Analysis and reevaluation of the neutron cross sections for 23Na

International Nuclear Information System (INIS)

Trykov, E.L.; Svinin, I.R.

2000-05-01

The reaction model calculations of the cross sections of neutron-induced reactions on 23 Na have been carried out for incident energies up to 20 MeV. The results of the calculations are compared to all available experimental data, including the most recent ones, and also to the previous evaluations. The discrepancies between the data and the present evaluation and also between evaluations themselves were analyzed. The probable reasons of these discrepancies were considered. On the whole, the calculation results agree well enough with the experimental data. (author)

Slow neutron total cross-section, transmission and reflection calculation for poly- and mono-NaCl and PbF{sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Mansy, Muhammad S., E-mail: mmansy88@asrt.sci.eg [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt); Radioactive Waste Management Unit, Hot Labs Centre, Atomic Energy Authority, Cairo (Egypt); Adib, M.; Habib, N. [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt)

2016-10-01

Highlights: • Slow neutron cross-section calculation for poly- and mono-crystalline materials. • Monochromatic features of PbF{sub 2} and NaCl mono-crystals. • Characterization of poly- and mono-crystal filters used in neutron diffraction. • Computer code developed calculates neutron cross-section, transmission & reflection. - Abstract: A detailed study about the calculation of total neutron cross-section, transmission and reflection from crystalline materials was performed. The developed computer code is approved to be sufficient for the required calculations, also an excellent agreement has been shown when comparing the code results with the other calculated and measured values. The optimal monochromator and filter parameters were discussed in terms of crystal orientation, mosaic spread, and thickness. Calculations show that 30 cm thick of PbF{sub 2} poly-crystal is an excellent cold neutron filter producing neutron wavelengths longer than 0.66 nm needed for the investigation of magnetic structure experiments. While mono-crystal filter PbF{sub 2} cut along its (1 1 1), having mosaic spread (η = 0.5°) and thickness 10 cm can only transmit thermal neutrons of the desired wavelengths and suppress epithermal and γ-rays forming unwanted background, when it is cooled to liquid nitrogen temperature. NaCl (2 0 0) and PbF{sub 2} (1 1 1) monochromator crystals having mosaic spread (η = 0.5°) and thickness 10 mm shows high neutron reflectivity for neutron wavelengths (λ = 0.114 nm and λ = 0.43 nm) when they used as a thermal and cold neutron monochromators respectively with very low contamination from higher order reflections.

Neutron spectra and dosimetric features of isotopic neutron sources: a review

Energy Technology Data Exchange (ETDEWEB)

Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Martinez O, S. A., E-mail: fermineutron@yahoo.com [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte 39-115, 150003 Tunja, Boyaca (Colombia)

2015-10-15

A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of {sup 24}NaBe, {sup 24}NaD{sub 2}O, {sup 116}InBe, {sup 140}LaBe, {sup 238}PuLi, {sup 239}PuBe, {sup 241}AmB, {sup 241}AmBe, {sup 241}AmF, {sup 241}AmLi, {sup 242}CmBe, {sup 210}PoBe, {sup 226}RaBe, {sup 252}Cf and {sup 252}Cf/D{sub 2}O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

Resonance neutron capture in 23Na and 27Al from 3 to 600 keV

International Nuclear Information System (INIS)

Musgrove, A.R. de L.; Allen, B.J.; Macklin, R.L.

1978-01-01

The radiative capture cross sections of 23 Na and 27 Al were measured with the high resolution facility at the 40 m station of the Oak Ridge Electron Linear Accelerator. Resonance parameters for the individual resonances below 600 keV are given. Particular care was taken to correct the data for prompt neutron scattering effects by Monte Carlo methods

Lattice dynamics of NaI studied by inelastic neutron scattering: absence of thermally induced discrete breathers

Czech Academy of Sciences Publication Activity Database

Kempa, Martin; Ondrejkovič, Petr; Bourges, P.; Márton, Pavel; Hlinka, Jiří

2014-01-01

Roč. 89, č. 5 (2014), "054308-1"-"054308-5" ISSN 1098-0121 R&D Projects: GA ČR GPP204/11/P404 Institutional support: RVO:68378271 Keywords : NaI * alkali halides * inelastic neutron scattering * discrete breathers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

Basics of Neutrons for First Responders

Energy Technology Data Exchange (ETDEWEB)

Rees, Brian G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2018-02-05

These are slides from a presentation on the basics of neutrons. A few topics covered are: common origins of terrestrial neutron radiation, neutron sources, neutron energy, interactions, detecting neutrons, gammas from neutron interactions, neutron signatures in gamma-ray spectra, neutrons and NaI, neutron fluence to dose (msV), instruments' response to neutrons.

Effect of using FLiBe and FLiNaBe molten salts bearing plutonium fluorides on the neutronic performance of PACER

International Nuclear Information System (INIS)

Acir, Adem

2012-01-01

In this paper, the effects of using FLiBe and FLiNaBe Molten Salts Bearing Plutonium Fluorides on the neutronic performance of the PACER are investigated. The optimum radial thickness for tritium self-sufficiency of the blankets addition of plutonium fluorides to FLiNaBe (LiF-/NaF BeF 2 ) and FLiBe (LiF-/BeF 2 ) of a dual purpose modified PACER concept are determined. The calculations are carried out with the one dimensional transport code XSDRNPM/SCALE5. The tritium breeding capacities of FLiNaBe and FLiBe with addition of plutonium fluorides in molten salt zone are investigated and compared. The optimum molten salt zone thickness is computed as 155 cm for tritium self-sufficiency of the blankets using FLiBe +1% PuF 4 whereas, the optimum thickness with FLiNaBe +1% PuF 4 is calculated as 170 cm. In addition, neutron transport calculations have been performed to evaluate the energy multiplication factor, total fission rate, displacement per atom and helium gas generation for optimal radial thickness in the blanket. Also, the tritium production and the radiation damage limits should be evaluated together in a fusion blanket for determining the optimum thickness of molten salt layer. (orig.)

Coulomb excitation of neutron-rich$^{28,29,30}$Na nuclei with MINIBALL at REX-ISOLDE: Mapping the borders of the island of inversion

CERN Multimedia

Butler, P; Cederkall, J A; Reiter, P; Wiens, A; Blazhev, A A; Kruecken, R; Voulot, D; Kalkuehler, M; Wadsworth, R; Gernhaeuser, R A; Hess, H E; Holler, A; Finke, F; Leske, J; Huyse, M L; Seidlitz, M

We propose to study the properties of neutron-rich nuclei $^{28,29,30}$Na via Coulomb excitation experiments using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Reliable B(E2,0$^{+}$ $\\rightarrow$ 2$^{+}$) values for $^{30,32}$Mg were obtained at ISOLDE. Together with recent new results on $^{31}$Mg, collective and single particle properties are probed for Z=12 at the N=20 neutron closed shell, the 'island of inversion'. We would like to extend this knowledge to the neighbouring $^{28,29,30}$Na isotopes where a different transition from the usual filling of the neutron levels into the region with low lying 2p-2h cross shell configurations is predicted by theory. Detailed theoretical predictions on the transition strength in all three Na nuclei are awaiting experimental verification and are the subject of this proposal. At REX beam energies of 3.0 MeV /nucleon the cross-sections for Coulomb excitation are sufficient. Moreover the results from the close-by $^{30,31,32}$Mg nuclei de...

Analysis of neutron flux increase in the horizontal experimental channels of Ra reactor - masters thesis; Analiza povecanja neutronskog fluksa na horizontalnim eksperimentalnim kanalima reaktora RA - magistarski rad

Energy Technology Data Exchange (ETDEWEB)

Strugar, P [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1964-12-01

Calculation and experimental results shown in this paper show that higher thermal neutron flux is obtained in the reactor core with central horizontal reflector at the same power level. The flux is increased when the moderation capability of the core is decreased. Apart from increase of the thermal component of the neutron flux in the experimental channels, the central reflector causes decrease of the epithermal neutron flux and gamma radiation intensity. This is very useful for studying (n, {gamma}) reaction, neutron diffraction, etc. [Serbo-Croat] Rezultati proracuna i merenja prikazanih u ovom radu ukazuju na cinjenicu da se u reaktoru sa ugradjenim centralnim horizontalnim reflektorom dobija veci fluks termalnih neutron pri istoj snazi i to utoliko veci ukoliko je moderaciona sposobnost aktivne zone manja. Pored uvecanja termalne komponente neutrona u snopu na horizontalnim eksperimentalnim kanalima centralni reflektor uslovljava i smanjenje epitermalne komponente, kao i intenzitet gamma zracenja. Ovo je pozeljno za proucavanje (n,{gamma}) reakcija, neutron diffraction, etc.

Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yahia, H. Ben [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Essehli, R., E-mail: ressehli@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Avdeev, M. [Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 2234 (Australia); Park, J-B.; Sun, Y-K. [Department of Energy Engineering Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Al-Maadeed, M.A. [Center for Advanced Materials (CAM), Qatar University, 2713 Doha (Qatar); Belharouak, I., E-mail: ibelharouak@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar)

2016-06-15

The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.

Deep inelastic neutron scattering on 207Pb and NaHF 2 as a test of a detectors array on the VESUVIO spectrometer

Science.gov (United States)

Pietropaolo, A.; Senesi, R.

2008-01-01

A prototype array of resonance detectors for deep inelastic neutron scattering experiments has been installed on the VESUVIO spectrometer, at the ISIS spallation neutron source. Deep inelastic neutron scattering measurements on a reference lead sample and on NaHF 2 molecular system are presented. Despite on an explorative level, the results obtained for the values of mean kinetic energy are found in good agreement with the theoretical predictions, thus assessing the potential capability of the device for a routine use on the instrument.

Deep inelastic neutron scattering on 207Pb and NaHF2 as a test of a detectors array on the VESUVIO spectrometer

International Nuclear Information System (INIS)

Pietropaolo, A.; Senesi, R.

2008-01-01

A prototype array of resonance detectors for deep inelastic neutron scattering experiments has been installed on the VESUVIO spectrometer, at the ISIS spallation neutron source. Deep inelastic neutron scattering measurements on a reference lead sample and on NaHF 2 molecular system are presented. Despite on an explorative level, the results obtained for the values of mean kinetic energy k > are found in good agreement with the theoretical predictions, thus assessing the potential capability of the device for a routine use on the instrument

Geologia e quimioestratigrafia do Grupo Vazante em Lagamar (Minas Gerais, Brasil)

OpenAIRE

Carla Sofia de Sousa Marques

2015-01-01

Este trabalho tem como base um mapeamento geologico na escala 1:50.000 de uma area de 400km2 nos arredores da cidade de Lagamar (MG) e um estudo de perfis quimioestratigraficos com isotopos estaveis de 13C, 18O e 87Sr/86Sr nas formacoes Lagamar e Rocinha do Grupo Vazante. Na regiao afloram rochas da porcao basal do Grupo Vazante, em contato tectonico com o Grupo Bambui. Foram identificadas as formacoes Santo Antonio do Bonito, Rocinha, Lagamar e Serra do Garrote no Grupo Vazante, e no Grup...

Neutron personal dosimetry in criticality accidents

International Nuclear Information System (INIS)

Fonseca, E.S. da; Mauricio, C.L.P.

1996-01-01

In the present work an innovating method is proposed to estimate the absorbed dose received by individuals irradiated with neutrons in an accident, even in the case that the victim is not using any kind of neutron dosemeter. The method combines direct measurements of 24 Na and 32 P activated in the human body. The calculation method was developed using data taken from previously published papers and experimental measurements. Other irradiations results in different neutron spectra prove the validity of the method here proposed. Using a whole body counter to measure 24 Na activity, it is possible to evaluate neutron absorbed doses in the order of 140 μ Gy of very soft (thermal) spectra. For fast neutron fields, the lower limit for neutron dose detection increases, but the present method continues to be very useful in accidents, with higher neutron doses. (author)

Neutron Diffractometer; Neutronski difraktometar

Energy Technology Data Exchange (ETDEWEB)

Zivadinovic, M [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1961-12-15

RA nuclear reactor is considered as a relatively strong neutron source producing the thermal neutron flux of about 3x10{sup 13} n/cm{sup 2} sec when operating at nominal power of 6.5 MW. Neutron diffraction method is applied in the field of solid state physics, material science, crystallography, magnetism, nuclear physic. Neutron diffractometer at the RA reactor consists of: system for obtaining collimated neutron beam from the horizontal experimental channel neutron monochromator; goniometer and electronic equipment for measurements and collecting the the measurement data. Nuklearni reaktor RA koji pri radu na snazi od 6,5 MW ima fluks termalnih neutrona oko 3x10{sup 13} n/cm{sup 2} sec predstavlja relativno jak izvor neutrona. Tehnika difrakcije neutrona primenjuje se u istrazivanjima fizike crvstog stanja, strukture materijala, kristalografije, magnetizma, nuklearne fizike. Neutronski difraktometar na reaktoru RA sastoji se od sistema za dobijanje kolimisanog snopa neutrona kroz horizontalni kanal reaktora; neutroskog monohromatora; goniometra i elektronskih uredjaja za merenja i registrovanje rezultata. Ovaj izvestaj sadrzi detaljan opis i seme neutronskog difraktometra sa pratecom opremom i elektronskim komponentama.

Reactor neutron dosimetry

International Nuclear Information System (INIS)

Najzer, M.; Pauko, M.; Glumac, B.; Acquah, I.N.; Moskon, F.

1977-01-01

An analysis of requirements and possibilities for experimental neutron spectrum determination during the reactor pressure vessel surveil lance programme is given. Fast neutron spectrum and neutron dose rate were measured in the Fast neutron irradiation facility of our TRIGA reactor. It was shown that the facility can be used for calibration of neutron dosimeters and for irradiation of samples sensitive to neutron radiation. The investigation of the unfolding algorithm ITER was continued. Based on this investigations are two specialized unfolding program packages ITERAD and ITERGS written this year. They are able to unfold data from activation detectors and NaI(T1) gamma spectrometer respectively

Multielemental nondestructive neutron activation analysis of Dy, Mn, Eu, Na, Ga, W, La and Sm involving cyclic irradiations with 252Cf

International Nuclear Information System (INIS)

Narkhede, S.S.; Turel, Z.R.

1995-01-01

Dy, Mn, Eu, Na, Ga, W, La and Sm respond very well to INAA technique because of their favourable nuclear properties such as high thermal neutron cross-section or abundance. In the present work a method has been developed for the determination of these elements employing cycle irradiation with 252 Cf thermal neutron source. Radioassaying of the irradiated sample and standard was done employing HPGe detector in conjunction with a PC based MCA units. (author). 2 tabs

Neutron converter at reactor RB; Konvertor neutrona na reaktoru RB

Energy Technology Data Exchange (ETDEWEB)

Strugar, P; Sotic, P; Ninkovic, M; Pesic, M [Boris Kidric Institute of nuclear sciences, Vinca, Belgrade (Yugoslavia)

1977-07-01

A neutron converter at Reactor RB in the 'Boris Kidric' Institute of Nuclear Sciences - Vinca has been constructed. Preliminary measurements have been shown that the converted neutron spectrum is very similar to the fission neutron spectrum. For the same integral reactor power, the measured neutron radiation dose has been for about ten times larger with the neutron converter. The neutron converter offers wide possibilities, as in investigations in the reactor physics, where the fission neutron spectra have been required, as well as in the field of neutron dosimetry and biological irradiations (author)

Deep inelastic neutron scattering on {sup 207}Pb and NaHF{sub 2} as a test of a detectors array on the VESUVIO spectrometer

Energy Technology Data Exchange (ETDEWEB)

Pietropaolo, A. [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica and Centro NAST - Nanoscienze and Nanotecnologie and Strumentazione, via della Ricerca Scientifica 1, 00133 Rome (Italy)], E-mail: antonino.pietropaolo@roma2.infn.it; Senesi, R. [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica and Centro NAST - Nanoscienze and Nanotecnologie and Strumentazione, via della Ricerca Scientifica 1, 00133 Rome (Italy)

2008-01-11

A prototype array of resonance detectors for deep inelastic neutron scattering experiments has been installed on the VESUVIO spectrometer, at the ISIS spallation neutron source. Deep inelastic neutron scattering measurements on a reference lead sample and on NaHF{sub 2} molecular system are presented. Despite on an explorative level, the results obtained for the values of mean kinetic energy are found in good agreement with the theoretical predictions, thus assessing the potential capability of the device for a routine use on the instrument.

Fast neutron fields at the RB reactor; Polja brzih neutron na reacktoru RB

Energy Technology Data Exchange (ETDEWEB)

Strugar, P; Pesic, M; Dasic, N [Institut za nuklearne nauke Boris Kidric Vinca, Beograd (Yugoslavia)

1984-07-01

Paper deals with the reasons and methods of realization of the RB neutron converters. The methods and results of neutron flux intensities and spectra measurements as well as gamma dose determination are presented. (author)

Slow neutron total cross-section, transmission and reflection calculation for poly- and mono-NaCl and PbF2 crystals

Science.gov (United States)

Mansy, Muhammad S.; Adib, M.; Habib, N.; Bashter, I. I.; Morcos, H. N.; El-Mesiry, M. S.

2016-10-01

A detailed study about the calculation of total neutron cross-section, transmission and reflection from crystalline materials was performed. The developed computer code is approved to be sufficient for the required calculations, also an excellent agreement has been shown when comparing the code results with the other calculated and measured values. The optimal monochromator and filter parameters were discussed in terms of crystal orientation, mosaic spread, and thickness. Calculations show that 30 cm thick of PbF2 poly-crystal is an excellent cold neutron filter producing neutron wavelengths longer than 0.66 nm needed for the investigation of magnetic structure experiments. While mono-crystal filter PbF2 cut along its (1 1 1), having mosaic spread (η = 0.5°) and thickness 10 cm can only transmit thermal neutrons of the desired wavelengths and suppress epithermal and γ-rays forming unwanted background, when it is cooled to liquid nitrogen temperature. NaCl (2 0 0) and PbF2 (1 1 1) monochromator crystals having mosaic spread (η = 0.5°) and thickness 10 mm shows high neutron reflectivity for neutron wavelengths (λ = 0.114 nm and λ = 0.43 nm) when they used as a thermal and cold neutron monochromators respectively with very low contamination from higher order reflections.

Neutron activation analysis of Cl, K and Na content in whole blood of horses used in hyperimmune sera production

International Nuclear Information System (INIS)

Baptista, T.S.; Zamboni, C.B.; Medeiros, J.A.G.; Freitas, M.G.; Higashi, H.G.; Marcelino, J.R.

2009-01-01

Using neutron activation analysis technique Cl, K and Na concentration were obtained in whole blood of equines used for antivenom production at Butantan Institute (Sao Paulo, Brazil). These data were compared with the human whole blood estimation. No significant difference was observed suggesting that this model animal is adequate sera production. (author)

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

Quasielastic neutron scattering measurements and ab initio MD-simulations on single ion motions in molten NaF

Energy Technology Data Exchange (ETDEWEB)

Demmel, F. [ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Mukhopadhyay, S. [ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)

2016-01-07

The ionic stochastic motions in the molten alkali halide NaF are investigated by quasielastic neutron scattering and first principles molecular dynamics simulation. Quasielastic neutron scattering was employed to extract the diffusion behavior of the sodium ions in the melt. An extensive first principles based simulation on a box of up to 512 particles has been performed to complement the experimental data. From that large box, a smaller 64-particle box has then been simulated over a runtime of 60 ps. A good agreement between calculated and neutron data on the level of spectral shape has been obtained. The obtained sodium diffusion coefficients agree very well. The simulation predicts a fluorine diffusion coefficient similar to the sodium one. Applying the Nernst-Einstein equation, a remarkable large cross correlation between both ions can be deduced. The velocity cross correlations demonstrate a positive correlation between the ions over a period of 0.1 ps. That strong correlation is evidence that the unlike ions do not move completely statistically independent and have a strong association over a short period of time.

Elastic Coulomb breakup of 34Na

Science.gov (United States)

Singh, G.; Shubhchintak, Chatterjee, R.

2016-08-01

Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

Investigation on U - O - Na, Pu - O - Na and U,Pu - O - Na phase diagrams

International Nuclear Information System (INIS)

Pillon, S.

1989-03-01

The thermochemical interaction between the nuclear fuel (uranium and plutonium mixed oxides) and the sodium has been investigated and particularly the three phase diagrams: U - O - Na; Pu - O - Na; U,Pu - O - Na. High temperature neutron diffraction, microcalorimetry and powder X-ray diffraction were used for the characterization of the compounds synthetized. This study allowed to complete the knowledge about each of these diagrams and to measure some physical and thermal properties on the compounds. The limits on the modelization of the fuel-sodium interaction are discussed from the results of the UO 2 - Na reaction [fr

Measurements at the RA Reactor related to the VISA-2 project - Part 3, calculation of VISA-2 samples influence on the reactor reactivity, on the depression of thermal neutron flux in VK-5 channel and VISA-2 samples; Fizicka merenja na reaktoru RA u vezi projekta VISA-2 - III deo, Proracun uticaja uzoraka VISA-2 na reaktivnost reaktora, na depresiju fluksa termalnih neuntrona u kanalu VK-5 i u uzorcima VISA-2

Energy Technology Data Exchange (ETDEWEB)

Markovic, H; Martinc, R [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1962-07-01

The objective of this task was to determine the thermal neutron flux in the RA reactor cell with VISA-2 samples, the influence of VISA-2 samples on the thermal neutron flux distribution in the vicinity of VK-5 channel and the antireactivity of VISA-2 samples placed in the RA reactor core. This distribution is needed for calculating the mean value of absorption and thermal efficiency factor in the reactor cell with the sample. Thermal neutron flux distribution without the sample was calculated by diffusion theory. Fast neutron flux space distribution was assumed to be constant, i.e. that it is dependent only on the nuclear properties of the materials. Macroscopic thermal neutron flux distribution was determined by two-group diffusion theory using the four factor formula applied for two regions: active RA region, and reactor region with calls containing VISA-2 samples. This calculation enables estimation of the VISA-2 samples influence on the thermal neutron flux distribution in the VK-5 channel. Antireactivity of VISA-2 samples was calculated by neutron diffusion theory applying the perturbation method. [Serbo-Croat] Cilj ovog zadatka je da se odredi raspodela fluksa termalnih neutrona u celiji reaktora RA sa uzorcima VISA-2, uticaj uzoraka VISA-2 na makroskopsku raspodelu termalnih neutrona u blizini uzoraka, tj. u kanalu VK-5, kao i antiraktivnost uzoraka VISA-2 ubacenih u jezgro RA. Poznavanje ove raspodele potrebno je za izracunavanje srednje apsorpcije i faktora termalnog iskoriscenja u celiji reaktora sa uzorkom. Raspodela fluksa termalnih neutrona u celiji RA bez uzorka izracunata je na bazi difuzione teorije. Fluks brzih neutrona uzet je kao konstanta s obzirom na prostorne koordinate, tj. da zavisi samo od nuklearnih karakteristika materijala. Makroskopska raspodela fluksa termalnih neutrona u okolini VISA-2 odredjena je na bazi dvogrupne difuzione teorije preko formule cetiri faktora, primenjene na dve zone: prva aktivna zona RA, i druga reaktorka sredina

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

Energy Technology Data Exchange (ETDEWEB)

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

2001-09-15

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

The Ca, Cl, Mg, Na, and P mass fractions in benign and malignant giant cell tumors of bone investigated by neutron activation analysis

International Nuclear Information System (INIS)

Vladimir Zaichick; German Davydov; Tatyana Epatova; Sofia Zaichick

2015-01-01

The Ca, Cl, Mg, Na, and P content and Ca/P, Ca/Mg, Ca/Na, Cl/Ca, and Cl/Na ratios in samples of intact bone, benign and malignant giant cell tumor (GCT) of bone were investigated by neutron activation analysis with high resolution spectrometry of short-lived radionuclides. It was found that in GCT tissue the mass fractions of Cl and Na are higher and the mass fraction of Ca and P are lower than in normal bone tissues. Moreover, it was shown that higher Cl/Na mass fraction ratios as well as lower Ca/Cl, Ca/Mg, and Ca/Na mass fraction ratios are typical of the GCT tissue compared to intact bone. Finally, we propose to use the estimation of such parameters as the Cl mass fraction and the Ca/Cl mass fraction ratio as an additional test for differential diagnosis between benign and malignant GCT. (author)

Neutron capture cross section of ^243Am

Science.gov (United States)

Jandel, M.

2009-10-01

The Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL) was used for neutron capture cross section measurement on ^243Am. The high granularity of DANCE (160 BaF2 detectors in a 4π geometry) enables the efficient detection of prompt gamma-rays following neutron capture. DANCE is located on the 20.26 m neutron flight path 14 (FP14) at the Manuel Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE). The methods and techniques established in [1] were used for the determination of the ^243Am neutron capture cross section. The cross sections were obtained in the range of neutron energies from 0.02 eV to 400 keV. The resonance region was analyzed using SAMMY7 and resonance parameters were extracted. The results will be compared to existing evaluations and calculations. Work was performed under the auspices of the U.S. Department of Energy at Los Alamos National Laboratory by the Los Alamos National Security, LLC under Contract No. DE-AC52-06NA25396 and at Lawrence Livermore National Laboratory by the Lawrence Livermore National Security, LLC under Contract No. DE-AC52-07NA27344. [4pt] [1] M. Jandel et al., Phys. Rev. C78, 034609 (2008)

Neutron radiative capture methods for surface elemental analysis

Science.gov (United States)

Trombka, J.I.; Senftle, F.; Schmadebeck, R.

1970-01-01

Both an accelerator and a 252Cf neutron source have been used to induce characteristic gamma radiation from extended soil samples. To demonstrate the method, measurements of the neutron-induced radiative capture and activation gamma rays have been made with both Ge(Li) and NaI(Tl) detectors, Because of the possible application to space flight geochemical analysis, it is believed that NaI(Tl) detectors must be used. Analytical procedures have been developed to obtain both qualitative and semiquantitative results from an interpretation of the measured NaI(Tl) pulse-height spectrum. Experiment results and the analytic procedure are presented. ?? 1970.

Estimate of absorbed dose received by individuals irradiated with neutrons

International Nuclear Information System (INIS)

Fonseca, E.S. da; Mauricio, C.L.P.

1995-01-01

An innovating methodology is proposed to estimate the absorbed dose received by individuals irradiated with neutrons in an accident, even in the case that the victim is not using any kind of neutron dosemeter. The method combines direct measurements of 24 Na and 32 P activated in the human body. The calculation method was developed using data taken from previously published papers and experimental measurements. Other irradiations results in different neutron spectra prove the validity of the methodology here proposed. Using a whole body counter to measure 24 Na activity, it is possible to evaluate neutron absorbed doses in the order of 140 μGy of very soft (thermal) spectra. For fast neutron fields, the lower limit for neutron dose detection increases, but the present method continues to be very useful in accidents, with higher neutron doses. (author). 5 refs., 1 fig., 4 tabs

Autopercepcao da saude bucal entre adultos na regiao Nordeste do Brasil

Directory of Open Access Journals (Sweden)

Edivania Barbosa do Vale

2013-12-01

Full Text Available OBJETIVO: Identificar a autopercepção da saúde bucal por adultos e variáveis associadas. MÉTODOS: Estudo realizado com os dados da Pesquisa Nacional de Saúde Bucal SBBrasil 2010 relativos a 2.456 adultos de 35 a 44 anos da região Nordeste. A variável dependente foi a autopercepção da saúde bucal. As variáveis independentes foram agrupadas em: demográficas, predisposição/facilitação, condição de saúde bucal e relacionadas à autopercepção da necessidade de tratamento. O teste de Rao e Scott foi utilizado para avaliar a associação entre essas variáveis. O efeito das variáveis independentes sobre o desfecho foi avaliado pelo modelo de regressão logística multinominal segundo modelo hierarquizado, em duas etapas: análise simples e análise múltipla hierarquizada. RESULTADOS: A autopercepção positiva da saúde bucal foi observada em 37% dos participantes. No modelo final, as características diretamente associadas a essa autopercepção foram: ser branco, ter renda familiar superior a R$ 500,00, possuir número de bens acima da mediana, ter maior número de dentes hígidos, não apresentar sangramento, não necessitar de prótese, Oral Impacts on Daily Performances = 0, não necessitar de tratamento e ter ido ao dentista há menos de três anos. CONCLUSÕES: Os resultados mostram que a autopercepção da saúde bucal dos adultos residentes no Nordeste brasileiro está diretamente associada a uma estrutura multidimensional de fatores. As baixas condições econômicas associadas às condições clínicas deficientes dessa população causam grande impacto na sua autopercepção da saúde bucal.

Shape coexistence in the N=19 neutron-rich nucleus 31Mg explored by β–γ spectroscopy of spin-polarized 31Na

Directory of Open Access Journals (Sweden)

H. Nishibata

2017-04-01

Full Text Available The structure of excited states in the neutron-rich nucleus 31Mg, which is in the region of the “island of inversion” associated with the neutron magic number N=20, is studied by β–γ spectroscopy of spin-polarized 31Na. Among the 31Mg levels below the one neutron separation energy of 2.3 MeV, the spin values of all five positive-parity levels are unambiguously determined by observing the anisotropic β decay. Two rotational bands with Kπ=1/2+ and 1/2− are proposed based on the spins and energies of the levels. Comparison on a level-by-level basis is performed between the experimental results and theoretical calculations by the antisymmetrized molecular dynamics (AMD plus generator coordinate method (GCM. It is found that various nuclear structures coexist in the low excitation energy region in 31Mg.

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

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

International Nuclear Information System (INIS)

Matsumoto, Tetsuo; Aizawa, Otohiko; Nozaki, Tetsuya

1981-01-01

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

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

Investigations into the fast ionic conductors γ-CuBr, Li2S, Na2S, Ba2NH, NaTaN2 and Li3HoCl6 by means of neutron scattering

International Nuclear Information System (INIS)

Altorfer, F.

1994-01-01

The main topic of this work was the investigation of ionic diffusion in solids by means of neutron scattering. Experiments were carried out on the antifluorites Li 2 S, Na 2 S and γ-CuBr (zinc-blende type) as well as on Barium-Nitride-Hydride Ba 2 NH, NaTaN 2 and Li 3 HoCl 6 which represent three-and two-dimensional ionic conductors, respectively. In the sulphur based antifluorites Li 2 S and Na 2 S the occupation of the interstitial empty cube site by cations occurs at elevated temperatures. The temperature-dependence of the diffusion process has been investigated by quasielastic, incoherent neutron scattering. The cations hop between their regular lattice sites and the interstitial empty cube site, whereas the sulphur ions vibrate in good approximation harmonically even at high temperatures. The jump vectors define a three-dimensional net of possible cation paths through the crystal. The analysis of quasielastic scattering experiments on a Li 2 S single crystal enabled us to determine the jump vectors and the jump rates 1/τ. The temperature dependence of the anharmonic contributions to the copper structure factor was the main point in our neutron diffraction experiments on γ-CuBr. It could be shown that the copper density function deviates strongly from the isotropic form with increasing temperature. Barium-Nitride-Hydride is one of the few documented H - -ionic conductors. The electronic part of the ds-conductivity is only 1/10000 of the ionic contribution. Since Ba 2 NH is a layer compound, where H - and N 3- layers alternate along the c-axis, the probability of jumps out of the plane is suppressed in favour of in plane jumps. This compound is therefore a model system in which two-dimensional diffusion can be studied and in fact the analysis of the quasielastic data proved that the H-diffusion is caused by jumps between regular H - lattice sites. (author) figs., tabs., refs

Study of {sup 24}Na activity in concrete using 20-MeV proton beam on Cu

Energy Technology Data Exchange (ETDEWEB)

Oranj, Leila Mokhtanri; Jung, Nam Suk; Lee, Arim; Heo, Tae Min; Bakhtian, Mahdi; Lee, Hee Seock [POSTECH, Pohang (Korea, Republic of)

2017-04-15

The number of medical cyclotrons capable of accelerating protons to about 20 MeV is increasing in Korea. In such facilities, various radionuclides could be induced in shielding materials like concrete from secondary neutrons which Causes problems from the view point of radiation safety. Among these radionuclides, gamma-ray from {sup 24}Na (Tz1/2 = 15 h) is the most important origin of radiation exposure. {sup 24}Na could be produced from secondary neutrons on Na, Al and Mg component which exist in the concrete. {sup 24} Na Could be produced from thermal neutrons on Na and fast neutron with energy lower than 20 MeV on Al and Mg. Due to interaction of 20 MeV protons on Cu target, secondary neutrons with the energy of less than 20 MeV were produced. therefore, among the concrete components, Na, Al and Mg are only corespondent to produce {sup 24}Na. In this work, {sup 24}Na activity induced in concrete and chemical reagents of concrete (NaHCO{sub 3}, Al{sub 2}O{sub 3} and MgO) were measured. To produce neutrons, Cu target was irradiated by 20 MeV protons. Measured data were compared with results of simulations by FLUKA and MARS as well as earlier works and theocratical data. In the case of Mg and Al chemical reagents, FLUKA code overestimates our measurements by approximately four times, while, for Na sample, FLUKA underestimates the experimental data by almost 0.5. Data from FLUKA and measurement for the concrete are consistent. Calculation from TALYS for Mg overestimates the measured data by a factor of 2.5.

Neutron-Induced Charged Particle Studies at LANSCE

Science.gov (United States)

Lee, Hye Young; Haight, Robert C.

2014-09-01

Direct measurements on neutron-induced charged particle reactions are of interest for nuclear astrophysics and applied nuclear energy. LANSCE (Los Alamos Neutron Science Center) produces neutrons in energy of thermal to several hundreds MeV. There has been an effort at LANSCE to upgrade neutron-induced charged particle detection technique, which follows on (n,z) measurements made previously here and will have improved capabilities including larger solid angles, higher efficiency, and better signal to background ratios. For studying cross sections of low-energy neutron induced alpha reactions, Frisch-gridded ionization chamber is designed with segmented anodes for improving signal-to-noise ratio near reaction thresholds. Since double-differential cross sections on (n,p) and (n,a) reactions up to tens of MeV provide important information on deducing nuclear level density, the ionization chamber will be coupled with silicon strip detectors (DSSD) in order to stop energetic charged particles. In this paper, we will present the status of this development including the progress on detector design, calibrations and Monte Carlo simulations. This work is funded by the US Department of Energy - Los Alamos National Security, LLC under Contract DE-AC52-06NA25396.

Unconventional spin order in the triangular lattice system NaCrO2: A neutron scattering study

International Nuclear Information System (INIS)

Hsieh, D.; Qian, D.; Berger, R.F.; Cava, R.J.; Lynn, J.W.; Huang, Q.; Hasan, M.Z.

2008-01-01

We report high resolution neutron scattering measurements on the rhombohedrally stacked triangular antiferromagnet NaCrO 2 which has recently been shown to exhibit an unusually broad fluctuating cross-over regime extending far below the onset of spin freezing at T c . Our results show that at T c purely two-dimensional quasi-static spin correlations of the 120 o type exist. Below some cross-over temperature (T∼0.75T c ) a small incommensuration develops which helps resolve the inter-layer spin frustration and drives short-range three-dimensional magnetic order. This incommensuration assisted dimensional cross-over suggests that inter-layer frustration is responsible for stabilizing the rare 2D correlated phase above 0.75T c

Neutron Fluence Evaluation using an Am-Be Neutron Sources Assembly and P ADC Detectors

International Nuclear Information System (INIS)

Seddik, U.

2008-01-01

An assembly of four 241 Am-Be sources has been constructed at Nuclear Reactions Unit (NRU) of Nuclear Research Center (NRU) to perform analysis of different materials using thermal and fast neutrons. In the present paper, we measure the value of transmittance (T) in percentage of etched CR-39 detectors using a spectrophotometer at different neutron fluences ,to relate the transmittance of the detector with the neutron fluence values. The exposed samples to neutrons with accumulated fluence of order between 10 10 and 10 12 cm -2 were etched for 15 time intervals between 10-600 min in 6.25 N NaOH at 70 degree C. The etched samples were analyzed using Tech 8500 II spectrophotometer. A trend of the sample transmission and the etching time is observed which is different for each fluence value. A linear relation between the transmittance decay constant and the neutron fluence is observed which could be used as a calibration to determine unknown neutron fluence

Shape transition in the neutron rich sodium isotopes

International Nuclear Information System (INIS)

Campi, X.; Flocard, H.; Kerman, A.K.; Koonin, S.; Massachusetts Inst. of Tech., Cambridge

1975-06-01

Mass spectrometer measurements of the neutron rich sodium isotopes show a sudden increase at 31 Na in the values of the two neutron separation energies. The spherical shell model naturally predicts a sudden decrease at 32 Na after the N=20 shell closure. It is proposed that the explanation for this disagreement lies in the fact that sodium isotopes in this mass region are strongly deformed due to the filling of negative parity orbitals from the 1fsub(7/2) shell. Hartree-Fock calculations are presented in support of this conjecture [fr

Fast neutron radiography using photoluminescent imaging plates

International Nuclear Information System (INIS)

Rant, J.; Kristof, E.; Balasko, M.; Stade, J.

1999-01-01

Fast neutron radiography (FNR) and resonance neutron radiography (RNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation used for the inspection of thick metal objects. In both non-destructive methods, the contrast sensitivity and the penetration power can be improved by using higher energy neutrons. At present direct techniques based either n Solid State Nuclear Track detectors (SSNTDs) or scintillating screens and transfer techniques using activation threshold detectors and radiographic films are applied for the detection of fast neutron images. Rather low detection sensitivity of film and SSNTD based fast neutron imaging methods and also rather poor inherent image contrast of SSNTD pose a problem for FNR in the fast neutron energy region 1-15 MeV interesting for NDT. For more efficient detection of fast neutron images the use of novel highly sensitive photoluminescent imaging plates (IP) in combination with threshold at the KFKI research reactor. The conventional IP produced by FUJI Photo Film Co. for the detection of beta and X-ray radiation were used. The threshold activation detectors were the reactions 115 In(n, n') 115m In, 64 Zn(n,p) 64 Cu, 56 Fe(n, p) 56 Mn, 24 Mg(n, p) 24 Na and 27 Al(n, α) 24 Na. These threshold reactions cover the fast neutron energy region between 0,7 MeV and 12 MeV. Pure, commercially available metals 0,1 mm to 0,25 mm thick made of In, Zn, Fe, Mg and Al were used as converter screens. The very high sensitivity of IP, the linearity of their response over 5 decades of exposure dose and the high dynamic digitalisation latitude enabled fast neutron radiography of image quality comparable to the quality of thermal NR. In our experimental conditions (φ n ∼ 10 8 n/cm 2 s, R Cd ∼ 2) the neutron exposure and IP exposure periods were still practical and comparable to the half life of the corresponding reaction products (half an hour to several hours). Even with the 27 Al(n.α) 24

Small-angle neutron scattering studies of sodium butyl benzene

Indian Academy of Sciences (India)

Na-NBBS), in aqueous solutions is investigated by small-angle neutron scattering (SANS). Nearly ellipsoidal aggregates of Na-NBBS at concentrations well above its minimum hydrotrope concentration were detected by SANS. The hydrotrope ...

Determining the amount of Br, Na and K in six wheat samples with neutron activation analysis (NAA) method in Arak, I.R. Iran

International Nuclear Information System (INIS)

Reza Pourimani; Khatoon Abasnejad; Khadijeh Ghanbarzadeh; Mohammad Reza Zare; Mahdi Kamali

2013-01-01

Accurate knowledge of the trace elemental concentrations in wheat and its products is of great importance from a nutritional point of view. In this study, six wheat samples were prepared from the agriculture research center of Arak named Sardari, Amir, MV-17, Batava, Karaj-2 and Alvand; they were analyzed by neutron activation method (NAA). In this method, Isfahan miniature reactor as a neutron source and relative NAA method has been used as the analysis type. In this design in order to record gamma spectrum the MCA system and high purity germanium detector were used. Finally, the concentration of the trace elements such as Br, K and Na value was determined for the Sardari, Amir, Alvand, MV-17, Batava, Karaj-2 wheat samples. The average concentration of trace elements in all wheat samples in the studied area are 2.41(0.8597-6.1175) mg kg -1 for Br, 13.42(8.7063-24.696) mg kg -1 for Na and 463.30(434.22-505.45) mg kg -1 for K, respectively. These were compared with other reports results. This study has been conducted as the first time for this region. (author)

Neutron-absorption cross section of sodium-22

International Nuclear Information System (INIS)

Rundberg, R.; Elgart, M.F.; Finston, H.L.; Williams, E.T.; Bond, A.H. Jr.

1975-01-01

A simple method for determining the neutron-absorption cross sections for radionuclides produced and consumed in a reactor-neutron flux is described. Data were obtained for 22 Na which, through application of Westcott's procedure, yielded the following: sigma 0 = 51.5 +- 3.1 kbarns, s 0 = 2.3 +- 0.1, and Σ' = 100 +- 10 kbarns. (3 tables) (U.S.)

Radioisotopes produced by neutron irradiation of food

International Nuclear Information System (INIS)

Albright, S.; Seviour, R.

2016-01-01

The use of neutrons for cargo interrogation has the potential to drastically improve threat detection. Previous research has focussed on the production of "2"4Na, based on the isotopes produced in pharmaceuticals and medical devices. For both the total activity and the ingestion dose we show that a variety of isotopes contribute and that "2"4Na is only dominant under certain conditions. The composition of the foods has a strong influence on the resulting activity and ingestion dose suggesting that the pharmaceuticals and medical devices considered initially are not a viable analogue for foodstuffs. There is an energy dependence to the isotopes produced due to the cross-sections of different reactions varying with neutron energy. We show that this results in different isotopes dominating the ingestion dose at different energies, which has not been considered in the previous literature. - Highlights: • We show that neutron interrogation of food can produce many radioisotopes. • We show a strong dependance between food and certain radioisotopes. • Some isotopes are shown to have an energy dependence. • Previous claims that 24Na is the main threat is shown to only apply in special cases.

Neutron crystallographic studies of amino acids and nucleic acids

International Nuclear Information System (INIS)

Kashiwagi, Tatsuki

2014-01-01

Neutron crystallographic studies of two representative umami materials were executed utilizing iBLX at MLF/J-PARC. The results of them will be summarized in this report. At first, structure analysis of the alpha form crystal of L-glutamic acid was performed in order to assess the usefulness of neutron crystallography at iBIX to our company's R and D. Neutron crystal structure of it was successfully determined at 0.6 A resolution. All hydrogen atoms were clearly observed. Next, the mixed crystal of disodium Inosine-5'-phosphate (IMP · 2Na) and disodium Guanosine-5'-phosphate (GMP · 2Na) was analyzed by neutron crystallography. Neutron crystal structure of the mixed crystal of IMP and GMP (IM/GMP rate = 1.7) was successfully determined at 0.8 A resolution. In the neutron crystal structure of the mixed crystal, the hydrogen atom bonded to the C2 atom of purine base in IMP and the nitrogen atom bonded to the C2 atom of purine base in GMP were clearly observed in the nuclear density map, structurally demonstrating that this crystal is the mixed crystal. (author)

Determination of boron and lithium in diverse biological matrices using neutron activation-mass spectrometry (NA-MS)

International Nuclear Information System (INIS)

Iyengar, G.V.; Downing, R.G.; Clarke, W.B.

1990-01-01

Essential features of the neutron activation-mass Spectrometry (NA-MS) technique are described. Applicability of this technique for the simultaneous determination of boron and lithium is demonstrated for a diverse group of biomaterials. NA-MS is a nondestructive analytical technique, and dynamic in nature since its coverage extends to a broad range of concentration levels. Contamination after the irradiation step, extraneous by natural lithium or boron is inconsequential, since only the activation products are the analyted assayed. Coupling the nuclear activation phenomenon which generates 4 He and 3 He (from 10 B and 6 Li, respectively), with the high precision potential of mass spectrometry forms the bases of this technique. Under ideal conditions the detection limit is extendable to pg g -1 concentration ranges and therefore, it is extremely well suited to investigate the natural concentration levels of boron and lithium in biomaterials. The potential of this method for the determination of lithium in biomedical trace element research is of special significance since determination of sub-ppb levels of lithium by other analytical techniques faces serious analytical difficulties mainly due to contamination control and in some cases to insufficiently low detection limits. (orig.)

Elemental Study in Soybean and Products by Neutron Activation Analysis

International Nuclear Information System (INIS)

Vorapot, Permnamtip; Arporn Busamongkol; Sirinart, Laoharojanaphand

2009-07-01

Full text: Elements were analyzed in soybean and products by Instrumental Neutron Activation Analysis (INAA), Pseudo-Cyclic Instrumental Neutron Activation Analysis (PCINAA) and Epithermal Instrumental Neutron Activation Analysis (EINAA). Elements detected in sample were include Al, Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn Na, Se and Zn. The result showed that the nutritional contents changed after food processing. From experiments (n = 2), it was found that after food processing, the concentration of Cl and Na in soy bean curd increased from 0.0045 and 0.0011% to found 0.91 and 0.39 %, respectively. Other elements did not differ from soybean. Limits of detection for Al, Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn Na, Se and Zn were 0.05, 0.2, 50, 6, 10, 15, 0.05, 30, 40, 5, 5, 0.05 and 1 mg.kg - 1, respectively

Neutron polarization measurements using the pulsed-polarized proton and deuteron beams at TUNL

International Nuclear Information System (INIS)

Walter, R.L.

1981-01-01

Nanosecond wide pulses of polarized protons or deuterons at a repetition rate of 4 MHz are now routinely available for studying interactions involving outgoing neutrons. Up to 90 nA of protons and 200 nA of deuterons have been observed on target. The authors' first experiments involved the determination of the analyzing power A /SUB y/ (UJ) for a few (→p,n) and (→d,n) reactions using conventional neutron time-of-flight detection. A major program for observing polarization effects in neutron elastic scattering has been initiated. The source of polarized neutrons for this program is the 2 H(→d,n→) 3 He reaction which yields a neutron beam having 90% of the polarization of the incident deuterons

The CERES / NA45 experiment

CERN Multimedia

Laurent Guiraud

2000-01-01

Ceres is one of the second generation heavy ion experiments at CERN's SPS. It is dedicated to the study of electron-positron pairs in relativistic nuclear collisions. NA45 is one of the seven experiments (NA44, NA45, NA49, NA50, NA52, WA97/NA57 and WA98) involved in CERN's Heavy Ion programme which provided evidence for the existence of a new state of matter, the quark-gluon plasma. In this state, quarks, instead of being bound up into more complex particles such as protons and neutrons, are liberated and roam freely. Theory predicts that this state must have existed at about 10 microseconds after the Big Bang, before the formation of matter as we know it today.

Rapid evaluation of the neutron dose following a criticality accident by measurement of {sup 24}Na activity; Evaluation rapide de la dose de neutrons a la suite d'un accident de criticite par mesure de l'activite de {sup 24}Na

Energy Technology Data Exchange (ETDEWEB)

Estournel, R [Centre de Production de Plutonium de Marcoule, Service de Protection contre les Rayonnements, 30 (France); Henry, Ph [Centre de Production de Plutonium de Marcoule, Section Medicale et Sociale, 30 (France); Beau, P; Ergas, A [Commissariat a l' Energie Atomique, Service d' Hygiene Atomique, Dept. de la Protection Sanitaire, Chusclan, (France)

1966-07-01

By external measurement of the gamma activity of {sup 24}Na induced in the human organs by a neutron flux during a criticality accident, it is possible to evaluate the personal dose received. Detectors designed for everyday use in health physics can be applied to these measurements, and this is described in the first part of the work. The response of a certain number of induced-activity detectors is presented. The induced activity-dose relationship is studied theoretically in the second part taking into account the neutron spectrum to which the individual has been subjected. The characteristic spectra of three possible types of accident have been used for deducing this relationship. The results obtained show that the method is sufficiently sensitive for present purposes. The accuracy of this method for calculating the dose received during an experiment is discussed. (authors) [French] La mesure par detection externe de l'activite gamma du sodium 24 induit dans l'organisme humain par un flux de neutrons lors d'un accident de criticite rend possible l'evaluation de la dose recue par un individu irradie. L'utilisation de detecteurs d'un emploi courant en radioprotection fait l'objet d'une experimentation qui constitue la premiere partie de cette etude. La reponse d'un certain nombre de detecteurs a une activite induite connue est presentee. La relation dose-activite induite, est etudiee, de maniere theorique, dans la seconde partie, correlativement au spectre des neutrons qui ont atteint l'individu irradie. Les spectres caracteristiques de trois types d'accidents possibles ont ete retenus pour l'etablissement de ces relations. Les resultats obtenus montrent que la methode satisfait avec une sensibilite suffisante au but recherche. La precision avec laquelle on peut ainsi calculer la dose recue au cours d'un accident de criticite est discutee. (auteurs)

Dose evaluation based on {sup 24}Na activity in the human body at the JCO criticality accident in Tokai-mura

Energy Technology Data Exchange (ETDEWEB)

Momose, Takumaro; Tsujimura, Norio; Tasaki, Takashi; Kanai, Katsuta; Kurihara, Osamu; Hayashi, Naomi; Shinohara, Kunihiko [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

2001-09-01

{sup 24}Na in the human body, activated by neutrons emitted at the JCO criticality accident, was observed for 62 subjects, where 148 subjects were measured by the whole body counter of JNC Tokai Works. The 148 subjects, including JCO employees and the contractors, residents neighboring the site and emergency service officers, were measured by the whole-body counter. The neutron-energy spectrum around the facility was calculated using neutron transport codes (ANISN and MCNP), and the relation between an amount of activated sodium in human body and neutron dose was evaluated from the calculated neutron energy spectrum and theoretical neutron capture probability by the human body. The maximum {sup 24}Na activity in the body was 7.7 kBq (83 Bq({sup 24}Na)/g({sup 23}Na)) and the relevant effective dose equivalent was 47 mSv. (author)

A pulsed fast reactor; Un reacteur pulse a neutrons rapides; Impul'snyj reaktor na bystrykh nejtronakh; Reactor rapido pulsado

Energy Technology Data Exchange (ETDEWEB)

Blokhin, G. E.; Blokhintsev, D. I.; Blyumkina, Yu. A.; Bondarenko, I. I.; Deryagin, B. N.; Zajmovskij, A. S.; Zinov' ev, V. P.; Kazachkovskij, O. D.; Krasnoyarov, N. V.; Lejpunskij, A. I.; Malykh, V. A.; Nazarov, P. M.; Nikolaev, S. K.; Stavisskij, Yu. Ya.; Ukraintsev, F. I.; Frank, I. M.; Shapiro, F. Ji.; Yazvitskij, Yu. S. [Akademiya Nauk, Moscow, SSSR (Russian Federation)

1962-03-15

los impulsos de potencia. Asimismo, se efectuaron mediciones del periodo de los neutrones instantaneos, de la fraccion efectiva de neutrones retardados y de los coeficientes de variacion de la reactividad en funcion de la temperatura. (author) [Russian] Impul'snyj reaktor na bystrykh nejtronakh (IBR) rabotaet na nominal'noj moshchnosti v Obedinennom institute yadernykh issledovanij s dekabrya 1960 goda. Reaktor ispol'zuetsya v kachestve impul'snogo istochnika nejtronov dlya fizicheskikh ehksperimentov, provodimykh metodom vremeni proleta. Provodyatsya izmereniya polnogo secheniya, secheniya zakhvata dlya promezhutochnykh nejtronov, issledo- vaniya vzaimodejstviya medlennykh nejtronov s tverdym telom i s zhidkost'yu, izmereniya spektrov nejtronov, ustanavlivayushchikhs ya v. razlichnykh sredakh. V doklade opisany osnovy konstruktsii reaktora i rezul'taty ego issledovanij. Osnovnoj rezhim raboty reaktora-rezhim periodicheskikh impul'sov. Impul'sy moshchnosti voznikayut pri bystrom peremeshchenii podvizhnoj chasti aktivnoj zony reaktora cherez ego nepodvizhnuyu zonu. Podvizhnaya chast' aktivnoj zony zakreplena vo vrashchayushchemsya diske i dvizhetsya so skorost'yu-230 m/sek. Chastota impul'sov moshchnosti mozhet izmenyat'sya s pomoshch'yu vspomogatel'noj podvizhnoj zony v diapazone 2,3-88 im/sek. Srednyaya moshchnost' reaktora - 1 kvt. Polushirina impul'sa moshchnosti - 36 mksek. Reaktor snabzhen sistemoj upravleniya i zashchity, obespechivayushchej avtomaticheskoe podderzhanie srednej moshchnosti reaktora i ego bystruyu ostanovku v sluchae narusheniya rezhima. Reaktor snabzhen sistemoj vakuumirovanny kh nektronovodov, ispol'zuemykh v ehksperimentakh po vremeni proleta. Glavnyj nejtronovod imeet dlinu 1000 m. V protsesse puska i fizicheskikh issledovanij reaktora izuchalos' vliyanie peremeshcheniya organov regulirovaniya i podvizhnykh chastej aktivnoj zony na reaktivnost', izmeryalas' dlitel'nost' impul'sa pri razlichnykh rezhimakh raboty reaktora, izuchalis

Neutrons and the crystal ball experiments

International Nuclear Information System (INIS)

Alyea, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H.; Stanislaus, S.

1997-01-01

The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4π st (20 degree le θ le 160degree and 0degree le φ le 360degree) from the center. The Crystal Ball detector was used for two long series of experiments at the e + e - colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include π - pr a rrow neutrals with pion beam momenta approximately400-750 MeV/c and K - pr a rrow neutrals with kaon beam momenta approximately600-750 MeV/c. Each of these reactions will include a neutron in the final state. whereas the fraction of e + e - interactions with neutrons at SLAC or DESY was quite small. Consequently, there is relatively little experience understanding the behavior of neutrons in the Crystal Ball

Hydrogen dynamics in Na3AlH6: A combined density functional theory and quasielastic neutron scattering study

DEFF Research Database (Denmark)

Voss, Johannes; Shi, Qing; Jacobsen, Hjalte Sylvest

2007-01-01

alanate with TiCl3, and here we study hydrogen dynamics in doped and undoped Na3AlH6 using a combination of density functional theory calculations and quasielastic neutron scattering. The hydrogen dynamics is found to be vacancy mediated and dominated by localized jump events, whereas long-range bulk......Understanding the elusive catalytic role of titanium-based additives on the reversible hydrogenation of complex hydrides is an essential step toward developing hydrogen storage materials for the transport sector. Improved bulk diffusion of hydrogen is one of the proposed effects of doping sodium...... defect motion in sodium alanate could result from vacancy-mediated sodium diffusion....

Bulk moisture determination in building materials by fast neutron/gamma technique

International Nuclear Information System (INIS)

Padron Diaz, I.; Felipe Desdin, L.; Martin Hernandez, G.; Shtejer, K.; Perez Tamayo, N.; Ceballos, C.; Lemus, O.

1998-01-01

Fast Neutron/Gamma Transmission technique has been improved to allow to measure moisture content in building materials. In order to improve fast neutron/gamma discrimination in the transmission system employing the NE-213 scintillation detector a pulse shape discrimination system was constructed at the CEADEN. A separate neutron/gamma detection approach was used with neutron transmission measurement using an Am-Be neutron source and a BF 3 detector and gamma transmission measurement using a collimated 137 Cs source and a NaI scintillator

A dynamic range upgrade for neutron backscattering spectroscopy

International Nuclear Information System (INIS)

Cook, J.C.; Petry, W.; Heidemann, A.; Barthelemy, J.F.

1992-01-01

We report on an instrumental development of the cold neutron backscattering spectrometer IN10 at the Institut Laue-Langevin which has led to a significant increase in its dynamic range. Thermal expansion of a variety of neutron monochromator crystals is used instead of a mechanical oscillation of the monochromator, yielding an increase in the energy transfer range by nearly two orders of magnitude in an elastic wave vector transfer range of 0.07≤Q (A -1 )≤2.0. Using this new configuration, first inelastic measurements have been performed using the (200) reflections from KCl and NaCl monochromators with crystal temperatures between 80 K and 700 K. The thermal expansion of these crystals in this temperature range gives rise to energy transfer ranges (neutron energy gain) of -16<ℎω(μeV)<+83 for KCl and -530<ℎω(μeV)<-420 for NaCl with energy resolution (FWHM) of around 0.6 and 1.4 μeV for KCl and NaCl respectively. These figures represent the highest energy resolution currently available at these energy and wave vector transfers. (orig.)

The investigation of fast neutron Threshold Activation Detectors (TAD)

International Nuclear Information System (INIS)

Gozani, T; King, M J; Stevenson, J

2012-01-01

constituent of available scintillators (e.g., BaF 2 , CaF 2 , hydrogen free liquid fluorocarbon). Thus the activation products of the fast prompt neutrons, in particular, the beta particles, can be measured with a very high efficiency in the detector. Other detectors and substances were investigated, such as 6 Li and even common detectors such as NaI. The principles and experimental results obtained with F, NaI and 6 Li based TAD are shown. The various contributing activation products are identified. The insensitivity of the fluorine based TAD to (d,D) neutrons is demonstrated. Ways and means to reduce or subtract the various neutron induced activations of NaI detector are elucidated along with its fast neutron detection capabilities. 6 Li could also be a useful TAD.

The investigation of fast neutron Threshold Activation Detectors (TAD)

Science.gov (United States)

Gozani, T.; King, M. J.; Stevenson, J.

2012-02-01

constituent of available scintillators (e.g., BaF2, CaF2, hydrogen free liquid fluorocarbon). Thus the activation products of the fast prompt neutrons, in particular, the beta particles, can be measured with a very high efficiency in the detector. Other detectors and substances were investigated, such as 6Li and even common detectors such as NaI. The principles and experimental results obtained with F, NaI and 6Li based TAD are shown. The various contributing activation products are identified. The insensitivity of the fluorine based TAD to (d,D) neutrons is demonstrated. Ways and means to reduce or subtract the various neutron induced activations of NaI detector are elucidated along with its fast neutron detection capabilities. 6Li could also be a useful TAD.

Radiation shielding for neutron guides

International Nuclear Information System (INIS)

Ersez, T.; Braoudakis, G.; Osborn, J.C.

2005-01-01

Full text: Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions. (authors)

Radiation shielding for neutron guides

International Nuclear Information System (INIS)

Ersez, T.; Braoudakis, G.; Osborn, J.C.

2006-01-01

Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions

The First Test of the New Neutron Generator at the Všb / Technical University of Ostrava První Test Nového Neutronového Generátoru Na Všb-Tu Ostrava

Directory of Open Access Journals (Sweden)

Alexa Petr

2013-09-01

Full Text Available Kompaktní neutronový generátor MP320 (Thermo Scientific Inc. pracující na principu deuterium-tritiové reakce byl testován před plánovaným využitím jako zdroj neutronů pro neutronovou aktivační analýzu pomocí rychlých neutronů. Destičky vyrobené z Al, Fe, Sn a Si byly ozářeny svazkem neutronů s energií 14 MeV a byly identifikovány reakce indukované neutrony typické pro uvedené prvky.

Measurement of thermal, epithermal and fast neutrons fluxes by the activation foil method at IEA-R1 reactor

International Nuclear Information System (INIS)

Dias, M.S.; Koskinas, M.F.; Berretta, J.R.; Fratin, L.; Botelho, S.

1990-01-01

The thermal, epithermal and fast neutron fluxes have been determined experimentally by the activation foil method at position GI, located near the IEA-R1 reactor core. The reactions used were 197 Au (n,gamma) 198 Au, for thermal and epithermal neutrons and 27 Na (n,alpha) 24 Na, for fast neutrons. The activities were measured by the 4π(PC)β-γ coincidence method. (author)

Beta decay of 30Na: experiment and theory

International Nuclear Information System (INIS)

Baumann, P.; Dessagne, P.; Huck, A.; Klotz, A.; Knipper, A.; Miehe, C.; Ramdane, M.; Walter, G.; Marguier, G.; Poves, A.

1988-01-01

The 30 Na β decay was studied on-line by means of mass-separation techniques. Gamma-ray, gamma-gamma, neutron-gamma spectra, neutron time-of-flight singles and γ-coincidence measurements, were registered. High-energy neutron branches (E n >2 MeV) were found complementing previouly reported data. A 30 Na β-decay scheme to 30 Mg bound and unbound states is established. The distribution of the transition strength as a function of the excitation energy for particle-unbound levels in 30 Mg is compared to shell-model calculations performed in the 0-12 MeV excitation energy range. An overall renormalization yields a B(GT) quenching factor of 0.28 substantially lower than generally observed in this mass region. Three levels in 29 Mg which are strongly populated via the 1n-channel are related to negative parity intruder states

Analysis of some Egyptian cosmetic samples by fast neutron activation analysis

International Nuclear Information System (INIS)

Medhat, M.E.; Ali, M.A.; Hassan, M.F.

2001-01-01

A description of D-T neutron generator (NG) is presented. This generator can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. The concentrations of the elements Na, Mg, Al, Si, K, Cl, Ca and Fe were determined in two domestic brands of face powder by using 14 MeV neutron activation analysis

Compact DD generator based in vivo neutron activation analysis (IVNAA) system to determine sodium concentrations in human bone.

Science.gov (United States)

Coyne, Mychaela Dawn; Neumann, Colby R; Zhang, Xinxin; Byrne, Patrick; Liu, Yingzi; Weaver, Connie M; Nie, Linda Huiling

2018-04-16

This study presents the development of a non-invasive method for monitoring Na in human bone. Many diseases, such as hypertension and osteoporosis, are closely associated with sodium (Na) retention in the human body. Na retention is generally evaluated by calculating the difference between dietary intake and excretion. There is currently no method to directly quantify Na retained in the body. Bone is a storage for many elements, including Na, which renders bone Na an ideal biomarker to study Na metabolism and retention. Approach: A customized compact deuterium-deuterium (DD) neutron generator was used to produce neutrons for in vivo neutron activation analysis (IVNAA), with a moderator/ reflector/ shielding assembly optimized for human hand irradiation in order to maximize the thermal neutron flux inside the irradiation cave and to limit radiation exposure to the hand and the whole body. Main Results: The experimental results show that the system is able to detect sodium levels in the bone as low as 12 g Na/g dry bone with an effective dose to the body of about 27 μSv. The simulation results agree with the numbers estimated from the experiment. Significance: This is expected to be a feasible method for measuring the change of Na in bone. The low detection limit indicates this will be a useful system to study the association between Na retention and related diseases. © 2018 Institute of Physics and Engineering in Medicine.

Evaluation of radioactivity in the bodies of mice induced by neutron exposure from an epi-thermal neutron source of an accelerator-based boron neutron capture therapy system

Science.gov (United States)

NAKAMURA, Satoshi; IMAMICHI, Shoji; MASUMOTO, Kazuyoshi; ITO, Masashi; WAKITA, Akihisa; OKAMOTO, Hiroyuki; NISHIOKA, Shie; IIJIMA, Kotaro; KOBAYASHI, Kazuma; ABE, Yoshihisa; IGAKI, Hiroshi; KURITA, Kazuyoshi; NISHIO, Teiji; MASUTANI, Mitsuko; ITAMI, Jun

2017-01-01

This study aimed to evaluate the residual radioactivity in mice induced by neutron irradiation with an accelerator-based boron neutron capture therapy (BNCT) system using a solid Li target. The radionuclides and their activities were evaluated using a high-purity germanium (HP-Ge) detector. The saturated radioactivity of the irradiated mouse was estimated to assess the radiation protection needs for using the accelerator-based BNCT system. 24Na, 38Cl, 80mBr, 82Br, 56Mn, and 42K were identified, and their saturated radioactivities were (1.4 ± 0.1) × 102, (2.2 ± 0.1) × 101, (3.4 ± 0.4) × 102, 2.8 ± 0.1, 8.0 ± 0.1, and (3.8 ± 0.1) × 101 Bq/g/mA, respectively. The 24Na activation rate at a given neutron fluence was found to be consistent with the value reported from nuclear-reactor-based BNCT experiments. The induced activity of each nuclide can be estimated by entering the saturated activity of each nuclide, sample mass, irradiation time, and proton current into the derived activation equation in our accelerator-based BNCT system. PMID:29225308

Analysis of Some Egyptian Cosmetic Samples by Fast Neutron Activation Analysis

CERN Document Server

Medhat, M E; Fayez-Hassan, M

2001-01-01

A description of D-T neutron generator (NG) is presented. This generator can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. In our work, the concentration of the elements Na, Mg, Al, Si, K, Cl, Ca and Fe, were determined in two domestic brands of face powder by using 14 MeV neutron activation analysis.

Dose evaluation on the basis of 24Na activity in the human body for the criticality accident at JCO Tokai nuclear fuel processing plant

International Nuclear Information System (INIS)

Momose, T.; Tsujimura, N.; Tasaki, T.; Kanai, K.; Hayashi, N.; Shinohara, K.

2001-01-01

24 Na in the human body, activated by neutrons emitted at the JCO criticality accident, was observed for 62 subjects, where 148 subjects were measured by the whole body counter of JNC Tokai Works. The 148 subjects, including JCO employees and the contractors, residents neighboring the site and emergency service officers, were measured by the whole-body counter. The neutron-energy spectrum around the facility was calculated using neutron transport codes (ANISN and MCNP), and the relation between an amount of activated sodium in human body and neutron dose was evaluated from the calculated neutron energy spectrum and theoretical neutron capture probability by the human body. The maximum 24 Na activity in the body was 7.7 kBq (83 Bq( 24 Na)/g( 23 Na)) and the relevant effective dose equivalent was 47 mSv. (author)

Absolute measurements of the fast neutron flux in the reactor RA

Energy Technology Data Exchange (ETDEWEB)

Berovic, N; Boreli, F; Dragin, R [Institute of Nuclear Sciences Boris Kidric, Department of physics, Vinca, Beograd (Serbia and Montenegro)

1961-10-15

The absolute neutron flux in the vertical VK-5 hole of the reactor RA was determined by using the {sup 27}Al (n, alpha) {sup 24}Na reaction, and by counting the {sup 24}Na - 2.5 MeV gamma line photopeak activity. A method for the determination of {sigma}{sub eff} as a mean value between the two large limiting cases of neutron spectra is used. The flux at the power level of 5 MW was found to be (2.5{+-}0.9){center_dot}10{sup 12}n/cm{sup 2}sec (author)

Gamma ray attenuation coefficient measurement for neutron-absorbent materials

International Nuclear Information System (INIS)

Jalali, Majid; Mohammadi, Ali

2008-01-01

The compounds Na 2 B 4 O 7 , H 3 BO 3 , CdCl 2 and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the γ rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H 3 BO 3 with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds

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

A gamma-ray discriminating neutron scintillator

International Nuclear Information System (INIS)

Eschbach, P.A.; Miller, S.D.; Cole, M.C.

1994-01-01

A neutron scintillator has been developed at Pacific Northwest Laboratory which responds directly to as little as 10 mrem/hour dose equivalent rate fast neutron fields. The scintillator is composed of CaF 2 :Eu or of NaI grains within a silicone rubber or polystyrene matrix, respectively. Neutrons colliding with the plastic matrix provide knockon protons, which in turn deposit energy within the grains of phosphor to produce pulses of light. Neutron interactions are discriminated from gamma-ray events on the basis of pulse height. Unlike NE-213 liquid scintillators, this solid scintillator requires no pulseshape discrimination and therefore requires less hardware. Neutron events are anywhere from two to three times larger than the gamma-ray exposures are compared to 0.7 MeV gamma-ray exposures. The CaF 2 :Eu/silicone rubber scintillator is nearly optically transparent, and can be made into a very sizable detector (4 cm x 1.5 cm) without degrading pulse height. This CaF 2 :Eu scintillator has been observed to have an absolute efficiency of 0.1% when exposed to 5-MeV accelerator-generated neutrons (where the absolute efficiency is the ratio of observed neutron events divided by the number of fast neutrons striking the detector)

Dose evaluation on the basis of {sup 24}Na activity in the human body for the criticality accident at JCO Tokai nuclear fuel processing plant

Energy Technology Data Exchange (ETDEWEB)

Momose, T.; Tsujimura, N.; Tasaki, T.; Kanai, K.; Hayashi, N.; Shinohara, K. [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan)

2001-11-01

{sup 24}Na in the human body, activated by neutrons emitted at the JCO criticality accident, was observed for 62 subjects, where 148 subjects were measured by the whole body counter of JNC Tokai Works. The 148 subjects, including JCO employees and the contractors, residents neighboring the site and emergency service officers, were measured by the whole-body counter. The neutron-energy spectrum around the facility was calculated using neutron transport codes (ANISN and MCNP), and the relation between an amount of activated sodium in human body and neutron dose was evaluated from the calculated neutron energy spectrum and theoretical neutron capture probability by the human body. The maximum {sup 24}Na activity in the body was 7.7 kBq (83 Bq({sup 24}Na)/g({sup 23}Na)) and the relevant effective dose equivalent was 47 mSv. (author)

Performance of a tagged neutron inspection system (TNIS) based on portable sealed generators

International Nuclear Information System (INIS)

Nebbia, G.; Pesente, S.; Lunardon, M.; Viesti, G.; LeTourneur, P.; Heuveline, F.; Mangeard, M.; Tcheng, C.

2004-01-01

A portable sealed neutron generator has been modified to produce 14MeV tagged neutron beams with an embedded YAP:Ce scintillation detector. The system has been tested by detecting the coincident gamma-rays produced in the irradiation of a graphite sample by means of a standard NaI(Tl) scintillator. Time resolution of about δt=4-5ns (FWHM) has been measured. The sealed neutron tube has been operated up to 10 7 neutron/s. Possible applications in non-destructive assays and future developments of the Tagged Neutron Inspection System concept are discussed

Analysis of human enamel and dentine by neutron activation analysis

International Nuclear Information System (INIS)

Soares, Marco A.B.

2005-01-01

Determination of trace elements in dental tissues has been of great interest to study the correlation between element composition and caries as well as food habits of individuals. In the present study dentine and enamel samples from healthy individuals were analysed by neutron activation analysis. The teeth were provided form dental clinics, and they were previously washed using purified water and acetone. Then they were dried at 40 deg C and ground in a agate mortar. The samples and element standards were irradiated with thermal neutrons at the IEA-R1 nuclear reactor. Long irradiations of 8 h under thermal neutron flux of 5x10 12 n cm -2 s -1 were used for Ca, Na, Sr and Zn determinations. In short irradiations of 15 s and under neutron flux of 10 12 n cm -2 s -1 the elements Mg, Mn, Na e Sr were determined. The induced gamma activities of the samples and standards were measured using a hyperpure Ge detector coupled to a gamma ray spectrometer. Elemental concentrations were calculated by comparative method. Results obtained showed that Ca, Mg and Na are present in both tissues at the level of percentages and the elements Mn, Sr and Zn at the μg g -1 levels. For quality control of the results the certified reference materials NIST 1400 Bone Ash and NIST 1486 Bone Meal were analysed. (author)

Neutron-neutron-resonance logging of boron in boreholes with the use of the PRKS-2 radiometer

International Nuclear Information System (INIS)

Vakhtin, B.S.; Ivanov, V.S.; Filippov, E.M.; Novoselov, A.V.

1973-01-01

The well rig of the PRKS-2 logging radiometer is supplemented with a probe device for neutron measurements permitting to vary the probe size from 20 to 45 cm. To decrease the natural gamma radiation effect an external lead shield 7-mm thick having 50-mm outer diameter is fixed on the instrument sleeve. The instrument is provided with a NaI detector and a set of foils of Cd, Ag, Rh, Tu, In, Ta, and a Pu-Be source of 1x10 6 n/sec strength. The optimal size of the probe is assumed as 25 cm. From the results of well measurements a better differentiation of neutron resonance logging was noticed in comparison with neutron gamma logging. Comparing the data obtained with those of kern analysis a calibration curve was derived of neutron resonance logging versus B for wells of 59 mm dia

Analysis of human enamel and dentine by neutron activation analysis; Analise de esmalte e dentina de humanos pelo metodo de ativacao com neutrons

Energy Technology Data Exchange (ETDEWEB)

Soares, Marco A.B. [Sao Paulo Univ., SP (Brazil). Inst. de Quimica]. E-mail: vankfire@gmail.com; Adachi, Eduardo M.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

2005-07-01

Determination of trace elements in dental tissues has been of great interest to study the correlation between element composition and caries as well as food habits of individuals. In the present study dentine and enamel samples from healthy individuals were analysed by neutron activation analysis. The teeth were provided form dental clinics, and they were previously washed using purified water and acetone. Then they were dried at 40 deg C and ground in a agate mortar. The samples and element standards were irradiated with thermal neutrons at the IEA-R1 nuclear reactor. Long irradiations of 8 h under thermal neutron flux of 5x10{sup 12} n cm{sup -2} s{sup -1} were used for Ca, Na, Sr and Zn determinations. In short irradiations of 15 s and under neutron flux of 10{sup 12} n cm{sup -2} s{sup -1} the elements Mg, Mn, Na e Sr were determined. The induced gamma activities of the samples and standards were measured using a hyperpure Ge detector coupled to a gamma ray spectrometer. Elemental concentrations were calculated by comparative method. Results obtained showed that Ca, Mg and Na are present in both tissues at the level of percentages and the elements Mn, Sr and Zn at the {mu}g g{sup -1} levels. For quality control of the results the certified reference materials NIST 1400 Bone Ash and NIST 1486 Bone Meal were analysed. (author)

Neutron activation analysis of Ca, Cl, K, Mg, Mn, Na, P, and Sr contents in the crowns of human permanent teeth

International Nuclear Information System (INIS)

Zaichick, V.

2009-01-01

The effect of age and gender on chemical element contents in intact crowns of permanent teeth of 84 apparently healthy 15-55 year old women (n 38) and men (n = 46) was investigated. Mass fractions of Ca, Cl, K, Mg, Mn, Na, P, and Sr in crowns were determined by instrumental neutron activation analysis using short-lived radionuclides. Mean values (M ± SEL) for female and male combined were (on dry weight basis): 350 ± 5 g/kg, 2920± 150 mg/kg, 839 ± 80 mg/kg, 4880 ± 240 mg/kg, 3.20 ± 0.30 mg/kg, 6240 ± 140 mg/kg, 181 ± 4 g/kg, and 293 ± 24 mg/kg respectively. A statistically significant decrease of Sr (P ≤ 0.01) and increase of Na (P ≤ 0.01) content in the tooth crowns with age was found for women. Sex-related comparison did not show any differences. (author)

Fast Neutron Dose Distribution in a Linac Radiotherapy Facility

International Nuclear Information System (INIS)

Al-Othmany, D.Sh.; Abdul-Majid, S.; Kadi, M.W.

2011-01-01

CR-39 plastic detectors were used for fast neutron dose mapping in the radiotherapy facility at King AbdulAziz University Hospital (KAUH). Detectors were calibrated using a 252 Cf neutron source and a neutron dosimeter. After exposure chemical etching was performed using 6N NaOH solution at 70 degree C. Tracks were counted using an optical microscope and the number of tracks/cm 2 was converted to a neutron dose. 15 track detectors were distributed inside and outside the therapy room and were left for 32 days. The average neutron doses were 142.3 mSv on the accelerator head, 28.5 mSv on inside walls, 1.4 mSv beyond the beam shield, and 1 mSv in the control room

International fusion materials irradiation facility and neutronic calculations for its test modules

International Nuclear Information System (INIS)

Sokcic-Kostic, M.

1997-01-01

The International Fusion Material Irradiation Facility (IFMIF) is a projected high intensity neutron source for material testing. Neutron transport calculations for the IFMIF project are performed for variety of here explained reasons. The results of MCNP neutronic calculations for IFMIF test modules with NaK and He cooled high flux test cells are presented in this paper. (author). 3 refs., 2 figs., 3 tabs

Scintillation efficiency measurement of Na recoils in NaI(Tl) below the DAMA/LIBRA energy threshold

Energy Technology Data Exchange (ETDEWEB)

Xu, Jingke; Shields, Emily; Calaprice, Frank; Westerdale, Shawn; Froborg, Francis; Suerfu, Burkhant; Alexander, Thomas; Aprahamian, Ani; Back, Henning O.; Casarella, Clark; Fang, Xiao; Gupta, Yogesh K.; Ianni, Aldo; Lamere, Edward; Lippincott, W. Hugh; Liu, Qian; Lyons, Stephanie; Siegl, Kevin; Smith, Mallory; Tan, Wanpeng; Kolk, Bryant Vande

2015-07-01

The dark matter interpretation of the DAMA modulation signal depends on the NaI(Tl) scintillation efficiency of nuclear recoils. Previous measurements for Na recoils have large discrepancies, especially in the DAMA/LIBRA modulation energy region. We report a quenching effect measurement of Na recoils in NaI(Tl) from 3 to 52 keVnr, covering the whole DAMA/LIBRA energy region for dark matter-Na scattering interpretations. By using a low-energy, pulsed neutron beam, a double time-of-flight technique, and pulse-shape discrimination methods, we obtained the most accurate measurement of this kind for NaI(Tl) to date. The results differ significantly from the DAMA reported values at low energies but fall between the other previous measurements. We present the implications of the new quenching results for the dark matter interpretation of the DAMA modulation signal.

Gamma ray attenuation coefficient measurement for neutron-absorbent materials

Energy Technology Data Exchange (ETDEWEB)

Jalali, Majid [Isfahan Nuclear Science and Technology Research Institute (NSTRT), Reactor and Accelerators Research and Development School, Atomic Energy Organization (Iran, Islamic Republic of)], E-mail: m_jalali@entc.org.ir; Mohammadi, Ali [Faculty of Science, Department of Physics, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)

2008-05-15

The compounds Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the {gamma} rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H{sub 3}BO{sub 3} with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.

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

Science.gov (United States)

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

2018-02-17

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

Neutron dosimetry in boron neutron capture therapy

International Nuclear Information System (INIS)

Fairchild, R.G.; Miola, U.J.; Ettinger, K.V.

1981-01-01

The recent development of various borated compounds and the utilization of one of these (Na 2 B 12 H 11 SH) to treat brain tumors in clinical studies in Japan has renewed interest in neutron capture therapy. In these procedures thermal neutrons interact with 10 B in boron containing cells through the 10 B(n,α) 7 Li reaction producing charged particles with a maximum range of approx. 10μm in tissue. Borated analogs of chlorpromazine, porphyrin, thiouracil and deoxyuridine promise improved tumor uptake and blood clearance. The therapy beam from the Medical Research Reactor in Brookhaven contains neutrons from a modified and filtered fission spectrum and dosimetric consequences of the use of the above mentioned compounds in conjunction with thermal and epithermal fluxes are discussed in the paper. One of the important problems of radiation dosimetry in capture therapy is determination of the flux profile and, hence, the dose profile in the brain. This has been achieved by constructing a brain phantom made of TE plastic. The lyoluminescence technique provides a convenient way of monitoring the neutron flux distributions; the detectors for this purpose utilize 6 Li and 10 B compounds. Such compounds have been synthesized specially for the purpose of dosimetry of thermal and epithermal beams. In addition, standard lyoluminescent phosphors, like glutamine, could be used to determine the collisional component of the dose as well as the contribution of the 14 N(n,p) 14 C reaction. Measurements of thermal flux were compared with calculations and with measurements done with activation foils

Calculation of neutron kerma in tissues

International Nuclear Information System (INIS)

Vega C, H.R.; Manzanares A, E.

2004-01-01

Neutron kerma of normal and tumor tissues has been calculated using the tissues elemental concentration. A program developed in Math cad contains the kerma factors of C, H, O, N, Na, Mg, P, S, Cl, K, etc. that are in normal and tumor human tissues. Having the elemental composition of any human tissue the neutron kerma can be calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic, also neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large. (Author)

Small angle neutron scattering studies of mixed micelles of sodium

Indian Academy of Sciences (India)

The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long rod-shaped micelles with ...

Local computer network of the JINR Neutron Physics Laboratory

International Nuclear Information System (INIS)

Alfimenkov, A.V.; Vagov, V.A.; Vajdkhadze, F.

1988-01-01

New high-speed local computer network, where intelligent network adapter (NA) is used as hardware base, is developed in the JINR Neutron Physics Laboratory to increase operation efficiency and data transfer rate. NA consists of computer bus interface, cable former, microcomputer segment designed for both program realization of channel-level protocol and organization of bidirectional transfer of information through direct access channel between monochannel and computer memory with or witout buffering in NA operation memory device

Neutron activation determination of impurities in molybdenum

International Nuclear Information System (INIS)

Usmanova, M.M.; Mukhamedshina, N.M.; Obraztsova, T.V.; Saidakhmedov, K.Kh.

1984-01-01

Instrumental neutron-activation techniques of impurity element determination in molybdenum and MoO 3 (solid and powdered samples) have been developed. When determining impurities of Na, K, Mn, Cu, W, Re molybdenum has been irradiated by thermal neutrons in reactor for 20 min, the sample mass constituted 200-300 mg, sample cooling time after irradiation - 2.5-3.5 h. It is shown that in the process of Cr, Fe, Co, Zn determination the samples should be irradiated with thermal neutrons, and in the process of Sb, Ta and Ni determination - with resonance and fast neutrons. Simultaneous determination of the elements during irradiation with neutrons with reactor spectrum is possible. When determining P and S the samples are irradiated with thermal and epithermal neutrons and β-activity of samples and comparison samples are measured using β-spectrometer with anthracene crystal. The techniques developed permit to determine impurities in Mo with a relative standard deviation 0.07-0.15 and lower boundaries of contents determined - 10 -4 - 10 -7 %

Dose evaluation on the basis of {sup 24}Na activity in the human body for the criticality accident at JCO Tokai nuclear fuel processing plant

Energy Technology Data Exchange (ETDEWEB)

Momose, T.; Tsujimura, N.; Tasaki, T.; Kanai, K.; Hayashi, N.; Shinohara, K. [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan)

2000-07-01

Sodium-24({sup 24}Na) generated in human body due to neutron activation was measured by whole body counter (WBC) in JNC Tokai works. Total 148 persons (JCO employees and contractor, public member, fire fighters, etc.) were measured and {sup 24}Na was detected in the 62 persons. Neutron energy spectrum around the facility was calculated using ANISN and MCNP code and estimated mean capture probability {xi} of neutron for human body at this accident was around 0.25-0.28 at any distance from the center of the precipitation tank. Effective dose equivalent for the 62 persons were estimated based on the calculated conversion factors from {sup 24}Na specific activity to neutron dose. Maximum {sup 24}Na activity was 7.7 kBq (83 Bq({sup 24}Na)/g({sup 23}Na)) in total body and the evaluated effective dose equivalent was 47 mSv. (author)

A large animal model for boron neutron capture therapy

International Nuclear Information System (INIS)

Gavin, P.R.; Kraft, S.L.; DeHaan, C.E.; Moore, M.P.; Griebenow, M.L.

1992-01-01

An epithermal neutron beam is needed to treat relatively deep seated tumors. The scattering characteristics of neutrons in this energy range dictate that in vivo experiments be conducted in a large animal to prevent unacceptable total body irradiation. The canine species has proven an excellent model to evaluate the various problems of boron neutron capture utilizing an epithermal neutron beam. This paper discusses three major components of the authors study: (1) the pharmacokinetics of borocaptate sodium (NA 2 B 12 H 11 SH or BSH) in dogs with spontaneously occurring brain tumors, (2) the radiation tolerance of normal tissues in the dog using an epithermal beam alone and in combination with borocaptate sodium, and (3) initial treatment of dogs with spontaneously occurring brain tumors utilizing borocaptate sodium and an epithermal neutron beam

Potes meleiros e colmenas em cerâmica: una tradicâo milenar

Directory of Open Access Journals (Sweden)

Rui Morais

2006-01-01

Full Text Available Neste estudo apresenta-se uma breve resenha sobre a importância do mel na antiguidade e destaca-se a existência de contentores destinados ao seu armazenamento. Tendo em conta a maior antiguidade destes contentores recolhidos na Península (datáveis, pelo menos, a partir de c. de 600 a.C., a sua persitência ao longo dos tempos, e a existência de paralelos etnográficos ainda hoje documentados, admitimos tratar-se de uma tradicâo com origem da Península.Destaca-se, ainda, a importância dos mellaria na economia do mundo antigo e realça-se a identificacâo de colmeias em cerâmica na regiao de Valência e de uma inédita recolhida em Bracara Augusta, uma cidade romana localizada no extremo ocidente da Península. Por fim, faz-se uma breve alusao à importância do mel em épocas posteriores ao período romano.

Formation of oriented membrane multilayers of Na/K-ATPase

International Nuclear Information System (INIS)

Pachence, J.M.; Knott, R.; Edelman, I.S.; Schoenborn, B.P.; Wallace, B.A.

1982-01-01

The isolated membrane-bound enzyme retains its ouabain-sensitive ATP hydrolysis activity, and produces ATP-dependent Na + and K + fluxes when incorporated into phospholipid vesicles. The ultimate goal of this work is to determine its low resolution structure using both X-ray and neutron diffraction. A number of methods were used to impart lamellar stacking order to highly purified pig Na/K-ATPase membranes. Upon partial dehydration, x-ray diffraction from Na/K-ATPase membrane multilayers at 98% relative humidity yielded discrete reflections of 118 A periodicity, diffracting to 1/14.8 A -1 , additionally, continuous diffraction to 1/10 A -1 was obtained. Subjecting the membrane multilayers to high magnetic fields improved the quality of the lamellar diffraction dramatically. Neutron diffraction studies of the partially dehydrated Na/K-ATPase membrane multilayers detected a mosaic spread of 2 0 when the samples were subjected to a magnetic field of 5 Tesla perpendicular to the membrane surface; the reflections were narrower than the camera line width; hence, the lattice disorder has also decreased significantly, although only four orders were measured

Pulsed neutron activation calibration technique

International Nuclear Information System (INIS)

Kehler, P.

1979-01-01

A pulsed neutron activation (PNA) for measurement of two-phase flow consists of a pulsed source of fast neutron to activate the oxygen in a steam-water mixture. Flow is measured downstream by an NaI detector. Measured counts are sorted by a multiscaler into different time channels. A counts vs. time distribution typical for two-phase flow with slip between the two phases is obtained. Proper evaluation for the counts/time distribution leads to flow-regime independent equations for the average of the inverse transil time and the average density. After calculation of the average mass flow velocity, the true mass flow is derived

Low-lying dipole strength of neutron-rich 'island of inversion' nuclei around n ∼ 20

International Nuclear Information System (INIS)

Datta Pramanik, U.; Chakraborty, S.; Ray, I.

2009-01-01

Magic numbers are the basic building blocks of nuclear structure since last fifty years. Recently, through various experimental results using Radioactive Ion Beam (RIB) facilities, it has been observed that those long cherished magic numbers are not valid anymore in the neutron rich nuclei like 32 Mg etc. The breakdown of magic number was hinted in the late 1980 's by Thibault et. al. in sodium nuclei ( 31,32 Na). Motobayashi et. al. showed large deformation for 32 Mg which leads to the failure of magic number at N = 20. Exploration into the cause of this breakdown shows the filling of higher pf orbitals rather than the pure lower sd orbitals in the ground state of the neutron-rich nuclei like Ne, Na, Mg in the region N∼20. Thus there is obviously an inversion in nuclear orbitals and hence the so called name 'island of inversion'. This year, we have performed an experiment at GSI, Darmstadt. The measurement of dipole threshold strength of neutron-rich nucleus (N∼20) through electromagnetic excitation was done using LAND-FRS setup. Through this dipole strength, we would like to probe directly the quantum numbers of the valence neutrons in neutron rich nuclei like 31-33 Mg, 33-35 Al, 29-30 Na, 25-27 Ne, 24 F etc.

Neutron shielding properties of a borated high-density glass

Directory of Open Access Journals (Sweden)

Saeed Aly Abdallah

2017-01-01

Full Text Available The neutron shielding properties of a borated high density glass system was characterized experimentally. The total removal macroscopic cross-section of fast neutrons, slow neutrons as well as the linear attenuation coefficient of total gamma rays, primary in addition to secondary, were measured experimentally under good geometric condition to characterize the attenuation properties of (75-x B2O3-1Li2O-5MgO-5ZnO-14Na2O-xBaO glassy system. Slabs of different thicknesses from the investigated glass system were exposed to a collimated beam of neutrons emitted from 252Cf and 241Am-Be neutron sources in order to measure the attenuation properties of fast and slow neutrons as well as total gamma rays. Results confirmed that barium borate glass was suitable for practical use in the field of radiation shielding.

Neutron magnetic scattering experiments performed by VIKRA group at the RA reactor in Vinca; Eksperimenti grupe VIKRA na reaktoru RA u Vinci sa rasejanjem neutrona na magnetnim materijalima

Energy Technology Data Exchange (ETDEWEB)

Kranicki, S; Rzany, H; Wanic, A [Institute of Nuclear Physics, Krakov (Poland); Szytula, A [Jagiellonian University, Krakov (Poland); Todorovic, J; Dimitrijevic, Z; Radenkovic, S [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1978-05-15

A short communication about investigations of magnetic materials by means of the neutron magnetic scattering performed by Polish-Yugoslav group VIKRA (Vinca-Krakov) at the RA reactor in Vinca in the period 1962-1977 will be presented. In the field of neutron inelastic scattering information about magnetic interactions (exchange integrals) and their temperature behaviour in such substances as Fe{sub 7}S{sub 8}, {alpha}-Fe{sub 2}O{sub 3}, CR{sub 2}O{sub 3}, {alpha}-Co, Cu{sub 2}MnAl and Mn{sub 1.88}Cr{sub 0.12}Sb was obtained by measuring magnon dispersion relations. In the field of neutron elastic scattering valuable results concerning crystallographic and magnetic structures of oxyhydroxides, several Heusler alloys and intermetallic compounds of 3d metals (for instance of NiMnGe, CoMnSi) were obtained. A short description of the KSN spectrometer used in all experiments will also be given. (author) Dato je kratko saopstenje o istrazivanjima magnetnih materijala magnetnim neutronskim rasejanjem izvrsenim od strane poljsko-jugoslovenske grupe VIKRA (Vinca-Krakov) na reaktoru RA u Vinci u periodu od 1962-1977. U oblasti neelasticnog rasejanja neutrona, obavestenja o magnetnim uzajamnim dejstvima (integralima izmene) i njihovim temperaturskim ponasanjima su dobijeni merenjem disperzione relacije magnona u takvim materijalima kao sto su Fe{sub 7}S{sub 8}, {alpha}-Fe{sub 2}O{sub 3}, CR{sub 2}O{sub 3}, {alpha}-Co, Cu{sub 2}MnAl and Mn{sub 1.88}Cr{sub 0.12}Sb. U oblasti neutronskog elasticnog rasejanja dobijeni su korisni rezultati o kristalografskim i magnetnim strukturama oksihidroksida gvozdja, niza Heuslerovih legura i intermetalnih jedinjenja 3d metala (napr. NiMnGe, Co,MnSi). Dat je kratak opis KSN spektrometra upotrebljenog u svim ovim eksperimentima. (author)

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

Determination of Au, Sb, As, Br, Na, K, Cd, Mn and Cl in rice from Vietnam by neutron activation analysis

International Nuclear Information System (INIS)

Tran Van, L.; Teherani, D.K.

1988-01-01

Gold, antimony, arsenic, bromine, sodium, potassium, cadmium, manganese and chlorine were determined by neutron activation analysis in various rice seed, brand layer and husk samples from Vietnam. The following concentration values were found: Au 0.05-0.28 ppm, Sb 0.05-1.08 ppm, As 0.08-0.94 ppm, Br 0.82-6.72 ppm, Na 16.71-25.71 ppm, K 2582-5163 ppm, Mn 19.26-33.43 ppm, Cd 0.51-2.42 ppm and Cl 205.20-828.61 ppm in rice seed. Statistically significant differences in Au, Sb, Cd contents were detected in rice seed and husk, as well as brand layer and husk. (author) 8 refs.; 3 figs

Characterization of the radiation background at the Spallation Neutron Source

International Nuclear Information System (INIS)

DiJulio, Douglas D.; Cherkashyna, Nataliia; Scherzinger, Julius; Khaplanov, Anton; Pfeiffer, Dorothea; Cooper-Jensen, Carsten P.; Fissum, Kevin G.; Kanaki, Kalliopi; Kirstein, Oliver; Hall-Wilton, Richard J.; Bentley, Phillip M.; Ehlers, Georg; Gallmeier, Franz X.; Hornbach, Donald E.; Iverson, Erik B.; Newby, Robert J.

2016-01-01

We present a survey of the radiation background at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, TN, USA during routine daily operation. A broad range of detectors was used to characterize primarily the neutron and photon fields throughout the facility. These include a WENDI-2 extended range dosimeter, a thermoscientific NRD, an Arktis 4 He detector, and a standard NaI photon detector. The information gathered from the detectors was used to map out the neutron dose rates throughout the facility and also the neutron dose rate and flux profiles of several different beamlines. The survey provides detailed information useful for developing future shielding concepts at spallation neutron sources, such as the European Spallation Source (ESS), currently under construction in Lund, Sweden. (paper)

Neutron Imaging Developments at LANSCE

Science.gov (United States)

Nelson, Ron; Hunter, James; Schirato, Richard; Vogel, Sven; Swift, Alicia; Ickes, Tim; Ward, Bill; Losko, Adrian; Tremsin, Anton

2015-10-01

Neutron imaging is complementary to x-ray imaging because of its sensitivity to light elements and greater penetration of high-Z materials. Energy-resolved neutron imaging can provide contrast enhancements for elements and isotopes due to the variations with energy in scattering cross sections due to nuclear resonances. These cross section differences exist due to compound nuclear resonances that are characteristic of each element and isotope, as well as broader resonances at higher energies. In addition, multi-probe imaging, such as combined photon and neutron imaging, is a powerful tool for discerning properties and features in materials that cannot be observed with a single probe. Recently, we have demonstrated neutron imaging, both radiography and computed tomography, using the moderated (Lujan Center) and high-energy (WNR facility) neutron sources at LANSCE. Flat panel x-ray detectors with suitable scintillator-converter screens provide good sensitivity for both low and high neutron energies. Micro-Channel-Plate detectors and iCCD scintillator camera systems that provide the fast time gating needed for energy-resolved imaging have been demonstrated as well. Examples of recent work will be shown including fluid flow in plants and imaging through dense thick objects. This work is funded by the US Department of Energy, National Nuclear Security Administration, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

Radioisotopes produced by neutron irradiation of food.

Science.gov (United States)

Albright, S; Seviour, R

2016-04-01

The use of neutrons for cargo interrogation has the potential to drastically improve threat detection. Previous research has focussed on the production of (24)Na, based on the isotopes produced in pharmaceuticals and medical devices. For both the total activity and the ingestion dose we show that a variety of isotopes contribute and that (24)Na is only dominant under certain conditions. The composition of the foods has a strong influence on the resulting activity and ingestion dose suggesting that the pharmaceuticals and medical devices considered initially are not a viable analogue for foodstuffs. There is an energy dependence to the isotopes produced due to the cross-sections of different reactions varying with neutron energy. We show that this results in different isotopes dominating the ingestion dose at different energies, which has not been considered in the previous literature. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effect of chloride substitution on the order–disorder transition in NaBH4 and Na11BD4

International Nuclear Information System (INIS)

Olsen, Jørn Eirik; Karen, Pavel; Sørby, Magnus H.; Hauback, Bjørn C.

2014-01-01

Graphical abstract: Interactions that order the BD 4 - tetrahedra below the order–disorder transition became increasingly frustrated by the solute in the Na( 11 BD 4 ) 1−x Cl x solid solutions, and the order disappears at x = 0.158. Highlights: • The order–disorder transition temperature for Na(BH 4 ) 1−x Cl x and Na( 11 BD 4 ) 1−x Cl x is highly dependent on the Cl-content, x. • The transition is characterized by DSC for Na( 11 BD 4 ) 1−x Cl x for x = 0, 0.10 and 0.15. • No transition is observed for x ⩾ 0.20 on cooling to 8 K. • The crystal structures are reported for Na 11 BD 4 at room temperature and 8 K and Na( 11 BD 4 ) 1−x Cl x (x = 0.10, 0.15, 0.20 and 0.25) at 8 K from powder neutron diffraction. -- Abstract: Phase transition associated with anion disordering over two orientations in Na 11 BD 4 (NaBH 4 ) and its solid solutions with NaCl, Na( 11 BD 4 ) 1−x Cl x , is investigated with powder diffraction (neutron and synchrotron radiation), differential scanning calorimetry and Raman spectroscopy. Upon heating, the transition temperature extrapolated to zero rate of heating is 192.2 K for Na 11 BD 4 , ΔS = 4.41 J/mol K, hysteresis 1.7 K and the volume increase 0.43%. Thermal parameters of the transition in Na( 11 BD 4 ) 1−x Cl x follow a colligative-property model of an ideal solution, with x = 0.158(1) as the critical concentration at which the ordering interactions and the transition itself are eliminated. On approaching this limit, the tetragonal distortion of the ordered structure decreases somewhat towards the cubic average, and this is associated with a partial disorder of the tetrahedral anions seen by diffraction methods. In fact, a 3% disorder is already present in the pure solvent of the solid solution (Na 11 BD 4 ) at 8 K

Fast Neutron Dosimetry Using CR-39 Nuclear Track Detector

International Nuclear Information System (INIS)

ZAKI, M.; ABDEL-NABY, A.; MORSY, A.

2010-01-01

Measurement of the neutron dose in and around the neutron sources is important for the purpose of personnel and environmental neutron dosimetry. In the present study, a method for the measurement of neutron dose using the UV-Vis spectra of CR-39 plastic track detector was investigated. A set of CR-39 plastic detectors was exposed to 252 Cf neutron source, which had the yield of 0.68x10 8 /s, and neutron dose equivalent rate 1m apart from the source is equal to 3.8 mrem/h. The samples were etched for 10 h in 6.25 N NaOH at 70 o C. The absorbance of the etched samples was measured using UV-visible spectrophotometer as a function of neutron dose. It was observed that there was a linear relationship between the optical absorption of these detectors and neutron dose. This means that the exposure dose of neutron can be determined by knowing the optical absorption of the sample. These results were compared with previous study. It was found that there was a matching and good agreement with their investigations.

On-line neutron activation analyzers

International Nuclear Information System (INIS)

Flahaut, V.; Colmon, A.

1999-01-01

A neutronic analyser has been designed to determine the composition of the flow of raw materials entering a cement factory on the conveyor belt. This new system gives a reliable analysis of the whole cargo that outdates the sampling or the usual surface analysis based on fluorescence spectrometry. The accuracy is about 1%.The neutrons interact with the materials on an average depth of 25 cm and are absorbed by nuclei, these nuclei produce photons whose energy is characteristic of the chemical element itself. The composition can be deduced by measuring the number of photons emitted and their energy. The analysis is made on-line and can concern the search for about 10 compounds. In the case of cement the list of compounds is: SiO 2 , CaO, Al 2 O 3 , Fe 2 O 3 , MgO, Na 2 O, TiO 2 , S, Mn 2 O 3 , K 2 O, and H 2 O. The neutron generator involves a deuterium ion source whose deuterium ions are accelerated by means of an electrical field and impinge on a tritiated target, the nuclear reactions between deuterium and tritium produce 14 MeV neutrons. This neutron analysing technique can be adapted to any need of on-line composition determination. (A.C.)

Method to determine the strength of a neutron source

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Chacon R, A.; Mercado, G.A. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Depto. Ingenieria Nuclear, Universidad Politecnica de Madrid, (Spain)

2006-07-01

The use of a gamma-ray spectrometer with a 3 {phi} x 3 NaI(Tl) detector, with a moderator sphere has been studied in the aim to measure the neutron fluence rate and to determine the source strength. Moderators with a large amount of hydrogen are able to slowdown and thermalize neutrons; once thermalized there is a probability that thermal neutron to be captured by hydrogen producing 2.22 MeV prompt gamma-ray. The pulse-height spectrum collected in a multicharmel analyzer shows a photopeak around 2.22 MeV whose net area is proportional to total neutron fluence rate and to the neutron source strength. The characteristics of this system were determined by a Monte Carlo study using the MCNP 4C code, where a detailed model of the Nal(Tl) was utilized. As moderators 3, 5, and 10 inches-diameter spheres where utilized and the response was calculated for monoenergetic and isotopic neutrons sources. (Author)

Absolute measurement of the cross sections of neutron radiative capture for 23Na, Cr, 55Mn, Fe, Ni, 103Rh, Ta, 197Au and 238U in the 10-600keV energy range

International Nuclear Information System (INIS)

Le Rigoleur, Claude; Arnaud, Andre; Taste, Jean.

1976-10-01

The total energy weighting technique has been applied to measuring absolute neutron capture cross sections for 23 Na, Cr, 55 Mn, Fe, Ni, 103 Rh, Ta, 197 Au, 238 U in the 10-600keV energy range. A non hydrogeneous liquid scintillator was used to detect the gamma from the cascade. The neutron flux was measured with a 10 B INa(Tl) detector or a 6 Li glass scintillator of well known efficiency. The fast time-of-flight technique was used with on line digital computer data processing [fr

Report from the neutron diffraction work group

International Nuclear Information System (INIS)

1978-08-01

This progress report of the neutron diffraction group at the Hahn Meitner Institute in Berlin comprises the following contributions: Three-dimensional critical properties of CsNiF 3 around the Neel point; Spin waves in CsNiF 3 with an applied magnetic field; Solitons in CsNiF 3 : Their experimental evidence and their thermodynamics; Neutron diffraction study of DAG at very low temperatures and in external magnetic field; Neutron diffraction investigation of tricritical behaviour in DyPO 4 ; Crystalline modifications and structural phase transitions of NaOH; Gitterdynamik von Cerhydrid; Investigation of the ferroelectric-ferroelastic phase transition in KH 2 PO 4 and RbH 2 PO 4 by means of γ-ray diffractometry; A γ-ray diffractometer for systematic measurements of absolute structure factors; Electron density in pyrite by combined γ-ray and neutron diffraction measurements: Thermal parameters from short wavelength neutron data; Accurate determination of temperature parameters from neutron diffraction data: Direct observation of the thermal diffuse scattering from silicon using perfect crystals; A Compton spectrometer for momentum density studies using 412 keV γ-radiation; Investigation of the electronic structure of Niobiumhydrides by means of gamma-ray Compton scattering; Interpretation of Compton profile data in position space; High resolution neutron scattering measurements on single crystals using a horizontally bent monochromator and a multidetecter; Statistical analysis of neutron diffraction studies of proteins. (orig.) [de

D-T neutron skyshine experiments at JAERI/FNS

Energy Technology Data Exchange (ETDEWEB)

Nishitani, Takeo; Ochiai, Kentaro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yoshida, Shigeo [Tokai Univ., Hiratsuka, Kanagawa (JP)] (and others)

2003-03-01

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 as far as about 550 m away from the D-T target point with a spherical rem-counter. The highest neutron dose was about 0.5 {mu}Sv/hr at a distance of 30 m from the D-T target point and the dose rate was attenuated to 0.002 {mu}Sv/hr 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 250 m. The neutron spectra were evaluated with a {sup 3}He detector with different thickness of polyethylene neutron moderators. Secondary gamma-rays were measured with high purity Ge detectors and NaI scintillation detectors. (author)

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)

Measurements of keV-neutron capture {gamma} rays of fission products. 3

Energy Technology Data Exchange (ETDEWEB)

Igashira, Masayuki [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors

1997-03-01

{gamma} rays from the keV-neutron capture reactions by {sup 143,145}Nd and {sup 153}Eu have been measured in a neutron energy region of 10 to 80 keV, using a large anti-Compton NaI(Tl) {gamma}-ray spectrometer and the {sup 7}Li(p,n){sup 7}Be pulsed neutron source with a 3-MV Pelletron accelerator. The preliminary results for the capture cross sections and {gamma}-ray spectra of those nuclei are presented and discussed. (author)

Measurements of keV-neutron capture γ rays of fission products. 2

International Nuclear Information System (INIS)

Igashira, Masayuki

1996-01-01

γ rays from the keV-neutron capture reactions by 140 Ce, 141 Pr, and 147,148,149,150 Sm have been measured in a neutron energy region of 10 to 550 keV, using a large anti-Compton NaI(Tl) γ-ray spectrometer and the 7 Li(p,n) 7 Be pulsed neutron source with a 3-MV Pelletron accelerator. The preliminary results for the capture cross sections and γ-ray spectra of those nuclei are presented and discussed. (author)

NaI Detector Network at Aragats

International Nuclear Information System (INIS)

Avakyan, Karen; Arakelyan, Karen; Chilingarian, Ashot; Daryan, Ara; Kozliner, Lev; Mailyan, Bagrat; Hovsepyan, Gagik; Pokhsraryan, David; Sargsyan, David

2013-01-01

The Aragats Space Environmental Center (ASEC) provides monitoring of different species of secondary cosmic rays and consists of two high altitude research stations on Mt. Aragats in Armenia. Along with solar modulation effects, ASEC detectors register several coherent enhancements associated with thunderstorm activity. The experimental techniques used allowed for the first time to simultaneously measure fluxes of the electrons, muons, gamma rays, and neutrons correlated with thunderstorm activity. Ground-based observations by a complex of surface particle detectors, measuring in systematically and repeatable fashion, gamma quanta, electrons, muons and neutrons from atmospheric sources are necessary for proving the theory of particle acceleration and multiplication during thunderstorms. Energy spectra and correlations between fluxes of different particles, measured on Earth's surface address the important issues of research of the solar modulation effects and the atmospheric high-energy phenomena. In May 26 2011, launched 5 NaI(Tl) (thallium-doped sodium iodide) scintillation detectors and 1 plastic one in the new ASEC laboratory on Aragats to detect low energy gamma rays from the thunderclouds and short particle bursts. Including NaI(Tl) detectors in ASEC detectors system is of great importance for investigation thunderstorm phenomena because NaI(Tl) detectors have high efficiency of gamma ray detecting in comparison with plastic ones.

An in-beam Compton-suppressed Ge spectrometer for nondestructive neutron activation analysis

International Nuclear Information System (INIS)

Zaghloul, R.; Abd El-Haleam, A.; Mostafa, M.; Gantner, E.; Ache, H.J.

1993-04-01

A high-efficiency compton background suppressed gamma-ray spectrometer by anti-coincidence counting with a NaI(Tl)-shield around a central HPGe-detector for in-beam prompt gamma-ray neutron activation analysis (AC-PGNAA) using a Cf-252 neutron source has been designed and built to provide simultaneous anti-coincidence spectrometry of natural, industrial and environmental samples. The spectrometer consists of a high-purity germanium detector as the main detector and a large volume cylindrical NaI(Tl) detector as a guard detector. The assembly has the ability to measure instantaneously, simultaneously and nondestructively bulk samples up to about 50 cm 3 . Major constituent elements in several rocks and minerals such as H, B, N, Na, Mg, Al, Si, Cl, K, Ca, P, S, Ti, Fe, Sm, Nd, Mn and Gd can be determined, while oxygen cannot be measured due to its small capture cross section (0.27 mb). Several important minor and trace elements such as B, Cd and Hg beside the low residual activity, rare earths and short-lived isotopes could be detected. The sensitivity of the AC-PGNAA technique is limited by the available neutron flux at the target matrix and the neutron absorption cross section of the elements of interest. PGNAA has the advantage to estimate the constituent elements which are difficult to be measured through the delayed gamm-ray measurements such as B, Bi, C, H, P, Tl, Be, Cl and S in industrial and reference materials and those elements which are transformed into other stable isotopes when undergoing neutron capture. The design of the spectrometer assembly, its properties and performance are described

Neutron and gamma-ray spectra of 239PuBe and 241AmBe

International Nuclear Information System (INIS)

Vega-Carrillo, H.R.; Manzanares-Acuna, Eduardo; Becerra-Ferreiro, A.M.; Carrillo-Nunez, Aureliano

2002-01-01

Neutron and gamma-ray spectra of 239 PuBe and 241 AmBe were measured and their dosimetric features were calculated. Neutron spectra were measured using a multisphere neutron spectrometer with a 6 LiI(Eu) scintillator. The 239 PuBe neutron spectrum was measured in an open environment, while the 241 AmBe neutron spectrum was measured in a closed environment. Gamma-ray spectra were measured using a NaI(Tl) scintillator using the same experimental conditions for both sources. The effect of measuring conditions for the 241 AmBe neutron spectrum indicates the presence of epithermal and thermal neutrons. The low-resolution neutron spectra obtained with the multisphere spectrometer allows one to calculate the dosimetric features of neutron sources. At 100 cm both sources produce approximately the same count rate as that of the 4.4 MeV gamma-ray per unit of alpha emitter activity

Neutron diffraction utilizing the T-O-F method

Energy Technology Data Exchange (ETDEWEB)

Niimura, N [Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science

1974-12-01

Characteristic features of the TOF (time of flight) neutron diffraction are summarized. In this method, i) all the reciprocal points on the rod passing through the origin in the reciprocal space can be scanned by each burst of white neutrons, ii) it is easy to measure high index reflections at the large scattering angle, iii) each reflection is not affected by the higher-order harmonics, and iv) it is easy to measure the physical properties depending on the neutron wavelength. The pulse neutron generator as well as the data acquisition system in the Laboratory of Nuclear Science of Tohoku University is described. The TOF method seems to be very powerful if it is applied to accurate structure analysis. The data correction methods are discussed. The TOF method is prospective to the study of transient phenomena. In this method one can apply to the crystalline sample an external field pulsed with the same frequency as the neutrons. By using this method, the transient state of the polarization reversal of the ferroelectric NaNO/sub 2/ has been observed. The magnetically pulsed neutron TOF spectrometer is briefly introduced after a review of the chopper history.

Surto de sarampo na regiao metropolitana de Campinas, SP

Directory of Open Access Journals (Sweden)

Eder Gatti Fernandes

2013-12-01

Full Text Available O Brasil não apresenta circulação endêmica do vírus do sarampo desde o ano 2000. Entre maio e junho de 2011, a Região Metropolitana de Campinas, Estado de São Paulo, registrou três casos de sarampo. Foram descritos casos, as medidas de controle, a busca de possível fonte e de casos secundários. A caracterização genotípica do vírus identificou o genótipo D4, circulante no continente europeu. Não foram encontrados casos índice ou secundários. As medidas de controle efetuadas, aliadas à cobertura vacinal adequada da Região Metropolitana de Campinas contribuíram para que a transmissão da doença fosse interrompida.

Capture cross-section measurements for different elements at neutron energies between 0.5 and 3.0 MeV

International Nuclear Information System (INIS)

Grenier, Gerard; Voignier, Jacques; Joly, Serge.

1981-03-01

Neutron capture cross-sections have been measured for the nuclides: Rb, Y, Nb, Gd, W, Pt, Tl, and for the isotopes 155 Gd, 156 Gd, 157 Gd, 158 Gd, 160 Gd, 182 W, 183 W, 184 W, 186 W, 203 Tl and 205 Tl in the 0.5 MeV to 3.0 MeV neutron energy range. Neutron capture cross-sections are determined through direct γ-ray spectrum emitted by the sample. The gamma-rays are detected by a NaI scintillator surrounded by an annular NaI detector. The time-of-flight method is used. Our results are compared with previous data, evaluations and statistical model calculations [fr

Feasibility studies on the production of essential radioisotopes (24Na and 32P) using the Ghana Miniature Neutron Source Reactor (GHARR-1)

International Nuclear Information System (INIS)

Dotse, S.C.

2012-01-01

Feasibility studies on the production of 32 P and 24 Na using a Miniature Neutron Source Reactor named Ghana Research Reactor-1 (GHARR-1) has been conducted. A theoretical model of the cyclic activation technique was developed for the simulation of specific activities under varying parameters. Specific activity values estimated for four cycles of irradiation with activation parameters falling within the specifications of the reactor were experimentally validated. Experimented results were compared to those theoretically estimated for both 24 Na and 32 P. Experimented specific activity values for both radioisotopes generally fell below their theoretical values but recorded activity build-ups from one cycle to the other. The 24 Na nuclide showed a regular pattern for the increase in specific activity from one cycle to the next with an average percentage difference of experimented to theoretical value of 19%. The 32 P nuclide showed an irregular pattern for the increase in specific activity from one cycle to the next with an average percentage difference of experimental to theoretical value of 11%. The specific activities experimentally attained, with reference to activity levels used for various applications in agriculture and industry suggests the cyclic activation technique can be used for the production of radioisotopes of appreciable activities using low power research reactors, which are characterised with limited excess core reactivity and cannot sustain long periods of irradiation. (au)

Investigations of fast neutron production by 190 GeV/c muon interactions on graphite target

CERN Document Server

Chazal, V; Cook, B; Henrikson, H; Jonkmans, G; Paic, A; Mascarenhas, N; Vogel, P; Vuilleumier, J L

2002-01-01

The production of fast neutrons (1 MeV - 1 GeV) in high energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon target. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross section.

Implosion anisotropy of neutron kinetic energy distributions as measured with the neutron time-of-flight diagnostics at the National Ignition Facility

Science.gov (United States)

Hartouni, Edward; Eckart, Mark; Field, John; Grim, Gary; Hatarik, Robert; Moore, Alastair; Munro, David; Sayer, Daniel; Schlossberg, David

2017-10-01

Neutron kinetic energy distributions from fusion reactions are characterized predominantly by the excess energy, Q, of the fusion reaction and the variance of kinetic energy which is related to the thermal temperature of the plasma as shown by e.g. Brysk. High statistics, high quality neutron time-of-flight spectra obtained at the National Ignition Facility provide a means of measuring small changes to the neutron kinetic energy due to the spatial and temporal distribution of plasma temperature, density and velocity. The modifications to the neutron kinetic energy distribution as described by Munro include plasma velocity terms with spatial orientation, suggesting that the neutron kinetic energy distributions could be anisotropic when viewed by multiple lines-of-sight. These anisotropies provide a diagnostic of burn averaged plasma velocity distributions. We present the results of measurements made for a variety of DT implosions and discuss their possible physical interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

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.

Observation of a low-lying neutron-unbound state in 19C

International Nuclear Information System (INIS)

Thoennessen, M.; Mosby, S.; Badger, N.S.; Baumann, T.; Bazin, D.; Bennett, M.; Brown, J.; Christian, G.; DeYoung, P.A.; Finck, J.E.; Gardner, M.; Hook, E.A.; Luther, B.; Meyer, D.A.; Mosby, M.; Rogers, W.F.

2013-01-01

Proton removal reactions from a secondary 22 N beam were utilized to populate unbound states in neutron-rich carbon isotopes. Neutrons were measured with the Modular Neutron Array (MoNA) in coincidence with carbon fragments. A resonance with a decay energy of 76(14) keV was observed in the system 18 C+n corresponding to a state in 19 C at an excitation energy of 653(95) keV. This resonance could correspond to the first 5/2 + state which was recently speculated to be unbound in order to describe 1n and 2n removal cross section measurements from 20 C

Elemental analysis of fertilizer by fast neutron activation

International Nuclear Information System (INIS)

Bodart, F.; Deconninck, G.

1977-01-01

A simple and accurate technique has been developed to analyse commercial fertilizers for phosphorus, potassium, chlorine, magnesium and silicon. The method is based on fast-neutron activation using a neutron flux of 2x10 11 neutrons/second. The optimum analytical conditions are tabulated. After irradiation, the sample is measured on a conventional counting system including a Ge(Li) detector (10% efficiency and 2 keV resolution for 60 Co) and a multichannel analyser. Monitor foils radioactivity are measured separately at the same time with a 2''x2''NaI detector coupled with a single channel analyser and a scaler. Fast neutron activation has proved to be a fast, simple, reliable and low cost analytical technique for the determination of phosphorus, silicon, potassium, magnesium and chlorine in fertilizers. Not less than five phosphorus determinations are possible in one hour, while two potassium, magnesium and chlorine determinations are made at the same time. (T.G.)

Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

Energy Technology Data Exchange (ETDEWEB)

Lau, Ch

2000-09-15

This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons.

NIF total neutron yield diagnostic

International Nuclear Information System (INIS)

Cooper, Gary W.; Ruiz, Carlos L.

2001-01-01

We have designed a total neutron yield diagnostic for the National Ignition Facility (NIF) which is based on the activation of In and Cu samples. The particular approach that we have chosen is one in which we calibrate the entire counting system and which we call the ''F factor'' method. In this method, In and/or Cu samples are exposed to known sources of DD and DT neutrons. The activated samples are then counted with an appropriate system: a high purity Ge detector for In and a NaI coincidence system for Cu. We can then calculate a calibration factor, which relates measured activity to total neutron yield. The advantage of this approach is that specific knowledge of such quantities as cross sections and detector efficiencies is not needed. Unless the actual scattering environment of the NIF can be mocked up in the calibration experiment, the F factor will have to be modified using the results of a numerical simulation of the NIF scattering environment. In this article, the calibration factor methodology will be discussed and experimental results for the calibration factors will be presented. Total NIF neutron yields of 10 9 --10 19 can be measured with this method assuming a 50 cm stand-off distance can be employed for the lower yields

Investigations of fast neutron production by 190 GeV/c muon interactions on different targets

International Nuclear Information System (INIS)

Chazal, V.; Boehm, F.; Cook, B.; Henrikson, H.; Jonkmans, G.; Paic, A.; Mascarenhas, N.; Vogel, P.; Vuilleumier, J.-L.

2002-01-01

The production of fast neutrons (1 MeV-1 GeV) in high-energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon, copper and lead targets. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross-section

Damping of forward neutrons in pp collisions

International Nuclear Information System (INIS)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Soffer, J.

2008-01-01

We calculate absorptive corrections to single pion exchange in the production of leading neutrons in pp collisions. Contrary to the usual procedure of convolving the survival probability with the cross section, we apply corrections to the spin amplitudes. The nonflip amplitude turns out to be much more suppressed by absorption than the spin-flip one. We identify the projectile proton Fock state responsible for the absorptive corrections as a color octet-octet 5-quarks configuration. Calculations within two very different models, color-dipole light-cone description, and in hadronic representation, lead to rather similar absorptive corrections. We found a much stronger damping of leading neutrons than in some of previous estimates. Correspondingly, the cross section is considerably smaller than was measured at ISR. However, comparison with recent measurements by the ZEUS collaboration of neutron production in deep-inelastic scattering provides a strong motivation for challenging the normalization of the ISR data. This conjecture is also supported by preliminary data from the NA49 experiment for neutron production in pp collisions at SPS.

MASURCA, a Fast-Neutron Critical Mock-Up: Operation and Uses; MASURCA. Maquette Critique a Neutrons Rapides. Description Fonctionnelle et Obiectifs; ''MAZURKA'' - kriticheskaya model' na bystrykh nejtronakh. funktsional'noe opisanie i tseli; Descripcion Funcional y Objetivos de la Maqueta Critica de Neutrones Rapidos 'MASURCA '

Energy Technology Data Exchange (ETDEWEB)

Schmitt, A. P.; Storrer, F.; Vendryes, G. [Association CEA-EURATOM, Cadarache (France); Tavernier, G.; Van Dievoet, J. [Societe Belgo-Nucleaire, Bruxelles (Belgium)

1964-02-15

Under the EURATOMCEA Association project a fast-neutron critical mock-up, Masurca, is now being built at the Cadarache Nuclear Research Centre. The main purpose of this extremely versatile facility is the study of non-moderated, plutonium critical assemblies of large volume and hence having a relatively soft neutron spectrum. The paper explains what these studies are for. The facility must satisfy certain conditions and, in essence, combine great versatility with almost absolute operational safety. The safety problem was dealt with by: (1) Seeking inherent safety: with simulated fuel elements it was possible to obtain (a) a negative reactivity coefficient from the cumulative longitudinal expansion of these elements: (b) a negative Doppler coefficient; (2) Using a set of shim-safety rods which can be placed in a square lattice with spacings of about 30cm; (3) A pressure vessel, containing reserves of argon in case of fire: and (4) Strict administrative supervision. A U-Pu-Fe metallic alloy being chosen as the basic element in the fuel simulation, provision for cooling large-volume critical assemblies must be incorporated in the facility. Sodium, the coolant used in simulated reactors, will be represented by sodium strips clad in stainless steel. The facility is designed as a vertical single-block unit in view of the maximum volume of the cores to be simulated (about 5000 1). The simulated elements are shaped like a right prism with a square base (except in the case of fuel elements which have a circular base) with an outer side (or diameter) of 12.7 mm and a height of 102 mm. They are placed in tubes having an over- all length of about 4 m and square sections whose outer side is 10.6 mm. These tubes are placed side by side and suspended. Smaller tubes can be placed in the central area of the suspension plate so that smaller cores can be made. A special heating loop can also be placed in the central part of the facility to measure the Doppler coefficient. The paper

Estimation of covariances of 16O, 23Na, Fe, 235U, 238U and 239Pu neutron nuclear data in JENDL-3.2

International Nuclear Information System (INIS)

Shibata, Keiichi; Nakajima, Yutaka; Kawano, Toshihiko; Oh, Soo-Youl; Matsunobu, Hiroyuki; Murata, Toru.

1997-10-01

Covariances of nuclear data have been estimated for 6 nuclides contained in JENDL-3.2. The nuclides considered are 16 O, 23 Na, Fe, 235 U, 238 U, and 239 Pu, which are regarded as important for the nuclear design study of fast reactors. The physical quantities for which covariances are deduced are cross sections, resolved and unresolved resonance parameters, and the first order Legendre-polynomial coefficient for the angular distribution of elastically scattered neutrons. As for 235 U, covariances were obtained also for the average number of neutrons emitted in fission. The covariances were estimated by using the same methodology that had been used in the JENDL-3.2 evaluation in order to keep a consistency between mean values and their covariances. The least-squares fitting code GMA was used in estimating covariances for reactions of which JENDL-3.2 cross sections had been evaluated by taking account of measurements. In nuclear model calculations, the covariances were calculated by the KALMAN system. The covariance data obtained were compiled in the ENDF-6 format, and will be put into the JENDL-3.2 Covariance File which is one of JENDL special purpose files. (author). 193 refs

Electron-volt spectroscopy at a pulsed neutron source using a resonance detector technique

CERN Document Server

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

2002-01-01

The effectiveness of the neutron resonance detector spectrometer for deep inelastic neutron scattering measurements has been assessed by measuring the Pb scattering on the eVS spectrometer at ISIS pulsed neutron source and natural U foils as (n,gamma) resonance converters. A conventional NaI scintillator with massive shielding has been used as gamma detector. A neutron energy window up to 90 eV, including four distinct resonance peaks, has been assessed. A net decrease of the intrinsic width of the 6.6 eV resonance peak has also been demonstrated employing the double difference spectrum technique, with two uranium foils of different thickness.

Determination of neutron dose from criticality accidents with bioassays for sodium-24 in blood and phosphorus-32 in hair

International Nuclear Information System (INIS)

Feng, Y.; Miller, L.F.; Brown, K.S.; Casson, W.H.; Mei, G.T.; Thein, M.

1993-06-01

A comprehensive review of accident neutron dosimetry using blood and hair analysis was performed and is summarized in this report. Experiments and calculations were conducted at Oak Ridge National Laboratory (ORNL) and the University of Tennessee (UT) to develop measurement techniques for the activity of 24 Na in blood and 32 P in hair for nuclear accident dosimetry. An operating procedure was established for the measurement of 24 Na in blood using an HPGe detector system. The sensitivity of the measurement for a 20-mL sample is 0.01-0.02 Gy of total neutron dose for hard spectra and below 0.005 Gy for soft spectra based on a 30- to 60-min counting time. The operating procedures for direct counting of hair samples are established using a liquid scintillation detector. Approximately 0.06-0.1 Gy of total neutron dose can be measured from a 1-g hair sample using this procedure. Detailed procedures for chemical dissolution and ashing of hair samples are also developed. A method is proposed to use blood and hair analysis for assessing neutron dose based on a collection of 98 neutron spectra. Ninety-eight blood activity-to-dose conversion factors were calculated. The calculated results for an uncollided fission spectrum compare favorably with previously published data for fission neutrons. This nuclear accident dosimetry system makes it possible to estimate an individual's neutron dose within a few hours after an accident if the accident spectrum can be approximated from one of 98 tabulated neutron spectrum descriptions. If the information on accident and spectrum description is not available, the activity ratio of 32 P in hair and 24 Na in blood can provide information related to the neutron spectrum for dose assessment

Introduction to Neutron Coincidence Counter Design Based on Boron-10

Energy Technology Data Exchange (ETDEWEB)

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

2012-01-22

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

Neutron activation analysis for environmental sample in Thailand

International Nuclear Information System (INIS)

Busamongkol, Arporn; Nouchpramool, Sunun; Bunprapob, Supamatthree; Sumitra, Tatchai

2003-01-01

Neutron Activation Analysis has been applied for the trace elements analysis in environmental samples. Thirty three samples of airborne particulate were collected every week at Ongkharak Nuclear Research Center (ONRC) during the period of June 1998 to March 1999. The Ti, I, Mg, Na, V, K, Cl, Al, Mn, Ca, As, Sm, Sb, Br, La, Ce, Th, Cr, Cs, Sc, Rb, Fe, Zn and Co were analyzed by Neutron Activation Analysis utilizing 2 MW TRIGA MARK III research reactor. The certified reference materials 1632a and 1633a from National Bureau of Standard were select as standard. (author)

An investigation of tungsten by neutron activation techniques

International Nuclear Information System (INIS)

Svetsreni, R.

1978-01-01

This investigation used neutron from Plutonium-Beryllium source (5 curie) to analyse the amount of tungsten in tungsten oxide which was extracted from tungsten ores, slag and tungsten alloy of tungsten iron and carbon. The technique of neutron activation analysis with NaI(Tl) gamma detector 3'' x 3'' and 1024 multichannel analyzer. The dilution technique was used by mixing Fe 2 O 3 or pure sand into the sample before irradiation. In this study self shielding effect in the analysis of tungsten was solved and the detection limit of the tungsten in the sample was about 0.5%

Instrumental Neutron Activation Analysis for Human Hair

International Nuclear Information System (INIS)

Ratanatongchai, W.; Dharmvanij, W; Chongkum, S.

1998-01-01

Hair samples from students aged between 7 to 22 years old were analysed by neutron activation analysis at nuclear research reactor TRR-1.M1. From qualitative analysis of short-lived isotopes, A1, V, Ca, I, Cl, Mn, and Na were found. The quantity of those elements can be classified into three groups. The first group is A1, Ca, Na and Cl with variance less than 10%. The second group is V and I with variance between 10% to 50% and the third group, Mn, two samples have concentration about 12 times higher than the others

In vivo neutron activation facility at Brookhaven National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Ma, R.; Yasumura, Seiichi; Dilmanian, F.A.

1997-11-01

Seven important body elements, C, N, Ca, P, K, Na, and Cl, can be measured with great precision and accuracy in the in vivo neutron activation facilities at Brookhaven National Laboratory. The facilities include the delayed-gamma neutron activation, the prompt-gamma neutron activation, and the inelastic neutron scattering systems. In conjunction with measurements of total body water by the tritiated-water dilution method several body compartments can be defined from the contents of these elements, also with high precision. In particular, body fat mass is derived from total body carbon together with total body calcium and nitrogen; body protein mass is derived from total body nitrogen; extracellular fluid volume is derived from total body sodium and chlorine; lean body mass and body cell mass are derived from total body potassium; and, skeletal mass is derived from total body calcium. Thus, we suggest that neutron activation analysis may be valuable for calibrating some of the instruments routinely used in clinical studies of body composition. The instruments that would benefit from absolute calibration against neutron activation analysis are bioelectric impedance analysis, infrared interactance, transmission ultrasound, and dual energy x-ray/photon absorptiometry.

β Decay processes of neutron-rich isotopes of sodium and magnesium

International Nuclear Information System (INIS)

Guillemaud, D.

1982-01-01

The γ and n activities from the β decay of Na isotopes up to 34 Na, which are formed in high-energy fragmentation and analysed through mass-spectrometry techniques, are observed as well as those from their Mg descendants. Their intensities Isub(γ) and Isub(β) are measured; some radioactive half lives are determined. Delayed-neutron branching ratios Pn are measured. The existence of 35 Na is for the first time indicated. The position of the first excited 2 + level is taken as an indication of a stronger deformation for that isotope [fr

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.

The measurements of thermal neutron flux distribution in a paraffin ...

Indian Academy of Sciences (India)

outputs and the best agreement was generated using NaI(Tl) by a minimum discrepancy of .... the four possible reactions with neutron absorption, our desire is to form 116m1In, which .... According to Geiger user's manual, its efficiency for.

The structure of phosphate glass biomaterials from neutron diffraction and 31P nuclear magnetic resonance data

International Nuclear Information System (INIS)

Pickup, D M; Ahmed, I; Guerry, P; Knowles, J C; Smith, M E; Newport, R J

2007-01-01

Neutron diffraction and 31 P nuclear magnetic resonance spectroscopy were used to probe the structure of phosphate glass biomaterials of general composition (CaO) 0.5-x (Na 2 O) x (P 2 O 5 ) 0.5 (x = 0, 0.1 and 0.5). The results suggest that all three glasses have structures based on chains of Q 2 phosphate groups. Clear structural differences are observed between the glasses containing Na 2 O and CaO. The P-O bonds to bridging and non-bridging oxygens are less well resolved in the neutron data from the samples containing CaO, suggesting a change in the nature of the bonding as the field strength of the cation increases Na + → Ca 2+ . In the (CaO) 0.5 (P 2 O 5 ) 0.5 glass most of the Ca 2+ ions are present in isolated CaO x polyhedra whereas in the (Na 2 O) 0.5 (P 2 O 5 ) 0.5 glass the NaO x polyhedra share edges leading to a Na-Na correlation. The results of the structural study are related to the properties of the (CaO) 0.4 (Na 2 O) 0.1 (P 2 O 5 ) 0.5 biomaterial

Nuclear spectroscopy using the neutron capture reaction

International Nuclear Information System (INIS)

Egidy, T.

1982-01-01

Experimental methods using neutron spectroscopy as a means to study the nucleus structure are described. Since reactions of neutron capture (n, γ) are non-selective, they permit to study the nature of excitation (monoparticle and collective) of nuclear levels, the nature of vibrational excitations, to check the connection between shell model and liquid drop model etc. In many cases (n, γ) reactions are the only way to check the forecast of nuclear models. Advantages of (n, γ) spectroscopy, possessing a high precision of measurement and high sensitivity, are underlined. Using neutron spectroscopy on facilities with a high density of neutron flux the structures of energy levels of a large group of nuclei are studied. In different laboratories complete schemes of energy levels of nuclei are obtained, a great number of new levels are found, the evergy level densities are determined, multipolarities of γ-transitions, spins, level parities are considered. StrUctures of rotational bands of heavy deformed nuclei are studied. The study of the structure of high-spin states is possible only using the methods of (n, γ) spectroscopy Investigation results of the nuclei 24 Na, 114 Cd, 154 Eu, 155 Cd, 155 Sm, 233 Th are considered as examples. The most interesting aspects of the investigations using neutron spectroscopy are discUssed

Calculations of neutron spectra after neutron-neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Crawford, B E [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S L [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Howell, C R [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G E [North Carolina State University, Raleigh, NC 27695-8202 (United States); Tornow, W [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Furman, W I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Muzichka, A Yu [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V N [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

2004-09-01

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

Effect of chloride substitution on the order–disorder transition in NaBH{sub 4} and Na{sup 11}BD{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Olsen, Jørn Eirik [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway); Karen, Pavel [University of Oslo, Department of Chemistry, P.O. Box 1033 Blindern, NO-0315 Oslo (Norway); Sørby, Magnus H. [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway); Hauback, Bjørn C., E-mail: bjorn.hauback@ife.no [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway)

2014-02-25

Graphical abstract: Interactions that order the BD{sub 4}{sup -} tetrahedra below the order–disorder transition became increasingly frustrated by the solute in the Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x} solid solutions, and the order disappears at x = 0.158. Highlights: • The order–disorder transition temperature for Na(BH{sub 4}){sub 1−x}Cl{sub x} and Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x} is highly dependent on the Cl-content, x. • The transition is characterized by DSC for Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x} for x = 0, 0.10 and 0.15. • No transition is observed for x ⩾ 0.20 on cooling to 8 K. • The crystal structures are reported for Na{sup 11}BD{sub 4} at room temperature and 8 K and Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x} (x = 0.10, 0.15, 0.20 and 0.25) at 8 K from powder neutron diffraction. -- Abstract: Phase transition associated with anion disordering over two orientations in Na{sup 11}BD{sub 4} (NaBH{sub 4}) and its solid solutions with NaCl, Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x}, is investigated with powder diffraction (neutron and synchrotron radiation), differential scanning calorimetry and Raman spectroscopy. Upon heating, the transition temperature extrapolated to zero rate of heating is 192.2 K for Na{sup 11}BD{sub 4}, ΔS = 4.41 J/mol K, hysteresis 1.7 K and the volume increase 0.43%. Thermal parameters of the transition in Na({sup 11}BD{sub 4}){sub 1−x}Cl{sub x} follow a colligative-property model of an ideal solution, with x = 0.158(1) as the critical concentration at which the ordering interactions and the transition itself are eliminated. On approaching this limit, the tetragonal distortion of the ordered structure decreases somewhat towards the cubic average, and this is associated with a partial disorder of the tetrahedral anions seen by diffraction methods. In fact, a 3% disorder is already present in the pure solvent of the solid solution (Na{sup 11}BD{sub 4}) at 8 K.

Gamma signatures of the C-BORD Tagged Neutron Inspection System

Directory of Open Access Journals (Sweden)

Sardet A.

2018-01-01

Full Text Available In the frame of C-BORD project (H2020 program of the EU, a Rapidly relocatable Tagged Neutron Inspection System (RRTNIS is being developed to non-intrusively detect explosives, chemical threats, and other illicit goods in cargo containers. Material identification is performed through gamma spectroscopy, using twenty NaI detectors and four LaBr3 detectors, to determine the different elements composing the inspected item from their specific gamma signatures induced by fast neutrons. This is performed using an unfolding algorithm to decompose the energy spectrum of a suspect item, selected by X-ray radiography and on which the RRTNIS inspection is focused, on a database of pure element gamma signatures. This paper reports on simulated signatures for the NaI and LaBr3 detectors, constructed using the MCNP6 code. First experimental spectra of a few elements of interest are also presented.

Neutron and gamma-ray spectra of {sup 239}PuBe and {sup 241}AmBe

Energy Technology Data Exchange (ETDEWEB)

Vega-Carrillo, H.R. E-mail: rvega@cantera.reduaz.mx; Manzanares-Acuna, Eduardo; Becerra-Ferreiro, A.M.; Carrillo-Nunez, Aureliano

2002-08-01

Neutron and gamma-ray spectra of {sup 239}PuBe and {sup 241}AmBe were measured and their dosimetric features were calculated. Neutron spectra were measured using a multisphere neutron spectrometer with a {sup 6}LiI(Eu) scintillator. The {sup 239}PuBe neutron spectrum was measured in an open environment, while the {sup 241}AmBe neutron spectrum was measured in a closed environment. Gamma-ray spectra were measured using a NaI(Tl) scintillator using the same experimental conditions for both sources. The effect of measuring conditions for the {sup 241}AmBe neutron spectrum indicates the presence of epithermal and thermal neutrons. The low-resolution neutron spectra obtained with the multisphere spectrometer allows one to calculate the dosimetric features of neutron sources. At 100 cm both sources produce approximately the same count rate as that of the 4.4 MeV gamma-ray per unit of alpha emitter activity.

The activation method for determining neutron spectra and fluences

International Nuclear Information System (INIS)

Hogel, J.; Vespalec, R.

1980-01-01

3 mm thick foils of 4 and 17 mm in diameter were used for measurements. NaI scintillation detectors 45 mm in diameter by 50 mm thick and 40 mm in diameter by 1 mm thick, and a Ge-Li spectrometer of 53 cm 3 in volume were used for gamma detection. A photopeak or a certain part of the integral spectrum was measured for each radionuclide. Computer code PIKAR was applied in automatic calculation of a simple gamma spectrum obtained using the semiconductor spectrometer. The FACT code was used for calculating foil activity. Codes SAND II and RFSP were used for neutron spectra unfolding. Ge-Li detector spectrometry was used for determining neutron fluence. Code FLUE was used for determining the mean value of neutron flux density and fluence. (J.P.)

Neutron-transparent first wall for module testing

International Nuclear Information System (INIS)

Fuller, G.M.; Cramer, B.A.; Haines, J.R.; Kirchner, J.; Engholm, B.A.; Seki, M.

1983-01-01

Major design goals for FED-R are the achievement of: (1) a high level of neutron exposure of the test modules and (2) a capability for rapid changeout of test modules. A major factor in rapid changeout is perceived to be the location of the vacuum boundary. In FED-R this boundary was set at the first wall so that module changeout did not require the plasma chamber to be brought up to atmosphere. Efforts to realize these goals in the design resulted in a neutronically thin outboard wall for the vacuum vessel constructed of 316 stainless steel (SS) with helium as a coolant. A normalized 14-MeV neutron transmission of 0.82 is expected, with an inlet pressure of 2 MPa and a pumping power requirement of 8.7 MW. Other options considered in the study were aluminum as a wall material and water and sodium potassium (NaK) as coolants

Design of active-neutron fuel rod scanner

International Nuclear Information System (INIS)

Griffith, G.W.; Menlove, H.O.

1996-01-01

An active-neutron fuel rod scanner has been designed for the assay of fissile materials in mixed oxide fuel rods. A 252 Cf source is located at the center of the scanner very near the through hole for the fuel rods. Spontaneous fission neutrons from the californium are moderated and induce fissions within the passing fuel rod. The rod continues past a combined gamma-ray and neutron shield where delayed gamma rays above 1 MeV are detected. We used the Monte Carlo code MCNP to design the scanner and review optimum materials and geometries. An inhomogeneous beryllium, graphite, and polyethylene moderator has been designed that uses source neutrons much more efficiently than assay systems using polyethylene moderators. Layers of borated polyethylene and tungsten are used to shield the detectors. Large NaI(Tl) detectors were selected to measure the delayed gamma rays. The enrichment zones of a thermal reactor fuel pin could be measured to within 1% counting statistics for practical rod speeds. Applications of the rod scanner include accountability of fissile material for safeguards applications, quality control of the fissile content in a fuel rod, and the verification of reactivity potential for mixed oxide fuels. (orig.)

Time-of-flight pulsed neutron diffraction of molten salts

Energy Technology Data Exchange (ETDEWEB)

Fukushima, Y; Misawa, M; Suzuki, K [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

1975-06-01

In this work, the pulsed neutron diffraction of molten alkali metal nitrate and bismuth trihalide was measured by the time-of-flight method. An electron linear accelerator was used as the pulsed neutron source. All the measurements were carried out with the T-O-F neutron diffractometer installed on the 300 MeV electron lineac. Molten NaNO/sub 3/ and RbNO/sub 3/ were adopted as the samples for alkali metal nitrate. The measurement is in progress for KNO/sub 3/ and LiNO/sub 3/. As the first step of the study on bismuth-bismuth trihalide system, the temperature dependence of structure factors was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/ in the liquid state. The structure factors Sm(Q) for molten NaNO/sub 3/ at 340/sup 0/C and RbNO/sub 3/ at 350/sup 0/C were obtained, and the form factor F/sub 1/(Q) for single NO/sub 3//sup -/ radical with equilateral triangle structure was calculated. In case of molten NaNO/sub 3/, the first peak of Sm(Q) is simply smooth and a small hump can be observed in the neighbourhood of the first minimum Q position. The first peak of Sm(Q) for molten RbNO/sub 3/ is divided into two peaks, whereas a hump at the first minimum becomes big, and shifts to the low Q side of the second peak. The size of the NO/sub 3//sup -/ radical in molten NaNO/sub 3/ is a little smaller than that in molten RbNO/sub 3/. The values of the bond length in the NO/sub 3//sup -/ radical are summarized for crystal state and liquid state. The temperature dependence of the structure factor S(Q) was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/, and shown in a figure.

Miniature Neutron-Alpha Activation Spectrometer

Science.gov (United States)

Rhodes, E.; Goldsten, J.

2001-01-01

We are developing a miniature neutron-alpha activation spectrometer for in situ analysis of samples including rocks, fines, ices, and drill cores, suitable for a lander or Rover platform, that would meet the severe mass, power, and environmental constraints of missions to the outer planets. In the neutron-activation mode, a gamma-ray spectrometer will first perform a penetrating scan of soil, ice, and loose material underfoot (depths to 10 cm or more) to identify appropriate samples. Chosen samples will be analyzed in bulk in neutron-activation mode, and then the sample surfaces will be analyzed in alpha-activation mode using Rutherford backscatter and x-ray spectrometers. The instrument will provide sample composition over a wide range of elements, including rock-forming elements (such as Na, Mg, Si, Fe, and Ca), rare earths (Sm and Eu for example), radioactive elements (K, Th, and U), and light elements present in water, ices, and biological materials (mainly H, C, O, and N). The instrument is expected to have a mass of about l kg and to require less than 1 W power. Additional information is contained in the original extended abstract.

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)

The Control of Fast Reactors: Current Methods and Future Prospects; Controle des Reacteurs a Neutrons Rapides. Methodes Actuelles et Perspectives d'Avenir; Upravlenie reaktorami na bystrykh nejtronakh. sushchestvuyushchie metody i dal'nejshie perspektivy; Control de Reactores Rapidos: Metodos Actuales y Perspectivas

Energy Technology Data Exchange (ETDEWEB)

Loewenstein, W. B. [Argonne National Laboratory, IL (United States)

1964-06-15

efectividad de los mecanismos de control han evolucionado desde evaluaciones poco precisas hasta calculos muy fidedignos confirmados experimentalmente en conjuntos criticos. El autor describe los resultados experimentales y las tecnicas analiticas, que suelen ser seguras. Los experimentos criticos que precedieron la construccion de los actuales modelos de reactores de neutrones rapidos comprendieron muchas investigaciones sobre la efectividad de sus mecanismos de control y experimentos marginales para sistemas perfeccionados en los que el cuerpo tiene un volumen mayor. El autor cita algunos estudios analiticos provisionales de los que se puede deducir que no habra necesidad de efectuar en lo sucesivo investigaciones experimentales detalladas en maquetas. (author) [Russian] Obsuzhdajutsja prakticheskie aspekty obespechenija sootvetstvujushhej reaktivnosti dlja upravlenija reaktorami na bystryh nejtronah, kotorye sushhestvenno otlichajutsja ot analogichnyh aspektov pri osushhestvlenii kontrolja sistem teplovyh nejtronov. Jeti razlichija vyzvany glavnym obrazom blagodarja nebol'shim sechenijam na bystryh nejtronah. V sistemah na bystryh nejtronah otsutstvujut sil'nye poglotiteli nejtronov. V rezul'tate jetogo takie sil'nye poglotiteli nejtronov v teplovyh reaktorah, kak produkty raspada (naprimer He i Zt)trebujut znachitel'no men'she reaktivnosti na ih kompensaciju, chem poterja reaktivnosti, vyzvannaja deleniem i zahvatom rasshhepljajushhihsja materialov. Poskol'ku atomnye sechenija bystrogo spektra dovol'no maly po sravneniju s sechenijami dlja teplovyh nejtronov atomnaja plotnost' materiala igraet vazhnuju rol' pri vybore materialov dlja regulirujushhih sterzhnej. Opisyvajutsja sushhestvujushhie tipy kontrol'nyh mehanizmov reaktorov na bystryh nejtronah. Jeti sposoby napravleny na vozmozhnost' ispol'zovanija, tam, gde jeto priemlemo,, kontrolja za utechkoj nejtronov. Kogda takoj kontrol' prakticheski neosushhestvim, to pri menjaetsja kontrol' s pomoshh'ju peredvizhenija

Determination of Ca, Cr, Cu, Fe, K, Mg, Na and Zn in Brazilian medicinal plants by neutron activation and atomic absorption; Determinacao de Ca, Cr, Cu, Fe, K, Mg, Na e Zn em plantas medicinais brasileiras por ativacao neutronica e absorcao atomica

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Ricardo P. de; Sabino, Claudia de Vilhena S.; Franco, Milton B.; Amaral, Angela M.; Guedes, Joao B.; Assis, Adilson de C. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Leite, Simone C.A.L.; Silva, Isabel R. [Pontificia Univ. Catolica de Minas Gerais, Belo Horizonte, MG (Brazil)

2002-07-01

Medicinal plants are available in the markets in Belo Horizonte, Minas Gerais. The objective of this work is to investigate the Ca, Cr, Cu, Fe, K, Mg, Na e Zn concentrations in two lots of usually known diuretics plants (azeitona do mato, cabelo de milho, cavalinha, cervejinha do campo, chapeu de couro, congonha de bugre, marmelinho do campo and quebra pedra) bought with an interval of time - six months - between the purchases. The elemental concentrations were determined applying k{sub 0} instrumental neutron activation analysis and atomic absorption spectrophotometry analysis. (author)

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

Solid thermoluminescent dosemeter of sodium tetraborate and brazilian fluorite sensible to thermic neutrons

International Nuclear Information System (INIS)

Fratin, L.; Cruz, M.T. da

1987-01-01

The production of solid thermoluminescent dosemeters sensible to thermic neutrons is described. The stages of the production are described: vitrification of sodium tetraborate, mixture and cold pressing, syntherization. The obtention of a CaF 2 : natural dosemeter with NaCl which presents sensibility to gamma radiation similar to CaF 2 : natural dosemeter with Na 2 B 4 O 7 is studied. (M.A.C.) [pt

Seminar on Heat-transfer fluids for fast neutron reactors

International Nuclear Information System (INIS)

Brechet, Yves; Dautray, Robert; Friedel, Jacques; Brezin, Edouard; Martin, Georges; Pineau, Andre; Carre, Francois; Gauche, Francois; Rodriguez, Guillaume; Latge, Christian; Cabet, Celine; Garnier, Jean-Claude; Bamberger, Yves; Sauvage, Jean-Francois; Buisine, Denis; Agostini, Pietro; Ulyanov, Vladimir; Auger, Thierry; Heuer, Daniel; Ghetta, Veronique; Bubelis, Evaldas; Charlaix, Elisabeth; Barrat, Jean-Louis; Boquet, Lyderic; Glickman, Evgueny; Escaravage, Claude

2014-03-01

This book reports the content of a two-day meeting held by the Academy of Sciences on the use of heat-transfer fluids in fast neutron reactors. After a first part which proposes an overview of scientific and technical problems related to these heat-transfer fluids (heat transfer process, nuclear properties, chemistry, materials, risks), a contribution proposes a return on experience on the use of heat-transfer fluids in the different design options of reactors of fourth generation: from mercury to NaK in the first fast neutron reactor projects, specific assets and constraints of sodium used as heat-transfer fluid, concepts of fast neutron reactors cooled by something else than sodium, perspectives for projects and research in fast neutron reactors. The next contribution discusses the specifications of future fast-neutron reactors: expectations for fourth-generation reactors, expectations in terms of performance and of safety, specific challenges. The last contribution addresses actions to be undertaken in the field of research and development: actions regarding all reactor types or specific types as sodium-cooled reactors, lead cooled reactors, molten salt reactors, and gas-cooled fast reactors

Beta-Delayed Neutron Spectroscopy of 72Co with VANDLE

Science.gov (United States)

Keeler, Andrew; Grzywacz, Robert; King, Thomas; Taylor, Steven; Paulauskas, Stanley; Zachary, Christopher; Vandle Collaboration

2017-09-01

Measurements of simple, closed-shell isotopes far from stability provide important benchmarks for nuclear models and are a key constraint in r-process calculations. In particular, r-process models are sensitive to beta decay lifetimes and branching ratios of these neutron-rich isotopes. In this experiment, the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was used to observe decays of nuclei produced by the fragmentation of 82Se at the National Superconducting Cyclotron Laboratory (NSCL). The neutron and gamma emissions of 72Co were measured to map the beta strength distribution (S_beta) above the neutron separation energy and infer the size of the Z = 28 shell gap in the 78Ni region. An implantation detector made of a radiation-hardened, inorganic scintillator was used to correlate implanted ions with beta decays as well as provide a start signal for the neutron Time of Flight measurement. Funded by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Award No. DE-NA0002132 and by the Office of Nuclear Physics, U.S. Department of Energy under Awards No. DE-FG02-96ER40983 (UTK).

Neutron--neutron logging

International Nuclear Information System (INIS)

Allen, L.S.

1977-01-01

A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures

Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons

International Nuclear Information System (INIS)

Lau, Ch.

2000-01-01

This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons

Workshop on neutron spin-echo

Energy Technology Data Exchange (ETDEWEB)

Aynajian, P.; Habicht, K.; Keller, Th.; Keimer, B.; Mezei, F.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Fetters, L.J.; Muller, K.; Kreiling, S.; Dehnicke, K.; Greiner, A.; Ehlers, G.; Arbe, A.; Colmenero, J.; Richter, D.; Farago, B.; Monkenbusch, M.; Ohl, M.; Butzek, M.; Kozielewski, T.; Monkenbusch, M.; Richter, D.; Pappas, C.; Hillier, A.; Manuel, P.; Cywinski, R.; Bentley, P.; Alba, M.; Mezei, F.; Campbell, I.A.; Zimmermann, U.; Ellis, J.; Jobic, H.; Pickup, R.M.; Pappas, C.; Farago, B.; Cywinski, R.; Haussler, W.; Holderer, O.; Frielinghaus, H.; Byelov, D.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Egger, H.; Hellweg, Th.; Malikova, N.; Cadene, A.; Marry, V.; Dubois, E.; Turq, P.; Gardner, J.S.; Ehlers, G.; Bramwell, St.S.; Grigoriev, S.; Kraan, W.; Rekveldt, T.; Bouwman, W.; Van Dijk, N.; Falus, P.; Vorobiev, A.; Major, J.; Felcher, G.P.; Te-velthuis, S.; Dosch, H.; Vorobiev, A.; Dridi, M.H.; Major, J.; Dosch, H.; Falus, P.; Felcher, G.P.; Te Velthuis, S.G.E.; Bleuel, M.; Broell, M.; Lang, E.; Littrell, K.; Gahler, R.; Lal, J.; Lauter, H.; Toperverg, B.; Lauter, V.; Jernenkov, M.; Stueber, S.; Enderle, M.; Janoschek, M.; Keller, Th.; Klimko, S.; Boeni, P.; Nagao, M.; Yamada, N.; Kawabata, Y.; Seto, H.; Takeda, T.; Yoshizawa, H.; Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.C.; Longeville, St

2005-07-01

This document gathers the abstracts of most papers presented at the workshop. Neutron spin-echo (NSE) spectroscopy is a well established technique with a growing expert user community, the aim of the meeting was to discuss the latest achievements in neutron spin-echo science and instrumentation. One of the applications presented is the investigation on the microscopic scale of the dynamics of water in montmorillonite clays with Na{sup +} and Cs{sup +} ions in monolayer and bilayer states. The NSE technique has been used in the normal and resonance modes. NSE results show consistently slower dynamics (higher relaxation times) than both time-of-flight technique (TOF) and classical molecular dynamics simulations (MD). In the present TOF and NSE experiments, anisotropy of the water motion in the interlayer is almost impossible to detect, due to the use of powder samples and insufficient resolution. (A.C.)

Studies on airborne dust particles by neutron activation analysis

International Nuclear Information System (INIS)

Aoki, Atsushi; Ishii, Taka; Tomiyama, Tsuyoshi; Yamamoto, Isao.

1974-01-01

Neutron activation analysis was performed on the airborne dust particles collected at six places with different contaminating circumstances in Kyoto city and the suburbs of Okayama city, using an open type low volume air sampler with a membrance filter attached. Radioactivation by neutrons was performed with the reactor in the Research Reactor Institute of Kyoto University. Short half-life nuclides activated by thermal neutrons were measured. The concentration of airborne dust was usually high in November and December, while Na, Mn, K, etc. probably owing to soil origin showed similar seasonal change to the dust particles, as expected. The concentrations Cl and Br were in proportion to traffic volume, and it was considered to be caused by the exhaust gas from cars. Zn, V. et. were thick in factory areas, which seemed to show the relationship with oil fuel consumption. (Kobatake, H.)

Rotational dynamics of propylene inside Na-Y zeolite cages

Indian Academy of Sciences (India)

We report here the quasielastic neutron scattering (QENS) studies on the dynamics of propylene inside Na-Y zeolite using triple axis spectrometer (TAS) at Dhruva reactor, Trombay. Molecular dynamics (MD) simulations performed on the system had shown that the rotational motion involves energy larger than that involved ...

Application of laboratory sourceless object counting for the estimation of the neutron dose

International Nuclear Information System (INIS)

Cheng Jie; Ning Jing; Zhang Xiaomin; Qu Decheng; Xie Xiangdong; Nan Hongjie

2011-01-01

Objective: To estimate the neutron dose using 24 Na energy spectrum analysis method. Methods: Genius-2000 GeomComposer software package was used to calibrate the efficiency of the detector. Results: The detection efficiency of the detector toward γ photon with an energy of 1.368 MeV was quickly found to be 4.05271×10 -3 while the error of the software was 4.0% . The estimated dose value of the neutron irradiation samples was between 1.94 Gy and 2.82 Gy, with an arithmetic mean value of 2.38 Gy. The uncertainty of the dosimetry was about 20.07% . Conclusion: The application of efficiency calibration without a radioactive source of the energy spectrum analysis of the 24 Na contained in human blood with accelerate the estimation process. (authors)

Consumo de alcool e risco para doenca coronariana na regiao metropolitana de Sao Paulo: uma analise do Projeto GENACIS

Directory of Open Access Journals (Sweden)

Maria Cristina Pereira Lima

2013-03-01

Full Text Available OBJETIVOS: Examinar a associação entre consumo de álcool e risco para doença coronariana em amostra populacional. MÉTODOS: Estudo transversal, de base populacional, conduzido de janeiro/2006 a junho/2007, na região metropolitana de São Paulo, como parte do estudo internacional (Gender, Alcohol, and Culture: an International Study. Os sujeitos (1.501, sendo 609 homens e 892 mulheres eram residentes da região metropolitana de São Paulo, tinham 30 anos ou mais de idade e foram selecionados aleatoriamente, a partir de amostragem complexa por conglomerados. Todos os indivíduos consentiram em participar da pesquisa. A variável dependente foi risco cardíaco avaliado através do WHO Rose Angina Questionnaire. A análise multivariada consistiu em regressão logística, tendo sido realizado ajuste para uso de tabaco e índice de massa corpórea. RESULTADOS: A taxa de resposta foi 75%. Ser mulher, ter mais idade, ser negro, fumante e ter um índice de massa corpórea elevado, foram associados a maior risco para doença coronariana. Indivíduos que nunca beberam na vida (OR = 2,22 e ex-bebedores (OR = 2,42 tiveram maior risco de doença cardíaca do que aqueles que informaram beber até 19 g de álcool por dia, sem episódios de beber excessivo. Entre os que tiveram episódios de embriaguês observou-se uma tendência a maior risco (OR = 3,95, p = 0,09. CONCLUSÕES: Nossos achados sugerem um menor risco para doença coronariana entre os bebedores moderados. Destaca-se que os estudos que avaliam o impacto do álcool sobre doença cardíaca precisam identificar o padrão de uso de álcool dos sujeitos, visto que este aspecto pode modificar o risco. Políticas públicas são necessárias para reduzir o uso nocivo de álcool e a morbidade a ele relacionada no país.

First Measurement of Reaction-in-Flight Neutrons at the National Ignition Facility

Science.gov (United States)

Tonchev, A.; Becker, J.; Bleuel, D.; Bionta, R.; Fortner, D.; Henry, E.; Khater, H.; Shaughnessy, D.; Schnider, D.; Stoeffl, W.; Yeamans, C.; Boswell, M.; Bredeweg, T.; Grim, G.; Jungman, G.; Fowler, M.; Hayes, A.; Obst, A.; Rundberg, R.; Schulz, A.; Wilhelmy, J.; Tornow, W.; Bhike, M.; Howell, C.; Gooden, M.; LLNL/LANL/TUNL Collaboration

2013-10-01

The first measurement of reaction-in-flight (RIF) neutrons, also known as tertiary neutrons, has been performed at the National Ignition Facility (NIF) using an activation technique. Thulium foils positioned at 50 cm from the burning deuterium-tritium (DT) capsule have been exposed to the characteristic DT neutron spectrum. The high-energy part of these neutrons with energies above 15.0 MeV can produce 167Tm via the 169Tm(n,3n) reaction. The 208-keV γ-ray, emitted from the decay of 167Tm with a half-life of 9.2 days, has been measured using two clover detectors. The first preliminary result implies that the ratio of RIF neutrons (En > 15.0 MeV) versus the total neutrons is 1 × 10 -4 +/- 3 × 10 -5. The important implication of these measurements on our knowledge of the charged-particle stopping power in strongly coupled quantum-degenerate plasma will be presented. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

Effects of Hot-Spot Geometry on Backscattering and Down-Scattering Neutron Spectra

Science.gov (United States)

Mohamed, Z. L.; Mannion, O. M.; Forrest, C. J.; Knauer, J. P.; Anderson, K. S.; Radha, P. B.

2017-10-01

The measured neutron spectrum produced by a fusion experiment plays a key role in inferring observable quantities. One important observable is the areal density of an implosion, which is inferred by measuring the scattering of neutrons. This project seeks to use particle-transport simulations to model the effects of hot-spot geometry on backscattering and down-scattering neutron spectra along different lines of sight. Implosions similar to those conducted at the Laboratory of Laser Energetics are modeled by neutron transport through a DT plasma and a DT ice shell using the particle transport codes MCNP and IRIS. Effects of hot-spot geometry are obtained by ``detecting'' scattered neutrons along different lines of sight. This process is repeated for various hot-spot geometries representing known shape distortions between the hot spot and the shell. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Use of reference materials for validating analytical methods. Applied to the determination of As, Co, Na, Hg, Se and Fe using neutron activation analysis

International Nuclear Information System (INIS)

Munoz, L; Andonie, O; Kohnenkamp, I

2000-01-01

The main purpose of an analytical laboratory is to provide reliable information on the nature and composition of the materials submitted for analysis. This purpose can only be attained if analytical methodologies that have the attributes of accuracy, precision, specificity and sensitivity, among others, are used. The process by which these attributes are evaluated is called validation of the analytical method. The Chilean Nuclear Energy Commission's Neutron Activation Analysis Laboratory is applying a quality guarantee program to ensure the quality of its analytical results, which aims, as well, to attain accreditation for some of its measurements. Validation of the analytical methodologies used is an essential part of applying this program. There are many forms of validation, from comparison with reference techniques to participation in inter-comparison rounds. Certified reference materials were used in this work in order to validate the application of neutron activation analysis in determining As, Co, Na, Hg, Se and Fe in shellfish samples. The use of reference materials was chosen because it is a simple option that easily detects sources of systematic errors. Neutron activation analysis is an instrumental analytical method that does not need chemical treatment and that is based on processes which take place in the nuclei of atoms, making the matrix effects unimportant and different biological reference materials can be used. The following certified reference materials were used for validating the method used: BCR human hair 397, NRCC dogfish muscle DORM-2, NRCC -dogfish liver DOLT-2, NIST - oyster tissue 1566, NIES - mussel 6 and BCR - tuna fish 464. The reference materials were analyzed using the procedure developed for the shellfish samples and the above-mentioned elements were determined. With the results obtained, the parameters of accuracy, precision, detection limit, quantification limit and uncertainty associated with the method were determined for each

Cr-39 fast neutron dosemeter based on A (n, α) converter

International Nuclear Information System (INIS)

Widayati, S.; Budiantari, T.

1998-01-01

The aim of this experiment is to obtained the response of Cr-39 as fast neutron dosemeter based on an (n, α) converter. Cr-39 was irradiated to AmBe fast neutron flux from 0.10 mSv to 2.5 mSv. Cr-39 processed by chemical etching with NaOH 20 % at temperature of 60 oC in six hours. The results of experiment showed that the response of Cr-39 based on an (n, α) converter is 6 times bigger than the response of Cr-39 without (n, α) converter. (author)

Neutronics of pulsed spallation neutron sources

CERN Document Server

Watanabe, N

2003-01-01

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

Beta decay of 31,32Na and 31Mg

International Nuclear Information System (INIS)

Klotz, G.; Baumann, P.; Bounajma, M.; Huck, A.; Knipper, A.; Walter, G.; Poves, A.; Retamosa, J.

1993-01-01

31,32 Na and 31 Mg beta decays were studied at the CERN on-line mass separator ISOLDE by gamma, gamma-gamma and neutron-gamma measurements. In the 31 Na decay, the assignment of previously reported γ transitions and the observation of a new level at 3760 keV lead to a revised decay scheme. In the 31 Mg → 31 Al decay, a new decay scheme involves ten β branches and three states are reported for the first time. New spectroscopic results have been obtained in the 32 Na β - decay. A previously non-interpreted 1436 keV γ ray is now assigned in the 32 Mg scheme. (author) 33 refs., 16 figs., 12 tabs

Neutronics of pulsed spallation neutron sources

International Nuclear Information System (INIS)

Watanabe, Noboru

2003-01-01

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

Determination of elemental concentrations in airborne particulate matter in the City of Santiago de Chile, through neutron activation analysis using epithermal neutrons and Compton suppression system

International Nuclear Information System (INIS)

Rojas S, Ximena

1995-01-01

In order to optimize the Neutron-Activation Analysis (NAA) technique currently carried out in our country, the present work was carried out in the United States where irradiations with epithermal neutrons and a Compton suppression system were used, which allowed the characterization of aerosols of the city of Santiago de Chile. With this purpose, 54 filters of polycarbonate membranes were analysed with aerosols collected in an area of the capital during Spring 1993 and Winter of 1994. As a result, an improvement in the detection limits was observed, specially in elements such as Ni and Zn, which are not easily detectable through NAA. The application of both systems also permits the usage of this technique in geological and biological samples, where the presence of Na, Al and Cl obstruct the determination of some elements. The determined elements in both fractions were Mn, V, Cu, As, Sb, Co, Br, Cl, Ni, Zn, Ca, Al, Na and Fe. (author). 8 refs., 7 figs., 9 tabs

Using Neutron-based techniques to investigate battery behaviour

International Nuclear Information System (INIS)

Pramudita, James C.; Goonetilleke, Damien; Sharma, Neeraj; Peterson, Vanessa K.

2016-01-01

The extensive use of portable electronic devices has given rise to increasing demand for reliable high energy density storage in the form of batteries. Today, lithium-ion batteries (LIBs) are the leading technology as they offer high energy density and relatively long lifetimes. Despite their widespread adoption, Li-ion batteries still suffer from significant degradation in their performance over time. The most obvious degradation in lithium-ion battery performance is capacity fade – where the capacity of the battery reduces after extended cycling. This talk will focus on how in situ time-resolved neutron powder diffraction (NPD) can be used to gain a better understanding of the structural changes which contribute to the observed capacity fade. The commercial batteries studied each feature different electrochemical and storage histories that are precisely known, allowing us to elucidate the tell-tale signs of battery degradation using NPD and relate these to battery history. Moreover, this talk will also showcase the diverse use of other neutron-based techniques such as neutron imaging to study electrolyte concentrations in lead-acid batteries, and the use of quasi-elastic neutron scattering to study Na-ion dynamics in sodium-ion batteries.

New feature of the neutron color image intensifier

Science.gov (United States)

Nittoh, Koichi; Konagai, Chikara; Noji, Takashi; Miyabe, Keisuke

2009-06-01

We developed prototype neutron color image intensifiers with high-sensitivity, wide dynamic range and long-life characteristics. In the prototype intensifier (Gd-Type 1), a terbium-activated Gd 2O 2S is used as the input-screen phosphor. In the upgraded model (Gd-Type 2), Gd 2O 3 and CsI:Na are vacuum deposited to form the phosphor layer, which improved the sensitivity and the spatial uniformity. A europium-activated Y 2O 2S multi-color scintillator, emitting red, green and blue photons with different intensities, is utilized as the output screen of the intensifier. By combining this image intensifier with a suitably tuned high-sensitive color CCD camera, higher sensitivity and wider dynamic range could be simultaneously attained than that of the conventional P20-phosphor-type image intensifier. The results of experiments at the JRR-3M neutron radiography irradiation port (flux: 1.5×10 8 n/cm 2/s) showed that these neutron color image intensifiers can clearly image dynamic phenomena with a 30 frame/s video picture. It is expected that the color image intensifier will be used as a new two-dimensional neutron sensor in new application fields.

New feature of the neutron color image intensifier

International Nuclear Information System (INIS)

Nittoh, Koichi; Konagai, Chikara; Noji, Takashi; Miyabe, Keisuke

2009-01-01

We developed prototype neutron color image intensifiers with high-sensitivity, wide dynamic range and long-life characteristics. In the prototype intensifier (Gd-Type 1), a terbium-activated Gd 2 O 2 S is used as the input-screen phosphor. In the upgraded model (Gd-Type 2), Gd 2 O 3 and CsI:Na are vacuum deposited to form the phosphor layer, which improved the sensitivity and the spatial uniformity. A europium-activated Y 2 O 2 S multi-color scintillator, emitting red, green and blue photons with different intensities, is utilized as the output screen of the intensifier. By combining this image intensifier with a suitably tuned high-sensitive color CCD camera, higher sensitivity and wider dynamic range could be simultaneously attained than that of the conventional P20-phosphor-type image intensifier. The results of experiments at the JRR-3M neutron radiography irradiation port (flux: 1.5x10 8 n/cm 2 /s) showed that these neutron color image intensifiers can clearly image dynamic phenomena with a 30 frame/s video picture. It is expected that the color image intensifier will be used as a new two-dimensional neutron sensor in new application fields.

Response of CR-39 Detector Against Fast Neutron Using D-Polyethylene and H-Polyethylene Radiator

International Nuclear Information System (INIS)

Sofyan, Hasnel

1996-01-01

The research on the response of detector CR-39 by using D-Polyethylene and H-Polyethylene radiator has been carried out. The optimum number of nuclear tracks was found with the use of 30 % NaOH at 80 + 0,5oC for 80 minutes of etching time. The comparison of CR-39 detector response caused by D-Polyethylene radiator against H-Polyethylene radiator of irradiation in air, were found to be 1.18 and 0.84 for 241Am-Be neutron source and neutron source from reactor respectively. For phantom irradiation, the results were found to be 1.75 for 241Am-Be neutron source, and 0.77 for neutron source from reactor

Scanning of Cargo Containers by Gamma-Ray and Fast Neutron Radiography

International Nuclear Information System (INIS)

Yousri, A.M.; Bashter, I.I.; Megahid, M.R.; Osman, A.M.; Kansouh, W.A.; Reda, A.M.

2011-01-01

This paper describes the combined systems which were installed and tested to detect contraband smuggled in cargo containers. These combined systems are based on radiographers work by gamma-rays emitted from point source 60 Co with 0.5 Ci activity and neutrons emitted from point isotopic sources of Pu-α-Be as well as 14 MeV neutrons emitted from sealed tube neutron generator. The transmitted gamma ray through the inspected object was measured by gamma detection system with NaI(Tl) detector while the transmitted fast neutron beam was measured by a neutron gamma detection system with stilbene organic scintillator. The later possess the capability of discrimination between between gamma and neutron pulses using a discrimination system based on pulse shape discrimination method. The measured intensities of primary incident and transmitted beams of gamma-rays and fast neutrons were used to construct 2D cross-sectional images of the inspected objects hidden directly within benign materials of the container and for object screened by high dense material to stop object detection by gamma or X-rays. The constructed images for the inspected objects show the good capability and effectiveness of the installed gamma and neutron radiographers to detect illicit materials hidden in air cargo containers and sea containers of med size. They have also indicated that the developed scanning systems possess the ease of mobility and low cost of scanning

Investigating the response of Micromegas detector to low-energy neutrons using Monte Carlo simulation

Science.gov (United States)

Khezripour, S.; Negarestani, A.; Rezaie, M. R.

2017-08-01

Micromegas detector has recently been used for high-energy neutron (HEN) detection, but the aim of this research is to investigate the response of the Micromegas detector to low-energy neutron (LEN). For this purpose, a Micromegas detector (with air, P10, BF3, 3He and Ar/BF3 mixture) was optimized for the detection of 60 keV neutrons using the MCNP (Monte Carlo N Particle) code. The simulation results show that the optimum thickness of the cathode is 1 mm and the optimum of microgrid location is 100 μm above the anode. The output current of this detector for Ar (3%) + BF3 (97%) mixture is greater than the other ones. This mixture is considered as the appropriate gas for the Micromegas neutron detector providing the output current for 60 keV neutrons at the level of 97.8 nA per neutron. Consecuently, this detector can be introduced as LEN detector.

Hydrogen dynamics in Na3AlH6: A combined density functional theory and quasielastic neutron scattering study

DEFF Research Database (Denmark)

Zsigmond, G.; Manoshin, S.; Lieutenant, K.

2007-01-01

Handling of polarization became very important in simulations of neutron scattering. One of the very comprehensive and open-source neutron simulation package, VITESS, has been intensely involved in polarized neutron simulations. Several examples will be shown here. Another similar package NISP also...... contains polarization tools. McStas has implemented an initial set of routines handling polarization, as our examples will also show....

Neutron radiography with ultracold neutrons

International Nuclear Information System (INIS)

Bates, J.C.

1981-01-01

The neutron transmission factor of very thin films may be low if the neutron energy is comparable to the pseudo-potential of the film material. Surprisingly, perhaps, it is relatively easy to obtain neutrons with such low energies in sufficient numbers to produce neutron radiographs. (orig.)

Neutron Skins and Neutron Stars

OpenAIRE

Piekarewicz, J.

2013-01-01

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

Feasibility of calibration of liquid sodium flowmeters by neutron activation techniques

International Nuclear Information System (INIS)

Kehler, P.

1976-07-01

Velocities of fluids in pipes can be measured by injecting radioactive tracers into the fluid and recording the activity downstream of the injection point. One convenient method of injecting radioactive tracers is by neutron activation of the fluid itself. The present report describes a FORTRAN program that can be used for the prediction of the counting rates of fluid flow tests performed with a pulsed neutron source and a scintillation detector. The program models the flow profile and the mixing of the fluid, the attenuation of neutrons and gamma rays in the fluid, and the geometric arrangement of the source and the detector. Using this program, an experiment for the measurement of the secondary sodium flow of the EBR-II was optimized. A pulsed D,T neutron source and a 5 in. x 5 in. NaI detector will be used in the EBR-II test. Under optimized conditions, the expected accuracy of the flow measurement is about 2 percent

Equivalent-spherical-shield neutron dose calculations

International Nuclear Information System (INIS)

Russell, G.J.; Robinson, H.

1988-01-01

Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab

Neutron-neutron probe for uranium exploration

International Nuclear Information System (INIS)

Smith, R.C.

1979-01-01

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

Radioactive beam EXperiments at ISOLDE : Coulomb excitation and neutron transfer reactions of exotic nuclei.

CERN Multimedia

Kugler, E; Ratzinger, U; Wenander, F J C

2002-01-01

% IS347 \\\\ \\\\We propose to perform a pilot experiment to study very neutron rich (A<32) Na-Mg and (A<52) K-Ca isotopes in the region around the neutron shell closures of N=20 and N=28 after Coulomb excitation and neutron transfer, and to demonstrate highly efficient and cost-effective ways to bunch, charge-state breed and accelerate already existing mass-separated singly-charged radioactive ion beams. \\\\ \\\\To do this we plan to accelerate the ISOLDE beams up to 2~MeV/u by means of a novel acceleration scheme and to install an efficient $\\gamma$-ray array for low-multiplicity events around the target position.

Neutron radiation damage in NbO single crystals

International Nuclear Information System (INIS)

Onozuka, T.; Koiwa, M.; Ishikawa, Y.; Yamaguchi, S.; Hirabayashi, M.

1977-01-01

The effect of neutron irradiation and subsequent recovery has been studied for Nb0 single crystals of a defective NaCl structure containing 25% vacancies of niobium and oxygen. A very large increase (about 1%) in the lattice constant is observed after irradiation of 1.5 x 10 19 and 1 x 10 20 nvt (> 1 MeV). From the intensity measurements of x-ray and neutron diffraction, it is revealed that the knock-on atoms fill preferentially their respective vacant sites; Nb atoms occupy Nb-vacancies, and 0 atoms occupy 0-vacancies with nearly the same probabilities; 0.53 for 1.5 x 10 19 nvt. The mean threshold energy for displacement is estimated to be about 3 eV. (author)

Thermal neutron activation analysis of different varieties of mustard and sunflower seeds

International Nuclear Information System (INIS)

Rajurkar, N.S.; Bhamare, C.S.

1991-01-01

Neutron activation analysis (NAA) technique has been used for the estimation of Mn, Na and K in different varietes of oil seeds of mustard and sunflower in India. The samples were irradiated in a 252 Cf source with neutron flux of ∼10 9 n s -1 and the analysis was done using a multichannel analyzer (MCA) coupled to high purity germanium (HPGe) detector. Different varieties of seeds are found to have different concentrations of tracer elements when compared among themselves. (author) 5 refs.; 1 fig.; 1 tab

Neutron shielding properties of a new high-density concrete

International Nuclear Information System (INIS)

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

2008-01-01

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

Analysis of some egyptian cosmetic samples by using fast neutron activation analysis

International Nuclear Information System (INIS)

Medhat, M.E.; Hassan, M.F.; Ali, M.A.; Awaad, Z.

2002-01-01

A description of our neutron generator (NG) facility for neutron activation analysis is presented. As an example, the concentration of Na, Mg, Al, Si, K, Cl, Ca and Fe elements were determined in two domestic brands of face powder by using a beam of 14 MeV neutrons. An empirical expression for detector efficiency in terms of incident gamma ray energy and the source-detector distance has been obtained for a hyper pure germanium detector (HPGe) using different standard point sources. The comparison of the calculated efficiencies and the measured values in the energy range from 59.5 to 1332.2 keV and for source-to-detector distances of 5-30 cm show the agreement between the calculated values and the measured experimental values

Instrumental neutron activation analysis of kidney stones

International Nuclear Information System (INIS)

Sarmani, S.; Kuan, L.L.; Bakar, M.A.A.

1990-01-01

Kidney stone samples of the types calcium oxalate, uric acid, and xanthine were analyzed for their elemental contents by neutron activation analysis to study both the elemental correlation and influence of element on stone precipitation processes. Elements, such as Al, Au, Br, Ca, Cl, Co, Cr, Fe,H, I, K, Mg, Na, Sb, Se, Sr, and Zn, were determined quantitatively. Calcium oxalate stones contained higher concentration of all the elements analyzed compared to uric acid or xanthine stones. The concentrations of Cl, Fe, K, Na, Sr, and Zn were relatively higher than Au, Co, Cr, and Sb. A positive correlation exists between Ca and Zn, whereas a negative correlation exists between Sr and Ca. Zinc may play an important role in the formation of calcium oxalate stone

Quantitative neutron radiography using neutron absorbing honeycomb

International Nuclear Information System (INIS)

Tamaki, Masayoshi; Oda, Masahiro; Takahashi, Kenji; Ohkubo, Kohei; Tasaka, Kanji; Tsuruno, Akira; Matsubayashi, Masahito.

1993-01-01

This investigation concerns quantitative neutron radiography and computed tomography by using a neutron absorbing honeycomb collimator. By setting the neutron absorbing honeycomb collimator between object and imaging system, neutrons scattered in the object were absorbed by the honeycomb material and eliminated before coming to the imaging system, but the neutrons which were transmitted the object without interaction could reach the imaging system. The image by purely transmitted neutrons gives the quantitative information. Two honeycombs were prepared with coating of boron nitride and gadolinium oxide and evaluated for the quantitative application. The relation between the neutron total cross section and the attenuation coefficient confirmed that they were in a fairly good agreement. Application to quantitative computed tomography was also successfully conducted. The new neutron radiography method using the neutron-absorbing honeycomb collimator for the elimination of the scattered neutrons improved remarkably the quantitativeness of the neutron radiography and computed tomography. (author)

Levitation effect in zeolites: Quasielastic neutron scattering and molecular dynamics study of pentane isomers in zeolite NaY.

Science.gov (United States)

Borah, Bhaskar J; Jobic, H; Yashonath, S

2010-04-14

We report the quasielastic neutron scattering (QENS) and molecular dynamics (MD) investigations into diffusion of pentane isomers in zeolite NaY. The molecular cross section perpendicular to the long molecular axis varies for the three isomers while the mass and the isomer-zeolite interaction remains essentially unchanged. Both QENS and MD results show that the branched isomers neopentane and isopentane have higher self-diffusivities as compared with n-pentane at 300 K in NaY zeolite. This result provides direct experimental evidence for the existence of nonmonotonic, anomalous dependence of self-diffusivity on molecular diameter known as the levitation effect. The energetic barrier at the bottleneck derived from MD simulations exists for n-pentane which lies in the linear regime while no such barrier is seen for neopentane which is located clearly in the anomalous regime. Activation energy is in the order E(a)(n-pentane)>E(a)(isopentane)>E(a)(neopentane) consistent with the predictions of the levitation effect. In the liquid phase, it is seen that D(n-pentane)>D(isopentane)>D(neopentane) and E(a)(n-pentane)

Neutron dosimetry; Dosimetria de neutrons

Energy Technology Data Exchange (ETDEWEB)

Fratin, Luciano

1993-12-31

A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

Neutron dosimetry; Dosimetria de neutrons

Energy Technology Data Exchange (ETDEWEB)

Fratin, Luciano

1994-12-31

A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

Possible application of boron neutron capture therapy to canine osteosarcoma

International Nuclear Information System (INIS)

Takeuchi, Akira

1985-01-01

Possibility for successful treatment of canine osteosarcoma by boron neutron capture therapy (BNCT) was demonstrated based upon an uptake study of the boron compound and an experimental treatment by BNCT. In the up take study following intravenous administration of Na 2 B 12 H 11 SH, satisfactorily higher boron concentration with some variation between tumors is likely to be obtained 12 hours after the administration, together with significantly lower boron levels in blood and bone. Based upon these results, osteosarcoma of a mongrel dog was successfully treated by BNCT. The tumor received approximately 3800 rads with single neutron irradiation (approximately 1.4 x 10 13 n./cm 2 ) about 12 hours after intravenous infusion of Na 2 B 12 H 11 SH of 96 % enriched 10 B in the ratio of 50 mg 10 B/kg. Clinical and radiographical improvements were remarkable and no neoplastic cell was found in any part of the original neoplastic lesion and its surrounding tissue at the time of autopsy after 30 days. (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.

Gamma rays from fast neutron capture in silicon and sulphur

International Nuclear Information System (INIS)

Lindholm, A.; Nilsson, L.; Bergqvist, I.

1975-01-01

Gamma-ray spectra from neutron capture in natural samples of silicon and sulphur have been recorded at eight neutron energies between 4 and 15 MeV. Time-of-flight techniques were used to improve the signal-to-background ratio and the gamma radiation was detected by a large NaI(Tl) scintillator. Cross sections have been determined for transitions to individual (or groups of) levels in the final nucleus. Calculations based on the direct-semidirect model show that this model gives a reasonable description of the shapes of the gamma-ray spectra, but fails to account for observed excitation functions. The inclusion of the compound-nucleus capture process gives a conclusive improvement in the description of the excitation functions, in particular at low neutron energies. The ability of the compound-nucleus model to account for the shapes of the gamma-ray spectra is as good as that of the direct-semidirect model. At higher neutron energies, an improvement is obtained for transitions to the region of weakly bound levels, where the single-particle structure is poorly known. (Auth.)

Measurement and analysis of fast neutron spectra in reactor materials by time-of-flight method

International Nuclear Information System (INIS)

Hayashi, Shuhei; Kimura, Itsuro; Kobayashi, Shohei; Yamamoto, Shuji; Nishihara, Hiroshi.

1982-01-01

The LINAC-TOF experiments have been done to measure the neutron energy spectra in the assemblies of reactor materials. The sample materials to be measured were iron, stainless steel, aluminum, nickel, zirconium, thorium, lithium, and so on. The shapes of assemblies were piles (rectangular parallelopiped, sphere, and polyhedron) and slab. A photoneutron target was set at the center of the pile assemblies. Each assembly has an electron injection hole and a re-entrant hole. In case of a slab, a photo neutron target was placed at the outside of the slab. Neutrons were generated by using an electron linear accelerator (LINAC). The length of the flight path was 20 m. The neutron detectors were a Li-6 glass scintillator and a B-10 vaseline-NaI(Tl) scintillator. The spatial distributions of neutrons in the piles were measured by the foil activation method. The neutron transport calculation was performed, and the evaluation of group constants was made. (Kato, T.)

Neutron moderation in a bulk sample and its effects on PGNAA setup geometry

International Nuclear Information System (INIS)

Al-Jarallah, M.I.; Naqvi, A.A.; Fazal-ur-Rehman,; Maselehuddin, M.; Abu-Jarad, F.; Raashid, M.

2003-01-01

In a prompt gamma ray neutron activation analysis (PGNAA) setup, the neutron moderation in the bulk sample also plays a key role. This can even dominate the thermalization effects of the external moderator in some cases. In order to study the neutron moderation effect in the bulk sample, moderators with two different sizes of the sample were tested at the King Fahd University of Petroleum and Minerals (KFUPM) PGNAA facility. In these tests, the thermal neutron relative intensity and prompt gamma ray yield from the two moderators were measured using nuclear track detectors (NTDs) and NaI detector, respectively. As predicted by Monte Carlo simulations, the measured intensity of thermal neutron inside the large sample cavity due to the external moderator was smaller than that from the smaller sample cavity. Due to its larger size, additional thermalization of neutrons will take place in the larger sample. In spite of smaller thermal neutron yield from the external moderator at the large sample location, higher yield of the prompt gamma ray was observed as compared to that from the smaller sample. This confirms the significance of neutron moderation effects in the bulk sample and can thereby affect the PGNAA geometry size. This allows larger samples in conjunction with smaller moderators in the PGNAA setup

Neutron moderation in a bulk sample and its effects on PGNAA setup geometry

Energy Technology Data Exchange (ETDEWEB)

Al-Jarallah, M.I. E-mail: mibrahim@kfupm.edu.sa; Naqvi, A.A.; Fazal-ur-Rehman,; Maselehuddin, M.; Abu-Jarad, F.; Raashid, M

2003-06-01

In a prompt gamma ray neutron activation analysis (PGNAA) setup, the neutron moderation in the bulk sample also plays a key role. This can even dominate the thermalization effects of the external moderator in some cases. In order to study the neutron moderation effect in the bulk sample, moderators with two different sizes of the sample were tested at the King Fahd University of Petroleum and Minerals (KFUPM) PGNAA facility. In these tests, the thermal neutron relative intensity and prompt gamma ray yield from the two moderators were measured using nuclear track detectors (NTDs) and NaI detector, respectively. As predicted by Monte Carlo simulations, the measured intensity of thermal neutron inside the large sample cavity due to the external moderator was smaller than that from the smaller sample cavity. Due to its larger size, additional thermalization of neutrons will take place in the larger sample. In spite of smaller thermal neutron yield from the external moderator at the large sample location, higher yield of the prompt gamma ray was observed as compared to that from the smaller sample. This confirms the significance of neutron moderation effects in the bulk sample and can thereby affect the PGNAA geometry size. This allows larger samples in conjunction with smaller moderators in the PGNAA setup.

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

Verification of nuclear effect of acoustic cavitation using fast neutron activation method

International Nuclear Information System (INIS)

Li Xinnian; Feng Tao; Fang Xiaoming; Qian Menglu; Cheng Qian

2014-01-01

14 MeV neutrons originated in acoustic cavitation fusion were determined using copper threshold detector. According to the nuclear reaction of 14 MeV neutrons with copper, the characteristic γ peaks of some radioactive nuclides were measured and the activation parameters of Cu were optimized. With neutron irradiation time of 50 min, 511 keV characteristic γ peak counts of activated copper pieces with or without ultrasonic field after 30 min and 198 min were respectively determined by NaI detector. Measurement results show that the characteristic γ peak counts of "6"2Cu and "6"4Cu can be respectively determined after 30 min and 198 min. 511 keV characteristic γ peak net count increments are positive values and statistical significance, which indicates that 14 MeV and 2.45 MeV neutron generation rates originated in fusion with ultrasound are greater than that without ultrasound in nuclear reaction liquid. These results verify the nuclear effect of acoustic cavitation (NEAC). The mechanism of NEAC nucleated by neutrons was proposed initially. (authors)

Determination of cadmium in zinc ores by thermal neutron absorption analysis

International Nuclear Information System (INIS)

De Norre, L.; Op de Beeck, J.; Hoste, J.

1983-01-01

A method has been developed for routine determination of cadmium in zinc ores by thermal neutron absorption analysis, based on the attenuation of a thermal neutron flux passing through a neutron absorbing material. The thermal neutron flux in related to the 52 V activity induced in a vanadium detector, surrounded by pellets pressed from a mixture of powdered material with graphite. Besides cadmium, also the major constituents zinc, iron and sulfur contribute significantly to the total attenuation of the thermal neutron flux. Calibration lines for these elements are worked out. All irradiations are carried out for 200 s in the partially thermalized neutron flux of a 5 Ci 227 Ac-Be isotope neutron source. After a decay of 30 s, the 52 V activity of the vanadium detector is measured for 400 s with a NaI(Tl) scintillation detector. The analysis sequence, including the computation of the results from the counting data, is automated by means of a LSI-11 Microprocessor with 12Kx16 bit memory. Zinc ores, containing 0.02 to 1.45% cadmium, have been analyzed with a precision ranging from 12.6% to 0.54%, resp. As a test for the reliability of the method, two NBS standard reference materials were analyzed in the same way as the zinc ore samples. (author)

Neutron field characterization in the installation for BNCT study in the IEA-R1 reactor; Caracterizacao do campo de neutrons na instalacao para estudo em BNCT no reator IEA-R1

Energy Technology Data Exchange (ETDEWEB)

Carneiro Junior, Valdeci

2008-07-01

This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the conventional techniques, for example, the Glioblastoma Multiform - a brain cancerigenous tumor. Neutron flux measurements were carried out: thermal, resonance and fast, as well as neutron and gamma rays doses, in the sample position, using activation foils detectors and thermoluminescent dosimeters. For the determination of the neutron spectrum and intensity, a set of different threshold activation foils and gold foils covered and uncovered with cadmium irradiated in the installation was used, analyzed by a high Pure Germanium semiconductor detector, coupled to an electronic system suitable for gamma spectrometry. The results were processed with the SAND-BP code. The doses due to gamma and neutron rays were determined using thermoluminescent dosimeters TLD 400 and TLD 700 sensitive to gamma and TLD 600, sensitive to neutrons. The TLDs were selected and used for obtaining the calibration curves - dosimeter answer versus dose - from each of the TLD three types, which were necessary to calculate the doses due to neutron and gamma, in the sample position. The radiation field, in the sample irradiation position, was characterized flux for thermal neutrons of 1.39.10{sup 8} {+-} 0,12.10{sup 8} n/cm{sup 2}s the doses due to thermal neutrons are three times higher than those due to gamma radiation and confirm the reproducibility and consistency of the experimental findings obtained. Considering these results, the neutron field and gamma radiation showed to be appropriated for research in BNCT. (author)

Multi elementary analysis in medicinal plants through the neutron activation method

International Nuclear Information System (INIS)

Vaz, M.S.; Saiki, M.; Vasconcellos, M.B.A.; Sertie, J.A.A.

1990-01-01

A instrumental method by neutron activation in multielementary analysis was applied. Samples of Centelha asiatica (Cairucu) and Paulinia cupana (Guarana) were used. The elements Al, Br, Ca, Cl, Fe, K, Mn, Na, Rb, Sc, and Zn were determined. The results like precision and exactitude were analysed. (L.M.J.) [pt

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.

Preliminary study of elemental analysis of hydroxyapatite used neutron activation analysis method

International Nuclear Information System (INIS)

Yustinus Purwamargapratala; Rina Mulyaningsih

2010-01-01

Preliminary study has been carried out elemental analysis of hydroxyapatite synthesized using the method of neutron activation analysis. Hydroxyapatite is the main component constituent of bones and teeth which can be synthesized from limestone and phosphoric acid. Hydroxyapatite can be used as a bone substitute material and human and animal teeth. Tests on the metal content is necessary to prevent the risk of damage to bones and teeth due to contamination. Results of analysis using neutron activation analysis method with samples irradiated at the neutron flux 10"3 n.det"-"1cm"-"2 for one minute, the impurities of Al (48.60±6.47 mg/kg), CI (38.00±7.47 mg/kg), Mn (1.05±0.19 mg/kg), and Mg (2095.30±203.66 mg/kg), were detected, whereas with irradiation time for 10 minutes and 40 minutes with a time decay of three days there were K (103.89 ± 26.82 mg/kg), Br (1617.06 ± 193.66 mg/kg), and Na (125.10±9.57 mg/kg). These results indicate that there is impurity Al, CI, Mn, Mg, Br, K and Na, although in very small amounts and do not cause damage to bones and teeth. (author)

Influence of cross-section structure on unfolded neutron spectra

International Nuclear Information System (INIS)

Ertek, C.; Vlasov, M.F.; Cross, B.; Smith, P.M.

1979-01-01

The influence of cross-section structure on neutron spectra unfolded by multiple foil activation technique, SAND-II case, has been studied. For three reactions with evident structure in neutron cross-section above threshold: 27Al(n,α)24Na, 31P(n,p)31Si and 32S(n,p)32P, two remarkably different sets of evaluated data were selected from the available evaluations; one set of data was ''smooth'', the structure having been averaged over by a smooth curve; the other set was ''sharp'' with structure given in detail. These data were used in unfolding procedure together with other reactions, the same in both cases (as well as input spectra and measured reaction rates). It was found that during unfolding calculations less iteration steps were needed to unfold the neutron flux spectrum with the set of ''sharp'' data. In case of ''smooth'' data it was difficult to obtain an agreement between measured and calculated activity values even by increasing the number of iteration steps. Contrary to expectations, considerable deformation of unfolded neutron flux spectrum has been observed in the case of the ''smooth'' data set. (author)

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

Energy Technology Data Exchange (ETDEWEB)

Malikova, N

2005-09-15

Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Neutron stars

International Nuclear Information System (INIS)

Irvine, J.M.

1978-01-01

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

Charge radii of neutron-deficient Ca isotopes

Science.gov (United States)

Miller, A. J.; Minamisono, K.; Klose, A.; Everett, N.; Kalman, C.; Powel, R. C.; Watkins, J.; Garand, D.; Sumithrarachchi, C.; Krämer, J.; Maa, B.; Nörtershäuser, W.; Rossi, D. M.; Kujawa, C.; Pineda, S.; Lantis, J.; Liu, Y.; Mantica, P. F.; Pearson, M. R.

2017-09-01

Nucleon shell closures are generally associated with a local minimum in mean-square charge radii, 〈r2 〉 , along an isotopic chain. The 〈r2 〉 of 18Ar and 19K isotopes, however, do not show this signature at the N = 20 neutron shell closure. To gain a microscopic understanding of this abnormal behavior, measurements of 〈r2 〉 of neutron-deficient Ca isotopes below N = 20 have been proposed at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU. Preliminary results will be presented and the deduced charge radii will be compared to theoretical calculations and the trends in the nearby isotopic chains. Work supported in part by NSF Grant PHY-15-65546, U.S. DOE Grant DE-NA0002924 and by the Deutsche Forschungsgemeinschaft through Grant SFB 1245.

Study and application of neutron activation analysis and related methods for determination of content of Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in a lot of speciality fruits of Vietnam (banana, orange, longan, dragon and mango)

International Nuclear Information System (INIS)

Nguyen Van Minh; Le Thi Ngoc Trinh; Le Thai Dung; Ta Thi Tuyet Nhung; Nguyen Dang Khoa; Nguyen Tien Dat; Nguyen Thi Hong Tham; Cao Dong Vu

2007-01-01

To study the content of trace elements Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in the speciality fruits is necessary and very important. We collected the studying samples in four Cities such as: Dalat, NhaTrang, HoChiMinh and BinhDuong. The studying samples are: Banana, Orange, Longan, Dragon and Mango. These samples were dried in the Deepfreezer at -40 o C. We analyzed Na, K, Cu, Co, Mn, Ca, Mg, Fe and Zn by neutron activation analysis (INAA, RNAA) and after irradiation measured total β for P. The studying results were shown in the tables. (author)

Study and application of neutron activation analysis and related methods for determination of content of Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in a lot of speciality fruits of Vietnam (banana, orange, longan, dragon and mango)

Energy Technology Data Exchange (ETDEWEB)

Minh, Nguyen Van; Ngoc Trinh, Le Thi; Dung, Le Thai; Tuyet Nhung, Ta Thi; Khoa, Nguyen Dang; Dat, Nguyen Tien; Hong Tham, Nguyen Thi; Vu, Cao Dong [Center for Analytical Techniques, Nuclear Research Institute, Dalat (Viet Nam)

2007-12-15

To study the content of trace elements Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in the speciality fruits is necessary and very important. We collected the studying samples in four Cities such as: Dalat, NhaTrang, HoChiMinh and BinhDuong. The studying samples are: Banana, Orange, Longan, Dragon and Mango. These samples were dried in the Deepfreezer at -40{sup o}C. We analyzed Na, K, Cu, Co, Mn, Ca, Mg, Fe and Zn by neutron activation analysis (INAA, RNAA) and after irradiation measured total {beta} for P. The studying results were shown in the tables. (author)

Relative Biological Effectiveness of 14-MeV Fast Neutrons to Co{sup 60} Gamma-Rays in Einkorn Wheat; Efficacite Biologique Relative des Neutrons Rapides de 14 MeV par Rapport aux Rayons Gamma de {sup 60}Co sur l'Engrain; Otnositel'naya biologicheskaya ehffektivnost' bystrykh nejtronov s ehnergiej 14 MeV i gamma-luchej CO{sup 60} pri ikh dejstvii na pshenitsu odnozernyanku; EBR de los Neutrones Rapidos de 14 MeV y de los Rayos Gamma del {sup 60}Co en el Trigo Escanda Menor

Energy Technology Data Exchange (ETDEWEB)

Fujii, T. [National Institute of Genetics, Misima (Japan)

1964-05-15

, sobrevivio entre 60 y 80% de las plantulas y en los grupos tratados con rayos gamma, la supervivencia fue del 100%. En cambio, en el grupo sometido a la irradiacion neutronica con la dosis mas elevada, solo sobrevivio un 4% de las plantulas. No se observaron mutaciones en el grupo testigo y el numero de plantas que presentaba retonos rayados crecio al aumentar la dosis de ambos tipos de radiacion. Se observaron retoflos con mutaciones en un 15% de las plantas sobrevivientes tratadas con la dosis inferior de neutrones y la misma frecuencia se registro para la dceis mayor de rayos gamma. Al parecer, la EBR de los neutrones de 14 MeV con respecto a los rayos gamma de {sup 60}Co, para la mutacion somatica, es 20 como minimo. (author) [Russian] Avtor izuchal OBJe nejtronov s jenergiej 14 Mjev i gamma-luchej Sobo pri ih dejstvii na pshenicu odnozernjanku s pomoshh'ju special'nogo lokusnogo metoda. Dlja opyta ispol'zovalis' semena generacii F{sub 1} gibrida mezhdu ishodnym sortom i mutantom Chlorina (mutant Chlorina byl poluchen kak edinstvennyj recessivnyj rentgenomutant; ot stadii sejanca do nastuplenija spelosti on byl odnorodno svetlozelenym s otnositel'no vysokoj vyzhivaemost'ju i urozhajnost'ju). U rastenij F{sub 1} byla normal'naja zelenaja okraska i normal'nyj harakter rosta. Pokojashhiesja semena Ft obluchali bystrymi nejtronami v dozah 0,5, 1,0 i 1,4 krad i gamma-luchami v dozah 4,3 8,6 i 12,9 krad. Mutacii ot dominantnyh normal'nyh zelenyh do Chlorina nabljudalis' posle oboih vidov obluchenija i pojavljalis' v list'jah i stebljah geterozigotnyh rastenij X{sub 1} v vide prodol'nyh polos. Okolo 80% semjan vzoshlo na kontrol'nyh uchastkah i na uchastkah posle obluchenija ca- mymi nizkimi dozami nejtronov i gamma-luchej, procent vshozhesti postepenno snizhalsja s povysheniem dozy pri oboih vidah obluchenija. Krome togo, takaja zhe tendencija nabljudalas' i na rannih stadijah rosta sejancev, kotoryj postepenno tormozilsja s povysheniem dozy. Soglasno jetim dannym nejtronnoe

The k0-NAA Standardization Method Using an Am-Be Neutron Source

International Nuclear Information System (INIS)

Soliman, N.F.; Mohamed, G.Y.; Hassan, M.F.; Ali, M.A.

2012-01-01

Instrumental neutron activation analysis is a well established technique for the analysis of trace elements in different samples. Precise elemental concentrations of Al, Mn, Mg and Na in two unknown geological samples were determined by using the k 0 -standardization method. For such measurements two sets of standard monitors of Gold (Au), Indium (In), Tungsten (W) and Titanium (Ta) were used. One set is bare and the other is cadmium covered. These monitors were used for measuring the irradiation position factors f and α and using the cadmium ratios of the 115 In(n,γ) 116 In and 182 Ta(n,γ) 183 Ta interactions. Neutrons were obtained from CNIF 2 facility that uses an Am-Be radio-isotopic neutron source with a modification to have thermal and epi-thermal neutrons. Measurements were carried out using a gamma-ray spectrometer consisting of a hyper pure germanium detector and necessary associated electronics. The k 0 -standardization method can be used for quality control tests.

Design and construction of a fast critical facility; Etude et construction d'un ensemble critique a neutrons rapides; Proektirovanie i sooruzhenie kriticheskoj sborki na bystrykh nejtronakh; Proyecto u construccion de un conjunto critico de neutrones rapidos

Energy Technology Data Exchange (ETDEWEB)

Kato, W Y; Dates, L R [Argonne National Laboratory, Argonne, IL (United States)

1962-03-15

Design and construction of a fast critical facility. In a fast-power-reactor development programme, a critical facility is found to be a highly useful tool to ascertain calculational techniques, to verify neutron cross-section sets, and to obtain integral reactor-physics parameters necessary for the nuclear design of a power system. Since it is primarily a physics instrument, the design of a fast critical facility itself poses a number of different problems not found in the design of a power reactor. In addition to usual questions of site, containment, core design and instrumentation , there arise such problems as: how to obtain a large degree of flexibility consistent with safety, the determination of the size and type of facility to meet the experimental physics requirements, the determination of the number and location of control and safety rods minimizing perturbation effects and the specification of the reproducibility of control rods and other movable components to obtain the accuracy required in reactivity measurements. These are some of the problems which are discussed in this paper based on recent experience at the Argonne National Laboratory which has under construction a fast critical facility, ZPR-VI at its Lemont, Illinois site for fast-reactor-physics studies. The ZPR-VI is a movable half- or split-table-type machine similar to ZPR-III. It has a matrix about two and a half times the volume of the earlier machine and will be used to investigate the physics of large, highly dilute, metal and cermet, unmoderated and partially moderated systems having core volumes up to about 1500 l. A detailed description of the ZPR-VI with a discussion on the criteria used in the design of its various components from the point of view of reactor physics is presented. In addition, such topics as management and operating procedures, potential hazards during operation, experimental techniques to be used and construction costs are also included. (author) [French] Etude et

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering

International Nuclear Information System (INIS)

Malikova, N.

2005-09-01

Montmorillonite clays in low hydration states, with Na + and Cs + compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na + and C + counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Neutron Exposures in Human Cells: Bystander Effect and Relative Biological Effectiveness

Science.gov (United States)

Seth, Isheeta; Schwartz, Jeffrey L.; Stewart, Robert D.; Emery, Robert; Joiner, Michael C.; Tucker, James D.

2014-01-01

Bystander effects have been observed repeatedly in mammalian cells following photon and alpha particle irradiation. However, few studies have been performed to investigate bystander effects arising from neutron irradiation. Here we asked whether neutrons also induce a bystander effect in two normal human lymphoblastoid cell lines. These cells were exposed to fast neutrons produced by targeting a near-monoenergetic 50.5 MeV proton beam at a Be target (17 MeV average neutron energy), and irradiated-cell conditioned media (ICCM) was transferred to unirradiated cells. The cytokinesis-block micronucleus assay was used to quantify genetic damage in radiation-naïve cells exposed to ICCM from cultures that received 0 (control), 0.5, 1, 1.5, 2, 3 or 4 Gy neutrons. Cells grown in ICCM from irradiated cells showed no significant increase in the frequencies of micronuclei or nucleoplasmic bridges compared to cells grown in ICCM from sham irradiated cells for either cell line. However, the neutron beam has a photon dose-contamination of 5%, which may modulate a neutron-induced bystander effect. To determine whether these low doses of contaminating photons can induce a bystander effect, cells were irradiated with cobalt-60 at doses equivalent to the percent contamination for each neutron dose. No significant increase in the frequencies of micronuclei or bridges was observed at these doses of photons for either cell line when cultured in ICCM. As expected, high doses of photons induced a clear bystander effect in both cell lines for micronuclei and bridges (pbystander effect in these cells. Finally, neutrons had a relative biological effectiveness of 2.0±0.13 for micronuclei and 5.8±2.9 for bridges compared to cobalt-60. These results may be relevant to radiation therapy with fast neutrons and for regulatory agencies setting standards for neutron radiation protection and safety. PMID:24896095

Analysis of medicinal plant extracts by neutron activation method; Analise de extratos de plantas medicinais pelo metodo de ativacao com neutrons

Energy Technology Data Exchange (ETDEWEB)

Vaz, Sandra Muntz

1996-12-31

This dissertation has presented the results from analysis of medicinal plant extracts using neutron activation method. Instrumental neutron activation analysis was applied to the determination of the elements Al, Br, Ca, Ce, Cl, Cr, Cs, Fe, K, La, Mg, Mn, Na, Rb, Sb, Sc and Zn in medicinal extracts obtained from Achyrolcline satureoides DC, Casearia sylvestris, Centella asiatica, Citrus aurantium L., Solano lycocarpum, Solidago microglossa, Stryphnondedron barbatiman and Zingiber officinale R. plants. The elements Hg and Se were determined using radiochemical separation by means of retention of Se in HMD inorganic exchanger and solvent extraction of Hg by bismuth diethyl-dithiocarbamate solution. Precision and accuracy of the results have been evaluated by analysing reference materials. The therapeutic action of some elements found in plant extracts analyzed was briefly discussed 70 refs., 13 figs., 15 tabs

Analysis of medicinal plant extracts by neutron activation method; Analise de extratos de plantas medicinais pelo metodo de ativacao com neutrons

Energy Technology Data Exchange (ETDEWEB)

Vaz, Sandra Muntz

1995-12-31

This dissertation has presented the results from analysis of medicinal plant extracts using neutron activation method. Instrumental neutron activation analysis was applied to the determination of the elements Al, Br, Ca, Ce, Cl, Cr, Cs, Fe, K, La, Mg, Mn, Na, Rb, Sb, Sc and Zn in medicinal extracts obtained from Achyrolcline satureoides DC, Casearia sylvestris, Centella asiatica, Citrus aurantium L., Solano lycocarpum, Solidago microglossa, Stryphnondedron barbatiman and Zingiber officinale R. plants. The elements Hg and Se were determined using radiochemical separation by means of retention of Se in HMD inorganic exchanger and solvent extraction of Hg by bismuth diethyl-dithiocarbamate solution. Precision and accuracy of the results have been evaluated by analysing reference materials. The therapeutic action of some elements found in plant extracts analyzed was briefly discussed 70 refs., 13 figs., 15 tabs

A CVD Diamond Detector for (n,a) Cross-Section Measurements

CERN Document Server

Weiss, Christina; Griesmayer, Erich; Guerrero, Carlos

A novel detector based on the chemical vapor deposition (CVD) diamond technology has been developed in the framework of this PhD, for the experimental determination of (n,a) cross-sections at the neutron time-of-flight facility n_TOF at CERN. The 59Ni(n,a)56Fe cross-section, which is relevant for astrophysical questions as well as for risk-assessment studies in nuclear technology, has been measured in order to validate the applicability of the detector for such experiments. The thesis is divided in four parts. In the introductory part the motivation for measuring (n,a) cross-sections, the experimental challenges for such measurements and the reasons for choosing the CVD diamond technology for the detector are given. This is followed by the presentation of the n_TOF facility, an introduction to neutron-induced nuclear reactions and a brief summary of the interaction of particles with matter. The CVD diamond technology and the relevant matters related to electronics are given as well in this first part of the t...

Failure analysis of glass-ceramic insulators of shock tested vacuum (neutron) tubes

International Nuclear Information System (INIS)

Spears, R.K.

1980-01-01

Eight investigative techniques were used to examine the glass-ceramic insulators in vacuum (neutron) tubes. The insulators were extracted from units that had been subjected to low temperature mechanical shock tests. Two of the three units showed reduced neutron output after these tests and an insulator on one of these two was cracked completely through which probably occurred during shock testing. The objective of this study was to determine if any major differences existed between the insulators of these tubes. After eight analyses, it was concluded that no appreciable differences existed. It appeared that cracking of the one glass-ceramic sample was initiated at inner-sleeve interface voids. For this sample, the interface void density was much higher than is presently acceptable. All insulators were made with glass-ceramic having a Na 2 O content of 4.6 wt%. An increased Na 2 O content will cause an increase in the coefficient of expansion and will reduce the residual stress level since the molybdenum has a higher coefficient of thermal expansion than the insulator. Thus, it is believed that a decrease in interface voids and an increase in Na 2 O should aid in reduced cracking of the insulator during these tests

A new method for the determination of unknown neutron fluence for 14.0 MeV

Energy Technology Data Exchange (ETDEWEB)

Malik, Fariha [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan)]. E-mail: fariha@pinstech.org.pk; Khan, Ehsan U. [Department of Physics, CIIT, Islamabad (Pakistan); Qureshi, Imtinan [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Husaini, Syed N. [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Ahmad, Waqar [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Rajput, Usman [Physics Reasearch Division, PINSTECH, Nilore, Islamabad (Pakistan); Raza, Qaiser [Applied Physics Division, PINSTECH, Nilore, Islamabad (Pakistan)

2006-11-15

Measuring the correct neutron fluence in various energy intervals in and around the neutron sources is important for the purpose of personnel and environmental neutron dosimetry. In this paper, we present a new method for the measurement of the fluence of mono-energetic neutrons having the energy of 14.0 MeV. The samples exposed to neutrons from the 14.0 MeV neutron generator at PINSTECH with various fluence values ranging from 10{sup 7} to 10{sup 10} n cm{sup -2} were etched for 10 min in 6 N NaOH at 70.0{+-}1.0 {sup o}C and the transmittance of UV radiation was measured using a spectrophotometer. This procedure was repeated 20 times after etching the same sample each time for increasing time intervals till the stage when transmittance reached the constant minimum value. An exponential decay of the transmittance has been observed with respect to the increasing etching time interval in each of the samples exposed to various neutron fluence. Further, it has also been observed that there is a linear relationship between the transmittance decay constant and neutron fluence. Hence, the linear graph can be used as a calibration for measuring the unknown fluence of 14.0 MeV neutrons.

Evaluation of neutron cross-sections of {sup 127}I important for radiation transport calculations in large NaI detectors

Energy Technology Data Exchange (ETDEWEB)

Pronayaev, V G [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

1997-06-01

Evaluations were made of neutron inelastic scattering cross-sections with excitation of discrete levels of the residual nucleus, the (n,2n) reaction, secondary neutron emission spectra and secondary photons for reactions which contribute substantially to production of photons for {sup 127}I with the use of the theoretical model for neutrons with an initial energy of 60 keV-20 MeV. (author). 10 refs, 3 figs.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-01

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

Determination of sodium in biological samples by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Parwate, D.V.; Garg, A.N.

1981-01-01

Sodium is one of the most essential elements needed for metabolic processes amongst human beings. It is consumed in the form of sodium chloride but it is also present in edible plant leaves. Sodium is mostly analyzed by flame photometric method, a destructive and time consuming technique. Sodium has been determined in some green leave vegetables samples-palak, radish, khatta palak (ambat chuka), chaulai leaves, chauli bean covers and its seeds by instrumental neutron activation analysis. The method involves irradiation of samples with thermal neutrons from 241 Am-Be source and counting 24 Na activity (half life 15 hr) from the reaction 23 Na(n,γ) 24 Na. Activity due to 1.37 MeV photopeak was counted with a NaI(Tl) crystal coupled to gamma ray spectrometer. Green leaves of the vegetables were thoroughly washed, dried at constant temperature and powdered. Bowen's Kale powder was used as standard for measuring sodium abundances. About 2g each of samples and the standard were packed in polythene vials. They were irradiated for 24 hrs, delayed by 1 hr and then counted for 20 mts. It is found that radish leaves are most enriched in sodium (14.0 +-0.45%) amongst four leave samples analyzed. For three different parts of chaulai leaves, bean covers and seeds, sodium contents are 1.38%, 1820 and 1010 ppm. Palak contains 2.84 +-0.29% while khatta palak contains only 4210 +- 830 ppm sodium. All values reported here are for dry weight samples and are means of three replicate measurements with standard deviation. (author)

Sodium fast reactors energy conversion systems. Na-CO2 interaction. Comparison with Na-water interaction of conventional water Rankine cycle

International Nuclear Information System (INIS)

Latge, Christian; Simon, Nicole

2006-01-01

The Sodium Fast Reactor is a very promising candidate for the development of Fast Neutron Reactors. It is well known owing to its wide development since the 1950's, throughout all countries involved in the development of nuclear power plants. The development of Sodium-cooled fast neutron reactors is possible due to its very attractive sodium, nuclear, physical and even some of its chemical properties. Nevertheless, the operational feedback has shown that the concept has several drawbacks: difficulties for In-Service Inspection and Repair operations due to the sodium opacity and possible detrimental effects of its reactivity with air and water when the heat conversion is performed with a conventional Rankine cycle. Moreover, the various design projects have shown some difficulties in enhancing its competitiveness with regards to existing NPPs without any new innovative options, i.e. the possibility of suppressing the intermediate circuits and/or the development of an optimized energy conversion system. The Supercritical CO 2 Brayton Cycle option for the energy conversion has been widely suggested because of its high thermodynamic efficiency (over 40%), its potential compactness of the Balance Of Plant equipment due to the small-sized turbo machinery system, and for its applicability to both Direct or Indirect Cycle (Na, PbBi, He) assuming the hypothesis that the Supercritical CO 2 -Na interaction has less serious potential consequences than sodium-water consequences in the conventional Rankine cycle. Within the framework of the SMFR (Small Modular Fast Reactor) project, developed jointly by Argonne National Laboratory (ANL-USA), the 'Commissariat a l'Energie Atomique' (CEA) and Japan Atomic Energy Agency (JAEA, formerly Japan Nuclear Cycle development), this option has been selected and investigated. This paper deals with the study of the interaction between Na and CO 2 , based on a literature review: the result of this study will allow the definition of R and D

Isospin dependent Boltzmann-langevin equation and the production cross section of 19Na

International Nuclear Information System (INIS)

Ming Zhaoyu; Zhang Fengshou; Chen Liewen; Zhu Zhiyuan; Zhang Wenlong; Guo Zhongyan; Xiao Guoqing

2000-01-01

A new transport model (isospin dependent Boltzmann-Langevin equation) is developed and it is shown that this model can regenerate the experimental data for reaction of 12 C + 12 C at 28.7 MeV/u. The production cross section of 19 Na is systematically studied for reactions of 17-20,22 Ne + 12 C at 28.7 MeV/u. It is found that a neutron deficient projectile has larger 19 Na cross section than a stable projectile

Pulsed neutron sources for epithermal neutrons

International Nuclear Information System (INIS)

Windsor, C.G.

1978-01-01

It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

Elemental analysis of soil and hair sample by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Chung, Yong Sam; Quraishi, Shamshad Begum; Moon, Jong Hwa; Kim, Sun Ha; Baek, Sung Yeoil; Kang, Sang Hoon; Lim, Jong Myoung; Cho, Hyun Je; Kim, Young Jin

2004-03-01

Myanmar soil sample was analyzed by using the instrumental neutron activation analysis. The elemental concentrations in the sample, altogether 34 elements, Al As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Ga, Gd, Hf, Ir, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Se, Sm, Th, Ti, V, Yb, Zn and Zr were determined. The concentration of 17 elements (Al, Au, Br, Ca, Cl, Cr, Cu, Co, Fe, Hg, K, Na, Mn, Mg, Sb, Se, Zn) in human hair samples were determined by INAA For quality control of analytical method, certified reference material was used

Elemental analysis of soil and hair sample by instrumental neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Chung, Yong Sam; Quraishi, Shamshad Begum; Moon, Jong Hwa; Kim, Sun Ha; Baek, Sung Yeoil; Kang, Sang Hoon; Lim, Jong Myoung; Cho, Hyun Je; Kim, Young Jin

2004-03-01

Myanmar soil sample was analyzed by using the instrumental neutron activation analysis. The elemental concentrations in the sample, altogether 34 elements, Al As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Ga, Gd, Hf, Ir, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Se, Sm, Th, Ti, V, Yb, Zn and Zr were determined. The concentration of 17 elements (Al, Au, Br, Ca, Cl, Cr, Cu, Co, Fe, Hg, K, Na, Mn, Mg, Sb, Se, Zn) in human hair samples were determined by INAA For quality control of analytical method, certified reference material was used.

Neutron radiography using neutron imaging plate

International Nuclear Information System (INIS)

Chankow, Nares; Wonglee, Sarinrat

2008-01-01

Full text: The aims of this research are to study properties of neutron imaging plate, to obtain a suitable condition for neutron radiography and to use the neutron imaging plate for testing of materials nondestructively. The experiments were carried out by using a neutron beam from the Thai Research Reactor TRR-1/M1 at a power of 1.2 MW. A BAS-ND 2040 FUJI neutron imaging plate and a MX125 Kodak X-ray film/Gadolinium neutron converter screen combination were tested for comparison. It was found that the photostimulated light (PSL) read out of the imaging plate was directly proportional to the exposure time. It was also found that radiography with neutron using the imaging plate was approximately 40 times faster than the conventional neutron radiography using x-ray film/Gd converter screen combination. The sensitivity of the imaging plate to gamma-rays was investigated by using gamma-rays from an 192 Ir and a 60 Co radiographic sources. The imaging plate was found to be 5-6 times less sensitive to gamma-rays than a FUJI BAS-MS 2040 gamma-ray imaging plate. Finally, some specimens were selected to be radiographed with neutrons using the imaging plate and the x-ray film/Gd converter screen combination in comparison to x-rays. Parts containing light elements could be clearly observed by the two neutron radiographic techniques. It could be concluded that the image quality from the neutron imaging plate was comparable to the conventional x-ray film/Gd converter screen combination but the exposure time could be approximately reduced by a factor of 40

Measurements of gamma rays from keV-neutron resonance capture by odd-Z nuclei in the 2s-1d shell region

Energy Technology Data Exchange (ETDEWEB)

Igashira, Masayuki; Lee, Sam Yol; Mizuno, Satoshi; Hori, Jun-ichi [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors; Kitazawa, Hideo

1998-03-01

Measurements of gamma rays from keV-neutron resonance capture by {sup 19}F, {sup 23}Na, and {sup 27}Al, which are odd-Z nuclei in the 2s-1d shell region, were performed, using an anti-Compton HPGe spectrometer and a pulsed neutron source by the {sup 7}Li(p,n){sup 7}Be reaction. Capture gamma rays from the 27-, 49-, and 97-keV resonances of {sup 19}F, the 35- and 53-keV resonances of {sup 23}Na, and the 35-keV resonance of {sup 27}Al were observed. Some results are presented. (author)

Ultracold neutrons

International Nuclear Information System (INIS)

Steenstrup, S.

Briefly surveys recent developments in research work with ultracold neutrons (neutrons of very low velocity, up to 10 m/s at up to 10 -7 eV and 10 -3 K). Slow neutrons can be detected in an ionisation chamber filled with B 10 F 3 . Very slow neutrons can be used for investigations into the dipole moment of neutrons. Neutrons of large wave length have properties similar to those of light. The limit angle for total reflection is governed by the wave length and by the material. Total reflection can be used to filter ultracold neutrons out of the moderator material of a reactor. Total reflection can also be used to store ultracold neutrons but certain problems with storage have not yet been clarified. Slow neutrons can be made to lose speed in a neutron turbine, and come out as ultracold neutrons. A beam of ultracold neutrons could be used in a neutron microscope. (J.S.)

Basic research of neutron radiography using cold neutron beam

International Nuclear Information System (INIS)

Oda, Masahiro; Tamaki, Masayoshi; Tasaka, Kanji

1995-01-01

As the result of demanding high quality images, now the nuclear reactors which can supply stably intense neutron beam have become the most general neutron source for radiography. For the purpose, mostly thermal neutrons have been used, but it is indispensable to use other neutrons than thermal neutrons for advancing neutron radiography technology and expanding the application fields. The radiography using cold neutrons is most behind in the development because the suitable neutron source was not available in Japan. The neutron sources for exclusively obtaining intense cold neutron beam were installed in the Kyoto University reactor in 1986 and in the JRR-3M of Japan Atomic Energy Research Institute in 1991. Basically as neutron energy lowers, the cross section of substances increases. In certain crystalline substances, the Bragg cutoff arises. The removal of scattered neutrons, the measurement of parallelism of beam and the relation of the thickness of objects with the transmissivity of cold neutrons are described. The imaging by TV method and the cold neutron CT in the CNRF and the simplified neutron CT by film method are reported. (K.I.)

Theoretical Interpretation of Pulsed Neutron Phenomena; Interpretation Theorique des Phenomenes dus aux Neutrons Pulses; Teoreticheskaya interpretatsiya yavlenij, svyazannykh s impul'snymi nejtronami; Interpretacion Teorica de los Fenomenos Debidos a Neutrones Pulsados

Energy Technology Data Exchange (ETDEWEB)

Corngold, N. [Brookhaven National Laboratory, Upton, NY (United States)

1965-08-15

The author discusses the present understanding of transient effects in the variation of neutron distributions in space, time and energy. In the analysis, particular attention is given to the pulsed neutron experiment in non-multiplying media, and to its interpretation in terms of space-energy modes and (time) decay constants. Theoretical research in this field, much of which has come from the Brookhaven National Laboratory, has been built upon the exact solution of several special problems, and approximate, numerical solutions in more realistic situations. Recently, a unified point of view, based on the Van Hove-Glauber theory of the scattering of slow neutrons, has been proposed. It has been found that the long-time behaviour of the pair correlation function, which enables one to distinguish between different types of moderating materials, also controls the type of decay-constant spectrum that one finds. In his discussion the author emphasizes the case of infinite medium solutions that are proportional to exp(iB * r), in media having 1/v absorption. The analytical work is concerned with modal solutions, proportional to exp({lambda}t) as well, while the numerical work is directed at the full, ''life-history'' solution, as well as the modal solutions. The author also remarks on phenomena encountered when the absorption is not 1/v and when the moderator sample is so small that the long-time solutions are no longer separable in space and energy. Finally, the paper discusses the bearing of these recent developments upon the interpretation of pulsed experiments. Particular reference is made to the measurement of diffusion and diffusion cooling coefficients, and to the nature of the approach to the asymptotic distribution. (author) [French] L'auteur examine la conception actuelle des effets transitoires dans la variation des distributions des neutrons dans l'espace, dans le temps et selon l'energie. Dans son etude, il accorde une attention particuliere aux experiences

A complex method for the neutron activation analysis of biological materials

International Nuclear Information System (INIS)

Ordogh, M.

1978-05-01

The destructive and nondestructive approach of neutron activation analysis used by the author is reviewed to determine some trace elements in biological materials: Ca, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, V and Zn. Bowen's kale was used to determine the accuracy and reliability. The parameters obtained were confirmed by participating in round robins organized by the IAEA: in which potato powder and animal bone have been analyzed for Zn, Co, Fe, Cr, Mn, Rb, Na, K and Cu. Tabulated results are given and compared with recommended values and literature data. Gamma spectra are shown. (T.G.)

Development and use of in vivo neutron activation analysis at Leeds

International Nuclear Information System (INIS)

Burkinshaw, L.; Oxby, C.B.; Ellis, R.E.

1986-01-01

We have devised a technique for measuring the total amounts of the elements K, N, Na, Cl, P and Ca in the living human body by neutron activation analysis. We have used it to study changes in body composition associated with disease and are now extending it to measure total body C, H and O also. (author)

Installation and measurement capacity of 3 x 592 GBq 241Am-Be neutron irradiation cell

International Nuclear Information System (INIS)

Bulut, Serdar; Celenk, I.

2013-01-01

In this study, the installation and measurement capacity of the neutron irradiation system are investigated. First of all an irradiation geometry enabling optimum irradiation was designed for three 241 Am-Be sources each of it having 592 GBq activity. Neutron irradiation system was installed after design and optimization of the system including the design of appropriate moderator and shielding were completed. Radiation safety standards of the Neutron Research Laboratory fulfilling the requirements of national regulation were achieved with unique configuration of the shielding materials. In this study the results of qualitative and quantitative detection limits obtained for Na, Al, Cl, K, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Mo, Ru, Ag, Cd, In, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Lu, Hf, W, Pt, Au, Th and U elements by using the neutron irradiation cell comprising 3 x 592 GBq 241 Am-Be isotopic neutron source are presented and discussed. (orig.)

Feasibility Study of Neutron Multiplicity Assay for a Heterogeneous Sludge Sample containing Na, Pu and other Impurities

International Nuclear Information System (INIS)

Nakamura, H.; Nakamichi, H.; Mukai, Y.; Yoshimoto, K.; Beddingfield, D.H.

2010-01-01

To reduce radioactivity of liquid waste generated at PCDF, a neutralization precipitation processes of radioactive nuclides by sodium hydroxide is used. We call the precipitate a 'sludge' after calcination. Pu mass in the sludge is normally determined by sampling and DA within the required uncertainty on DIQ. Annual yield of the mass is small but it accumulates and reaches to a few kilograms, so it is declared as retained waste and verified at PIV. A HM-5-based verification is applied for sludge verification. The sludge contains many chemical components. For example, Pu (-10wt%), U, Am, SUS components, halogens, NaNO 3 (main component), residual NaOH, and moisture. They are mixed together as an impure heterogeneous sludge sample. As a result, there is a large uncertainty in the sampling and DA that is currently used at PCDF. In order to improve the material accounting, we performed a feasibility study using neutron multiplicity assay for impure sludge samples. We have measured selected sludge samples using a multiplicity counter which is called FCAS (Fast Carton Assay System) which was designed by JAEA and Canberra. The PCDF sludge materials fall into the category of 'difficult to measure' because of the high levels of impurities, high alpha values and somewhat small Pu mass. For the sludge measurements, it was confirmed that good consistency between Pu mass in a pure sludge standard (PuO 2 -Na 2 U 2 O 7 , alpha=7) and the DA could be obtained. For unknown samples, using 14-hour measurements, we could obtain quite low statistical uncertainty on Doubles (-1%) and Triples (-10%) count rate although the alpha value was extremely high (15-25) and FCAS efficiency was relatively low (40%) for typical multiplicity counters. Despite the detector efficiency challenges and the material challenges (high alpha, low Pu mass, heterogeneous matrix), we have been able to obtain assay results that greatly exceed the accountancy requirements for retained waste materials. We have

The application of the PARCS neutronics code to the Atucha-I and Atucha-II NPPs

Energy Technology Data Exchange (ETDEWEB)

Ward, Andrew; Collins, Ben; Xu, Yunlin; Downar, Thomas [Purdue University, West Lafayette, IN (United States); Madariaga, Marcelo [Autoridad Nuclear Regulatoria, Buenos Aires (Argentina)

2008-07-01

In order to analyze Central Nuclear Atucha II (CNA-II) with coupled RELAP5/PARCS, extensive benchmarking of the neutronics codes HELIOS and PARCS was completed. This benchmarking was performed using a range of test problems designed in collaboration with NA-SA. HELIOS has been previously used to model Candu systems, but the results were validated for this case as well. The validation of both HELIOS and PARCS was performed primarily by comparisons to MCNP results for the same problems. Though originally designed to model light water systems, the capability of the PARCS was validated for predicting the performance of a Pressurized Heavy Water Reactor. The other noteworthy issue was the control rods. Because the insertion of the rods is oblique, a special routine was added to PARCS to treat this effect. Lattice level and Core level calculations were compared to the corresponding NA-SA codes WIMS and PUMA. In all cases there was good agreement in the results which provided confidence that the neutronics methods and the core neutronics modelling would not be a significant source of error in coupled RELAP5/PARCS calculations. (authors)

Neutron stars as cosmic neutron matter laboratories

International Nuclear Information System (INIS)

Pines, D.

1986-01-01

Recent developments which have radically changed our understanding of the dynamics of neutron star superfluids and the free precession of neutron stars are summarized, and the extent to which neutron stars are cosmic neutron matter laboratories is discussed. 17 refs., 1 tab

Synthesis and structural characterization of the hexagonal anti-perovskite Na{sub 2}CaVO{sub 4}F

Energy Technology Data Exchange (ETDEWEB)

Green, Robert L., E-mail: rgreen@flpoly.org [Chemistry, Florida Polytechnic University, Lakeland, FL 33805 (United States); Avdeev, Maxim [Australian Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); School of Chemistry, The University of Sydney, Sydney, NSW 2006 (Australia); Vogt, Thomas [NanoCenter and Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States)

2017-06-15

The structural details of the ordered hexagonal oxyfluoride Na{sub 2}CaVO{sub 4}F prepared by solid-state synthesis using stoichiometric amounts of V{sub 2}O{sub 5}, CaCO{sub 3}, Na{sub 2}CO{sub 3} and NaF were characterized using high-resolution neutron powder diffraction. The structural changes between 25 °C and 750 °C revealed that the two structural subunits in this material behave different when heated: there is an expansion of the face-shared FNa{sub 4}Ca{sub 2} octahedra while the VO{sub 4} tetrahedra due to increased thermal disorder reveal marginal bond contractions. Bond valences and the global instability index point to significant structural disorder at 750 °C. - Graphical abstract: The structure of the novel oxyfluoride Na{sub 2}CaVO{sub 4}F is studied at room temperature and high-temperatures. The structure can be viewed as layers of compression and elongation of polyhedral subunits, which change as a function of temperature. - Highlights: • The novel oxyfluoride, Na{sub 2}CaVO{sub 4}F, is synthesized via solid-state method. • High-resolution neutron diffraction data is used to analyze the structure of Na{sub 2}CaVO{sub 4}F. • Structural subunits exhibit expansion and contraction with increasing temperature. • Higher temperatures increase instability within the structure of Na{sub 2}CaVO{sub 4}F.

Characterizing ICF Neutron Scintillation Diagnostics on the nTOF line at SUNY Geneseo

Science.gov (United States)

Lawson-Keister, Pat; Padawar-Curry, Jonah; Visca, Hannah; Fletcher, Kurt; Padalino, Stephen; Sangster, T. Craig; Regan, Sean

2015-11-01

Neutron scintillator diagnostics for ICF and HEDP can be characterized using the neutron time-of-flight (nTOF) line on Geneseo's 1.7 MV tandem Pelletron accelerator. Neutron signals can be differentiated from gamma signals by employing coincidence methods. A 1.8-MeV beam of deuterons incident on a deuterated polyethylene target produces neutrons via the 2H(d,n)3He reaction. Neutrons emerging at a lab angle of 88° have an energy of 2.96 MeV; the 3He ions associated with these neutrons are detected at a scattering angle of 43° using a surface barrier detector. The time of flight of the neutron can be measured by using the 3He detection as a ``start'' signal and the scintillation detection as a ``stop'' signal. This time of flight requirement is used to identify the 2.96-MeV neutron signals in the scintillator. To measure the light curve produced by these monoenergetic neutrons, two photomultiplier (PMT) tubes are attached to the scintillator. The full aperture PMT establishes the nTOF coincidence. The other PMT is fitted with a pinhole to collect single events. The time between the full aperture PMT signal and the arrival of the signal in the pinhole PMT is used to determine the light curve for the scintillator. This system will enable the neutron response of various scintillators to be compared. Supported in part by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Effect of fast-neutron irradiation on the electrical conductivity of NaKSO4 crystals

International Nuclear Information System (INIS)

Kassem, M.E.; El-Khatib, A.M.; El-Wahidy, E.F.; Gado, H.E.

1987-01-01

In recent years, the study of the physical properties of NaKSO 4 has drawn the attention of many investigators. Measurements on the electrical, thermal and elastic properties of NaKSO 4 in the temperature range 300 to 500 K show a structural phase transition at 453 K. Electrical conductivity measurements [4] on pure and doped compounds of NaKSO 4 reveal high ionic conductivity values in the high-temperature range. Order-disorder transitions and solid state kinetics in the same compound were also studied. (author)

Experimental research of neutron yield and spectrum from deuterium gas-puff z-pinch on the GIT-12 generator at current above 2 MA

Science.gov (United States)

Cherdizov, R. K.; Fursov, F. I.; Kokshenev, V. A.; Kurmaev, N. E.; Labetsky, A. Yu; Ratakhin, N. A.; Shishlov, A. V.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Dudkin, G. N.; Garapatsky, A. A.; Padalko, V. N.; Varlachev, V. A.

2017-05-01

The Z-pinch experiments with deuterium gas-puff surrounded by an outer plasma shell were carried out on the GIT-12 generator (Tomsk, Russia) at currents of 2 MA. The plasma shell consisting of hydrogen and carbon ions was formed by 48 plasma guns. The deuterium gas-puff was created by a fast electromagnetic valve. This configuration provides an efficient mode of the neutron production in DD reaction, and the neutron yield reaches a value above 1012 neutrons per shot. Neutron diagnostics included scintillation TOF detectors for determination of the neutron energy spectrum, bubble detectors BD-PND, a silver activation detector, and several activation samples for determination of the neutron yield analysed by a Sodium Iodide (NaI) and a high-purity Germanium (HPGe) detectors. Using this neutron diagnostic complex, we measured the total neutron yield and amount of high-energy neutrons.

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

International Nuclear Information System (INIS)

Kehayias, J.J.

2001-01-01

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

Evaluation and benchmarking of nuclear data of vanadium in integral experiments with 14-MeV neutrons

CERN Document Server

Blokhin, A I; Chuvilin, D; Livke, A V; Manokhin, V N; Markovskij, D; Nagorny, V; Nefedov, Yu A; Orlov, R; Savin, M; Semenov, V; Shmarov, A; Shvetsov, A M; Zagryadsky, V; Zhitnik, A

2001-01-01

The measurements of the gamma-ray and neutron leakage spectra from three vanadium spheres with diameter 10, 24 and 34 cm at their internal irradiation by 14-MeV neutrons were carried out in frame of the ISTC Project no. 910 in collaboration with FZK. All the spheres have the same geometry of the central hole of 3 cm in diameter. The neutron leakage spectra were measured by a scintillation detector, and by a gas proportional counter. The gamma-ray leakage spectra were measured with help of a crystal NaI(Tl). Analysis of these experiments is performed with the new evaluated nuclear data files prepared in frame of the project activities. A comparison of experimental and calculated neutron and gamma-ray leakage spectra from three vanadium spheres is given.

Neutron activation analysis methodology of marine sediments of the Cuban shelf

International Nuclear Information System (INIS)

Garcia, G.

1988-01-01

It is described the methodology followed for the neutron activation analysis of marine sediments of the Cuban shelf. A total of 35 elements were determined by means of the employment of thermal and epithermal fluxes of a nuclear reactor as well as from the flux of a generator of 14 MeV neutrons. It is signaled the particularities of detection and measurement of some elements and their interferences, with and special mention of the correction over 153 Sm, 113m In(Sn), 65 Zn, 160 Th, 169 Yb, 75 Sc and 177 Lu. It is concluded that 82% of elements may be determined with epithermal neutrons and 41%, with thermal neutrons. Only Si is determined with 14 MeV neutrons. Moreover, it is recommended the optimal periods of decaying (''cooling'') by groups of elements. The determined elements were: Ag, As, Au, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Mo, Na, Nd, Ni, Rb, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Th, U, W, Yb, Zn and Zr. The accuracy varied between 1% and 5% to 19 elements, between 6% and 10% to 5 elements, between 11% and 30% to 6 elements and it was greater than 30% to 5 elements

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

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

1.1 This test method covers procedures measuring reaction rates by the activation reaction 27Al(n,α)24Na. 1.2 This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about 2 days (for longer irradiations, see Practice E261). 1.3 With suitable techniques, fission-neutron fluence rates above 106 cm−2·s−1 can be determined. 1.4 Detailed procedures for other fast neutron detectors are referenced in Practice E261. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Measurement of resonance parameters of cross-sections affecting fast-neutron propagation in various media; Mesure des parametres de resonance de sections efficaces lies a la propagation des neutrons dans differents milieux; Izmerenie parametrov rezonansnoj struktury sechenij, vliyayushchikh na rasprostranenie bystrykh nejtronov v sredakh; Medicion de los parametros de resonancia de las secciones eficaces que afectan a la propagacion de los neutrones rapidos en distintos medios

Energy Technology Data Exchange (ETDEWEB)

Nikolaev, M N; Filippov, V V; Bondarenko, I I [Academy of Sciences, Moscow, Union of Soviet Socialist Republics (Russian Federation)

1962-03-15

propagacion de los neutrones en la materia abarca desde algunas decenas de kiloelectron-voltios , para los nucleos pesados, hasta unos cuantos mega-electron-voltios, para los nucleos intermedios. Para poder tener en cuenta los efectos de resonancia en el calculo de los parametros de los grupos, es indispensable conocer no solo las secciones eficaces medias correspondientes a las reacciones de los neutrones con la materia, sino tambien algunas magnitudes tales como (1/{Sigma}{sub t}), (1/{Sigma}{sub t}{sup 2}) etc. - los corchetes indican que se toman valores promedios de los grupos energeticos. La informacion de que se dispone actualement acerca de los parametros de resonancia en el terreno de los neutrones rapidos no permite calcular las magnitudes mencionadas con la exactitud necesaria. Por tal razon interesa medir directamente (1/{Sigma}{sub t}), (1/{Sigma}{sub t}{sup 2}) y otros valores analogos. Los autores presentan los resultados de las mediciones de una serie de parametros tales como ({Sigma}{sub t}), ({Sigma}{sub t}{sup 2}), (1/{Sigma}{sub t}), (1/{Sigma}{sub t}{sup 2}), (1/{Sigma}{sub t}{sup 3}), etc. que caracterizan la estructura de las secciones eficaces de una serie de nucleos intermedios para neutrones de energia comprendida entre 300 keV y 3 MeV. Dichos valores se dedujeron analizando las curvas de paso a traves de la materia, obtenidas con una geometria favorable, hasta un valor limite de 10{sup -2}, aproximadamente . Los datos obtenidos demuestran que los efectos de resonancia ejercen una notable influencia sobre las caracteristicas de la difusion en la materia. (author) [Russian] Pri sostavlenii sistem mnogogruppovykh konstant dlya rascheta reaktorov na bystrykh i promezhutochnykh nejtronakh vo mnogikh sluchayakh neobkhodimo uchityvat' ehffekty samoehkranirovki , svyazannye s rezonansnoj strukturoj sechenij. EHnergeticheskaya oblast', v kotoroj rezonansnaya struktura okazyvaet sushchestvennoe vliyanie na rasprostranenie nejtronov v veshchestve

Polarized neutrons

International Nuclear Information System (INIS)

Williams, W.G.

1988-01-01

The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

The effect of age on Br, Ca, Cl, K, Mg, Mn, and Na mass fraction in pediatric and young adult prostate glands investigated by neutron activation analysis

International Nuclear Information System (INIS)

Zaichick, Vladimir; Zaichick, Sofia

2013-01-01

The effect of age on chemical element mass fractions in intact prostate of 50 apparently healthy 0–30 year old males was investigated by neutron activation analysis with high resolution spectrometry of short-lived radionuclides. Mean values (M±SΕΜ) for mass fraction (mg kg −1 , dry mass basis) of chemical elements before the time of puberty and in the period of puberty and post-puberty were: Br 46.0±6.7, Ca 1151±140, Cl 14572±700, K 10147±700, Mg 771±131, Mn 2.13±0.25, Na 9880±659 and Br 29.0±4.6, Ca 2049±364, Cl 11518±1121, K 13029±542, Mg 1186±134, Mn 1.74±0.16, Na 9887±716, respectively. A tendency of age-related increase in Ca, K, and Mg mass fraction and of age-related decrease in Br mass fraction was observed in period of life from 0 to 30 years. This new data indicates that of the elements studied, only the Ca, K, and Mg mass fraction in prostate tissue is an androgen-dependent parameter

Neutron spectra produced by moderating an isotopic neutron source

International Nuclear Information System (INIS)

Carrillo Nunnez, Aureliano; Vega Carrillo, Hector Rene

2001-01-01

A Monte Carlo study has been carried out to determine the neutron spectra produced by an isotopic neutron source inserted in moderating media. Most devices used for radiation protection have a response strongly dependent on neutron energy. ISO recommends several neutron sources and monoenergetic neutron radiations, but actual working situations have broad spectral neutron distributions extending from thermal to MeV energies, for instance, near nuclear power plants, medical applications accelerators and cosmic neutrons. To improve the evaluation of the dosimetric quantities, is recommended to calibrate the radiation protection devices in neutron spectra which are nearly like those met in practice. In order to complete the range of neutron calibrating sources, it seems useful to develop several wide spectral distributions representative of typical spectra down to thermal energies. The aim of this investigation was to use an isotopic neutron source in different moderating media to reproduce some of the neutron fields found in practice. MCNP code has been used during calculations, in these a 239PuBe neutron source was inserted in H2O, D2O and polyethylene moderators. Moderators were modeled as spheres and cylinders of different sizes. In the case of cylindrical geometry the anisotropy of resulting neutron spectra was calculated from 0 to 2 . From neutron spectra dosimetric features were calculated. MCNP calculations were validated by measuring the neutron spectra of a 239PuBe neutron source inserted in a H2O cylindrical moderator. The measurements were carried out with a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. From the measurements the neutron spectrum was unfolded using the BUNKIUT code and the UTA4 response matrix. Some of the moderators with the source produce a neutron spectrum close to spectra found in actual applications, then can be used during the calibration of radiation protection devices

Cross sections for D-T neutron interaction with neodymium isotopes

International Nuclear Information System (INIS)

Luo, Junhua; An, Li; Jiang, Li; He, Long

2015-01-01

The cross-sections for (n, x) reactions with neodymium isotopes were measured at (D-T) neutron energies around 14 MeV with the activation technique. Samples were activated along with Nb and Al monitor foils to determine the incident neutron flux. Data are reported for the following reactions: 142 Nd(n,2n) 141 Nd, 148 Nd(n,2n) 147 Nd, 150 Nd(n,2n) 149 Nd, 142 Nd(n,p) 142 Pr, 146 Nd(n,α) 143 Ce, and 146 Nd(n,p) 146 Pr. Theoretical calculations of excitation functions were performed with the TALYS-1.6 nuclear model code, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.1, JENDL-4.0, and CENDL-3 libraries. - Highlights: • The cross sections for the (n,x) reactions on Neodymium have been measured. • Mono-energetic neutron beams using the D-T reaction; Energies: 13.5–14.8 MeV. • Neutron cross-section measurements by means of the activation technique. • Reference reactions 93 Nb(n,2n) 92m Nb and 27 (n, α) 24 Na were used as the monitor. • Nuclear reaction code TALYS-1.6 was used

Neutron beam design for low intensity neutron and gamma-ray radioscopy using small neutron sources

CERN Document Server

Matsumoto, T

2003-01-01

Two small neutron sources of sup 2 sup 5 sup 2 Cf and sup 2 sup 4 sup 1 Am-Be radioisotopes were used for design of neutron beams applicable to low intensity neutron and gamma ray radioscopy (LINGR). In the design, Monte Carlo code (MCNP) was employed to generate neutron and gamma ray beams suited to LINGR. With a view to variable neutron spectrum and neutron intensity, various arrangements were first examined, and neutron-filter, gamma-ray shield and beam collimator were verified. Monte Carlo calculations indicated that with a suitable filter-shield-collimator arrangement, thermal neutron beam of 3,900 ncm sup - sup 2 s sup - sup 1 with neutron/gamma ratio of 7x10 sup 7 , and 25 ncm sup - sup 2 s sup - sup 1 with very large neutron/gamma ratio, respectively, could be produced by using sup 2 sup 5 sup 2 Cf(122 mu g) and a sup 2 sup 4 sup 1 Am-Be(37GBq)radioisotopes at the irradiation port of 35 cm from the neutron sources.

Neutron cooling and cold-neutron sources (1962); Refroidissement des neutrons et sources de neutrons froids (1962)

Energy Technology Data Exchange (ETDEWEB)

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

1962-07-01

Intense cold-neutron sources are useful in studying solids by the inelastic scattering of neutrons. The paper presents a general survey covering the following aspects: a) theoretical considerations put forward by various authors regarding thermalization processes at very low temperatures; b) the experiments that have been carried out in numerous laboratories with a view to comparing the different moderators that can be used; c) the cold neutron sources that have actually been produced in reactors up to the present time, and the results obtained with them. (author) [French] Des sources intenses de neutrons froids sont utiles pour l'etude des solides par diffusion inelastique des neutrons. On presente une revue d'ensemble: a) des considerations theoriques faites par divers auteurs sur les processus de thermalisation a tres basse temperature; b) des experiences faites dans de nombreux laboratoires pour comparer les divers moderateurs possibles; c) des sources de neutrons froids effectivement realisees dans des piles a ce jour, et des resultats obtenus avec ces sources. (auteur)

Effects of Monoenergetic Neutron Radiation on Human Cells in Tissue Culture; Effets des Neutrons Monoenergetiques sur des Cellules de Tissus Humains en Culture; Dejstvie oblucheniya monoehnergeticheskimi nejtronami na kletki kul'tury tkanej cheloveka; Efectos de la Radiacion Neutronica Monoenergetica sobre las Celulas Humanas en Cultivos de Tejidos

Energy Technology Data Exchange (ETDEWEB)

Broerse, J. J.; Barendsen, G. W. [Radiobiological Institute of the Organization for Health Research TNO, Rijswijk (Z.H.) (Netherlands)

1964-03-15

determinaron midiendo la activacion de unas pastillas de azufre dispuestas entre las capsulas y los tubos. El calculo de las dosis a partir del flujo neutronico plantea una serie de problemas que los autores analizan. Como no se establece un equilibrio de radiacion en torno a las celulas, las respectivas determinaciones de dosis adolecen de falta de precision que se investigan en el trabajo. Los autores presentan curvas de la supervivencia en funcion de la dosis, para las dos energias neutronicas mencionadas. Con los neutrones de 3 MeV, comprobaron que la EBR varia desde 6,5 (dosis reducidas) hasta alrededor de 3,1 (dosis elevadas); con los neutrones de 15 MeV, la EBR varia entre 1,9 y 1,6. Combinando estos valores de la EBR con la relacion entre la TLE y la EBR establecida en experimentos previos con deuterones y particulas {alpha}, se pueden deducir valores de la TLE efectiva correspondientes a los neutrones utilizados. A fin de dilucidar algunos problemas relacionados con la muerte de animales de laboratorio sometidos a la accion de los rayos X o de los neutrones, los autores perfeccionaron un procedimiento basado en el empleo de celulas, contenidas en pequeflos tubos a fin de medir la dosis efectiva (es decir, la dosis corregida para tener en cuenta la EBR) en zonas determinadas de maniquies o de animales, que ofrecen interes para estos estudios. (author) [Russian] Soobshhaetsja o sootnoshenii doza-jeffekt na osnovanii izluchenija tormozhenija obrazovanija klona pochechnymi kletkami cheloveka posle obluchenija monojenergeticheskimi nejtronami s jenergiej primerno 3 Mjev i 15 Mjev. Dlja nejtronov s jenergiej 3 Mjev moshhnost' dozy ravnjalas' 0,2 rad/min, v to vremja kak dlja nejtronov s jenergiej v 15 Mjev byli polucheny moshhnosti dozy v 2,7 rad/min i 12 rad/min. Obluchenie kletok proizvodilos' v chashkah dlja kul'tury tkanej s tonkim dnom iz stekla Melimeks i v nebol'shih gibkih nejlonovyh rezinovyh trubkah. Potoki nejtronov opredeljalis' putem izmerenija aktivacii sernyh

Chemical contents in Lygeum spartum L. using instrumental neutron activation analysis

International Nuclear Information System (INIS)

Nedjimi, Bouzid

2015-01-01

The present investigation was conducted to determine the chemical contents of Lygeum spartum L. (Poaceae). Samples were analyzed in order to determine essential (Ca, K, Na, Fe, Co) and some potentially toxic elements (Eu, Sb, Tb) using instrumental neutron activation analysis (INAA). In general chemical element contents were in substantial amounts to meet adult sheep requirements. Potential intake of Ca, K, Zn, Co and Fe by ruminant weighing 50 kg BW consuming 2.0 kg per day DM was sufficient to satisfy their requirements. However, only Na level was still insufficient to meet the requirements for grazing ruminants. Potential toxic elements in this species were within the safety baseline of all the assayed elements recommended by NRC. Na supplementation would seem to be necessary in this zone, for optimum productivity of grazing animals.

Analysis of medicinal plant extracts by neutron activation method

International Nuclear Information System (INIS)

Vaz, Sandra Muntz

1995-01-01

This dissertation has presented the results from analysis of medicinal plant extracts using neutron activation method. Instrumental neutron activation analysis was applied to the determination of the elements Al, Br, Ca, Ce, Cl, Cr, Cs, Fe, K, La, Mg, Mn, Na, Rb, Sb, Sc and Zn in medicinal extracts obtained from Achyrolcline satureoides DC, Casearia sylvestris, Centella asiatica, Citrus aurantium L., Solano lycocarpum, Solidago microglossa, Stryphnondedron barbatiman and Zingiber officinale R. plants. The elements Hg and Se were determined using radiochemical separation by means of retention of Se in HMD inorganic exchanger and solvent extraction of Hg by bismuth diethyl-dithiocarbamate solution. Precision and accuracy of the results have been evaluated by analysing reference materials. The therapeutic action of some elements found in plant extracts analyzed was briefly discussed

Use of integral experiments to improve neutron propagation and gamma heating calculations

International Nuclear Information System (INIS)

Oceraies, Y.; Caumette, P.; Devillers, C.; Bussac, J.

1979-01-01

1) The studies to define and improve the accuracies of neutron propagation and gamma heating calculations from integral experiments are encompassed in the field of the fast reactor physics program at CEA. 2) A systematic analysis of neutron propagation in Fe-Na clean media, with variable volumic composition between 0 and 100% in sodium, has been performed on the HARMONIE source reactor. Gamma heating traverses in the core, the blankets and several control rods, have been measured in the R Z core program at MASURCA. The experimental techniques, the accuracies and the results obtained are given. The approximations of the calculational methods used to analyse these experiments and to predict the corresponding design parameters are also described. 3) Particular emphasis is given to the methods planned to improve fundamental data used in neutron propagation calculations, using the discrepancies observed between measured and calculated results in clean integral experiments. One of these approaches, similar to the techniques used in core physics, relies upon sensitivity studies and eventually on adjustment techniques applied to neutron propagation. (author)

Multielement determination in some egyptian vegetables by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Tadros, N.A.; Abdel-Fattah, A.A.; Sanad, W.A.

1999-01-01

Nondestructive instrumental neutron activation analysis (INAA) technique, with thermal neutrons, has been applied for multielement determination of major, trace and ultra trace elements in eleven types of the public public egyptian, edible vegetables, namely dill, moulokhyia, okra negro bean, parsley, green pea, grape leaves, spinach, mint, celery and salad chervil, cultivated and collected from El-Maadi, Cairo, E G. Concentrations of Na, K, Ca, Sc, Cr, Fe, Co, Ni, Zn, Rb, Zr, Nb, Mo, Sb, Cs, Ba, La, Ce, Tb, Yb, Hf, Ta, Th and U were determined. The standard reference materials (SRM's) G-2, J G-1 and MAG-1, provided from IAEA, were used, and high accuracy of the work was assured. The results were discussed

Neutron activation analysis for chemical characterization of Brazilian oxo-biodegradable plastics

International Nuclear Information System (INIS)

Mateus Eugenio Boscaro; De Nadai Fernandes, E.A.; Marcio Arruda Bacchi; Luis Gustavo Cofani dos Santos; Cofani dos Santos, S.N.S.; Sandra Mara Martins-Franchetti

2015-01-01

The chemical characterization of oxo-biodegradable plastic bags was performed by neutron activation analysis. The presence of several chemical elements (As, Br, Ca, Co, Cr, Fe, Hf, K, La, Na, Sb, Sc, Ta and Zn) with large variability of mass fractions amongst samples indicates that these plastics receive additives and may have been contaminated during manufacturing process thereby becoming potential environmental pollutants. (author)

Neutron radiography

International Nuclear Information System (INIS)

Hrdlicka, Z.

1977-01-01

Neutron radiography is a radiographic method using a neutron beam of a defined geometry. The neutron source usually consists of a research reactor, a specialized neutron radiography reactor or the 252 Cf radioisotope source. There are two types of the neutron radiography display system, viz., a system producing neutron radiography images by a photographic process or a system allowing a visual display, eg., using a television monitor. The method can be used wherever X-ray radiography is used except applications in the radiography of humans. The neutron radiography unit at UJV uses the WWR-S reactor as the neutron source and both types of the above mentioned display system. (J.P.)

Improvement of analytical capabilities of neutron activation analysis laboratory at the Colombian Geological Survey

Science.gov (United States)

Parrado, G.; Cañón, Y.; Peña, M.; Sierra, O.; Porras, A.; Alonso, D.; Herrera, D. C.; Orozco, J.

2016-07-01

The Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey has developed a technique for multi-elemental analysis of soil and plant matrices, based on Instrumental Neutron Activation Analysis (INAA) using the comparator method. In order to evaluate the analytical capabilities of the technique, the laboratory has been participating in inter-comparison tests organized by Wepal (Wageningen Evaluating Programs for Analytical Laboratories). In this work, the experimental procedure and results for the multi-elemental analysis of four soil and four plant samples during participation in the first round on 2015 of Wepal proficiency test are presented. Only elements with radioactive isotopes with medium and long half-lives have been evaluated, 15 elements for soils (As, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Th, U and Zn) and 7 elements for plants (Br, Co, Cr, Fe, K, Na and Zn). The performance assessment by Wepal based on Z-score distributions showed that most results obtained |Z-scores| ≤ 3.

Improvement of analytical capabilities of neutron activation analysis laboratory at the Colombian Geological Survey

Energy Technology Data Exchange (ETDEWEB)

Parrado, G., E-mail: gparrado@sgc.gov.co; Cañón, Y.; Peña, M., E-mail: mlpena@sgc.gov.co; Sierra, O., E-mail: osierra@sgc.gov.co; Porras, A.; Alonso, D.; Herrera, D. C., E-mail: dherrera@sgc.gov.co; Orozco, J. [Colombian Geological Survey, Nuclear Affairs Technical Division, Neutron Activation Analysis Laboratory, Bogota D. C. (Colombia)

2016-07-07

The Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey has developed a technique for multi-elemental analysis of soil and plant matrices, based on Instrumental Neutron Activation Analysis (INAA) using the comparator method. In order to evaluate the analytical capabilities of the technique, the laboratory has been participating in inter-comparison tests organized by Wepal (Wageningen Evaluating Programs for Analytical Laboratories). In this work, the experimental procedure and results for the multi-elemental analysis of four soil and four plant samples during participation in the first round on 2015 of Wepal proficiency test are presented. Only elements with radioactive isotopes with medium and long half-lives have been evaluated, 15 elements for soils (As, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sb, Sc, Th, U and Zn) and 7 elements for plants (Br, Co, Cr, Fe, K, Na and Zn). The performance assessment by Wepal based on Z-score distributions showed that most results obtained |Z-scores| ≤ 3.

Neutron matter, neutron pairing, and neutron drops based on chiral effective field theory interactions

Energy Technology Data Exchange (ETDEWEB)

Krueger, Thomas

2016-10-19

The physics of neutron-rich systems is of great interest in nuclear and astrophysics. Precise knowledge of the properties of neutron-rich nuclei is crucial for understanding the synthesis of heavy elements. Infinite neutron matter determines properties of neutron stars, a final stage of heavy stars after a core-collapse supernova. It also provides a unique theoretical laboratory for nuclear forces. Strong interactions are determined by quantum chromodynamics (QCD). However, QCD is non-perturbative at low energies and one presently cannot directly calculate nuclear forces from it. Chiral effective field theory circumvents these problems and connects the symmetries of QCD to nuclear interactions. It naturally and systematically includes many-nucleon forces and gives access to uncertainty estimates. We use chiral interactions throughout all calculation in this thesis. Neutron stars are very extreme objects. The densities in their interior greatly exceed those in nuclei. The exact composition and properties of neutron stars is still unclear but they consist mainly of neutrons. One can explore neutron stars theoretically with calculations of neutron matter. In the inner core of neutron stars exist very high densities and thus maybe exotic phases of matter. To investigate whether there exists a phase transition to such phases even at moderate densities we study the chiral condensate in neutron matter, the order parameter of chiral symmetry breaking, and find no evidence for a phase transition at nuclear densities. We also calculate the more extreme system of spin-polarised neutron matter. With this we address the question whether there exists such a polarised phase in neutron stars and also provide a benchmark system for lattice QCD. We find spin-polarised neutron matter to be an almost non-interacting Fermi gas. To understand the cooling of neutron stars neutron pairing is of great importance. Due to the high densities especially triplet pairing is of interest. We

The Los Alamos Neutron Science Center Spallation Neutron Sources

International Nuclear Information System (INIS)

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

2017-01-01

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutrons are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ~100 keV. The characteristics of these sources

The Los Alamos Neutron Science Center Spallation Neutron Sources

Science.gov (United States)

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutrons are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ∼100 keV. The characteristics of these sources, and

Workshop on polarized neutron filters and polarized pulsed neutron experiments

International Nuclear Information System (INIS)

Itoh, Shinichi

2004-07-01

The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

Neutron matter, symmetry energy and neutron stars

Energy Technology Data Exchange (ETDEWEB)

Stefano, Gandolfi [Los Alamos National Laboratory (LANL); Steiner, Andrew W [ORNL

2016-01-01

Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

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

Science.gov (United States)

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

2014-12-01

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

Toenail elemental analysis of Korean young adults by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Lee, O.

2016-01-01

The element contents in toenail clippings of healthy Korean young adults were measured using an instrumental neutron activation analysis. The average contents of elements such as Na, K, Cl, Ca, Fe, Se, and Zn are 449, 474, 1024, 1677, 66, 0.7 and 94 mg/kg in men, whereas those contents in women respectively 332, 476, 836, 1097, 66, 0.8 and 104 mg/kg. The correlation analysis of toenail elements with chronic disease risks showed positive associations between Na and serum HDL-cholesterol, blood pressure, and negative associations between Se and Hs-CRP, between Zn and hemoglobin level. (author)

Fail-safe neutron shutter used for thermal neutron radiography

International Nuclear Information System (INIS)

Sachs, R.D.; Morris, R.A.

1976-11-01

A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons [neutron flux = 3.876 x 10 6 (neutrons)/(cm 2 .s)]. Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available

Measurement of the high-energy neutron flux on the surface of the natural uranium target assembly QUINTA irradiated by deuterons of 4- and 8-GeV energy

International Nuclear Information System (INIS)

Adam, J.; Baldin, A.A.; Chilap, V.

2014-01-01

Experiments with a natural uranium target assembly QUINTA exposed to 4- and 8 GeV deuteron beams of the Nuclotron accelerator at the Joint Institute for Nuclear Research (Dubna) are analyzed. The 129 I, 232 Th, 233 U, 235 U, nat U, 237 Np, 238 Pu, 239 Pu and 241 Am radioactive samples were installed on the surface of the QUINTA set-up and irradiated with secondary neutrons. The neutron flux through the RA samples was monitored by Al foils. The reaction rates of 27 Al(n, y 1 ) 24 Na, 27 Al(n, y 2 ) 22 Na and 27 Al(n, y 3 ) 7 Be reactions with the effective threshold energies of 5, 27 and 119 MeV were measured at both 4- and 8-GeV deuteron beam energies. The average neutron fluxes between the effective threshold energies and the effective ends of the neutron spectra (which are 800 or 1000 MeV for energy of 4- or 8-GeV deuterons) were determined. The evidence for the intensity shift of the neutron spectra to higher neutron energies with the increase of the deuteron energy from 4 to 8 GeV was found from the ratios of the average neutron fluxes. The reaction rates and the average neutron fluxes were calculated with MCNPX2.7 and MARS15 codes.

Photofission of {sup NAT} Pt by monochromatic and polarized photons in the quasi-deuteron region; Fotofissao da {sup NAT} Pt por fotons monocromaticos e polarizados na regiao do quase-deuteron

Energy Technology Data Exchange (ETDEWEB)

Paiva, Eduardo de

1992-01-01

The measurement of the Nat Pt photofission yield at 69 MeV of effective average energy of the incident photon is made using a polarized and monochromatic photon beam from the LADON system of the National Laboratory of Frascati, Italy, produced by inverse Compton scattering of laser light by high energy electrons of the ADONE Accelerator and using as fission track solid detector the Makrofol, being the developing made by usual procedure. The experimental value of the nuclear fissionability is compared to a theoretical value obtained following a model at two stages: in the first, the photon energy is absorbed by a neutron-proton pair inducing to the nucleus excitation, and in the second the nucleus de-excites due to the competition between nucleon evaporation and fission. The effect of fast nucleon emission during the first stage and the successive evaporation of neutrons in the second stage are considered. 40 refs, 12 figs, 9 tabs.

Absolute calibration system of neutron sources by the manganese sulphate bath

International Nuclear Information System (INIS)

Fonseca, E.S. da; Sachett, I.A.

1990-01-01

The calibration system consists of deep the neutron source, protected by plastic container, at the center of spherical polietilene tank, in a concentrated solution of manganese sulphate. The neutrons emitted by the source are moderated and when reach the termal energy are catched by manganese atoms activating the solution. After the saturation activity has been reached the source is removed and one scintilation detector (NaI(Tl) 3' x 3') is put in the same place to follow the decay activity. The gama couting rate (845 KeV 54 Mn photopeak), after the corrections is used to estimate the saturation activity, and calculate the neutron source emission rate. These calculations are executed by one computer program. The uncertainties in the final value of emission rate are about 2.5 - 3.0 % to AmBe sources in the 1.11 x 10 10 Bq (0,3 Ci) - 3.7 x 10 11 Bq (10 Ci) range. (author) [pt

Neutron reflectometry studies of aluminum–saline water interface under hydrostatic pressure

International Nuclear Information System (INIS)

Junghans, A.; Chellappa, R.; Wang, P.; Majewski, J.; Luciano, G.; Marcelli, R.; Proietti, E.

2015-01-01

Highlights: • We investigated corrosion of aluminum via neutron reflectometry. • The hypothesis of an effect on corrosion due to hydrostatic pressure is confirmed. • The speed of corrosion is lower in the early stage compared to results found in the literature. • Nature of the corrosion compounds is investigated. - Abstract: The structural stability of Al layers in contact with 3.5 wt.% NaCl water solution was investigated at a temperature of 25 °C and hydrostatic pressures from 1 to 600 atm using neutron reflectometry. A pressure–temperature (P–T) Neutron Reflectometry (NR) cell developed at Los Alamos National Laboratory (LANL) was used to understand the behavior of thin (∼900 Å) aluminum layers in contact with saline liquid. Experimental results suggest that in the preliminary stages of corrosion the influence of pressure accelerates the mechanism of interactions of the oxide film with Cl − and H 2 O with lower speed compared to results found in the literature

Characterization of Brazilian commercial milks by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Santos, L.G.C.; De Nadai Fernandes, E.A.; Tagliaferro, F.S.; Bacchi, M.A.

2008-01-01

Aiming at the determination of toxic and essential elements in Brazilian commercial bovine milk, 25 ultra high temperature (UHT) milk samples were acquired in the local market of Piracicaba, SP. The samples were freeze-dried and analyzed by instrumental neutron activation analysis (INAA) allowing the determination of Br, Ca, Co, Cs, Fe, K, Na, Rb and Zn. When the results were expressed as concentration (mg x l -1 ) no significant differences were found. However, considering the dry matter, results showed a clear difference between the mass fractions (mg x kg -1 d.w.) of skim milk and whole milk for the elements Br, Ca, K, Na, Rb and Zn, indicating that the removal of fat caused a concentration effect in the dry matter of skim milks. Discrepancies were found between the concentrations of Ca and Na measured by INAA and the values informed in the labels. Ca showed variations within 30% for most samples, while concentrations of Na were up to 190% higher than informed values. The sample preparation and the INAA procedure were appropriate for the determination of Br, Ca, Co, Cs, Fe, K, Na, Rb and Zn in milk samples. (author)

Extraction of the neutron-neutron scattering length ann from kinematically complete neutron-deuteron breakup experiments

International Nuclear Information System (INIS)

Witala, H.; Hueber, D.; Gloeckle, W.; Tornow, W.; Gonzalez Trotter, D.E.

1996-01-01

Data for the neutron-neutron final-state-interaction cross section obtained recently in a kinematically complete neutron-deuteron breakup experiment have been reanalyzed using rigorous solutions of the three-nucleon Faddeev equations with realistic nucleon-nucleon interactions. A discrepancy was found with respect to a recent analysis based on the W-matrix approximation to the Paris potential. We also estimate theoretical uncertainties in extracting the neutron-neutron scattering length resulting from the use of different nucleon-nucleon interactions and the possible action of the two pion-exchange three-nucleon force. We find that there exists a certain production angle for the interacting neutron-neutron pair where the uncertainties become minimal. (author)

Neutron Absorbing Ability Variation in Neutron Absorbing Material Caused by the Neutron Irradiation in Spent Fuel Storage Facility

Energy Technology Data Exchange (ETDEWEB)

Sohn, Hee Dong; Han, Seul Gi; Lee, Sang Dong; Kim, Ki Hong; Ryu, Eag Hyang; Park, Hwa Gyu [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

2014-10-15

In spent fuel storage facility like high density spent fuel storage racks and dry storage casks, spent fuels are stored with neutron absorbing materials installed as a part of those facilities, and they are used for absorbing neutrons emitted from spent fuels. Usually structural material with neutron absorbing material of racks and casks are located around spent fuels, so it is irradiated by neutrons for long time. Neutron absorbing ability could be changed by the variation of nuclide composition in neutron absorbing material caused by the irradiation of neutrons. So, neutron absorbing materials are continuously faced with spent fuels with boric acid solution or inert gas environment. Major nuclides in neutron absorbing material are Al{sup 27}, C{sup 12}, B{sup 11}, B{sup 10} and they are changed to numerous other ones as radioactive decay or neutron absorption reaction. The B{sup 10} content in neutron absorbing material dominates the neutron absorbing ability, so, the variation of nuclide composition including the decrease of B{sup 10} content is the critical factor on neutron absorbing ability. In this study, neutron flux in spent fuel, the activation of neutron absorbing material and the variation of nuclide composition are calculated. And, the minimum neutron flux causing the decrease of B{sup 10} content is calculated in spent fuel storage facility. Finally, the variation of neutron multiplication factor is identified according to the one of B{sup 10} content in neutron absorbing material. The minimum neutron flux to impact the neutron absorbing ability is 10{sup 10} order, however, usual neutron flux from spent fuel is 10{sup 8} order. Therefore, even though neutron absorbing material is irradiated for over 40 years, B{sup 10} content is little decreased, so, initial neutron absorbing ability could be kept continuously.

Neutron optics using transverse field neutron spin echo method

International Nuclear Information System (INIS)

Achiwa, Norio; Hino, Masahiro; Yamauchi, Yoshihiro; Takakura, Hiroyuki; Tasaki, Seiji; Akiyoshi, Tsunekazu; Ebisawa, Toru.

1993-01-01

A neutron spin echo (NSE) spectrometer with perpendicular magnetic field to the neutron scattering plane, using an iron yoke type electro-magnet has been developed. A combination of cold neutron guider, supermirror neutron polarizer of double reflection type and supermirror neutron analyser was adopted for the spectrometer. The first application of the NSE spectrometer to neutron optics by passing Larmor precessing neutrons through gas, solid and liquid materials of several different lengths which are inserted in one of the precession field have been examined. Preliminary NSE spectra of this sample geometry are discussed. (author)

The low-temperature structural behavior of sodium 1-carba-closo-decaborate: NaCB{sub 9}H{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Wu, Hui, E-mail: hui.wu@nist.gov [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Tang, Wan Si [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Zhou, Wei [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Tarver, Jacob D. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); National Renewable Energy Laboratory, Golden, CO 80401 (United States); Stavila, Vitalie [Energy Nanomaterials, Sandia National Laboratories, Livermore, CA 94551 (United States); Brown, Craig M. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Udovic, Terrence J., E-mail: udovic@nist.gov [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States)

2016-11-15

Two ordered phases of the novel solid superionic conductor sodium 1-carba-closo-decaborate (NaCB{sub 9}H{sub 10}) were identified via synchrotron x-ray powder diffraction in combination with first-principles calculations and neutron vibrational spectroscopy. A monoclinic packing of the large ellipsoidal CB{sub 9}H{sub 10}{sup −} anions prevails at the lowest temperatures, but a first-order transformation to a slightly modified orthorhombic packing is largely complete by 240 K. The CB{sub 9}H{sub 10}{sup −} anion orientational alignments and Na{sup +} cation interstitial sitings in both phases are arranged so as to minimize the cation proximities to the uniquely more positive C-bonded H atoms of the anions. These results provide valuable structural information pertinent to understanding the relatively low-temperature, entropy-driven, order-disorder phase transition for this compound. - Graphical abstract: Ordered monoclinic and orthorhombic NaCB{sub 9}H{sub 10} phases were determined by XRD and DFT computations and corroborated by neutron vibrational spectroscopy. - Highlights: • Two T-dependent ordered structures of Na(1-CB{sub 9}H{sub 10}) were determined by XRD. • The lower-T monoclinic to higher-T orthorhombic transition occurs from 210 to 240 K. • The main structural differences involve changes in the canting of the CB{sub 9}H{sub 10}{sup −} anions. • DFT and neutron vibrational spectroscopy corroborate the lower-T monoclinic structure. • The results are important for understanding the nature of this superionic conductor.

Measuring the energies and multiplicities of prompt gamma-ray emissions from neutron-induced fission of $^{235}$U using the STEFF spectrometer

CERN Document Server

AUTHOR|(CDS)2093036; Smith, Alastair Gavin; Wright, Tobias James

Following a NEA high priority nuclear data request, an experimental campaign to measure the prompt $\\gamma$-ray emissions from $^{235}$U has been performed. This has used the STEFF spectrometer at the new Experimental Area 2 (EAR2) within the neutron timeof-flight facility (n_TOF), a white neutron source facility at CERN with energies from thermal to approximately 1 GeV. Prior to the experimental campaign, STEFF has been optimised for the environment of EAR2. The experimental hall features a high background $\\gamma$-ray rate, due to the nature of the spallation neutron source. Thus an investigation into reduction of the background $\\gamma$-ray rate, encountered by the NaI(Tl) detector array of STEFF, has been carried out. This has been via simulations using the simulation package FLUKA. Various materials and shielding geometries have been investigated but the effects determined to be insufficient in reducing the background rate by a meaningful amount. The NaI(Tl) detectors have been modified to improve their ...

A study on cigarette tobacco by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Md Soot Haji Ahmad; Tey Nsan Yen

1987-01-01

The concentration of 25 elements in cigarette tobacco of popular brands locally marketed were determined using instrumental neutron activation analysis. These elements are: Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, Hg, K, La, Mg, Mn, Na, Rb, Sb, Sc, Se, Sr, Th, and Zn. Comparison of the element contents to the reported cigarette tobacco of Egypt, Iran and Turkey was also done. (author)

Determination of some elements present in black pepper by thermal neutron activation analysis. [/sup 124/Sb-Be neutron source

Energy Technology Data Exchange (ETDEWEB)

Chacharkar, M P; Vaidya, M M; Ray, M N [Nagpur Univ. (India). Dept. of Chemistry

1981-01-01

An analysis for the determination of some elements present in black pepper was carried out using low level isotopic neutron source. Gamma-ray spectra of the irradiated samples showed only one peak at 0.85 MeV. The decay curves, on the other hand exhibited the presence of at least two radioactive nuclides of halflives 2.6 h and 15 h which correspond to the halflives of /sup 56/Mn and /sup 24/Na respectively. The amount of Mn present was also determined. The results are confirmed by other physicochemical methods. 6 refs.

The distinction between chondroma and chondrosarcoma using chemical element mass fractions in tumors determined by neutron activation analysis as diagnostic markers

International Nuclear Information System (INIS)

Zaichick, Vladimir; Zaichick, Sofia

2016-01-01

The Ca, Cl, Mg, Na, and P content and Ca/P, Ca/Mg, Ca/Na, Cl/Ca, and Cl/Na ratios in tissue of intact bone, chondroma and chondrosarcoma were investigated by neutron activation analysis. It was shown that higher mass fraction of Cl and Na and also Cl/Na mass fraction ratio as well as lower Ca/Cl and Ca/Na mass fraction ratios are typical of the chondrosarcoma tissue compared to chondroma. Finally, it was proposed to use the estimation of such parameters as the Cl mass fraction and the Ca/Cl and Ca/Na mass fraction ratios as an additional test for differential diagnosis between chondroma and chondrosarcoma. (author)

Neutron and Gamma Imaging for National Security Applications

Science.gov (United States)

Hornback, Donald

2017-09-01

The Department of Energy, National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D/NA-22) possesses, in part, the mission to develop technologies in support of nuclear security efforts in coordination with other U.S. government entities, such as the Department of Defense and the Department of Homeland Security. DNN R&D has long supported research in nuclear detection at national labs, universities, and through the small business innovation research (SBIR) program. Research topics supported include advanced detector materials and electronics, detection algorithm development, and advanced gamma/neutron detection systems. Neutron and gamma imaging, defined as the directional detection of radiation as opposed to radiography, provides advanced detection capabilities for the NNSA mission in areas of emergency response, international safeguards, and nuclear arms control treaty monitoring and verification. A technical and programmatic overview of efforts in this field of research will be summarized.

Neutron radiography

International Nuclear Information System (INIS)

Hiraoka, Eiichi

1988-01-01

The thermal neutron absorption coefficient is essentially different from the X-ray absorption coefficient. Each substance has a characteristic absorption coefficient regardless of its density. Neutron deams have the following features: (1) neutrons are not transmitted efficiently by low molecular weight substances, (2) they are transmitted efficiently by heavy metals, and (3) the transmittance differs among isotopes. Thus, neutron beams are suitable for cheking for foreign matters in heavy metals and testing of composites consisting of both heavy and light materials. A neutron source generates fast neutrons, which should be converted into thermal neutrons by reducing their energy. Major neutron souces include nuclear reactors, radioisotopes and particle accelerators. Photographic films and television systems are mainly used to observe neutron transmission images. Computers are employed for image processing, computerized tomography and three-dimensional analysis. The major applications of neutron radiography include inspection of neclear fuel; evaluation of material for airplane; observation of fuel in the engine and oil in the hydraulic systems in airplanes; testing of composite materials; etc. (Nogami, K.)

A novel track density measurement method by thermal neutron activation of DYECETs

International Nuclear Information System (INIS)

Sohrabi, M.; Mahdi, Sh.

1995-01-01

A novel track density evaluation method based on thermal neutron activation of some elements of dyed electrochemically etched tracks (DYECETs) of charged particles in detectors like polycarbonate (PC) followed by measurements of gamma activity of the activated detectors is introduced. In this method, the tracks of charged particles like fast neutron-induced recoils in PC detectors were electrochemically etched, dyed by ''QuicDYECET'' methods as recently introduced by us, activated by thermal neutrons and counted for gamma activity determination to be correlated with track density. The activities of elements such as bromine-82 ( 82 Br) and sodium-24 ( 24 Na) on dyes such as Eosin Yellowish, Eosin Bluish, etc. determined by a hyper-pure germanium detector, were found to be in good correlation with DYECET density and thus particle fluence or dose. The effects of different types of dyes and their elements, dye concentration, neutron fluences and ECE durations on the DYECET density responses were studied. This new development is a method of scientific interest, potentially possessing some interesting features, as an alternative method for ECE track density determination using a gamma activity measuring system. It also has the drawback of being applicable only in centres having thermal neutron facilities. The results of the above studies are presented and discussed. (Author)

More accurate thermal neutron coincidence counting technique

International Nuclear Information System (INIS)

Baron, N.

1978-01-01

Using passive thermal neutron coincidence counting techniques, the accuracy of nondestructive assays of fertile material can be improved significantly using a two-ring detector. It was shown how the use of a function of the coincidence count rate ring-ratio can provide a detector response rate that is independent of variations in neutron detection efficiency caused by varying sample moderation. Furthermore, the correction for multiplication caused by SF- and (α,n)-neutrons is shown to be separable into the product of a function of the effective mass of 240 Pu (plutonium correction) and a function of the (α,n) reaction probability (matrix correction). The matrix correction is described by a function of the singles count rate ring-ratio. This correction factor is empirically observed to be identical for any combination of PuO 2 powder and matrix materials SiO 2 and MgO because of the similar relation of the (α,n)-Q value and (α,n)-reaction cross section among these matrix nuclei. However the matrix correction expression is expected to be different for matrix materials such as Na, Al, and/or Li. Nevertheless, it should be recognized that for comparison measurements among samples of similar matrix content, it is expected that some function of the singles count rate ring-ratio can be defined to account for variations in the matrix correction due to differences in the intimacy of mixture among the samples. Furthermore the magnitude of this singles count rate ring-ratio serves to identify the contaminant generating the (α,n)-neutrons. Such information is useful in process control

Estimation of covariances of {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U and {sup 239}Pu neutron nuclear data in JENDL-3.2

Energy Technology Data Exchange (ETDEWEB)

Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Nakajima, Yutaka; Kawano, Toshihiko; Oh, Soo-Youl; Matsunobu, Hiroyuki; Murata, Toru

1997-10-01

Covariances of nuclear data have been estimated for 6 nuclides contained in JENDL-3.2. The nuclides considered are {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U, and {sup 239}Pu, which are regarded as important for the nuclear design study of fast reactors. The physical quantities for which covariances are deduced are cross sections, resolved and unresolved resonance parameters, and the first order Legendre-polynomial coefficient for the angular distribution of elastically scattered neutrons. As for {sup 235}U, covariances were obtained also for the average number of neutrons emitted in fission. The covariances were estimated by using the same methodology that had been used in the JENDL-3.2 evaluation in order to keep a consistency between mean values and their covariances. The least-squares fitting code GMA was used in estimating covariances for reactions of which JENDL-3.2 cross sections had been evaluated by taking account of measurements. In nuclear model calculations, the covariances were calculated by the KALMAN system. The covariance data obtained were compiled in the ENDF-6 format, and will be put into the JENDL-3.2 Covariance File which is one of JENDL special purpose files. (author). 193 refs.

Ion conducting behavior in secondary battery materials detected by quasi-elastic neutron scattering measurements

International Nuclear Information System (INIS)

Nozaki, Hiroshi

2014-01-01

Ionic conducting behaviors in secondary battery materials, i.e. cathode and solid electrolyte, were studied with quasi-elastic neutron scattering (QENS) measurements. Although the incoherent scattering length for Li and Na is lower by two orders of magnitude than that for H, the QENS spectra were clearly detected using the combination of an intense neutron source and a low background spectrometer. The fundamental parameters, such as, the activation energy, the jump distance, and the diffusion coefficient were obtained by analyzing QENS spectra. These parameters are consistent with the previous results estimated by muon-spin relaxation (μSR) measurements and first principles calculations. (author)

In vivo measurements of nitrogen using a neutron activation technique

International Nuclear Information System (INIS)

Larsson, L.; Alpsten, M.; Toelli, J.; Drugge, N.; Mattsson, S.

1986-01-01

Knowledge of body composition is essential for understanding of many diseases such as obesity, anorexia, cancer, kidney and heart diseases. For many years, total body potassium (TBK) has been used as an estimate of the intracellular protein. In some diseases intracellular- and extracellular protein may vary significantly. Together with TBK, total body nitrogen (TBN) should in these cases be measured to estimate the total protein content. The nitrogen content can be measured by in vivo neutron activation. In this work the authors have used the prompt gamma technique: Thermalized neutrons from a Cf-252-source are captured in (n, δ)-reactions. Prompt 10.8 MeV photons are emitted and can be detected during irradiation. The source is contained in a polyethylene block which forms a collimator surrounded by a phi 1.40 m x 0.80 m water tank. The patient is irradiated from below by a 15 cm x 50 cm neutron field. It is possible to scan the whole patient or to measure a part of the body. A phi 15 cm x 15 cm NaI(T1)-detector is used for detection of the 10.8 MeV photons. The detector is mounted above the patient outside the neutron field

Improvement of Sodium Neutronic Nuclear Data for the Computation of Generation IV Reactors

International Nuclear Information System (INIS)

Archier, P.

2011-01-01

The safety criteria to be met for Generation IV sodium fast reactors (SFR) require reduced and mastered uncertainties on neutronic quantities of interest. Part of these uncertainties come from nuclear data and, in the particular case of SFR, from sodium nuclear data, which show significant differences between available international libraries (JEFF-3.1.1, ENDF/B-VII.0, JENDL-4.0). The objective of this work is to improve the knowledge on sodium nuclear data for a better calculation of SFR neutronic parameters and reliable associated uncertainties. After an overview of existing 23 Na data, the impact of the differences is quantified, particularly on sodium void reactivity effects, with both deterministic and stochastic neutronic codes. Results show that it is necessary to completely re-evaluate sodium nuclear data. Several developments have been made in the evaluation code Conrad, to integrate new nuclear reactions models and their associated parameters and to perform adjustments with integral measurements. Following these developments, the analysis of differential data and the experimental uncertainties propagation have been performed with Conrad. The resolved resonances range has been extended up to 2 MeV and the continuum range begins directly beyond this energy. A new 23 Na evaluation and the associated multigroup covariances matrices were generated for future uncertainties calculations. The last part of this work focuses on the sodium void integral data feedback, using methods of integral data assimilation to reduce the uncertainties on sodium cross sections. This work ends with uncertainty calculations for industrial-like SFR, which show an improved prediction of their neutronic parameters with the new evaluation. (author) [fr

Neutron Dosimetry

International Nuclear Information System (INIS)

Vanhavere, F.

2001-01-01

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

Instrumental neutron activation analysis of brewer's yeast

International Nuclear Information System (INIS)

Bergerioux, C.; Zikovsky, L.

1978-01-01

Instrumental neutron activation was used for the determination of 23 trace and minor elements in 4 different samples of brewer's yeast. Detection limits vary from 2 ppb to 100 ppm. The following average concentrations were found (ppm, dry weight): Al 597, Br 0.36, Cl 1473, Co 0.21, Cu 19, Fe 285, K 16400, Mg 1355, Mn 8.4, Na 2330, Rb 19, Sb 0.053, Se 1.2, V 2.2 and Zn 80. NBS standard 1569 was also analyzed and the following concentrations (in ppm) were measured: Al 2300, Br 0.65, Ce 0.23, Cl 460, Co 0.26, Cr 2.12, Cu 11, Fe 707, Gd 7.1, Hf 0.13, K 15500, Mg 1780, Mn 7, Na 510, Rb 16, Sb 0.075, Sc 0.18, Se 0.92, Th 3.7, Ti 38, U 0.49, V 4.1 and Zn 70. (author)

Neutron and x-ray scattering studies of ferroelectric phase transitions

International Nuclear Information System (INIS)

Dolling, G.

1982-08-01

The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students

Formation properties from high resolution neutron activation gamma-ray spectra

International Nuclear Information System (INIS)

Mellor, D.W.; Underwood, M.C.

1985-01-01

A neutron activation logging tool has been developed comprising a Five Curie /sup 241/ Am-Be neutron source and a large n-type hyper-pure germanium gamma-ray detector. The tool maintains a constant temperature cryogenic environment for periods in excess of twenty hours. No liquid nitrogen or other consumable material is used in the operating or recharging stages. A large calibration tank in simulated well-bore geometry has been constructed with sand bodies saturated with oil and low salinity water (14,000 ppm NaCl). In the water zone prompt neutron capture gamma-rays from silicon, hydrogen and chlorine were prominent; gamma-rays from inelastic scattering on oxygen and silicon were detected. No gamma-rays arising from inelastic scattering on carbon were detected. These data have been interpreted to yield the porosity, fluid saturations, salinity and matrix composition. In the oil zone, gamma-rays arising from inelastic scattering on oxygen, silicon and carbon were detected. The intensity of the carbon line was very poor, and inadequate for quantitative purposes

Neutron activation analysis of medullar and cortical bone tissues from animals

International Nuclear Information System (INIS)

Takata, Marcelo Kazuo; Saiki, Mitiko

2000-01-01

In this work, neutron activation analysis was applied in the determination of the elements Ba, Br, Ca, Cl, Cr, Fe, K, Mg, Mn, Na, P, Rb, Sb, Sc, Sr and Zn present in animal bone tissues. The obtained results indicated a significant difference between the elemental concentrations present in medullar and cortical tissues. The results obtained for bone tissues from distinct animal species were also different. (author)

Neutron Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Vanhavere, F

2001-04-01

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

Neutron activation determination of impurities in molybdenite and galena

International Nuclear Information System (INIS)

Blinov, V.A.; Gavrilov, V.M.; Zherekhov, V.G.; Egorov, Yu.E.; Krivokhatskij, A.S.

1975-01-01

A method is described for non-destructive neutron-activation determination of 14 chemical elements (Na, Ag, Zn, Sc, La, Eu, Tb, Yb, Sb, Ta, Gr, Se, Fe and Co) in molybdenite and galenite minerals. The samples and standards of Ag, Se, Co and Np have been wrapped in an aluminium foil and packed in an aluminium container; they have been then irradiated for 10 hr in the vertical channel of a nuclear reactor with flux of thermal neutrons (3.0, 0.45)x10 13 n/cm 2 xsec to record the γ-spectra of the samples and standards 1, 5, 16, 65, 265 and 350 days after irradiation on a γ-spectrometer with a Ge(Li)-detector. The results are found to be in a good agreement with the spectra of Ag, Sb, La and Fe

Determination of sodium in pharmaceuticals by neutron activation analysis

International Nuclear Information System (INIS)

Kanias, G.D.

1985-01-01

A simple, fast and accurate neutron activation analysis method for determination of Na in drugs concerning either active compound or total content was developed. The examined dosage forms consisted of 10 injectable ampoules and 10 bottles of oral solutions. The irradiation of samples and standards was carried out in the rotation system of the Reactor of Nuclear Research Center Democritos with maximal neutron flux of 2,9.10 13 n.cm -2 .sec -1 . Gamma-ray spectrometry of the irradiated samples and standards was accomplished with a coaxial Ge(Li) detector series Win 15 with an efficiency of 15% connected to an Ino-Tech 1024 channel analyser (Model IT 5200). The accuracy and precision of the method are found to be very high and therefore it could be established as an official one for the determination of sodium in parmaceuticals

Neutron activation analysis at the 'Instituto de Pesquisas Energeticas e Nucleares' (SP, Brazil)

International Nuclear Information System (INIS)

Vasconcellos, M.B.A.

1984-01-01

A review of the work carried out at IPEN using neutron activation analysis is made. The main characteristics of the technique and general experimental procedures applied for different samples and elements are reported. Geological samples were analysed by using activation with thermal, epithermal and delayed neutrons (for U and Th, specifically). Metallic samples were analysed for several elements in trace amounts (Ta in Nb, Hg in steel, Sn, Sb, As, Cu, Cr and Ag in a tin-lead alloy). Biological materials, such as tomatoes, animal and human viscera, food, hair, nails were also analysed for several components (Hg, Na, K, As, Au and others). (Author) [pt

The Idaho Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNCT) Program overview

International Nuclear Information System (INIS)

Dorn, R.V. III; Griebenow, M.L.; Ackermann, A.L.; Miller, L.G.; Miller, D.L.; Wheeler, F.J.; Bradshaw, K.M.; Wessol, D.E.; Harker, Y.D.; Nigg, D.W.; Randolph, P.D.; Bauer, W.F.; Gavin, P.R.; Richards, T.L.

1992-01-01

The Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNCT) Program has been funded since 1988 to evaluate brain tumor treatment using Na 2 B 12 H 11 SH (borocaptate sodium or BSH) and epithermal neutrons. The PBF/BNCT Program pursues this goal as a comprehensive, multidisciplinary, multiorganizational endeavor applying modern program management techniques. The initial focus was to: (1) establish a representative large animal model and (2) develop the generic analytical and measurement capabilities require to control treatment repeatability and determine critical treatment parameters independent of tumor type and body location. This paper will identify the PBF/BNCT Program elements and summarize the status of some of the developed capabilities

Theoretical and experimental cross sections for neutron reactions on 64Zinc

International Nuclear Information System (INIS)

Rutherford, D.A.

1987-01-01

Accurate measurements of the 64 Zn (n,2n) 64 Cu and 64 Zn (n,p) 63 Zn cross sections at 14.8 MeV have been made using a Texas Nuclear Neutron Generator and the activation technique. A NaI(T1) spectrometer (using two 6'' x 6'' NaI detectors/crystals) was used to measure the gamma radiation emitted in coincidence from the positron-emitting decay products. The measurements were made relative to 65 Cu (n,2n) /64/Cu and 63 Cu (n,2n) 62 Cu cross sections, which have similar half-lives, radiation emission, and were previously measured to high accuracy (2 percent). The value obtained for the (n,2n) measurement was 199 /+-/ 6 millibarns, and a value of 176 /+-/ 4.5 millibarns was obtained for the (n,p) measurement. In concert, a theoretical analysis of neutron induced reactions on /64/Zn was performed at Los Alamos National Laboratory using the Hauser-Feshbach statistical theory in the GNASH code over an energy range of 100 keV to 20 MeV. Calculations included width fluctuation corrections, direct reaction contributions, and preequilibrium corrections above 6 MeV. Neutron optical model potentials were determined for zinc. The theoretical values agree with the new 14.8 MeV measurements approximately within experimental error, with calculations of 201 millibarns for the (n,2n) cross section and 170 millibarns for the (n,p) cross section. Results from the analysis will be made available in National Evaluated Nuclear Data Format (ENDF/B) for fusion energy applications. 50 refs., 34 figs., 10 tabs

Neutronic analysis of JET external neutron monitor response

Energy Technology Data Exchange (ETDEWEB)

Snoj, Luka, E-mail: luka.snoj@ijs.si [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Lengar, Igor; Čufar, Aljaž [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Syme, Brian; Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom (United Kingdom); Batistoni, Paola [ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Conroy, Sean [VR Association, Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden)

2016-11-01

Highlights: • We model JET tokamak containing JET remote handling system. • We investigate effect of remote handling system on external neutron monitor response. • Remote handling system correction factors are calculated. • Integral correction factors are relatively small, i.e up to 8%. - Abstract: The power output of fusion devices is measured in terms of the neutron yield which relates directly to the fusion yield. JET made a transition from Carbon wall to ITER-Like Wall (Beryllium/Tungsten/Carbon) during 2010–11. Absolutely calibrated measurement of the neutron yield by JET neutron monitors was ensured by direct measurements using a calibrated {sup 252}Cf neutron source (NS) deployed by the in-vessel remote handling system (RHS) inside the JET vacuum vessel. Neutronic calculations were required in order to understand the neutron transport from the source in the vacuum vessel to the fission chamber detectors mounted outside the vessel on the transformer limbs of the tokamak. We developed a simplified computational model of JET and the JET RHS in Monte Carlo neutron transport code MCNP and analyzed the paths and structures through which neutrons reach the detectors and the effect of the JET RHS on the neutron monitor response. In addition we performed several sensitivity studies of the effect of substantial massive structures blocking the ports on the external neutron monitor response. As the simplified model provided a qualitative picture of the process only, some calculations were repeated using a more detailed full 3D model of the JET tokamak.

Precision mass measurements of very short-lived, neutron-rich Na isotopes using a radiofrequency spectrometer

CERN Document Server

Lunney, M D; Doubre, H; Henry, S; Monsanglant, C; De Saint-Simon, M; Thibault, C; Toader, C F; Borcea, C; Bollen, G

2001-01-01

Mass measurements of high precision have been performed on sodium isotopes out to $^{30}$Na using a new technique of radiofrequency excitation of ion trajectories in a homogeneous magnetic field. This method, especially suited to very short-lived nuclides, has allowed us to significantly reduce the uncertainty in mass of the most exotic Na isotopes: a relative error of 5x10$^{-7}$ was achieved for $^{28}$Na having a half-life of only 30.5 ms and 9x10$^{-7}$ for the weakly produced $^{30}$Na. Verifying and minimizing binding energy uncertainties in this region of the nuclear chart is important for clarification of a long standing problem concerning the strength of the $N$=20 magic shell closure. These results are the fruit of the commissioning of the new experimental program Mistral.

Investigation of Response of Several Neutron Surveymeters by a DT Neutron Generator

International Nuclear Information System (INIS)

Kim, Sang In; Jang, In Su; Kim, Jang Lyul; Lee, Jung IL; Kim, Bong Hwan

2012-01-01

Several neutron measuring devices were tested under the neutron fields characterized with two distinct kinds of thermal and fast neutron spectrum. These neutron fields were constructed by the mixing of both thermal neutron fields and fast neutron fields. The thermal neutron field was constructed using by a graphite pile with eight AmBe neutron sources. The fast neutron field of 14 MeV was made by a DT neutron generator. In order to change the fraction of fast neutron fluence rate in each neutron fields, a neutron generator was placed in the thermal neutron field at 50 cm and 150 cm from the reference position. The polyethylene neutron collimator was used to make moderated 14 MeV neutron field. These neutron spectra were measured by using a Bonner sphere system with an LiI scintillator, and dosimetric quantities delivered to neutron surveymeters were determined from these measurement results.

Instrumental neutron activation analysis of wheat bunt spores

Energy Technology Data Exchange (ETDEWEB)

Liu, Y G; Schmitt, R A [Oregon State Univ., Corvallis (USA). Dept. of Chemistry; Oregon State Univ., Corvallis (USA). Radiation Center); Trione, E J [Oregon State Univ., Corvallis (USA). Dept. of Botany; Laul, J C [Battelle Pacific Northwest Labs., Richland, WA (USA)

1982-01-01

The concentrations of seventeen elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Zn, Br, Rb, La, Sm) in two species of fungus which cause wheat bunt disease, Tilletia caries (DC.) Tul. and Tilletia controversa Kuehn, were determined by instrumental neutron activation analysis. A standard sequential INAA procedure was used. Differences in the K and Cl concentrations between these two species of spores are large and therefore can be used as a criterion of distinguishing between the two species of fungus.

Analysis of oxygen content in steel by means of 14 MeV neutrons

International Nuclear Information System (INIS)

Chuang, L.S.; Wong, K.C.; Chiu, W.Y.

1975-01-01

A sealed-tube type 14 MeV neutron generator with maximum neutron output of 10 11 n/sec, incorporating a pneumatic sample transfer system of single-tube type and with a single rotation of the sample during neutron irradiation, is used to develop a method suitable for routine work in industrial applications. A pulse shape analyser system incorporating an organic scintillation detector is used for monitoring neutron flux level during the neutron irradiation of the sample. Polyethylene, of oxygen content 163 ppm determined by comparison with lucite, is used as the steel sample carrier. A 3 x 3 in. NaI(Tl) crystal is used with a single channel analyser to count the 6.1 and 7.1 MeV gamma rays emitted from 16 N as a result of the reaction 16 O(n,p) 16 N. As the present activation analysis makes use of the comparison method, a steel-mylar standard made of layered steel and mylar discs is prepared and a calibration curve constructed. A method of correcting the oxygen contribution in the polyethylene sample carrier is devised and the content of oxygen in the steel standard is determined. A survey of neutron flux distribution is also attempted and it is found that nearly symmetrical distribution of the flux, about the centre of the sample carrier which is placed with its axis in parallel to the plane of the disc-shaped target of the neutron-generating tube, is far from being flat. (Auth.)

Epithermal neutron activation analysis using a boron carbide irradiation filter

International Nuclear Information System (INIS)

Ehmann, W.D.; Brueckner, J.

1980-01-01

The use of boron carbide as a thermal neutron filter in epithermal neutron activation (ENAA) analysis has been investigated. As compared to the use of a cadmium filter, boron provides a greater reduction of activities from elements relatively abundant in terrestrial rocks and fossil fuels, such as Na, La, Sc and Fe. These elements have excitation functions which follow the 1/v law in the 1 to 10 eV lower epithermal region. This enhances the sensitivity of ENAA for elements such as U, Th, Ba and etc. which have strong resonances in the higher epithermal region above 10 eV. In addition, a boron carbide filter has the advantages over cadmium of acquiring a relatively low level of induced activity which poses minimal radiation safety problems, when used for ENAA. (author)

Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan

Directory of Open Access Journals (Sweden)

Yoshiaki Kiyanagi

2018-03-01

Full Text Available Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented.

Determination of trace elements in a cigarette paper by neutron activation analysis

International Nuclear Information System (INIS)

Abedinzadeh, Z.; Khalkhali, Zh.; Razeghi, M.; Parsa, B.

The concentration of 19 trace elements in a cigarette paper (Zig-Zag Paper Company, France) which is used in making different brands of Iranian cigarettes, has been measured by neutron activation analysis, employing a high-resolution Ge(Li) detector. They include Na, K, Ca, Sc, Cr, Mn, Fe, Co, Zn, Br, Sr, Sb, Ba, Ce, Eu, Gd, Au, Hg, and Th. (author)

Accelerator based neutron source for neutron capture therapy

International Nuclear Information System (INIS)

Salimov, R.; Bayanov, B.; Belchenko, Yu.; Belov, V.; Davydenko, V.; Donin, A.; Dranichnikov, A.; Ivanov, A.; Kandaurov, I; Kraynov, G.; Krivenko, A.; Kudryavtsev, A.; Kursanov, N.; Savkin, V.; Shirokov, V.; Sorokin, I.; Taskaev, S.; Tiunov, M.

2004-01-01

Full text: The Budker Institute of Nuclear Physics (Novosibirsk) and the Institute of Physics and Power Engineering (Obninsk) have proposed an accelerator based neutron source for neutron capture and fast neutron therapy for hospital. Innovative approach is based upon vacuum insulation tandem accelerator (VITA) and near threshold 7 Li(p,n) 7 Be neutron generation. Pilot accelerator based neutron source for neutron capture therapy is under construction now at the Budker Institute of Nuclear Physics, Novosibirsk, Russia. In the present report, the pilot facility design is presented and discussed. Design features of facility components are discussed. Results of experiments and simulations are presented. Complete experimental tests are planned by the end of the year 2005

Analytical dosimetry for spontaneous tumor dogs receiving boron neutron capture therapy

International Nuclear Information System (INIS)

Wheeler, F.J.; Atkinson, C.A.; Gavin, P.R.

1992-01-01

The dog irradiation project of the Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNCT) Program is administered by Washington State University (WSU) with analytical and physical dosimetry provided by the Idaho National Engineering Laboratory (INEL). One subtask of this project includes BNCT safety studies for dogs with spontaneously-occurring brain tumors. The boron compound (Na 2 B 12 H 11 SH or BSH) was administered and single irradiations performed using the epithermal-neutron beam at the Brookhaven Medical Research Reactor (BMRR). The main goal of the study was not to provide therapy, but to determine tumorcidal effect while administering a subtolerance dose to healthy tissue. Irradiation times were based on delivery of 19 Gy peak physical dose to the blood

Design of hyper-thermal neutron irradiation fields for neutron capture therapy in KUR-heavy water neutron irradiation facility. Mounting of hyper-thermal neutron converter in therapeutic collimator

International Nuclear Information System (INIS)

Sakurai, Y.; Kobayashi, T.

2001-01-01

Neutron capture therapy (NCP) using thermal neutron needs to improve of depth dose distribution in a living body. Epi-thermal neutron following moderation of fast neutron is usually used for improving of the depth dose distribution. The moderation method of fast neutron, however, gets mixed some of high energy neutron which give some of serious effects to a living body, and involves the difficulty for collimation of thermal neutron to the diseased part. Hyper-thermal neutrons, which are in an energy range of 0.1-3 eV at high temperature side of thermal neutron, are under consideration for application to the NCP. The hyper-thermal neutrons can be produced by up-scattering of thermal neutron in a high temperature material. Fast neutron components in collimator for the NCP reduce on application of the up-scattering method. Graphite at high temperature (>1000k) is used as a hyper-thermal neutron converter. The hyper-thermal neutron converter is planted to mount on therapeutic collimator which is located at the nearest side of patient for the NCP. Total neutron flux, ratio of hyper-thermal neutron to total neutron, and ratio of gamma-ray dose to neutron flux are calculated as a function of thickness of the graphite converter using monte carlo code MCNP-V4B. (M. Suetake)

A survey of environmental exposure amongst locoshed workers by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Singh, V.K.N.; Garg, A.N.

1995-01-01

Instrumental neutron activation analysis (INAA) has been used for the determination of 16 elements in hair of locoshed workers (n=10) to study environmental exposure. A comparison of mean elemental contents with control (n=11) shows a significant enhancement for Cr, Th, Ca, Se and Na whereas Br and Sb show a declining trend. (author). 4 refs., 1 tab

A continuously self regenerating high-flux neutron-generator facility

Science.gov (United States)

Rogers, A. M.; Becker, T. A.; Bernstein, L. A.; van Bibber, K.; Bleuel, D. L.; Chen, A. X.; Daub, B. H.; Goldblum, B. L.; Firestone, R. B.; Leung, K.-N.; Renne, P. R.; Waltz, C.

2013-10-01

A facility based on a next-generation, high-flux D-D neutron generator (HFNG) is being constructed at UC Berkeley. The current generator, designed around two RF-driven multicusp deuterium ion sources, is capable of producing a neutron output of >1011 n/s. A specially designed titanium-coated copper target located between the ion sources accelerates D+ ions up to 150 keV, generating 2.45 MeV neutrons through the d(d,3He)n fusion reaction. Deuterium in the target is self loaded and regenerating through ion implantation, enabling stable and continuous long-term operation. The proposed science program is focused on pioneering advances in the 40Ar/39Ar dating technique for geochronology, new nuclear data measurements, basic nuclear science research including statistical model studies of radiative-strength functions and level densities, and education. An overview of the facility and its unique capabilities as well as first measurements from the HFNG commissioning will be presented. Work supported by NSF Grant No. EAR-0960138, U.S. DOE LBL Contract No. DE-AC02-05CH11231, and U.S. DOE LLNL Contract No. DE-AC52-07NA27344.

Evaluation of sodium-23 neutron capture cross section data for the ENDF/B V-III file

International Nuclear Information System (INIS)

Paik, N.C.; Pitterle, T.A.

1975-01-01

The evaluation of neutron cross sections of 23 Na, material number 1156, for the ENDF/B File is described. Cross sections were evaluated between 10 -5 eV and 15 MeV. Experimental data available up to March 1971 were included in the evaluation

The secondary neutron sources for generation of particular neutron fluxes

International Nuclear Information System (INIS)

Tracz, G.

2007-07-01

The foregoing paper presents the doctor's thesis entitled '' The secondary neutron sources for generation of particular neutron fluxes ''. Two secondary neutron sources have been designed, which exploit already existing primary sources emitting neutrons of energies different from the desired ones. The first source is devoted to boron-neutron capture therapy (BNCT). The research reactor MARIA at the Institute of Atomic Energy in Swierk (Poland) is the primary source of the reactor thermal neutrons, while the secondary source should supply epithermal neutrons. The other secondary source is the pulsed source of thermal neutrons that uses fast 14 MeV neutrons from a pulsed generator at the Institute of Nuclear Physics PAN in Krakow (Poland). The physical problems to be solved in the two mentioned cases are different. Namely, in order to devise the BNCT source the initial energy of particles ought to be increased, whilst in the other case the fast neutrons have to be moderated. Slowing down of neutrons is relatively easy since these particles lose energy when they scatter in media; the most effective moderators are the materials which contain light elements (mostly hydrogen). In order to increase the energy of neutrons from thermal to epithermal (the BNCT case) the so-called neutron converter should be exploited. It contains a fissile material, 235 U. The thermal neutrons from the reactor cause fission of uranium and fast neutrons are emitted from the converter. Then fissile neutrons of energy of a few MeV are slowed down to the required epithermal energy range. The design of both secondary sources have been conducted by means of Monte Carlo simulations, which have been carried out using the MCNP code. In the case of the secondary pulsed thermal neutron source, some of the calculated results have been verified experimentally. (author)

A transportable system for the determination of phosphorus in sheep bone by in vivo neutron activation analysis

International Nuclear Information System (INIS)

Whineray, S.; Thomas, B.J.; Ternouth, J.H.; Davies, H.M.S.

1980-01-01

An apparatus was constructed which measures the phosphorus in sheep leg bone, non-invasively, by neutron activation analysis. The results obtained show that with two 10 Ci isotopic neutron sources ( 241 Am/Be or 238 Pu/Be) and a single 7.5 x 7.5 cm NaI(Tl) detector, serial changes in leg bone phosphorus may be determined with a precision of 13% in 15 min of experimental time. This precision could be reduced to 5% by incorporating two large detectors into the system. (author)

Effect of fast-neutron irradiation on the electrical conductivity of NaKSO/sub 4/ crystals

Energy Technology Data Exchange (ETDEWEB)

Kassem, M.E.; El-Khatib, A.M.; El-Wahidy, E.F.; Gado, H.E.

1987-05-01

In recent years, the study of the physical properties of NaKSO/sub 4/ has drawn the attention of many investigators. Measurements on the electrical, thermal and elastic properties of NaKSO/sub 4/ in the temperature range 300 to 500 K show a structural phase transition at 453 K. Electrical conductivity measurements (4) on pure and doped compounds of NaKSO/sub 4/ reveal high ionic conductivity values in the high-temperature range. Order-disorder transitions and solid state kinetics in the same compound were also studied.

Double difference method in deep inelastic neutron scattering on the VESUVIO spectrometer

International Nuclear Information System (INIS)

Andreani, C.; Colognesi, D.; Degiorgi, E.; Filabozzi, A.; Nardone, M.; Pace, E.; Pietropaolo, A.; Senesi, R.

2003-01-01

The principles of the Double Difference (DD) method, applied to the neutron spectrometer VESUVIO, are discussed. VESUVIO, an inverse geometry spectrometer operating at the ISIS pulsed neutron source in the eV energy region, has been specifically designed to measure the single particle dynamical properties in condensed matter. The width of the nuclear resonance of the absorbing filter, used for the neutron energy analysis, provides the most important contribution to the energy resolution of the inverse geometry instruments. In this paper, the DD method, which is based on a linear combination of two measurements recorded with filter foils of the same resonance material but of different thickness, is shown to improve significantly the instrumental energy resolution, as compared with the Single Difference (SD) method. The asymptotic response functions, derived through Monte-Carlo simulations for polycrystalline Pb and ZrH 2 samples, are analysed in both DD and SD methods, and compared with the experimental ones for Pb sample. The response functions have been modelled for two distinct experimental configurations of the VESUVIO spectrometer, employing 6 Li-glass neutron detectors and NaI γ detectors revealing the γ-ray cascade from the (n,γ) reaction, respectively. The DD method appears to be an effective experimental procedure for Deep Inelastic Neutron Scattering measurements on VESUVIO spectrometer, since it reduces the experimental resolution of the instrument in both 6 Li-glass neutron detector and γ detector configurations

Double difference method in deep inelastic neutron scattering on the VESUVIO spectrometer

Science.gov (United States)

Andreani, C.; Colognesi, D.; Degiorgi, E.; Filabozzi, A.; Nardone, M.; Pace, E.; Pietropaolo, A.; Senesi, R.

2003-02-01

The principles of the Double Difference (DD) method, applied to the neutron spectrometer VESUVIO, are discussed. VESUVIO, an inverse geometry spectrometer operating at the ISIS pulsed neutron source in the eV energy region, has been specifically designed to measure the single particle dynamical properties in condensed matter. The width of the nuclear resonance of the absorbing filter, used for the neutron energy analysis, provides the most important contribution to the energy resolution of the inverse geometry instruments. In this paper, the DD method, which is based on a linear combination of two measurements recorded with filter foils of the same resonance material but of different thickness, is shown to improve significantly the instrumental energy resolution, as compared with the Single Difference (SD) method. The asymptotic response functions, derived through Monte-Carlo simulations for polycrystalline Pb and ZrH 2 samples, are analysed in both DD and SD methods, and compared with the experimental ones for Pb sample. The response functions have been modelled for two distinct experimental configurations of the VESUVIO spectrometer, employing 6Li-glass neutron detectors and NaI γ detectors revealing the γ-ray cascade from the ( n,γ) reaction, respectively. The DD method appears to be an effective experimental procedure for Deep Inelastic Neutron Scattering measurements on VESUVIO spectrometer, since it reduces the experimental resolution of the instrument in both 6Li-glass neutron detector and γ detector configurations.

Double difference method in deep inelastic neutron scattering on the VESUVIO spectrometer

Energy Technology Data Exchange (ETDEWEB)

Andreani, C.; Colognesi, D.; Degiorgi, E.; Filabozzi, A.; Nardone, M.; Pace, E.; Pietropaolo, A. E-mail: antonino.pietropaolo@roma2.infn.it; Senesi, R

2003-02-01

The principles of the Double Difference (DD) method, applied to the neutron spectrometer VESUVIO, are discussed. VESUVIO, an inverse geometry spectrometer operating at the ISIS pulsed neutron source in the eV energy region, has been specifically designed to measure the single particle dynamical properties in condensed matter. The width of the nuclear resonance of the absorbing filter, used for the neutron energy analysis, provides the most important contribution to the energy resolution of the inverse geometry instruments. In this paper, the DD method, which is based on a linear combination of two measurements recorded with filter foils of the same resonance material but of different thickness, is shown to improve significantly the instrumental energy resolution, as compared with the Single Difference (SD) method. The asymptotic response functions, derived through Monte-Carlo simulations for polycrystalline Pb and ZrH{sub 2} samples, are analysed in both DD and SD methods, and compared with the experimental ones for Pb sample. The response functions have been modelled for two distinct experimental configurations of the VESUVIO spectrometer, employing {sup 6}Li-glass neutron detectors and NaI {gamma} detectors revealing the {gamma}-ray cascade from the (n,{gamma}) reaction, respectively. The DD method appears to be an effective experimental procedure for Deep Inelastic Neutron Scattering measurements on VESUVIO spectrometer, since it reduces the experimental resolution of the instrument in both {sup 6}Li-glass neutron detector and {gamma} detector configurations.

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

Science.gov (United States)

Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

Energy Technology Data Exchange (ETDEWEB)

Čufar, Aljaž, E-mail: aljaz.cufar@ijs.si [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Batistoni, Paola [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Conroy, Sean [Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Ghani, Zamir [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Lengar, Igor [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Milocco, Alberto; Packer, Lee [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Pillon, Mario [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Snoj, Luka [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium–tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle–energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Calculation of neutron and gamma-ray emission spectra produced by p +2''2'Al reactions

International Nuclear Information System (INIS)

Arthur, E.D.

1985-01-01

As a contribution to the US/Japan cooperative program in fusion neutronics, we have prepared a library of multigroup neutron cross sections, scattering matrices, and covariances (uncertainties and their correlations). This 74-group library, called COVFILS-2, is being used at Los Alamos and at the University of California at Los Angeles in the sensitivity and uncertainty analysis of the Li 2 O integral experiment recently performed at the Fast Neutron Source (FNS) in Japan. Another intended use of this library is in the estimation of the uncertainty in key performance parameters (such as breeding ratio) of conceptual fusion reactors. The 14 materials included in the first version of COVFILS-2 are H, 6 Li, 7 Li, Be, C, N, O, Na, Al, Si, Cr, Fe, Ni, and Pb

Analysis of elements present in beers and brewing waters by neutron activation analysis

International Nuclear Information System (INIS)

Krausova, Ivana; Kucera, Jan; Dostalek, Pavel; Potesil, Vaclav

2011-01-01

Neutron activation analysis (NAA) was used for determination of Si, Na, K, Ca, Sc, V, Cr, Mn, Fe, Co, Zn, Rb, Cs, and La in Czech beers and brewing waters. The Si concentration in beer determined by the reaction 29 Si(n,p) 29 Al with fast neutrons confirmed that beer is an important Si source in human diet. Determination of other trace elements by NAA with the whole spectrum of reactor neutrons aimed at the feasibility of identification of Gambrinus beers brewed in various breweries. The elements Ca and V appeared to be the best candidates for this purpose. The concentrations of elements determined by NAA were also compared with the recommended daily element intake for humans. The accuracy of the method was proved by analysis of reference materials, specifically NIST SRM 2704 Buffalo River Sediment, NIST SRM 1633b Coal Fly Ash, and NIST SRM 1515 Apple Leaves. (author)

Medical aspects of boron-slow neutron capture therapy

International Nuclear Information System (INIS)

Sweet, W.H.

1986-01-01

Earlier radiations of patients with cerebral tumors disclosed the need: (1) to find a carrier of the boron compound which would leave the blood and concentrate in the tumor, (2) to use a more penetrating neutron beam, and (3) to develop a much faster method for assaying boron in blood and tissue. To some extent number1 has been accomplished in the form of Na 2 B 12 H 11 SH, number2 has yet to be achieved, and number3 has been solved by the measurement of the 478-keV gamma ray when the 10 B atom disintegrates following its capture of a slow neutron. The hitherto unreported data in this paper describe through the courtesy of Professor Hiroshi Hatanaka his studies on the pharmacokinetics and quality control of Na 2 B 12 H 11 SH based on 96 boron infusions in 86 patients. Simultaneous blood and tumor data are plotted here for 30 patients with glioblastomas (Grade III-IV gliomas), illustrating remarkable variability. Detailed autopsy findings on 18 patients with BNCT showed radiation injury in only 1. Clinical results in 12 of the most favorably situated glioblastomas reveal that 5 are still alive with a 5-year survival rate of 58% and the excellent Karnofsky performance rating of 87%. For the first time evidence is presented that slow-growing astrocytomas may benefit from BNCT. 10 references, 8 figures, 5 tables

Study of neutron fields around an intense neutron generator.

Science.gov (United States)

Kicka, L; Machrafi, R; Miller, A

2017-12-01

Neutron fields in the vicinity of the newly built neutron facility, at the University of Ontario Institute of Technology (UOIT), have been investigated in a series of Monte Carlo simulations and measurements. The facility hosts a P-385 neutron generator based on a deuterium-deuterium fusion reaction. The neutron fluence at different locations around the neutron generator facility has been simulated using MCNPX 2.7E Monte Carlo particle transport program. To characterize neutron fields, three neutron sources were modeled with distributions corresponding to different incident deuteron energies of 90kV, 110kV, and 130kV. Measurements have been carried out to determine the dose rate at locations adjacent to the generator using bubble detectors (BDs). The neutron intensity was evaluated and the total dose rates corresponding to different applied acceleration potentials were estimated at various locations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Miscellaneous neutron techniques

International Nuclear Information System (INIS)

Iddings, F.A.

1976-01-01

Attention is brought to the less often uses of neutrons in the areas of neutron radiography, well logging, and neutron gaging. Emphasis on neutron radiography points toward the isotopic sensitivity of the method versus the classical bulk applications. Also recognized is the ability of neutron radiography to produce image changes that correspond to thickness and density changes obtained in photon radiography. Similarly, neutron gaging applications center on the measurement of radiography. Similarly, neutron gaging applications center on the measurement of water, oil, or plastics in industrial samples. Well logging extends the neutron gaging to encompass many neutron properties and reactions besides thermalization and capture. Neutron gaging also gives information on organic structure and concentrations of a variety of elements or specific compounds in selected matrices

Discovery of the neutron (to the fiftieth anniversary of neutron discovery)

International Nuclear Information System (INIS)

Pasechnik, M.V.

1984-01-01

Development of neutron physics in the USSR for the recent 50 years from the moment of neutron discovery is considered. History of neutron discovery is presented in brief. Neutron properties and fundamental problems of physics: electric dipole neutron moment, neutron β-decay, neutron interaction with nuclei and potential of nucleon interaction not conserving spatial parity are discussed. Main aspects of neutron physics application in power engineering, nuclear technology and other branches of science and technique are set forth

Neutron rich matter, neutron stars, and their crusts

International Nuclear Information System (INIS)

Horowitz, C J

2011-01-01

Neutron rich matter is at the heart of many fundamental questions in Nuclear Physics and Astrophysics. What are the high density phases of QCD? Where did the chemical elements come from? What is the structure of many compact and energetic objects in the heavens, and what determines their electromagnetic, neutrino, and gravitational-wave radiations? Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that is using parity violation to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. Using large scale molecular dynamics, we model the formation of solids in both white dwarfs and neutron stars. We find neutron star crust to be the strongest material known, some 10 billion times stronger than steel. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, we describe a new equation of state for supernova and neutron star merger simulations based on the Virial expansion at low densities, and large scale relativistic mean field calculations.

Department of Mathematics and Physics, University of Aston in Birmingham: multiple neutron scattering effects in /sup 7/Li

Energy Technology Data Exchange (ETDEWEB)

Cox, A.J.; Warner, P.C.; Findlay, D.J.S.; Cookson, J.A. (eds.)

1986-06-01

Future fusion reactors will use lithium as a blanket material in order to breed tritium. Knowledge of the gamma ray production cross-sections associated with 14 MeV neutron interactions in lithium are therefore important for local heating and biological shielding calculations and neutron energy degradation studies. In the present work, the differential cross-sections have been measured for the production of 0.478 MeV gamma rays following the inelastic scattering of 14 MeV neutrons in large samples of LiF. The neutrons were produced using the /sup 3/H(d,n) /sup 4/He reaction, the deuterons being accelerated by a 150 kV SAMES type accelerator. In order to reduce the background level, the gamma ray signal was gated using a time-of-flight technique based on the alpha particle associated with neutron production. The gamma ray detector was a 3 x 3 inch NaI(T1) scintillator coupled to a 56AVP photomultiplier.

Neutron activation analysis of phytotherapic obtained from medicinal plants; Analise por ativacao com neutrons de fitoterapicos obtidos de plantas medicinais

Energy Technology Data Exchange (ETDEWEB)

Moreira, Henrique S. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas]. E-mail: hs_moreira@hotmail.com; Saiki, Mitiko; Vasconcellos, Marina B.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: mitiko@ipen.br; mbvascon@ipen.br

2007-07-01

This paper determines the inorganic constituents in phytotherapic samples for posterior study of the relationship existent among the concentrations of the found elements and the their possible therapeutical effects. The samples of phytotherapic pills (Centella asiatica, Ginkgo biloba and Ginseng) were analysed by using neutron activation analysis (NAA). The As, Br, Ca, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc, Se and Zn samples were determined in the phytotherapics, The Centella asiatica presented the higher concentrations of Br, Co, Cr, Fe, K, La, Na, Rb, Sc, Se and Zn. In the sample of Ginko biloba, higher levels of As and Ca were found, while in the sample ol Ginseng the element As were not detected. The found results have shown the the NAA method is appropriated for analysing this type of materials due to his simplicity, multielemental capacity and quality of the results obtained. (author)

Determination of trace elements in chewing gum by neutron activation analysis

International Nuclear Information System (INIS)

Dietz, M.L.

1990-01-01

Six trace elements of nutritional or toxicological interest (Al, Ca, Cl, Mn, Na and Sr) were determined in three different brands of chewing gum by instrumental neutron activation analysis. For the particular brands of gum examined, none of the detected elements was found to be present at a level representing a substantial contribution to the total dietary intake of the element for an American adult. (author) 11 refs.; 3 tabs

Neutron Beam Filters

International Nuclear Information System (INIS)

Adib, M.

2011-01-01

The purpose of filters is to transmit neutrons with selected energy, while remove unwanted ones from the incident neutron beam. This reduces the background, and the number of spurious. The types of commonly used now-a-day neutron filters and their properties are discussed in the present work. There are three major types of neutron filters. The first type is filter of selective thermal neutron. It transmits the main reflected neutrons from a crystal monochromate, while reject the higher order contaminations accompanying the main one. Beams coming from the moderator always contain unwanted radiation like fast neutrons and gamma-rays which contribute to experimental background and to the biological hazard potential. Such filter type is called filter of whole thermal neutron spectrum. The third filter type is it transmits neutrons with energies in the resonance energy range (En . 1 KeV). The main idea of such neutron filter technique is the use of large quantities of a certain material which have the deep interference minima in its total neutron cross-section. By transmitting reactor neutrons through bulk layer of such material, one can obtain the quasimonochromatic neutron lines instead of white reactor spectrum.

Determination of mercury in food by neutron activation

International Nuclear Information System (INIS)

Anand, S.J.S.

1976-01-01

Determination of mercury in food samples has been carried out by neutron activation followed by chemical separation to remove the interfering activities of copper, zinc etc. Chemical separation was carried out using anion exchange resin (DOWEX 1x8). Mercury was determined by counting 77 keV γ-rays of 197 Hg on a NaI(Tl) crystal in conjunction with a 400-channel pulse-height analyser. Levels of mercury in the following foods are tabulated: rice, wheat, pulses, millets, leafy vegetables, flower, carrot, potato, tomato, onion, chilli powder, sugar, tea leaves, milk. (T.I.)

Determination of mercury in food by neutron activation

Energy Technology Data Exchange (ETDEWEB)

Anand, S J.S. [Bhabha Atomic Research Centre, Bombay (India). Air Monitoring Section

1976-01-01

Determination of mercury in food samples has been carried out by neutron activation followed by chemical separation to remove the interfering activities of copper, zinc etc. Chemical separation was carried out using anion exchange resin (DOWEX 1x8). Mercury was determined by counting 77 keV ..gamma..-rays of /sup 197/Hg on a NaI(Tl) crystal in conjunction with a 400-channel pulse-height analyser. Levels of mercury in the following foods are tabulated: rice, wheat, pulses, millets, leafy vegetables, flower, carrot, potato, tomato, onion, chilli powder, sugar, tea leaves, milk.

Neutron stochastic transport theory with delayed neutrons

International Nuclear Information System (INIS)

Munoz-Cobo, J.L.; Verdu, G.

1987-01-01

From the stochastic transport theory with delayed neutrons, the Boltzmann transport equation with delayed neutrons for the average flux emerges in a natural way without recourse to any approximation. From this theory a general expression is obtained for the Feynman Y-function when delayed neutrons are included. The single mode approximation for the particular case of a subcritical assembly is developed, and it is shown that Y-function reduces to the familiar expression quoted in many books, when delayed neutrons are not considered, and spatial and source effects are not included. (author)

Neutron activation analysis and atomic absorption spectrophotometry for the analysis of fresh, pasteurised and powder milk

International Nuclear Information System (INIS)

Wasim, M.; Rehman, S.; Arif, M.; Fatima, I.; Zaidi, J.H.

2012-01-01

This study shows the application of semi-absolute k 0 instrumental neutron activation analysis (k 0 -INAA), epithermal neutron activation analysis (ENAA) and atomic absorption spectrophotometry (AAS) for the determination of 21 elements (Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sc Sr, and Zn) in different types of milk samples. The ENAA was required for the determination of iodine, AAS for Cu, Ni and Pb and the rest of the elements were measured by k 0 -INAA. Thirteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sr and Zn) were identified in all milk samples. Ni was detected in eleven and Pb in two samples. Concentrations of most of the elements were within the ranges of the world reported data. The data was further explored by principal component analysis to find relationships between samples and elements. (orig.)

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

International Nuclear Information System (INIS)

Sekita, Junichiro

1988-01-01

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

Review of Non-Neutron and Neutron Nuclear Data, 2004

International Nuclear Information System (INIS)

Holden, Norman E.

2005-01-01

Review articles are in preparation for the 2004 edition of the CRC Handbook of Chemistry and Physics dealing with the evaluation of both non-neutron and neutron nuclear data. Data on the discovery of element 110, Darmstadtium, and element 111 have been officially accepted, while data on element 118 have been withdrawn. Data to be presented include revised values for very short-lived nuclides, long-lived nuclides, and beta-beta decay measurements. There has been a reassessment of the spontaneous fission (sf) half-lives, which distinguishes between sf decay half-lives and cluster decay half-lives, and with cluster-fission decay. New measurements of isotopic abundance values for many elements will be discussed with an emphasis on the minor isotopes of interest for use in neutron activation analysis measurements. Neutron resonance integrals will be discussed emphasizing the differences between the calculated values obtained from the analytical integration over neutron resonances and the measured values in a neutron reactor-spectrum, which does not quite conform to the assumed 1/E neutron energy spectrum. The method used to determine the neutron resonance integral from measurement, using neutron activation analysis, will be discussed

Analysis of Brazilian snake venoms by neutron activation analysis

International Nuclear Information System (INIS)

Saiki, M.; Vasconcellos, M.B.A.; Rogero, J.R.; Cruz, M.C.G.

1991-01-01

Instrumental neutron activation analysis (INAA) has been applied to multielemental determinations of Brazilian snake venoms from the species: Bothrops jararacussu, Crotalus durissus terrificus and Bothrops jararaca. Concentrations of Br, Ca, Cl, Cs, K, Mg, Na, Rb, Sb, Se and Zn have been determined in lyophilized venoms by using short and long irradiations in the IEA-RI nuclear reactor under a thermal neutron flux of 10 11 to 10 13 n · cm -2 · s -1 . The reference materials NIST Bovine Liver 1577 and IUPAC Bowen's Kale were also analyzed simultaneously with the venoms to evaluate the accuracy and the reproducibility of the method. The concentrations of the elements found in snake venoms from different species were compared. The Crotalus durissus terrificus venoms presented high concentration of Se but low concentrations of Zn when these results are compared with those obtained from genera Bothrops venoms. (author) 9 refs.; 2 tabs

Observation of Neutron Skyshine from an Accelerator Based Neutron Source

Energy Technology Data Exchange (ETDEWEB)

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

2011-12-13

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

Pulsed neutron uranium borehole logging with prompt fission neutrons

International Nuclear Information System (INIS)

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

1976-01-01

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

Neutron reflectometry

International Nuclear Information System (INIS)

Van Well, A.A.

1999-01-01

Neutron research where reflection, refraction, and interference play an essential role is generally referred to as 'neutron optics'. The neutron wavelength, the scattering length density and the magnetic properties of the material determine the critical angle for total reflection. The theoretical background of neutron reflection, experimental methods and the interpretation of reflection data are presented. (K.A.)

Evaluation of cross-section data from threshold to 40-60 MeV for specific neutron reactions important for neutron dosimetry applications. Part 1: Evaluation of the excitation functions for the 27Al(n,α)24Na, 55Mn(n,2n)54Mn, 59Co(n,p)59Fe, 59Co(n,2n)58m+gCo and 90Zr(n,2n)89m+gZr reactions

International Nuclear Information System (INIS)

Zolotarev, K.I.

2009-04-01

Evaluations of cross sections and their associated covariance matrices have been carried out for five dosimetry reactions: - excitation functions were re-evaluated for the 27 Al(n,α) 24 Na, 55 Mn(n,2n) 54 Mn and 90 Zr(n,2n) 89m+g Zr reactions over the neutron energy range from threshold to 40 MeV; - excitation functions were re-evaluated for the 59 Co(n,p) 59 Fe and 59 Co(n,2n) 58m+g Co reactions over the neutron energy range from threshold to 60 MeV. Uncertainties in the cross sections for all of those reactions were also derived in the form of relative covariance matrices. Benchmark calculations performed for 235 U thermal fission and 252 Cf spontaneous fission neutron spectra show that the integral cross sections calculated from the newly evaluated excitation functions exhibit improved agreement with related experimental data when compared with the equivalent data from the IRDF-2002 library. (author)

Confirmation of identity and detection limit in neutron activation analysis

International Nuclear Information System (INIS)

Yustina Tri Handayani; Slamet Wiyuniati; Tulisna

2010-01-01

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

Pulsed neutron generator for use with pulsed neutron activation techniques

International Nuclear Information System (INIS)

Rochau, G.E.

1980-01-01

A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

Use of the Zetatron D-T neutron generator for the simultaneous measurement of carbon, oxygen, and hydrogen in vivo in humans

International Nuclear Information System (INIS)

Kehayias, J.J.; Zhuang, H.

1993-01-01

A small sealed D-T neutron generator is used for the pulsed (4-8 kHz) production of fast neutrons. Carbon and oxygen are detected in vivo by counting the 4.44 and 6.13 MeV gamma rays resulting from the inelastic scattering of the fast neutrons. Hydrogen is detected by thermal neutron capture. BGO detectors (127 mm diameter x 76 mm thick) were found more tolerant to neutron exposure and improved the signal to background ratio for the carbon detection by a factor of 6, compared to 152 x 152 mm NaI(Tl). The elemental analysis of the body is used to study the changes of body composition with aging. We investigate the causes of depletion of lean body mass and the development of ways of maintaining functional capacity and quality of life of the elderly. (orig.)

Use of the Zetatron D-T neutron generator for the simultaneous measurement of carbon, oxygen, and hydrogen in vivo in humans

Science.gov (United States)

Kehayias, J. J.; Zhuang, H.

1993-06-01

A small sealed D-T neutron generator is used for the pulsed (4-8 kHz) production of fast neutrons. Carbon and oxygen are detected in vivo by counting the 4.44 and 6.13 MeV gamma rays resulting from the inelastic scattering of the fast neutrons. Hydrogen is detected by thermal neutron capture. BGO detectors (127 mm diameter × 76 mm thick) were found more tolerant to neutron exposure and improved the signal to background ratio for the carbon detection by a factor of 6, compared to 152 × 152 mm NaI(Tl). The elemental analysis of the body is used to study the changes of body composition with aging. We investigate the causes of depletion of lean body mass and the development of ways of maintaining functional capacity and quality of life of the elderly.

Neutron nuclear physics under the neutron science project

Energy Technology Data Exchange (ETDEWEB)

Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-11-01

The concept of fast neutron physics facility in the Neutron Science Research project is described. This facility makes use of an ultra-short proton pulse (width < 1 ns) for fast neutron time-of-flight works. The current design is based on an assumption of the maximum proton current of 100 {mu}A. Available neutron fluence and energy resolution are explained. Some of the research subjects to be performed at this facility are discussed. (author)

Development of highly effective neutron shields and neutron absorbing materials

International Nuclear Information System (INIS)

Tsuda, K.; Matsuda, F.; Taniuchi, H.; Yuhara, T.; Iida, T.

1993-01-01

A wide range of materials, including polymers and hydrogen-occluded alloys that might be usable as the neutron shielding material were examined. And a wide range of materials, including aluminum alloys that might be usable as the neutron-absorbing material were examined. After screening, the candidate material was determined on the basis of evaluation regarding its adaptabilities as a high-performance neutron-shielding and neutron-absorbing material. This candidate material was manufactured for trial, after which material properties tests, neutron-shielding tests and neutron-absorbing tests were carried out on it. The specifications of this material were thus determined. This research has resulted in materials of good performance; a neutron-shielding material based on ethylene propylene rubber and titanium hydride, and a neutron-absorbing material based on aluminum and titanium hydride. (author)

Dual-Particle Imaging System with Neutron Spectroscopy for Safeguard Applications

Energy Technology Data Exchange (ETDEWEB)

Hamel, Michael C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weber, Thomas M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-11-01

A dual-particle imager (DPI) has been designed that is capable of detecting gamma-ray and neutron signatures from shielded SNM. The system combines liquid organic and NaI(Tl) scintillators to form a combined Compton and neutron scatter camera. Effective image reconstruction of detected particles is a crucial component for maximizing the performance of the system; however, a key deficiency exists in the widely used iterative list-mode maximum-likelihood estimation-maximization (MLEM) image reconstruction technique. For MLEM a stopping condition is required to achieve a good quality solution but these conditions fail to achieve maximum image quality. Stochastic origin ensembles (SOE) imaging is a good candidate to address this problem as it uses Markov chain Monte Carlo to reach a stochastic steady-state solution. The application of SOE to the DPI is presented in this work.

Methods for absorbing neutrons

Science.gov (United States)

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

2012-07-24

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

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2013-01-01

The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)

The chemical consequences of thermal neutron capture in alkali selenates

International Nuclear Information System (INIS)

Duplatre, G.; Vargas, J.I.

1977-01-01

The initial retention of the SeO 4 2- ion after thermal neutron capture has been studied in various matrices by chemical analysis. A comparison between the thermal behaviour of the chemically analyzed Sesup(IV) and the disappearance of the E.P.R. species SeO 3 - and SeO 4 3- showed that the retention fraction would include all species with oxidation state higher or equal to VI. The retentions observed in the different matrices show the existence of four families with respective retentions of: 2.6%[K 2 SeO 4 diluted in (NH 4 ) 2 SO 4 ], 9.2% [anhydrous and hydrated Li and Ca selenates; K 2 SeO 4 diluted in NaIO 3 ; Se + implanted in K 2 SeO 4 ; Triglycine selenate], 21.5% [K 2 SeO 4 diluted in KNO 3 , K 2 SO 4 , Na 2 WO 4 and Na 2 WO 4 .2H 2 O] and 32.0% [Na,K and Cs selenates]. Whereas chemical considerations may be invoked for the (NH 4 ) 2 SO 4 matrix, a mechanical model is proposed for the three other groups. (author)

Development of Cold Neutron Activation Station at HANARO Cold Neutron Source

International Nuclear Information System (INIS)

Sun, G. M.; Hoang, S. M. T.; Moon, J. H.; Chung, Y. S.; Cho, S. J.; Lee, K. H.; Park, B. G.; Choi, H. D.

2012-01-01

A new cold neutron source at the HANARO Research Reactor had been constructed in the framework of a five-year project, and ended in 2009. It has seven neutron guides, among which five guides were already allocated for a number of neutron scattering instruments. A new two-year project to develop a Cold Neutron Activation Station (CONAS) was carried out at the two neutron guides since May 2010, which was supported by the program of the Ministry of Education, Science and Technology, Korea. Fig. 1 shows the location of CONAS. CONAS is a complex facility including several radioanalytical instruments utilizing neutron capture reaction to analyze elements in a sample. It was designed to include three instruments like a CN-PGAA (Cold Neutron - Prompt Gamma Activation Analysis), a CN-NIPS (Cold Neutron - Neutron Induced Pair Spectrometer), and a CN-NDP (Cold Neutron - Neutron-induced prompt charged particle Depth Profiling). Fig. 2 shows the conceptual configuration of the CONAS concrete bioshield and the instruments. CN-PGAA and CN-NIPS measure the gamma-rays promptly emitted from the sample after neutron capture, whereas CN-NDP is a probe to measure the charged particles emitted from the sample surface after neutron capture. For this, we constructed two cold neutron guides called CG1 and CG2B guides from the CNS

Trace elements in Turkish tobacco determined by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Gulovali, M.C.

1977-01-01

This study was undertaken to determine the concentration of trace elements in nine different brands of Turkish cigarette tobacco, pipe tobacco and tobacco ash. Instrumental neutron activation analysis was employed, and a gamma-ray spectrometer consisting of 40 cm 3 Ge(Li) detector coupled to 1024 and 4096-channel analyzers were used. Samples were irradiated at a thermal neutron flux of about 10 13 cm -2 sec -1 . Concentrations of Na, K, Sc, Cr, Fe, Co, Zn, As, Se, Br, Rb, Sb, Cs, Ba, La, Ce, Eu, Hf, Hg and Th were determined in tobacco and ash; percent transference of these elements into ash were calculated. It was found out that trace elements in cigarette tobacco are left in the ash but only a small percentage is transferred into the smoke

Preparation of 3-7 MeV neutron source and preliminary results of activation cross section measurement

Energy Technology Data Exchange (ETDEWEB)

Furuta, T.; Masuda, T.; Tsurita, Y.; Hashimoto, A.; Miyajima, N. [Department of Nuclear Engineering, Nagoya University, Nagoya, Aichi (Japan); Sakane, H.; Shibata, M.; Yamamoto, H.; Kawade, K.

1999-03-01

A d-D gas target producing monoenergetic neutrons has been constructed for measurement of activation cross sections in the energy region of 3 to 7 MeV at Van de Graaff accelerator of Nagoya University. Neutron spectra and neutron fluxes were measured as a function of the incident deuteron energy. Preliminary results of activation cross sections were obtained for reactions {sup 27}Al(n, p){sup 27}Mg, {sup 27}Al(n, {alpha}){sup 24}Na, {sup 47}Ti(n, p){sup 47}Sc, {sup 56}Fe(n, p){sup 56}Mn, {sup 58}Ni(n, p){sup 58}Co and {sup 64}Zn(n, p){sup 64}Cu. The results are compared with the evaluated values of JENDL-3.2. A well-type HPGe detector was used for highly efficient detection. (author)

Differential Neutron Scattering from Hydrogenous Moderators; Diffusion Differentielle des Neutrons par des Ralentisseurs Hydrogenes; Differentsial'noe rasseyanie nejtronov iz vodorodosoderzhashchikh zamedlitelej; Dispersion Diferencial de Neutrones en Moderadores Hidrogenados

Energy Technology Data Exchange (ETDEWEB)

Beyster, J. R.; Young, J. C.; Neill, J. M.; Mowry, W. R. [General Atomic Division of General Dynamics Corporation, John Jay Hopkins Laboratory for Pure and Applied Science, San Diego, CA (United States)

1965-08-15

experiments, which are sensitive mainly to P{sub 0} scattering. In particular one may test the P{sub 1} scattering kernel appropriate to a given molecular model. Third, the transport cross-section may be calculated directly from the experiments for use in multigroup reactor analysis. (author) [French] On mesure par les methodes du temps de vol les sections efficaces differentielles de diffusion simple (d{sigma}/d {Omega}) pour les ralentisseurs usuels. On utilise des neutrons thermiques produits par une source puisee intense (accelerateur lineaire de la General Atomic) avec un parcours de vol de 12 m a l'extremite duquel est place un echantillon mince du ralentisseur a l*etude. En outre, on a egalement prevu un petit parcours de vol terminal pour les neutrons diffuses, entre l'echantillon et plusieurs detecteurs de neutrons entierement absorbants. Cette methode permet de mesurer simultanement la distribution angulaire de diffusion pour plus de 50 energies des neutrons incidents. Les intensites sont-elevees, le bruit de fond est faible et bien defini et on peut proceder a des mesures rapides pour tous les angles de diffusion compris entre 10 et 155 degres. Les auteurs presentent des mesures de la section efficace differentielle de diffusion pour le vanadium, H{sub 2}O, D{sub 2}O et ZrH. On a etudie le vanadium pour controler le dispositif experimental. On a fait des mesures avec H{sub 2}O pour diverses epaisseurs et orientations des echantillons en vue de les comparer aux calculs fondes sur divers modeles de diffusion par l'hydrogene lie et aux resultats obtenus par Springer et Reinsch. Toutes les mesures experimentales ont ete corrigees pour tenir compte des effets importants de la diffusion multiple dans les echantillons. Pour l'instant, on n'a pas observe experimentalement la variation accusee que fait prevoir le modele de diffusion de Nelkin lorsque l'energie des neutrons est d'environ 0,06 eV; ceci est du au fait que l'hypothese du rotateur unique inhibe a 0,06 eV n'a pas

Study of the 23Na EFG (Electrostatic Field Gradient) tensor on single crystals of Na2S.9H2O by wideline NMR

International Nuclear Information System (INIS)

Miksche, G.

1982-01-01

The quadrupole coupling constant |e 2 qQ/n| if 23 Na has been determined by measuring single crystals of Na 2 S.9H 2 O at room temperature. A value of 687.5 +- 1.2 kHz was found. The asymmetry parameter eta = (qsub(x'x') - qsub(y'y')) / qsub(z'z') of the efg-tensor is zero, there is axial symmetry. The principle axis of the efg-tensor runs parallel to the main crystallographic axis c, the value of the main component of the efg-tensor in c-direction is 171.875 +- 0.6 kHz. The longitudinal relaxation time T 1 has been evaluated as 1.8 s. On this account, the mean distance between two Na-atoms has been determined by measuring the splitting of the central line due to dipole-dipole interaction. The Na-Na distance was found with 0.36 +- 0.007 nm. This value is in good agreement with results from neutron diffraction studies. It was not possible to determine direction and length of hydrogen bonds by NMR-results. A method of growing single crystals of Na 2 S.9H 2 O of demanded size and purity has been described. Constructional details and technical data of a self-made wideline-NMR-spectrometer are added in an appendix. (Author)

The magnetic diffusion of neutrons; La diffusion magnetique des neutrons

Energy Technology Data Exchange (ETDEWEB)

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

1959-07-01

The purpose of this report is to examine briefly the diffusion of neutrons by substances, particularly by crystals containing permanent atomic or ionic magnetic moments. In other words we shall deal with ferromagnetic, antiferromagnetic, ferrimagnetic or paramagnetic crystals, but first it is necessary to touch on nuclear diffusion of neutrons. We shall start with the interaction of the neutron with a single diffusion centre; the results will then be applied to the magnetic interactions of the neutron with the satellite electrons of the atom; finally we shall discuss the diffusion of neutrons by crystals. (author) [French] Le but de ce rapport est d'examiner, brievement, la diffusion des neutrons par les substances, et surtout, par des cristaux qui contiennent des moments magnetiques atomiques ou ioniques permanents. C'est-a-dire que nous nous interesserons aux cristaux ferromagnetiques, antiferromagnetiques, ferrimagnetiques ou paramagnetiques; il nous faut cependant rappeler d'abord la diffusion nucleaire des neutrons. Nous commencerons par l'interaction du neutron avec un seul centre diffuseur; puis les resultats seront appliques aux interactions magnetiques du neutron avec les electrons satellites de l'atome; enfin nous discuterons la diffusion des neutrons par les cristaux. (auteur)

Neutron scattering. Lectures

Energy Technology Data Exchange (ETDEWEB)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

2010-07-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Study of heat and salt transport processes in the Espinheiro Channel (Ria de Aveiro)

Science.gov (United States)

Vaz, Nuno Alexandre Firmino

O principal objectivo deste trabalho consistiu no estudo da dinâmica termohalina do Canal do Espinheiro em funcao de dois forcamentos principais: mare e caudal fluvial, usando duas abordagens distintas: trabalho experimental e modelacao numerica. A propagacao da mare e o caudal fluvial do Rio Vouga sao determinantes no estabelecimento da estrutura horizontal da salinidade ao longo do canal. A estrutura termica horizontal ao longo do canal e, em grande parte, determinada pela variacao sazonal da temperatura da agua do Rio Vouga, bem como, pela variacao sazonal das condicoes meteorologicas devido a reduzida profundidade. Foi observada a formacao de fortes gradientes de salinidade (relacionados com a formacao de frentes estuarinas) numa regiao a cerca de 7-8 km da embocadura do canal, observando-se a sua migracao numa regiao de aproximadamente 1 km, dependendo do regime de mare. O balanco entre o transporte de sal de natureza advectiva e difusiva foi calculado, revelando que junto a embocadura os processos fisicos que mais contribuem para o transporte de sal sao a circulacao residual e o aprisionamento da agua em canais secundarios. Junto a foz do Rio Vouga os termos devidos a descarga fluvial e a circulacao gravitacional dominam o transporte de sal. Foi calibrado e validado um modelo numerico (Mohid, em modo 2D e 3D), sendo posteriormente utilizado para estudar a hidrologia do canal. Foi concedida particular atencao ao estudo da hidrologia em condicoes extremas de caudal fluvial e de mare. Os resultados da modelacao numerica permitiram numa primeira fase avaliar o bom desempenho do Mohid na reproducao dos escoamentos barotropicos na Ria de Aveiro, bem como na evolucao temporal das propriedades termohalinas da agua. Sob condicoes de caudal fluvial reduzido, a dinâmica do canal e essencialmente dominada pela mare. Com o aumento do caudal fluvial, a influencia da agua doce estende-se para jusante, estratificando a coluna de agua. As simulacoes 3D do Canal do

A feasibility study for measuring fluorine in bone, in-vivo, using neutron activation analysis

International Nuclear Information System (INIS)

Chamberlain, M.; McNeill, F.; Aslam; Byun, S.H.

2008-01-01

Full text: Skeletal fluorosis is a bone disease which is a result of excessive fluoride ingestion and may cause osteosclerosis, osteoporosis and calcification of tendons and ligaments. Endemic levels of fluorosis are commonly reported in areas of the world with naturally high concentrations of fluoride in the drinking water. However, fluorosis is difficult to medically diagnose, and due to its prevalence, a non-invasive method for measuring the concentration of fluoride in bone is warranted. A feasibility study has been conducted to determine the possibility of measuring fluorine non-invasively in exposed populations using neutron activation analysis. Neutron activation analysis has been used successfully to measure the amount of fluoride in bone biopsy samples. However, measurement of fluorine is challenging, and has not, to our knowledge, previously been attempted in vivo, as the 20 F isotope has the very short half life of 11s. Transfer from activation counting must therefore be fast. For this study, plaster of Paris powder phantoms doped with varying fluoride concentrations were created to simulate a fist. They were irradiated using a low energy neutron beam at McMaster's Tandem Accelerator facility. The 7 Li(p,n) 7 Be reaction was used as the source of neutrons; the Be target was irradiated with an incident proton energy of 2.15MeV. The fluorine was detected via the neutron capture reaction, 19 F(n,γ) 20 F, using two 20 cm x 5 cm NaI detectors. Fluorine emits a gamma ray at 1633 keV upon decay. A calibration curve of peak area versus phantom fluorine content was created and a detection limit of 1.8 mg F/g Ca, with a corresponding dose of approximately 12 mSv to the hand. This data will be presented and the feasibility of measurement discussed in the context of the delivered dose. In addition, results of the investigation of the competing reaction, 23 Na(n,α) 20 F, will be presented. Data illustrating the relative activation and count rates from fluorine

Multielement analysis of iliac crest bone by neutron activation

International Nuclear Information System (INIS)

Aras, N.K.; Yilmaz, G.; Korkusuz, F.; Olmez, I.; Sepici, B.; Eksioglu, F.; Bode, P.

2000-01-01

Bone samples from iliac crest were obtained from apparently healthy female (n = 4) and male (n = 8) subjects with ages between 15-50. Cortical and trabecular parts were separated and soft tissues like fat, muscle and blood were removed. Calcium, Mg, Na, Cl, Fe, Zn, Br, Sr, and Cs were determined by instrumental neutron activation analysis and other techniques, and their relations were discussed. Fairly good agreement was obtained with literature data. These values may serve as reference values for subjects from a Turkish population. (author)

Neutron polarization

International Nuclear Information System (INIS)

Firk, F.W.K.

1976-01-01

Some recent experiments involving polarized neutrons are discussed; they demonstrate how polarization studies provide information on fundamental aspects of nuclear structure that cannot be obtained from more traditional neutron studies. Until recently, neutron polarization studies tended to be limited either to very low energies or to restricted regions at higher energies, determined by the kinematics of favorable (p, vector n) and (d, vector n) reactions. With the advent of high intensity pulsed electron and proton accelerators and of beams of vector polarized deuterons, this is no longer the case. One has entered an era in which neutron polarization experiments are now being carried out, in a routine way, throughout the entire range from thermal energies to tens-of-MeV. The significance of neutron polarization studies is illustrated in discussions of a wide variety of experiments that include the measurement of T-invariance in the β-decay of polarized neutrons, a search for the effects of meson exchange currents in the photo-disintegration of the deuteron, the determination of quantum numbers of states in the fission of aligned 235 U and 237 Np induced by polarized neutrons, and the double- and triple-scattering of fast neutrons by light nuclei

Quasi-free Compton scattering and the polarizabilities of the neutron

International Nuclear Information System (INIS)

Kossert, K.; Camen, M.; Wissmann, F.; Schumacher, M.; Seitz, B.; Ahrens, J.; Arends, H.J.; Beck, R.; Caselotti, G.; Jahn, O.; Jennewein, P.; Olmos de Leon, V.; Annand, J.R.M.; McGeorge, J.C.; Rosner, G.; Grabmayr, P.; Natter, A.; Levchuk, M.I.; L'vov, A.I.; Petrun'kin, V.A.; Smend, F.; Thomas, A.; Weihofen, W.; Zapadtka, F.

2003-01-01

Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48cm diameter x 64cm NaI(Tl) photon detector and the Goettingen SENECA recoil detector. The data cover photon energies ranging from 200MeV to 400MeV at θ LAB γ =136.2 . Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(γ,π + n). The ''free'' proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron has been determined to be α n -β n =9.8±3.6(stat) +2.1 -1.1 (syst)±2.2(model) in units of 10 -4 fm 3 . In combination with the polarizability sum α n +β n =15.2±0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, α n =12.5±1.8(stat) + 1 .1 -0.6 (syst)±1.1(model) and β n =2.7±1.8(stat) +0.6 -1.1 (syst)±1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ (n) π =(58.6±4.0) x 10 -4 fm 4 . (orig.)

Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes.

Science.gov (United States)

Yakubova, Galina; Kavetskiy, Aleksandr; Prior, Stephen A; Torbert, H Allen

2017-08-24

The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of gamma rays created when neutrons interact with soil elements. The main parts of the INS system are a pulsed neutron generator, NaI(Tl) gamma detectors, split electronics to separate gamma spectra due to INS and thermo-neutron capture (TNC) processes, and software for gamma spectra acquisition and data processing. This method has several advantages over other methods in that it is a non-destructive in situ method that measures the average carbon content in large soil volumes, is negligibly impacted by local sharp changes in soil carbon, and can be used in stationary or scanning modes. The result of the INS method is the carbon content from a site with a footprint of ~2.5 - 3 m 2 in the stationary regime, or the average carbon content of the traversed area in the scanning regime. The measurement range of the current INS system is >1.5 carbon weight % (standard deviation ± 0.3 w%) in the upper 10 cm soil layer for a 1 hmeasurement.

Neutron imaging integrated circuit and method for detecting neutrons

Science.gov (United States)

Nagarkar, Vivek V.; More, Mitali J.

2017-12-05

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

High-Flux Neutron Generator Facility for Geochronology and Nuclear Physics Research

Science.gov (United States)

Waltz, Cory; HFNG Collaboration

2015-04-01

A facility based on a next-generation, high-flux D-D neutron generator (HFNG) is being commissioned at UC Berkeley. The generator is designed to produce monoenergetic 2.45 MeV neutrons at outputs exceeding 1011 n/s. The HFNG is designed around two RF-driven multi-cusp ion sources that straddle a titanium-coated copper target. D + ions, accelerated up to 150 keV from the ion sources, self-load the target and drive neutron generation through the d(d,n)3 He fusion reaction. A well-integrated cooling system is capable of handling beam power reaching 120 kW impinging on the target. The unique design of the HFNG target permits experimental samples to be placed inside the target volume, allowing the samples to receive the highest neutron flux (1011 cm-2 s-1) possible from the generator. In addition, external beams of neutrons will be available simultaneously, ranging from thermal to 2.45 MeV. Achieving the highest neutron yields required carefully designed schemes to mitigate back-streaming of high energy electrons liberated from the cathode target by deuteron bombardment. The proposed science program is focused on pioneering advances in the 40 Ar/39 Ar dating technique for geochronology, new nuclear data measurements, basic nuclear science, and education. An end goal is to become a user facility for researchers. This work is supported by NSF Grant No. EAR-0960138, U.S. DOE LBNL Contract No. DE-AC02-05CH11231, U.S. DOE LLNL Contract No. DE-AC52-07NA27344, and UC Office of the President Award 12-LR-238745.

Neutron reflector design with Californium 252 neutron for Boron neutron chapter therapy facility using MCNP5 simulation method

International Nuclear Information System (INIS)

Muhammad Fakhrurreza; Kusminanto; Y Sardjono

2014-01-01

In this research has made a reflector design to provide beams of Neutron for BNCT with Californium-252 radioactive source. This collimator is useful to obtain optimum epithermal neutron flux with the smallest impurity radiation (thermal neutron, fast neutron, and gamma). The design process is done using Monte Carlo N-Particle simulation version 5 (MCNP5) code to calculate the neutron flux tally form. The chosen reflector design is the reflectors which use material such as BeO ceramic with 13 cm thick. Moderator use sulfur material with the slope angle of the cone is 30°. From the calculation result, it is obtained that Reflector with 1 gram Californium-252 source can produce a neutron output thermal which has thermal neutron specification 2.23189 x 10 9 n/s.cm 2 , epithermal neutron 3.51548 x 10 9 n/s.cm 2 , and fast neutron 4.82241 x 10 9 n/s.cm 2 From the result, it needs additional collimator because the BNCT requirement. (author)

Neutron spectometers

International Nuclear Information System (INIS)

Poortmans, F.

1977-01-01

Experimental work in the field of low-energy neutron physics can be subdivided into two classes: 1)Study of the decay process of the compound-nucleus state as for example the study of the capture gamma rays and of the neutron induced fission process; 2)Study of the reaction mechanism, mainly by measuring the reaction cross-sections and resonance parameters. These neutron cross-sections and resonance parameters are also important data required for many technological applications especially for reactor development programmes. In general, the second class of experiments impose other requirements on the neutron spectrometer than the first class. In most cases, a better neutron energy resolution and a broader neutron energy range are required for the study of the reaction mechanism than for the study of various aspects of the decay process. (author)

Rotational dynamics of C60 in Na2RbC60

International Nuclear Information System (INIS)

Christides, C.; Prassides, K.; Neumann, D.A.; Copley, J.R.D.; Mizuki, J.; Tanigaki, K.; Hirosawa, I.; Ebbesen, T.W.

1993-01-01

We have measured the low-energy neutron inelastic-scattering (NIS) spectra of superconducting Na 2 RbC 60 in the temperature range 50-350 K. Well-defined librational peaks are observed at 50 K at 2.83(17) meV (FWHM = 1.7(5) meV). They soften and broaden with increasing temperature. Their behaviour mimics that found in solid C 60 and differs markedly from K 3 C 60 . The rotational barrier for C 60 reorientations in Na 2 RbC 60 is somewhat higher than in pristine C 60 and approximately half as large as in K 3 C 60 . An order-disorder transition is anticipated at a temperature higher than that found in C 60 . (orig.)

Measuring the scintillation decay time for different energy deposited by γ-rays and neutrons in a Cs{sub 2}LiYCl{sub 6}:Ce{sup 3+} detector

Energy Technology Data Exchange (ETDEWEB)

Wen, Xianfei, E-mail: wenxianfei@ufl.edu; Enqvist, Andreas

2017-05-01

In nuclear safeguards and homeland security applications, it is greatly beneficial to simultaneously detect γ-rays, thermal neutrons, and fast neutrons using a single detector with reasonable pulse shape discrimination capability, energy resolution comparable with or even better than NaI(Tl) detectors, and high detection efficiency. Cs{sub 2}LiYCl{sub 6}:Ce{sup 3+}(CLYC) scintillation detectors have been proven to be one promising candidate to meet these requirements. In this work, the decay time and fraction of each scintillation component for different energy deposition and incident particle type (γ-ray, thermal neutron, and fast neutron) were investigated based on fitting the PMT anode output with exponential functions. For γ-rays, four components were determined with ultrafast decay time of less than one nanosecond and slow time in the order of magnitude of microsecond. It was found that the dependence on the energy deposited by γ-rays of the fraction as well as the decay time of the three slow components was small. However, significant dependence was observed for the ultrafast component. Two or three components were determined for thermal neutrons and fast neutrons without observing a component with fast decay time. To verify the approach used it was first applied to scintillation pulses induced by γ-rays in a NaI(Tl) detector. The results were consistent with well-known data already published in the literature.

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2012-01-01

The following topics are dealt with: Neutron scattering in contemporary research, neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

Aerial Neutron Detection: Neutron Signatures for Nonproliferation and Emergency Response Applications

Energy Technology Data Exchange (ETDEWEB)

Maurer, Richard J.; Stampahar, Thomas G.; Smith, Ethan X.; Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Rourke, Timothy J.; LeDonne, Jeffrey P.; Avaro, Emanuele; Butler, D. Andre; Borders, Kevin L.; Stampahar, Jezabel; Schuck, William H.; Selfridge, Thomas L.; McKissack, Thomas M.; Duncan, William W.; Hendricks, Thane J.

2012-10-17

From 2007 to the present, the Remote Sensing Laboratory has been conducting a series of studies designed to expand our fundamental understanding of aerial neutron detection with the goal of designing an enhanced sensitivity detection system for long range neutron detection. Over 35 hours of aerial measurements in a helicopter were conducted for a variety of neutron emitters such as neutron point sources, a commercial nuclear power reactor, nuclear reactor spent fuel in dry cask storage, depleted uranium hexafluoride and depleted uranium metal. The goals of the project were to increase the detection sensitivity of our instruments such that a 5.4 × 104 neutron/second source could be detected at 100 feet above ground level at a speed of 70 knots and to enhance the long-range detection sensitivity for larger neutron sources, i.e., detection ranges above 1000 feet. In order to increase the sensitivity of aerial neutron detection instruments, it is important to understand the dynamics of the neutron background as a function of altitude. For aerial neutron detection, studies have shown that the neutron background primarily originates from above the aircraft, being produced in the upper atmosphere by galactic cosmic-ray interactions with air molecules. These interactions produce energetic neutrons and charged particles that cascade to the earth’s surface, producing additional neutrons in secondary collisions. Hence, the neutron background increases as a function of altitude which is an impediment to long-range neutron detection. In order to increase the sensitivity for long range detection, it is necessary to maintain a low neutron background as a function of altitude. Initial investigations show the variation in the neutron background can be decreased with the application of a cosmic-ray shield. The results of the studies along with a representative data set are presented.

Neutron activation in Cascade: the BeO/LiAlO/sub 2/ case

International Nuclear Information System (INIS)

Meier, W.R.

1986-01-01

Neutron activation calculations have been carried out for the Cascade inertial confinement fusion reactor concept. The Cascade chamber features a flowing granular blanket which consists of a carbon surface layer, a BeO multiplier, and a LiAlO/sub 2/ breeder. The blanket, with an effective thickness of 0.5 m, shields the chamber structural wall, which is made out of silicon carbide. A borated water shield surrounds the chamber. The results of the neutron activation calculations for Cascade indicate that the activity is significantly less than in recent magnetic fusion reactor designs. The activity at shutdown is dominated by /sup 24/Na, which is produced by (n,α) reactions with Al. The shutdown decay heat, which is also dominated by /sup 24/Na, can be dissipated by thermal radiation so that active shutdown cooling is not required to prevent melting of the blanket materials or chamber structures. In order to qualify for shallow land burial, both the BeO and LiAlO/sub 2/ require significant dilution; the BeO is limited by /sup 14/C, while LiAlO/sub 2/ is limited by /sup 39/Ar and /sup 26/Al

Synovectomy by Neutron capture; Sinovectomia por captura de neutrones

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R.; Torres M, C. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Penuela, 98000 Zacatecas (Mexico)

1998-12-31

The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu{sup 239} Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

Assessing neutron generator output using neutron activation of silicon

International Nuclear Information System (INIS)

Kehayias, Pauli M.; Kehayias, Joseph J.

2007-01-01

D-T neutron generators are used for elemental composition analysis and medical applications. Often composition is determined by examining elemental ratios in which the knowledge of the neutron flux is unnecessary. However, the absolute value of the neutron flux is required when the generator is used for neutron activation analysis, to study radiation damage to materials, to monitor the operation of the generator, and to measure radiation exposure. We describe a method for absolute neutron output and flux measurements of low output D-T neutron generators using delayed activation of silicon. We irradiated a series of silicon oxide samples with 14.1 MeV neutrons and counted the resulting gamma rays of the 28 Al nucleus with an efficiency-calibrated detector. To minimize the photon self-absorption effects within the samples, we used a zero-thickness extrapolation technique by repeating the measurement with samples of different thicknesses. The neutron flux measured 26 cm away from the tritium target of a Thermo Electron A-325 D-T generator (Thermo Electron Corporation, Colorado Springs, CO) was 6.2 x 10 3 n/s/cm 2 ± 5%, which is consistent with the manufacturer's specifications

Assessing neutron generator output using neutron activation of silicon

Energy Technology Data Exchange (ETDEWEB)

Kehayias, Pauli M. [Body Composition Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 (United States); Kehayias, Joseph J. [Body Composition Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 (United States)]. E-mail: joseph.kehayias@tufts.edu

2007-08-15

D-T neutron generators are used for elemental composition analysis and medical applications. Often composition is determined by examining elemental ratios in which the knowledge of the neutron flux is unnecessary. However, the absolute value of the neutron flux is required when the generator is used for neutron activation analysis, to study radiation damage to materials, to monitor the operation of the generator, and to measure radiation exposure. We describe a method for absolute neutron output and flux measurements of low output D-T neutron generators using delayed activation of silicon. We irradiated a series of silicon oxide samples with 14.1 MeV neutrons and counted the resulting gamma rays of the {sup 28}Al nucleus with an efficiency-calibrated detector. To minimize the photon self-absorption effects within the samples, we used a zero-thickness extrapolation technique by repeating the measurement with samples of different thicknesses. The neutron flux measured 26 cm away from the tritium target of a Thermo Electron A-325 D-T generator (Thermo Electron Corporation, Colorado Springs, CO) was 6.2 x 10{sup 3} n/s/cm{sup 2} {+-} 5%, which is consistent with the manufacturer's specifications.

Theory of Pulsed Neutron Experiments in Highly Heterogeneous Multiplying Media; Theorie des Experiences au Moyen des Neutrons Pulses, dans les Milieux Multiplicateurs Tres Heterogenes; O teorii ehksperimentov s impul'snymi neitronami v geterogennykh razmnozhayushchikh sredakh; Aspectos Teoricos de los Experimentos con Neutrones Pulsados en Medios Multiplicadores Muy Heterogeneos

Energy Technology Data Exchange (ETDEWEB)

Corno, S. E. [Instituto di Fisica ' ' A. Volta' ' (Italy); Unversity of Pavia, Pavia (Italy); SNAM, Milan [Italy

1965-10-15

como punto singular absorbente y multiplicador del campo neutronico. Como el auto: estudia sobre todo la variacion espacial y temporal del flujo neutronico, utiliza valores relativamente poco precisos por lo que respecta a la variacion de la poblacion neutronica en funcion de la energia. Dentro de los limites de validez de la teorfe de la edad de difusion, la instalacion responde en forma analitica a una excitacion provocada por los neutrones. Cuando se trata de una fuente de modulacion sinusoidal de frecuencia determinada, puede demostrarse facilmente que si el punto singular axial fuese puramente absorbente, las ondas neutronicas que se propagaran a lo largo de la instalacion poseerfan una fase, una longitud de onda y una constante de atenuacion dependiente de las propiedades absorbentes del punto singular. Esto se complica en caso de multiplicacion neutronica. Para este caso general, la solucion presentada en la memoria depende, desde luego, de las propiedades absorbentes y multiplicadoras del punto singular. Esta circunstancia, entre otras, ha inducido a utilizar una instalacion como la que se acaba de describir para ensayar los elementos combustibles de los reactores heterogeneos. (author) [Russian] Issledovalis' vremennaja i prostranstvennaja zavisimosti nejtronnogo potoka na vysoko geterogennoj sborke, kuda inzhektirujutsja impul'snye ili sinusoidno modulirovannye nejtrony. Dlja prostoty rassmatrivaetsja ustrojstvo, sostojashhee iz cilindricheskogo bloka zamedlitelja tjazhelyh nejtronov, po osi kotorogo nahoditsja vytjanutaja oblast' rasshhepljajushhegosja materiala. Predpolagaetsja, chto usiljajushhij istochnik nejtronov razmeshhaetsja na odnoj iz storon cilindra. Razmer rasshhepljajushhejsja oblasti pozvoljaet rassmatrivat' ee kak absorbirujushhuju i razmnozhajushhuju singuljarnuju sostavljajushhuju nejtronnogo polja. Poskol'ku vnimanie koncentriruvalos' glavnym obrazom na prostranstvennom i vremennom izmenenii nejtronnogo potoka, to sdelany dovol'no grubye

Hyper-thermal neutron irradiation field for neutron capture therapy

International Nuclear Information System (INIS)

Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

1994-01-01

The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwell distribution higher than the room temperature of 300 K, has been studied in order to improve the thermal neutron flux distribution in a living body for a deep-seated tumor in neutron capture therapy (NCT). Simulation calculations using MCNP-V3 were carried out in order to investigate the characteristics of the hyper-thermal neutron irradiation field. From the results of simulation calculations, the following were confirmed: (i) The irradiation field of the hyper-thermal neutrons is feasible by using some scattering materials with high temperature, such as Be, BeO, C, SiC and ZrH 1.7 . Especially, ZrH 1.7 is thought to be the best material because of good characteristics of up-scattering for thermal neutrons. (ii) The ZrH 1.7 of 1200 K yields the hyper-thermal neutrons of a Maxwell-like distribution at about 2000 K and the treatable depth is about 1.5 cm larger comparing with the irradiation of the thermal neutrons of 300 K. (iii) The contamination by the secondary gamma-rays from the scattering materials can be sufficiently eliminated to the tolerance level for NCT through the bismuth layer, without the larger change of the energy spectrum of hyper-thermal neutrons. ((orig.))

Effects of neutron spectrum and external neutron source on neutron multiplication parameters in accelerator-driven system

International Nuclear Information System (INIS)

Shahbunder, Hesham; Pyeon, Cheol Ho; Misawa, Tsuyoshi; Lim, Jae-Yong; Shiroya, Seiji

2010-01-01

The neutron multiplication parameters: neutron multiplication M, subcritical multiplication factor k s , external source efficiency φ*, play an important role for numerical assessment and reactor power evaluation of an accelerator-driven system (ADS). Those parameters can be evaluated by using the measured reaction rate distribution in the subcritical system. In this study, the experimental verification of this methodology is performed in various ADS cores; with high-energy (100 MeV) proton-tungsten source in hard and soft neutron spectra cores and 14 MeV D-T neutron source in soft spectrum core. The comparison between measured and calculated multiplication parameters reveals a maximum relative difference in the range of 6.6-13.7% that is attributed to the calculation nuclear libraries uncertainty and accuracy for energies higher than 20 MeV and also dependent on the reaction rate distribution position and count rates. The effects of different core neutron spectra and external neutron sources on the neutron multiplication parameters are discussed.

Neutron dosimetry at SLAC: Neutron sources and instrumentation

International Nuclear Information System (INIS)

Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.

1991-10-01

This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ( 238 PuBe, 252 Cf, 238 PuB, 238 PuF 4 , and 238 PuLi) and the neutron instrumentation (moderated BF 3 detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, 12 C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs

Production of 14 MeV neutrons from D-D neutron generators

International Nuclear Information System (INIS)

Cecil, F.E.; Nieschmidt, E.B.

1986-01-01

The production of 14 MeV neutrons from a D-D neutron generator resulting from tritium buildup from the d(d,p)t reaction in the target is discussed. The effect of the 14 MeV neutrons on fast neutron activation analysis with D-D neutron generators is evaluated. (orig.)

Pulsed neutron generator

International Nuclear Information System (INIS)

Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

1986-03-01

The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

Neutronic Analysis on Coolant Options in a Hybrid Reactor System for High Level Waste Transmutation

Energy Technology Data Exchange (ETDEWEB)

Hong, Seong Hee; Kim, Myung Hyun [Kyung Hee University, Seoul (Korea, Republic of)

2014-10-15

A fusion-fission hybrid reactor (FFHR) which is a combination of plasma fusion tokamak as a fast neutron source and a fission reactor as of fusion blanket is another potential candidate. In FFHR, fusion plasma machine can supply high neutron-rich and energetic 14.1MeV (D, T) neutrons compared to other options. Therefore it has better capability in HLW incineration. While, it has lower requirements compared to pure fusion. Much smaller-sized tokamak can be achievable in a near term because it needs relatively low plasma condition. FFHR has also higher safety potential than fast reactors just as ADSR because it is subcritical reactor system. FFHR proposed up to this time has many design concepts depending on the design purpose. FFHR may also satisfy many design requirement such as energy multiplication, tritium production, radiation shielding for magnets, fissile breeding for self-sustain ability also waste transmutation. Many types of fuel compositions and coolant options have been studied. Effect of choices for fuel and coolant was studied for the transmutation purpose FFHR by our team. In this study LiPb coolant was better than pure Li coolant both for neutron multiplication and tritium breeding. However, performance of waste transmutation was reduced with increased neutron absorption at coolant caused by tritium breeding. Also, LiPb as metal coolant has a problem of massive MHD pressure drop in coolant channels. Therefore, in a previous study, waste transmutation performance was evaluated with light water coolant option which may be a realistic choice. In this study, a neutronic analysis was done for the various coolant options with a detailed computation. One of solutions suggested is to use the pressure tubes inside of first wall and second wall In this work, performance of radioactive waste transmutation was compared with various coolant options. On the whole, keff increases with all coolants except for FLiBe, therefore required fusion power is decreased. In

Neutron PSDs for the next generation of spallation neutron sources

CERN Document Server

Eijk, C W

2002-01-01

A review of R and D for neutron PSDs to be used at anticipated new spallation neutron sources: the Time-of-Flight system facility, European Spallation Source, Spallation Neutron Source and Neutron Arena, is presented. The gas-filled detectors, scintillation detectors and hybrid systems are emphasized.

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

International Nuclear Information System (INIS)

Kiyanagi, Yoshiaki

2012-01-01

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

Neutron guides and scientific neutron equipment at CILAS/GMI

International Nuclear Information System (INIS)

Gautier-Picard, P.

2003-01-01

CILAS company is the world's leading supplier of complete neutron guides systems. The neutron optics with multilayer coatings produced by CILAS have become an international standard for neutron beam transportation in the modern research institutes. During the last 30 years, CILAS designed, produced and installed more than 5000 meters of guides in many European, American and Asian countries. To reinforce its leadership and presence in neutron research, CILAS acquired the company Grenoble Modular Instruments (GMI), a leading company in high precision mechanics, engineering and manufacturing of spectrometers and scientific equipment for neutron and synchrotron research. (author)

Neutron detector

Science.gov (United States)

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

2011-04-05

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

Effect of the plutonium isotopic composition on the performance of fast reactors; Effet de la composition isotopique du plutonium sur le rendement de reacteurs a neutrons rapides; Vliyanie izotopnogo sostava plutoniya na rabotu reaktorov na bystrykh nejtronakh; Efectos de la composicion isotopica del plutonio sobre el funcionamiento de los reactores rapidos

Energy Technology Data Exchange (ETDEWEB)

Yiftah, S [Israel Atomic Energy Commission (Israel)

1962-03-15

fisionables por neutrones termicos ({sup 239}Pu y {sup 241}Pu), cuanto mas impuro sea el plutonio, tanto menor sera la masa critica y mayor la razon de reproduccion. Tomando como ejemplo el reactor de 1500 l, se comprobo ademas que al eliminar un 40 por ciento del sodio inicialmente presente en el cuerpo, la variacion de reactividad tiende a ser negativa a medida que aumenta la proporcion de isotopos superiores contenidos en el combustible de plutonio (en forma de metal, oxido o carburo). (author) [Russian] Izotopnyj sostav plutoniya, kotoryj dolzhen ispol'zovat'sya v kachestve goryuchego dlya reaktorov na bystrykh nejtronakh, budet zaviset' ot istochnika polucheniya plutoniya. V printsipe vozmozhny tri razlichnykh istochnika: a) proizvodyashchie reaktory; b) teplovye ehnergeticheskie reaktory (ispol'zuyushchie v kachestve topliva estestvennyj ili obogashchennyj uran); c) zony vosproizvodstv a reaktora na bystrykh nejtronakh. V osnovnom istochnik (a) i v nekotorom otnoshenii istochnik (s) budut davat' sravnitel'no 'chistyj' plutonij, t.e. glavnym obrazom plutonij-239, togda kak plutonij iz istochnika (b) budet 'gryaznym', t.e. plutoniem, bogatym izotopami plutoniya-240, plutoniya-241 i plutoniya-242. Stepen' 'zagryazneniya' budet zaviset' ot tipa reaktora, velichiny vygoraniya i voobshche ot istorii oblucheniya topliva. V takom sluchae voznikaet vopros, mozhno li ispol'zovat' v kachestve goryuchego dlya reaktorov na bystrykh nejtronakh lyubye vidy plutoniya. Dlya izucheniya vliyaniya razlichnogo izotopnogo sostava plutonievogo topliva v metallicheskom, oksidnom i karbidnom vide na rabotu reaktorov na bystrykh nejtronakh byli osushchestvleny ogranichennye serii podschetov po 16-gruppovoj diffuzionnoj teorii sfericheskoj geometrii s pomoshch'yu 16-gruppovogo komplekta poperechnykh sechenij, razrabotannogo nedavno Iftakhom, Okrentom i Mol'dauerom s ispol'zovaniem trekh razlichnykh vidov plutoniya, nachinaya s chistogo plutoniya-239 i povyshaya kolichestvo bolee vysokikh izotopov

Development of fast neutron radiography system based on portable neutron generator

Energy Technology Data Exchange (ETDEWEB)

Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

2016-01-22

Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

Phonon instabilities in NaNbO3

International Nuclear Information System (INIS)

Mishra, S.K.; Gupta, M.K.; Mittal, R.; Chaplot, S.L.

2012-01-01

NaNbO 3 has antiferroelectric structure at room temperature and exhibits unusual complex sequence of temperature and pressure driven structural phase transitions. Temperature dependent measurements from 17 to 1075 K revealed that NaNbO 3 undergoes a series of phase transitions, ranging from non-polar antiferrodistortive to ferroelectric and antiferroelectric in nature. High pressure measurements carried out up to 11 GPa at ambient temperature indicate transition from antiferroelectric to paraelectric phase. These transitions are characterized by appearance and disappearance of superlattice reflections in the powder diffraction patterns. Numerous Raman and infrared measurements are also reported in literature to gain reliable insights into, and deeper understanding of phase transition behavior. The optical measurements are limited to the Brillouin zone centre, which does not give a complete picture of the dynamics. Inelastic neutron scattering and ab-initio calculations were carried out to understand the phase transitions behaviour and their relation to the phonon spectra

Neutron dosimetry at SLAC: Neutron sources and instrumentation

Energy Technology Data Exchange (ETDEWEB)

Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.

1991-10-01

This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ({sup 238}PuBe, {sup 252}Cf, {sup 238}PuB, {sup 238}PuF{sub 4}, and {sup 238}PuLi) and the neutron instrumentation (moderated BF{sub 3} detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, {sup 12}C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs.

Characterization of elements in trace amounts in imperial topaz through neutron activation analysis

International Nuclear Information System (INIS)

Oliveira, Ester Figueiredo de; Sabioni, Antonio C. S.; Ferreira, Cesar M.

2000-01-01

This work deals with the mineral characterization of the elements in trace amounts of imperial topaz, original form Mina Capao da Lama, Ouro Preto, MG, Brazil, through the neutron activation analysis. Recent results have permitted to quantify Cr, Cs, Mn, Na, Ga, Sb and Au. The main goal of this study is the contribution to the mineral and gemological research of the imperial topaz

Modern quantum magnetism by means of neutron scattering

International Nuclear Information System (INIS)

Grenier, B.; Ziman, T.

2007-01-01

We review a selection of recent applications of neutron scattering to the field of quantum magnetism. We focus on systems where, because of quantum fluctuations enhanced by frustration and low dimension, there is no long range magnetic order in the ground state. We select two examples that we treat in more depth to show how neutron studies, in conjunction with the results of other experimental techniques, can give new insights. The first is the case of the spin ladder NaV 2 O 5 , where the origin of the spin gap at low temperature is now understood in detail. Apparent contradictions between quantitative measures of the charge order from neutron inelastic scattering, resonant X-ray scattering and NMR have been resolved giving interesting insights into the correlations. The second case is that of spin dimer system Cs 3 Cr 2 X 9 (X = Br, Cl), undergoing transitions to field induced transverse magnetic order. The Br compound is attractive as the critical fields are sufficiently low that a complete study, in different field directions, is possible. In addition, it is noteworthy in that the magnon that softens and condenses is incommensurable with the lattice. The common description in terms of Bose-Einstein condensation must be extended to include a continuous degeneracy and single ion anisotropy, and conclusions can be drawn by comparison with the Cl compound. (authors)

Nuclear data measurements in 3x592 GBq 241Am-Be neutron cell

International Nuclear Information System (INIS)

2010-01-01

accurately. Cumulative fission yield for the fission products from 2 32Th(n, f) and 2 38U(n, f) reactions in a neutron spectrum of average 5.0 MeV energy, were measured. For 2 32Th(n, f) reaction, cumulative fission yield of 16 fission products between A = 87 - 143 was measured and for 2 38U(n, f) reaction, cumulative fission yield of 33 fission products between A = 87 - 146 was measured. Neutron threshold detectors are used for determining reactor radiation damage, neutron flux measurements and in neutron dosimeters. Cross section measurements were performed for the following threshold detectors in the given neutron energies: for 1 03Rh(n, n') 1 03mRh at 4.83 MeV, for 1 15In(n, n') 1 15mIn at 4.97 MeV, for 2 32Th(n, f) at 5.02 MeV, for 2 38U(n, f) at 5.04 MeV, for 4 7Ti(n, p) 4 7Sc at 5.23 MeV, for 6 4Zn(n, p) 6 4Cu at 5.45 MeV, for 5 8Ni(n, p) 5 8Co at 5.45 MeV, for 5 4Fe(n, p) 5 4Mn at 5.71 MeV, for 4 6Ti(n, p) 4 6Sc at 6.16 MeV, for 2 7Al(n, p) 2 7Mg at 6.47 MeV, for 5 6Fe(n, p) 5 6Mn at 7.72 MeV, for 2 4Mg(n, p) 2 4Na at 8.21 MeV, for 5 9Co(n, α) 5 6Mn at 8.21 MeV, for 2 7Al(n, α) 2 4Na at 8.43 MeV and for 4 8Ti(n, p) 4 8Sc at 8.72 MeV. It is especially crucial to know accurately the gamma ray intensities of 2 34Th, 2 34mPa and 2 34gPa nuclides, which are important for the evaluation of the dose balance of depleted uranium and the efficiency calibration of the high efficiency gamma detectors and are in secular equilibrium with 2 38U. Here, intensities (decay probabilities) of 72 gamma rays of 2 34mPa and 2 34gPa nuclides were measured. In 3 x 592 GBq Am-Be neutron irradiation cell, qualitative and quantitative detection limits were determined for Na, Al, Cl, K, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Mo, Ru, Ag, Cd, In, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Lu, Hf, W, Pt, Au, Th and U elements. By using the cyclic activation analysis method, half lives of 2 8Al, 5 2V, 6 6Cu, 7 7mSe, 8 6mRb, 1 08Ag, 1 10Ag, 1 22mSb, 1 61Gd, 1 65m

Directional epithermal neutron detector

International Nuclear Information System (INIS)

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

1986-01-01

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

Neutron Optics: Towards Applications for Hot Neutrons

International Nuclear Information System (INIS)

Schanzer, C; Schneider, M; Böni, P

2016-01-01

Supermirrors with large critical angles of reflection, i.e. large index m are an essential ingredient to transport, focus and polarise neutrons over a wide range of energy. Here we summarise the recent developments of supermirror with very large critical angles of reflection and high reflectivity that were conducted at SwissNeutronics as well as their implementation in devices. Approaching critical angles m = 8 times the critical angle of natural nickel makes new applications possible and extends the use of reflection optics towards the regime of hot and epithermal neutrons. Based on comparisons of simulations with experiment we demonstrate future possibilities of applications of large-m supermirrors towards devices for neutrons with short wavelength. (paper)

Neutron transportation simulator

International Nuclear Information System (INIS)

Uenohara, Yuzo.

1995-01-01