The Experts below are selected from a list of 41130 Experts worldwide ranked by ideXlab platform
N. V. Kornilov - One of the best experts on this subject based on the ideXlab platform.
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The Scale Method as an Approach for Prompt Fission Neutron Spectra Analysis and Evaluation
Nuclear Data Sheets, 2019Co-Authors: N. V. KornilovAbstract:Abstract The Scale Method was applied for an analysis of experimental and evaluated data of Prompt Fission Neutron Spectra for different isotopes and incident Neutron energies below 6 MeV. It was demonstrated that the method describes all experimental data sets in the outgoing Neutron energy range 0–7 MeV within uncertainties. Theoretical arguments were provided to support the application of this method. Some important peculiarities connected with the Neutron emission mechanism were identified, and proposals for future theoretical and experimental investigations were discussed. It was concluded that the new evaluations completed recently for 235 U systematically overestimate the average energy of experimental prompt fission Neutron Spectra.
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Inelastic Neutron scattering and prompt fission Neutron Spectra for 237Np
Annals of Nuclear Energy, 2000Co-Authors: N. V. Kornilov, A.b. Kagalenko, V. Ya. Baryba, V.g. Demenkov, S.v. Pupko, P.a. AndrosenkoAbstract:The secondary Neutron Spectra (inelastic, elastic, fission) for 237Np were measured by the Neutron time of flight spectrometer of the IPPE at the incident energy range 1–2.5 MeV. The solid tritium target was used as a Neutron source. The neptunium oxide (189 g) packed in the low mass stainless steel container was used as a scattering sample. The Neutron background due to scattering on the target environment and tritium into the target backing was measured and was calculated with the appropriate model of the Neutron source. The data were corrected for Neutron background, the scattering on the oxygen and iron nuclei, and the effect of the finite sample size. The fission Neutron Spectra were measured, evaluated and subtracted from the emission Neutron Spectra to estimate inelastic Neutron Spectra and cross-sections. The experimental results were compared with ENDF/B-VI, BROND-2, JENDL-3 Neutron data libraries.
Osamu Iwamoto - One of the best experts on this subject based on the ideXlab platform.
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Systematics of Prompt Fission Neutron Spectra
Journal of Nuclear Science and Technology, 2008Co-Authors: Osamu IwamotoAbstract:Prompt fission Neutron Spectra (PFNS) from Neutron-induced and spontaneous fissions were analysed using a modified Los Alamos model, in which an analytical expression of the inverse reaction cross section was used and a scission Neutron contribution was taken into account. The model parameters were estimated from available PFNS experimental data, and their systematics behaviors as a function of Z/A1/3, where Z is the atomic number and A is the mass number, were deduced. It was demonstrated that the calculated results using the present systematics predict experimental PFNS with good accuracy.
Valery Trenkin - One of the best experts on this subject based on the ideXlab platform.
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Precision Measurements of Prompt Neutron Spectra in 240Pu and 242Pu Spontaneous Fission
Journal of Nuclear Science and Technology, 2002Co-Authors: Boris Gerasimenko, L.v. Drapchinsky, Oleg Kostochkin, Tatyana Kuzmina, Nikolay Skovorodkin, Valery TrenkinAbstract:Under the Program of Measurements of Prompt Neutron Spectra in Minor Actinides Fission for Transmutation Purposes carried out at the V.G. Khlopin Radium Institute the integral Neutron Spectra in the 240Pu and 242Pu spontaneous fission have been measured. The measurements were performed by the time-of-flight method in the energy range of 0.1-15 MeV relative to the standard Neutron spectrum in 252Cf spontaneous fission. The accuracies of the average Neutron spectrum energies are better than 2%. The theoretical computation of the prompt Neutron Spectra in the 240Pu and 242Pu spontaneous fission was performed in the framework of statistical approach using Hauser-Feschbach model.
Hector Rene Vega-carrillo - One of the best experts on this subject based on the ideXlab platform.
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Neutron Spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel.
Applied Radiation and Isotopes, 2014Co-Authors: Hector Rene Vega-carrillo, V. M. Hernández-dávila, F. Aguilar, L. Paredes, T. RiveraAbstract:Abstract The Neutron Spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during Neutron Spectra measurements using a Bonner sphere spectrometer with a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The Neutron Spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured Spectra show fission, epithermal and thermal Neutrons, being harder in the radial beam port.
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Neutron Spectra and H*(10) in a 15 MV Linac
2010Co-Authors: J. Benites, Hector Rene Vega-carrillo, V. M. Hernández-dávila, T. Rivera, A. Carrillo, R. MondragonAbstract:Neutron Spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron Spectra in the vicinity of isocentre show the presence of evaporation and knock‐on Neutrons produced by the source term, while epithermal and thermal Neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze Neutron Spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r2 rule due to changes in the Neutron Spectra.
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Neutron Spectra in a 15 MV LINAC
2010Co-Authors: Hector Rene Vega-carrillo, Wei‐han Chu, Chuan‐jong Tung, Jen‐hong LanAbstract:Neutron Spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the Neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the Spectra in the treatment hall show the presence of evaporation and knock‐on Neutrons; also the room‐return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal Neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.
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Neutron Spectra re-binning and dose calculation using Monte Carlo methods
Revista Mexicana De Fisica, 2007Co-Authors: Hector Rene Vega-carrillo, E. Manzanares Acuña, J.m Ortiz Rodríguez, T Arteaga ArteagaAbstract:Resumen en: One hundred thirty lethargy Neutron Spectra in 60 energy groups were converted to energy Spectra and re-binned to 31 energy groups. Original Spectra wer...
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Neutron Spectra and dosimetric features around an 18 MV linac accelerator
Health physics, 2005Co-Authors: R. Barquero, Hector Rene Vega-carrillo, R Méndez, M. P. Iñiguez, T. M. EdwardsAbstract:Using the difference between responses to Neutrons of TLD-600 and TLD-700, three experimental devices were constructed and arranged to measure thermal Neutron fluences, Neutron Spectra, and Neutron doses inside the treatment room of a radiotherapy 18 MV Linear electron accelerator (Linac). Thermal Neutron fluences were measured with TLD-600/TLD-700 pairs arranged in both a bare and a cadmium (Cd) foil covered methacrylate box. Neutron Spectra were measured in 26 energy bins by introducing pairs of TLD-600/TLD-700 in air and into the middle of five polyethylene spheres with diameters of 3, 5, 8, 10, and 12 inches. A PC version of the BUNKI code was used to unfold the six measurements in each sphere to obtain the 26 energy bins. Neutron and photon doses were measured by introducing pairs of TLD-600/TLD-700 into the middle of a single 25-cm-diameter paraffin sphere. The three required Neutron calibrations were carried out at the Nuclear Technology Laboratory of the Polytechnique University of Madrid (UPM), using an 241Am-Be Neutron source with an alpha activity of 111 GBq and a yield of 6.6 x 10(6) Neutrons s(-1). Three devices were needed for the necessary calibrations: a BF3 counter for the thermal Neutron fluence calibration, a LUDLUM 42-5 Bonner spectrometer with five 0.95 g cm(-3) polyethylene spheres with a LiI(Eu) 4 x 4 mm2 scintillation counter for the Neutron spectrometer calibration and a NEMO 9140 remmeter for the paraffin remmeter calibration. The Monte Carlo code MCNP 4C has been used in two ways: to calculate the Neutron kerma contribution to two TLDs (type 600 and 700) both in air and inside the paraffin sphere, and to determine the Neutron Spectra at those Linac room zones where the Neutron Spectra were measured. Thermal Neutron fluences of 2.9 x 10(4) +/- 8.6 x 10(3) cm(-2) s(-1), measured around the Linac head plane, and 2.3 x 10(4) +/- 2.3 x 10(3) cm(-2) s(-1), measured at the patient couch plane, are in agreement with previous independent measurements from other authors. The calculated and measured Neutron Spectra obtained in the treatment room showed three distinct regions: a peak around 0.1 MeV, a flat epithermal region and a thermal region with values similar to those mentioned above. Patient dose equivalents of 0.5 mSv and 5 mSv from Neutrons and photons, respectively, were obtained per treatment Gray.
M. Ghiassi-nejad - One of the best experts on this subject based on the ideXlab platform.
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Fast Neutron Spectra determination by threshold activation detectors using neural networks
Radiation Measurements, 2004Co-Authors: Mohammad Reza Kardan, Saeed Setayeshi, R. Koohi-fayegh, M. Ghiassi-nejadAbstract:Neural network method was used for fast Neutron Spectra unfolding in spectrometry by threshold activation detectors. The input layer of the neural networks consisted of 11 neurons for the specific activities of Neutron-induced nuclear reaction products, while the output layers were fast Neutron Spectra which had been subdivided into 6, 8, 10, 12, 15 and 20 energy bins. Neural network training was performed by 437 fast Neutron Spectra and corresponding threshold activation detector readings. The trained neural network have been applied for unfolding 50 Spectra, which were not in training sets and the results were compared with real Spectra and unfolded Spectra by SANDII. The best results belong to 10 energy bin Spectra. The neural network was also trained by detector readings with 5% uncertainty and the response of the trained neural network to detector readings with 5%, 10%, 15%, 20%, 25% and 50% uncertainty was compared with real Spectra. Neural network algorithm, in comparison with other unfolding methods, is very fast and needless to detector response matrix and any prior information about Spectra and also the outputs have low sensitivity to uncertainty in the activity measurements. The results show that the neural network algorithm is useful when a fast response is required with reasonable accuracy.
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Neutron Spectra unfolding in Bonner spheres spectrometry using neural networks
Radiation protection dosimetry, 2003Co-Authors: Mohammad Reza Kardan, Saeed Setayeshi, R. Koohi-fayegh, M. Ghiassi-nejadAbstract:The neural network method has been used for the unfolding of Neutron Spectra in Neutron spectrometry by Bonner spheres. A back propagation algorithm was used for training of neural networks. 4 mm x 4 mm bare LiI (Eu) and in a polyethylene sphere set: 2, 3, 4, 5, 6, 7, 8, 10, 12, 18 inch diameter have been used for unfolding of Neutron Spectra. Neural networks were trained by 199 sets of Neutron Spectra, which were subdivided into 6, 8, 10, 12, 15 and 20 energy bins and for each of them an appropriate neural network was designed and trained. The validation was performed by the 21 sets of Neutron Spectra. A neural network with 10 energy bins which had a mean value of error of 6% for dose equivalent estimation of Spectra in the validation set showed the best results. The obtained results show that neural networks can be applied as an effective method for unfolding Neutron Spectra especially when the main target is Neutron dosimetry.