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Tsai, P.-E.; Iwamoto, Yosuke; Hagiwara, Masayuki*; Sato, Tatsuhiko; Ogawa, Tatsuhiko; Satoh, Daiki; Abe, Shinichiro; Ito, Masatoshi*; Watabe, Hiroshi*
Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 3 Pages, 2018/11
The energy spectra of primary knock-on atoms (PKAs) are essential for radiation damage assessment in design of accelerator facilities. However up to date the experimental data are still limited, due to the poor mass resolution and the high measurement threshold energies in the conventional setup of nuclear physics experiments using solid state detectors, which are typically above a few MeV/nucleon. In this study, a novel detection system consisting of two time detectors and one dE-E energy detector is proposed and being constructed to measure the PKA spectra. The system and detector design was based on Monte Carlo simulations by using the PHITS code. The PHITS simulations show that the system is able to distinguish the PKA isotopes above 
0.2-0.3 MeV/nucleon for A=2030 amu; the PKA mass identification thresholds decrease to 
0.1 MeV/nucleon for PKAs lighter than 20 amu. The detection system will be tested in the summer of 2017, and the test results will be presented at the conference.
-rays for low-energy neutron induced fissionMakii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, R.; L
guillon, R.*; Ogawa, Tatsuhiko; Soldner, T.*; Hambsch, F.-J.*; A
che, M.*; Astier, A.*; et al.
Nuclear Instruments and Methods in Physics Research A, 906, p.88 - 96, 2018/10
Percentile：100(Instruments & Instrumentation)We have developed a new setup to measure prompt fission -ray spectra in neutron induced fission up to energies sufficient to reveal the structure associated with giant dipole resonances of fission fragments. The setup consists of multi-wire proportional counters, to detect both fission fragments in coincidence, and two large volume (101.6 mm in diameter and 127.0 mm in length) LaBr
(Ce) scintillators, to measure the -rays. The setup was used to obtain the prompt fission -ray spectrum for thermal neutron induced fission of 
U at the PF1B cold-neutron beam facility of the Institut Laue-Langevin, Grenoble, France. We have successfully measured the -ray spectrum up to energies of about 20 MeV, what extends the currently known -ray spectrum limit to higher energies by approximately a factor of two.
rster quenching modelOgawa, Tatsuhiko; Yamaki, Tetsuya*; Sato, Tatsuhiko
PLoS ONE (Internet), 13(8), p.e0202011_1 - e0202011_19, 2018/08
Percentile：100(Multidisciplinary Sciences)Scintillators are generally used to detect various kinds of particles such as electrons, gammas, protons and heavy ions. Scintillators emit photons according to the energy deposited to the crystal. It is also known that light yield is suppressed for particles depositing energy densely owing to quenching. Moreover, it is suggested that quenching is attributed to transfer of energy from excited fluorescent molecules to damaged molecules (Frster mechanism). In this study, energy deposition in a scintillator crystal by radiation was calculated using radiation transport codes to finally obtain excitation and damage of fluorescent molecules. Based on the calculation, spatial configuration of exited and damaged molecules. Then the probability that Frster mechanism takes place in excited molecules were estimated to obtain the number of fluorescent molecules that emit photons. As a result, light yield is proportionally increased with increase in the incident energy in case of electron incidence. On the other hand, light yield is increased non-linearly in case of proton incidence. This trend is in a good agreement with the experimental results.
Ogawa, Tatsuhiko; Sato, Tatsuhiko; Hashimoto, Shintaro; Niita, Koji*
Physical Review C, 98(2), p.024611_1 - 024611_15, 2018/08
Percentile：100(Physics, Nuclear)Particle production by nucleus-nucleus reactions in the energy range from GeV to TeV is substantially important for safety evaluation in heavy ion accelerators and evaluation of space radiation dose. A lot of models and theories have been studied. In the models developed in the past, interaction between nucleons were dependent on the reference frame; therefore the moving incident nucleus and the target nucleus at rest transferred to the common frame were disintegrated. Previously, intentional bias was introduced to the calculation algorithms to supplement stability but residual nucleus mass and secondary particle production was underestimated. In this study, a reaction model JAMQMD was developed, in which intra-nucleon interaction was described in a frame-independent way. This model can reproduce the stability of nuclei regardless of the reference frame and the yield of residual nuclei as well as secondary particles including deuterons. JQMD Ver.2 developed 3 years ago can simulate nucleus-nucleus reactions up to 3 GeV/nucleon; therefore the development of JAMQMD is the doorway to simulate nucleus-nucleus reactions regardless of the incident energy. JAMQMD is an useful model for not only radiation protection studies but also analysis of fundamental physics studies.
Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Tsai, P.-E.; Matsuda, Norihiro; Iwase, Hiroshi*; et al.
Journal of Nuclear Science and Technology, 55(6), p.684 - 690, 2018/06
Times Cited Count：40 Percentile：0.03(Nuclear Science & Technology)We have upgraded many features of the Particle and Heavy Ion Transport code System (PHITS) and released the new version as PHITS3.02. The accuracy and the applicable energy ranges of the code were greatly improved and extended, respectively, owing to the revisions to the nuclear reaction models and the incorporation of new atomic interaction models. In addition, several user-supportive functions were developed, such as new tallies to efficiently obtain statistically better results, radioisotope source-generation function, and software tools useful for applying PHITS to medical physics. In this paper, we summarize the basic features of PHITS3.02, especially those of the physics models and the functions implemented after the release of PHITS2.52 in 2013.
Hashimoto, Shintaro; Sato, Tatsuhiko; Iwamoto, Yosuke; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Niita, Koji*
Kaku Deta Nyusu (Internet), (120), p.26 - 34, 2018/06
Particle and heavy-ion transport code system PHITS has been used for calculations of radiation shielding in accelerator facilities. PHITS describes physical phenomena induced by radiation as combination of transport and collision processes. The collision process including nuclear reactions is simulated by the three-step calculation: a generation of a reaction, pre-equilibrium, and compound processes. In the simulation, many physics models are used. This report explains roles of the models in PHITS and shows their developments we recently performed.
Ogawa, Tatsuhiko; Hashimoto, Shintaro; Sato, Tatsuhiko; Niita, Koji*; Kamae, Tsuneyoshi*
Proceedings of 3rd International Conference on Particle Physics and Astrophysics (ICPPA 2017) (Internet), p.391 - 398, 2018/04
In the reactions of cosmic-ray heavy ions producing high-energy gamma-rays, heavy ions are directed to the ground therefore prompt gamma-rays from projectile fragments are boosted by Doppler effect and observed on the ground. Recently, a lot of experiments pay attention to such high energy gamma-rays. In order to simulate such high-energy gammas, event-by-event simulation of fragmentation reaction which determines the excitation energy and angular momentum of the produced fragment, and de-excitation simulation based on the nuclear structure data. Such models are available in the general-purpose radiation transport simulation code PHITS. JAERI Quantum Molecular Dynamics model was recently updated to accurately simulate charge and mass distribution of fragments. EBITEM, which was released recently, can simulate gamma deexcitation after evaporation based on the excitation energy and angular momentum. Thus latest PHITS can accurately simulate production of -rays attributed to cosmic-ray heavy ions. This study shows a new approach to reproduce -rays by cosmic-ray heavy ions.
Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; Ono, Akira*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.
Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03
Times Cited Count：16 Percentile：1.01(Physics, Nuclear)International comparison of heavy-ion induced reaction models were discussed in the international conference "Transport2017" held in April 2017. Owing to their importance for safety assessment of heavy-ion accelerators and dosimetry of astronauts, various models to simulate heavy-ion induced reaction models are developed. This study is intended to clarify the difference among them to pinpoint their problems. In the comparison study, 320 protons and 320 neutrons were packed in a 20-fm-large cube to calculate the number of particle-particle collisions as well as the energies of collisions during the time evolution. In addition to the calculation, their algorithms were compared. The author contributed to this study by running calculation using JQMD (JAERI Quantum Molecular Dynamics). The results were compared with those calculated by the other 15 codes from over the world. Algorithm comparison showed that JQMD calculates collision probabilities from protons at first and collisions by neutrons are simulated later, which might be unreasonable. On the other hand, it was clarified that the calculation by JQMD agrees with those by the others. Despite the fact that some codes deviate from the average by a factor of 2, JQMD exhibited stable performance.
Sato, Tatsuhiko; Niita, Koji*; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuda, Norihiro; Okumura, Keisuke; et al.
EPJ Web of Conferences (Internet), 153, p.06008_1 - 06008_6, 2017/09
Times Cited Count：1 Percentile：14.04Particle and Heavy Ion Transport code System, PHITS, has been developed under the collaboration of several institutes in Japan and Europe. It can deal with the transport of nearly all particles up to 1 TeV (per nucleon for ion) using various nuclear reaction models and data libraries. More than 2,500 researchers and technicians have used the code for a variety of applications such as accelerator design, radiation shielding and protection, medical physics, and space and geosciences. This paper briefly summarizes physics models and functions newly implemented in PHITS between versions 2.52 and 2.82.
-rays from neutron induced fission of U-235Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, R.; Lguillon, R.; Ogawa, Tatsuhiko; Soldner, T.*; Hambsch, F.-J.*; Astier, A.*; Pollitt, A.*; et al.
EPJ Web of Conferences (Internet), 146, p.04036_1 - 04036_4, 2017/09
Times Cited Count：2 Percentile：4.05The measurement of the prompt fission -ray spectrum (PFGS) is quite important to study the de-excitation process of neutron-rich fission fragments as well as to generate data required to design a generation-IV reactors. The PFGS measured for spontaneous fission of 
Cf shows a broad hump at energies more than 8 MeV. This is interpreted as a giant dipole resonance (GDR) of the fragments centered around 15 MeV. To understand how the GDR is populated in the fission process, one needs to measure the PFGS for the reactions with the mass yields different from the spontaneous fission of Cf, such as (n,f). The measurements of the PFGS for (n,f), however, are limited less than 9 MeV even in the recent experiment. This prompts us to make a new measurement to extend the know PFGS up to 20 MeV. The measurement has been carried out at the PF1B beam line of Institut Laue-Langevin. In this contribution we will present the results obtained the measurement.
Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuda, Norihiro; Iwase, Hiroshi*; Niita, Koji*
Hoshasen, 43(2), p.55 - 58, 2017/05
Particle and Heavy Ion Transport code System, PHITS, has been developed under the collaboration of several institutes in Japan and Europe. It can deal with the transport of nearly all particles up to 1 TeV (per nucleon for ion) using various nuclear reaction models and data libraries. More than 2,500 registered researchers and technicians have used this system for various applications such as accelerator design, radiation shielding and protection, medical physics, and space- and geo-sciences. This paper summarizes the physics models and functions recently implemented in PHITS, between versions 2.52 and 2.88.
Iwamoto, Yosuke; Sato, Tatsuhiko; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuda, Norihiro; Hosoyamada, Ryuji*; Niita, Koji*
Journal of Nuclear Science and Technology, 54(5), p.617 - 635, 2017/05
Times Cited Count：14 Percentile：0.82(Nuclear Science & Technology)We performed a benchmark study for 58 cases using the recent version 2.88 of the Particle and Heavy Ion Transport code System (PHITS) in the following fields: particle production cross-sections for nuclear reactions, neutron transport calculations, and electro-magnetic cascade. This paper reports details for 22 cases. In cases of nuclear reactions with energies above 100 MeV and electro-magnetic cascade, overall agreements were found to be satisfactory. On the other hand, PHITS did not reproduce the experimental data for an incident proton energy below 100 MeV, because the intranuclear cascade model INCL4.6 in PHITS is not suitable for the low-energy region. For proton incident reactions over 100 MeV, PHITS did not reproduce fission product yields due to the problem of high-energy fission process in the evaporation model GEM. To overcome these inaccuracies, we are planning to incorporate a high-energy version of the evaluated nuclear data library JENDL-4.0/HE, and so on.
Iwamoto, Yosuke; Ogawa, Tatsuhiko
Nuclear Instruments and Methods in Physics Research B, 396, p.26 - 33, 2017/04
Percentile：100(Instruments & Instrumentation)It is important to validate the calculations of PKA spectra that are used to estimate radiation damage in materials. Here, the PKA spectra of fission-relevant materials were calculated using the Particle and Heavy Ion Transport code System (PHITS) and also using the data processing code NJOY with the nuclear data libraries. The heating number, which is the integral of the PKA spectrum, was also calculated using PHITS and compared with data extracted from the data libralies. From analyzing the PKA spectra, we found that the energy and angular recoil distributions were incorrect for 
Ge, 
As, 
Y, and 
Ag in the ENDF/B-VII.1 library. From analyzing the heating number, we found that the data extracted from the ACE file of TENDL2015 for all elements were problematic in the neutron capture region. However, PHITS+TENDL2015 can calculate PKA spectra and heating numbers correctly.
Ogawa, Tatsuhiko; Yamaki, Tetsuya*; Sato, Tatsuhiko
QST-M-2; QST Takasaki Annual Report 2015, P. 46, 2017/03
Modification of materials by irradiation, which is substantially important for radiation safety in facilities and industrial applications, is studied from various aspects. Material modification is induced by local energy deposition by incident radiation followed by the changes of chemical bonds in the spatial scale of nm to 
m. So far, absorbed dose was regarded as the best index of irradiation effects, however, it is also known that irradiation effects varies depending on the radiation species even under the same absorbed dose or LET. Radiation transport simulation code PHITS can calculate simulate energy deposition in nm to m scale to obtain LET and specific energy deposition (SED). By using SED calculation function, an attempt to reproduce radiation species dependence of material property change based on the theoretical prediction of chemical reactions induced by energy deposition in different irradiation conditions. Estimate on the decrease in Elongation at Break (EB) of poly-ether sulfone in three different irradiation conditions, 10 MeV protons, 50 MeV 
He and 
C showed that reduction of EB by carbon ions is twice as small as that by proton and that by helium for the same absorbed dose, which is in an agreement with experiment. Moreover, assuming that scission of polymer takes place at random and 100 eV energy deposition in the region result in loss of mechanical strength, saturating trend of EB reduction.
Tsuda, Shuichi; Sato, Tatsuhiko; Ogawa, Tatsuhiko; Sasaki, Shinichi*
JPS Conference Proceedings (Internet), 11, p.060004_1 - 060004_6, 2016/11
Track structure and energy deposition around charged particle beams in microscopic site of a living cell is important information for understanding of biological effects of energetic heavy ion beams. In this work, measurements of lineal energy (
) distributions for various kinds of ion beams have been performed for the verification of the microdosimetric function that incorporated in the PHITS code. In the international symposium focused on radiation detectors, the wall-less tissue equivalent proportional counter that developed in this study to measure distributions will be introduced, together with a series of data.
Ogawa, Tatsuhiko; Hashimoto, Shintaro; Sato, Tatsuhiko
Journal of Nuclear Science and Technology, 53(11), p.1766 - 1773, 2016/11
Times Cited Count：3 Percentile：42.29(Nuclear Science & Technology)Nuclear resonance fluorescence (NRF) is regarded as a useful phenomenon for application to non-destructive assay of fissile nuclei because NRF cross section peak energy is specific to isotopic species and detection system can be build using conventional photon detectors. So far, experimental technique such as monochromatic photon source based on inverse Compton scattering are intensively studied. In contrast, some unofficial release of nuclear reaction models to simulate NRF based on the literature data are available; however, no general-purpose NRF model was developed. In this study, general-purpose NRF model which can simulate NRF of 1071 nuclear species including unstable nuclei from Li to Bk was developed using nuclear structure data of ENSDF (Evaluated Nuclear Structure Data File) and theoretical description of the level transitions. Moreover, the model was applied for generation of radioactive nuclei and nuclear material assay to illustrate its effectiveness. This model was incorporated to PHITS ver.2.82 released Dec. 25th 2015 and provided to users.
Iwamoto, Yosuke; Sato, Tatsuhiko; Niita, Koji*; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuda, Norihiro; Iwase, Hiroshi*; et al.
JAEA-Conf 2016-004, p.63 - 69, 2016/09
A general purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS, is being developed through the collaboration of several institutes. PHITS can deal with the transport of nearly all particles, including neutrons, protons, heavy ions, photons, and electrons, over wide energy ranges using various nuclear reaction models and data libraries. PHITS users apply the code to various research and development fields such as nuclear technology, accelerator design, medical physics, and cosmic-ray research. This presentation briefly summarizes the physics models implemented in PHITS, and introduces some new models such as muon-induced nuclear reaction model and a de-excitation model EBITEM. We will also present the radiation damage cross sections for materials, PKA spectra and kerma factors calculated by PHITS under the IAEA-CRP activity titled "Primary radiation damage cross section."
Tsuda, Shuichi; Sato, Tatsuhiko; Ogawa, Tatsuhiko
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 141, 2016/09
Deposit energy distribution in microscopic site in a living cell is important information for understanding of biological effects of energetic heavy ion beams. In this work, a wall-less tissue equivalent proportional counter has been used for the measurement of lineal energy () distributions and dose-mean of (
) at radial direction of 30 MeV H at TIARA, for the verification of the microdosimetric function of PHITS. The measured 
() summed in radial direction agree with the corresponding data from the microdosimetric calculations using the PHITS code fairly well. The of 30 MeV proton beam presents the smallest value at 
= 0.0 and gradually increase with radial distance, while the values of heavy ions such as iron showed rapid decrease with radial distance. This experimental result demonstrates that the stochastic deposit energy distribution of high-energy protons in microscopic region is rather constant both in the core and in the penumbra region of the track structure.
Ogawa, Tatsuhiko; Hashimoto, Shintaro; Sato, Tatsuhiko; Niita, Koji*
EPJ Web of Conferences (Internet), 122, p.04005_1 - 04005_6, 2016/06
Percentile：100Nucleus-nucleus reactions models are important for radiological safety in heavy ions accelerator facilities such as heavy ion cancer therapy facilities. As one of such models, JAERI Quantum Molecular Dynamics (JQMD) has been successfully used to describe production of residue and secondary particles in nucleus-nucleus collisions. However, it has been pinpointed that formulation of interactions between nucleons were unstable through time evolution therefore heavy nuclei tended to decay before interactions. Such decays could not be distinguished from decay by collisions. In this study, we revised the description of interactions between nucleons to stabilize nuclei before collisions. Moreover, an algorithm to check the stability of ground-state nuclei was introduced. Description of nucleon-nucleon scattering cross sections were improved by introducing the in-medium effects. Fragment production cross sections for heavy targets (e.g. Ag) are predicted in better accuracy by thus developed revised JQMD (JQMD 2.0).
Ogawa, Tatsuhiko; Sato, Tatsuhiko; Hashimoto, Shintaro; Niita, Koji*
EPJ Web of Conferences (Internet), 117, p.03011_1 - 03011_8, 2016/05
Times Cited Count：1 Percentile：20.72Accurate prediction of fragment angular distribution in nucleus-nucleus collisions is essential for theoretical studies on nuclei and applications of particle beam. Quantum molecular dynamics is one of the approaches often adopted in general purpose radiation transport simulation codes to simulate formation of fragments, however, it is suggested that they tend to overestimate the width of fragment distribution angle. It is true for JQMD, the nucleus-nucleus reaction event generator incorporated to PHITS. By revising the description of peripheral collisions prediction of fragments angular distribution has been improved. First, spurious disintegration of nuclei before interaction is inhibited by introducing relativistic-covariant kinematics. By this improvement, one can distinguish nucleus spuriously disintegrated and nuclei interacted with other nuclei. Second, nucleon-nucleon scattering cross sections were increased by the suppression of Pauli blocking effect in the nucleus outer region to take into account for the increase in nucleon-nucleon scattering cross section. As a result, revised JQMD (RJQMD) predicts fragment angular distribution of fragments better than JQMD.
