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Meleshenkovskii, I.*; Van den Brandt, K.*; Ogawa, Tatsuhiko; Datema, C.*; Mauerhofer, E.*
European Physical Journal Plus (Internet), 139, p.565_1 - 565_9, 2024/07
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Fast neutron inelastic scattering is a promising non-destructive assay technique for various analytical applications. As an active neutron interrogation technique, its performance is a function of various different factors and parameters that require optimization. Monte Carlo simulation codes are indispensable for such tasks. However, the internal simulation routines implemented in such codes can rely on different physical models that can yield discrepancies in the simulation results. In this work we conduct an intercomparison of PHITS and Geant4 codes performance in application to fast neutron inelastic scattering simulations. The goal of this paper is twofold. First, we explain the differences in code configuration with respect to gamma and neutron transport, as well as internal simulation routines. Second, we conduct a performance assessment of the two codes using two different measurement configurations. One configuration consisted of a source of gamma-rays in a broad energy range (100 keV - 9000 keV) and a CeBr
detector. The other configuration consisted of a monoenergetic 2.5 MeV fast neutron source, Fe, Nd, Dy, B targets and a CeBr detector. Selected simulation configurations were chosen with a goal to compare the performance differences in neutron energy distribution, produced prompt gamma-rays and energy deposition in CeBr detector between the two codes. Results of our study reveal a good coherence of both codes performance in the application of fast neutron inelastic scattering simulations. The simulation geometries and observed differences are described in detail.
Meleshenkovskii, I.*; Ogawa, Tatsuhiko; Sari, A.*; Carrel, F.*; Boudergui, K.*
Nuclear Instruments and Methods in Physics Research B, 483, p.5 - 14, 2020/11
Times Cited Count：10 Percentile：68.22(Instruments & Instrumentation)For the purpose of fissile material detection, the technique to observe neutrons ejected from photo-fission induced by bremsstrahlung X-rays is being developed. This technique is advantageous in the sense that the machine can be compact compared to conventional neutron generators. However, photo-fission reaction cross sections are generally smaller than those of neutron-induced fission cross sections therefore optimization of the beam line is of high importance. In this study, we investigated the factors necessary to be optimized by using Monte-Carlo transport codes MCNP and PHITS. It was found that high-Z materials are advantageous to effectively produce bremsstrahlung X-rays but photons produce neutrons by secondary (
,n) reactions resulting in mixing of prompt and delayed fission reactions. Moreover, secondary neutrons are produced not only inside the target but also in the materials surrounding the target. Therefore it is necessary to select elements whose neutron separation energy is high to suppress parasitic secondary neutrons.
Meleshenkovskii, I.*; Ogawa, Tatsuhiko; Pauly, N.*; Labeau, P.-E.*
Nuclear Instruments and Methods in Physics Research B, 467, p.108 - 113, 2020/03
Times Cited Count：2 Percentile：20.23(Instruments & Instrumentation)CdZnTe (CZT) semiconductor detectors are featured by the fact that it can be operated in room-temperature. In CZT, however, the hole collection efficiency is substantially less than 100% owing to its low hole-mobility. Therefore the detector signal is suppressed depending on the distance of ionization from the anode. In particular, gamma-rays interact with the detector at random, which result in asymmetric pulse-height distribution. Among the radiation transport codes available up to now, other than PHITS which can consider symmetric gaussian distribution, any codes did not have functions to consider arbitrary response functions. On the other hand, Melechankovski et al proposed a function form that can reproduce the pulse-height spectrum of CZT detectors. In this study, the pulse-height spectra of a 500 mm
CZT detector exposed to gamma rays from 59 keV (
Am) to 1332 keV (
Co) was measured and compared with the energy deposition spectrum calculated PHITS with incorporating the Melechankovski's CZT detector response formula. The comparison showed satisfactory agreement between the calculated and measured pulse-height distribution featured by the gaussian peak shape and exponential decline in the lower energy side. This new function enables experimental design considering realistic detector performance as well as detector system design considering detector response. The arbitrary detector response function was incorporated to PHITS Ver.3.10 and later.
