

Heinzelmann, M.; Schneider, W.; Hoefert, M.; Kuehn, H.; Jahr, R.; Wagner, S.; Piesch, E.

1979-09-01

The present report deals with selected topics from the field of neutron dosimetry for radiation protection connected with the work of the subcommittee 6802 in the Standards Committee on Radiology (NAR) of the German Standards Institute (DIN). It is a sort of material collection. The topics are: 1. Measurement of the absorbed-energy dose by a) ionization chambers in fields of mixed radiation and b) recoil-proton proportional counting tubes. 2. Measurement of the equivalent dose, neutron monitors, combination methods by a) rem-meters, b) recoil-proton counting tubes, c) recombination method, tissue-equivalent proportional counters, activation methods for high energies in fields of mixed radiation, d) personnel dosimetry by means of ionization chambers and counting tubes, e) dosimetry by means of activation methods, nuclear track films, nonphotographic nuclear track detectors and solid-state dosimeters. (orig./HP) [de

Large subcriticality measurement by pulsed neutron method

International Nuclear Information System (INIS)

Yamane, Y.; Yoshida, A.; Nishina, K.; Kobayashi, K.; Kanda, K.

1985-01-01

To establish the method determining large subcriticalities in the field of nuclear criticality safety, the authors performed pulsed neutron experiments using the Kyoto University Critical Assembly (KUCA) at Research Reactor Institute, Kyoto University and the Cockcroft-Walton type accelerator attached to the assembly. The area-ratio method proposed by Sjoestrand was employed to evaluate subcriticalities from neutron decay curves measured. This method has the shortcomings that the neutron component due to a decay of delayed neutrons remarkably decreases as the subcriticality of an objective increases. To overcome the shortcoming, the authors increased the frequency of pulsed neutron generation. The integral-version of the area-ratio method proposed by Kosaly and Fisher was employed in addition in order to remove a contamination of spatial higher modes from the decay curve. The latter becomes significant as subcriticality increases. The largest subcriticality determined in the present experiments was 125.4 dollars, which was equal to 0.5111 in a multiplication factor. The calculational values evaluated by the computer code KENO-IV with 137 energy groups based on the Monte Carlo method agreed well with those experimental values

Space weather monitoring with neutron monitor measurements

Energy Technology Data Exchange (ETDEWEB)

Steigies, Christian [Christian-Albrechts-Universitaet zu Kiel (Germany)

2013-07-01

Space Weather affects many areas of the modern society, advance knowledge about space weather events is important to protect personnel and infrastructure. Cosmic Rays (CR) measurements by ground-based Neutron Monitors are influenced by Coronal Mass Ejections (CME), the intensity of the ever present Cosmic Rays is reduced in a Forbush decrease (Fd). In the case of very energetic CMEs, the measured intensity can be significantly increased in a Ground Level Enhancement (GLE). By detecting the anisotropy of the CR environment, a CME can be detected hours before it arrives at Earth. During a GLE the high-energy particles from the Sun can be detected before the more abundant lower energy particles arrive at Earth, thus allowing to take protective measures. Since the beginning of the Neutron Monitor Database (NMDB) project, which has been started in 2008 with funding from the European Commission, real-time data from Neutron Monitors around the world has been made available through one web-portal. We have more than doubled the number of stations providing data since the start of the project to now over 30 stations. The effectiveness of the ALERT applications which are based on NMDB data has been shown by the recent GLE71. We present different applications through which the measurements and different data products are accessible.

Using thermalizers in measuring 'Ukryttia' object's FCM neutron fluxes

CERN Document Server

Krasnyanskaya, O G; Odinokin, G I; Pavlovich, V N

2003-01-01

The results of research of a thermalizer (heater) width influence on neutron thermalization efficiency during FCM neutron flux measuring in the 'Ukryttia' are described. The calculations of neutron flux densities were performed by the Monte-Carlo method with the help of computer code MCNP-4C for FCM different models.Three possible installations of detectors were considered: on FCM surface,inside the FCM, and inside the concrete under the FCM layer. It was shown,that in order to increase the sensitivity of neutron detectors in intermediate and fast neutrons field,and consequently, to decrease the dependence of the readings of spectral distribution of neutron flux,it is necessary to position the detector inside the so-called thermalizer or heater. The most reasonable application of thick 'heaters' is the situation, when the detector is placed on FCM surface.

Effect of granulation of geological samples in neutron transport measurements

International Nuclear Information System (INIS)

Woznicka, Urszula; Drozdowicz, Krzysztof; Gabanska, Barbara; Krynicka, Ewa; Igielski, Andrzej

2001-01-01

The thermal neutron absorption cross section is one of the parameters describing the transport of thermal neutrons in a medium. Theoretical descriptions and experiments which determine the absorption cross section have a wide literature for homogeneous media. The situation comes true e.g. for fluids or amorphous solids. There are many other media which should be treated as heterogeneous. Among others - geological materials. The material heterogeneity for the thermal neutron transport in a considered volume is understood here as an existence of many small regions which differ significantly in their macroscopic neutron diffusion parameters (defined by the absorption and transport cross sections). The final difference, which influences the neutron transport, comes from a combination of the absolute differences between the parameters and of sizes of regions (related to the neutron mean free paths). A rock can be naturally heterogeneous in the above meaning. Besides, it can happen that a preparation of the rock sample for a neutron measurement can increase its natural heterogeneity. (For example, when the rock material is crushed and the measured sample consists of the obtained grains). The question is which granulation is allowed to treat the sample material as still homogeneous, and from which size of the rock grains we have to consider a two-component medium. It has been experimentally proved that the effective absorption of thermal neutrons in a heterogeneous two-component material can significantly differ from the absorption in a homogeneous one which consists of the same elements. The final effect is dependent on a few factors: the macroscopic absorption cross sections of the components, their total mass contributions, and the size of the grains. The ratio of the effective absorption cross section of the heterogeneous material to the cross section of the equivalent homogeneous, is a measure of the heterogeneity effect on the thermal neutron absorption

Pulsed neutron method for diffusion, slowing down, and reactivity measurements

International Nuclear Information System (INIS)

Sjoestrand, N.G.

1985-01-01

An outline is given on the principles of the pulsed neutron method for the determination of thermal neutron diffusion parameters, for slowing-down time measurements, and for reactivity determinations. The historical development is sketched from the breakthrough in the middle of the nineteen fifties and the usefulness and limitations of the method are discussed. The importance for the present understanding of neutron slowing-down, thermalization and diffusion are point out. Examples are given of its recent use for e.g. absorption cross section measurements and for the study of the properties of heterogeneous systems

Quantitative density measurements from a real-time neutron radiography system

International Nuclear Information System (INIS)

McRae, D.D.; Jenkins, R.W. Jr.; Brenizer, J.S.; Tobin, K.W.; Hosticka, B.; Sulcoski, M.F.

1986-01-01

An advanced video system has been assembled from commercially available equipment to support the real-time neutron radiography facility established jointly by the University of Virginia Department of Nuclear Engineering and Engineering Physics, and the Philip Morris Research Center. A schematic diagram of the equipment used for real-time neutron radiography is presented. To obtain quantitative density measurements with this system, several modifications of both hardware and image processing software were required. After implementation of these changes, the system was capable of determining material densities by measuring the degree of neutron attenuation

Neutron probe measurement of soil water content close to soil surface

International Nuclear Information System (INIS)

Faleiros, M.C.; Ravelo S, A.; Souza, M.D. de

1993-01-01

The problem of neutron probe soil water content measurements close to soil surface is analysed from the spatial variability and also from the slow neutron loss to the atmosphere points of view. Results obtained on a dark red latosol of the county of Piracicaba, SP, indicate the possibility of precisely measuring the neutron sphere of influence when different media are used on soil surface. (author). 7 refs, 5 figs, 1 tab

Development of the neutron technology for measuring the moisture content in China

International Nuclear Information System (INIS)