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Journal Articles

The Role of deposition of cosmogenic $$^{10}$$Be for the detectability of solar proton events

Schaar, K.*; Spiegl, T.*; Langematz, U.*; Sato, Tatsuhiko; Mekhaldi, F.*; Kunze, M.*; Miyake, Fusa*; Yoden, Shigeo*

Journal of Geophysical Research; Atmospheres, 129(11), p.e2023JD040463_1 - e2023JD040463_28, 2024/06

Journal Articles

Monte Carlo simulation study on the dose and dose-averaged linear energy transfer distributions in carbon ion radiotherapy

Ishikawa, Akihisa; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Hashimoto, Shintaro; Hirai, Yuta*; Sato, Tatsuhiko

Radiological Physics and Technology, 17(2), p.553 - 560, 2024/06

Journal Articles

Production rates of long-lived radionuclides $$^{10}$$Be and $$^{26}$$Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxes

Sakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.

Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05

Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as $$^{10}$$Be and $$^{26}$$Al have been accumulating in these rocks, concentrations of $$^{10}$$Be and $$^{26}$$Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced $$^{10}$$Be and $$^{26}$$Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.

Journal Articles

Defense and forecast of space weather impact on social infrastructure, 4; Aircrew exposure

Sato, Tatsuhiko; Kubo, Yuki*

Purazuma, Kaku Yugo Gakkai-Shi, 100(5), p.218 - 223, 2024/05

One of the space weather hazards is the sudden occurrence of cosmic radiation exposure due to high-energy protons associated with massive solar flares. This paper focuses on cosmic radiation exposure for airline crew members, explaining the mechanisms and current regulations. Additionally, it introduces an overview of the recently developed Aircraft Radiation Exposure Warning System (WASAVIES) in Japan.

Journal Articles

The Impact of dose rate on responses of human lens epithelial cells to ionizing irradiation

Matsuya, Yusuke; Sato, Tatsuhiko; Yachi, Yoshie*; Date, Hiroyuki*; Hamada, Nobuyuki*

Scientific Reports (Internet), 14, p.12160_1 - 12160_14, 2024/05

Understand mechanisms of radiation cataracts that are of concern in the field of radiation protection and radiation therapy. However, biological effects in HLEC following protracted exposure have not yet fully been explored. Here, we investigated the temporal kinetics of DNA double-strand breaks (DSBs) and cell survival of HLEC after exposure to photon beams at various dose rates, compared to those of human lung fibroblasts (WI-38). In parallel, we quantified the recovery for DSB and cell survival using a biophysical model. The study revealed that HLEC cells have a lower repair rate than WI-38 cells. There is no significant impact of dose rate on cell survival in both cell lines in the dose-rate range of 0.033-1.82 Gy/min. On the other hand, the experimental residual DSBs showed inverse dose rate effects (IDREs) compared to the model prediction, highlighting the importance of the IDREs in evaluating radiation effects on the ocular lens.

Journal Articles

Calculation of DNA damage yields using PHITS; Challenge from macroscopic to microscopic simulation

Sato, Tatsuhiko

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 66(3), p.143 - 145, 2024/03

DNA damage calculation using the track-structure mode of PHITS will be summarized in this report.

Journal Articles

Changes in molecular conformation and electronic structure of DNA under $$^{12}$$C ions based on first-principles calculations

Sekikawa, Takuya; Matsuya, Yusuke; Hwang, B.*; Ishizaka, Masato*; Kawai, Hiroyuki*; Ono, Yoshiaki*; Sato, Tatsuhiko; Kai, Takeshi

Nuclear Instruments and Methods in Physics Research B, 548, p.165231_1 - 165231_6, 2024/03

 Times Cited Count:0 Percentile:0.11(Instruments & Instrumentation)

One of the main causes of radiation effects on the human body is thought to be damage to DNA, which carries genetic information. However, it is not fully understood what kind of molecular structural changes DNA undergoes upon radiation damage. Since it has been reported that various types of DNA damage are formed when DNA is irradiated, our group has investigated the relationship between DNA damage and various patterns of radiation-induced ionization induced by radiation. Although we have so far analyzed DNA damage in a simple system using a rigid body model of DNA, more detailed calculations are required to analyze the molecular structural changes in DNA, which are considered to be important in considering the effects on the human body. In this study, we attempted to clarify the molecular conformational changes of DNA using OpenMX, a first-principles calculation software that can discuss electronic states based on molecular structures. Specifically, we calculated the most stable structure, band dispersion, and wave function of DNA under the assumption that one and two electrons are ionized by various radiation. In the presentation, we will discuss the relationship between the energy dependence of each incident radiation type and the molecular conformational change of DNA. In addition, the radiation-induced changes in the basic physical properties of DNA (corresponding to the initial stage of DNA damage) will be discussed from the viewpoints of both radiation physics and solid state physics.

Journal Articles

System of radiological protection; Towards a consistent framework on earth and in space

R$"u$hm, W.*; Ban, Nobuhiko*; Chen, J.*; Li, C.*; Dobynde, M.*; Durante, M.*; El-Jaby, S.*; Komiyama, Tatsuto*; Ozasa, Kotaro*; Sato, Tatsuhiko; et al.

Journal of Medical Physics - Zeitschrift f$"u$r medizinische Physik -, 34(1), p.4 - 13, 2024/02

 Times Cited Count:0 Percentile:0.12

The International Commission on Radiological Protection (ICRP) provides independent recommendations on radiological protection for the public benefit. For more than 90 years, the ICRP System of Radiological Protection has been guiding the development and implementation of national and international standards and regulations on radiological protection. In 2019, ICRP established Task Group (TG) 115 to address a broader range of topics related to dose and risk assessment for radiological protection of astronauts. This paper gives an overview of the System of Radiological Protection and a brief summary of ICRP's work on radiological protection of astronauts.

Journal Articles

Comparison of dose and risk estimates between ISS Partner Agencies for a 30-day Lunar Mission

Shavers, M. R.*; Semones, E. J.*; Shurshakov, V.*; Dobynde, M.*; Sato, Tatsuhiko; Komiyama, Tatsuto*; Tomi, L.*; Chen, J.*; El-Jaby, S.*; Straube, U.*; et al.

Journal of Medical Physics - Zeitschrift f$"u$r medizinische Physik -, 34(1), p.31 - 43, 2024/02

 Times Cited Count:0 Percentile:0.15

The Partner Agencies of the International Space Station (ISS) present an intracomparison of the ionizing radiation absorbed dose and risk quantities used to characterize example mission lunar space. The results and the work itself provide insights to the level of agreement with which space agencies can perform organ dosimetry and calculate effective dose. This work was performed in collaboration with the advisory and guidance efforts of the International Commission on Radiological Protection (ICRP) Task Group 115 and will be presented in an ICRP Report

Journal Articles

Development of a model for evaluating the luminescence intensity of phosphors based on the PHITS track-structure simulation

Hirata, Yuho; Kai, Takeshi; Ogawa, Tatsuhiko; Matsuya, Yusuke; Sato, Tatsuhiko

Nuclear Instruments and Methods in Physics Research B, 547, p.165183_1 - 165183_7, 2024/02

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

The luminescence efficiency of the phosphors for swift ions is known to decrease because of the quenching effects. To obtain the precise dose distributions using phosphor detectors, understanding the mechanisms of quenching effects is mandatory. Here, we developed a new model for estimating the luminescence intensity of phosphors based on the track-structure modes for arbitrary materials implemented in PHITS. The developed model enabled the simulation of the quenching effects of the BaFBr detector and was verified by comparing the results to the corresponding measured data. The present model is expected to contribute to developing phosphor detectors worldwide.

Journal Articles

A Step-by-step simulation code for estimating yields of water radiolysis species based on electron track-structure mode in the PHITS code

Matsuya, Yusuke; Yoshii, Yuji*; Kusumoto, Tamon*; Akamatsu, Ken*; Hirata, Yuho; Sato, Tatsuhiko; Kai, Takeshi

Physics in Medicine & Biology, 69(3), p.035005_1 - 035005_12, 2024/02

 Times Cited Count:0 Percentile:0.02(Engineering, Biomedical)

Time-dependent yields of chemical products resulted in water radiolysis play a great role in evaluating DNA damage response after exposure to ionizing radiation. Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo simulation code for radiation transport, which allows to determine several atomic interactions such as ionizations and electronic excitations as physical stage. However, a chemical code for simulating products of water radiolysis does not exist in the PHITS package. Here, we developed a chemical simulation code dedicated for the PHITS code, hereafter called PHITS-Chem code, which enables calculating G values of water radiolysis species (OH radical, e$$_{aq}$$$$^{-}$$, H$$_{2}$$, H$$_{2}$$O$$_{2}$$ etc) by electron beams. The estimated G values during 1 $$mu$$s are in agreement with the experimental ones and other simulations. This PHITS-Chem code enables simulating the dynamics in the presence of OH radical scavenger, and is useful for evaluating contributions of direct and indirect effects on DNA damage induction. This code will be included and be available in the future version of PHITS.

Journal Articles

Development of DynamicMC for PHITS Monte Carlo package

Watabe, Hiroshi*; Sato, Tatsuhiko; Yu, K. N.*; Zivkovic, M.*; Krstic, D.*; Nikezic, D.*; Kim, K. M.*; Yamaya, Taiga*; Kawachi, Naoki*; Tanaka, Hiroki*; et al.

Radiation Protection Dosimetry, 200(2), p.130 - 142, 2024/02

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

Previously, we have developed DynamicMC for modelling relative movement of ORNL phantom in a radiation field for MCNP. Using this software, 3-dimensional dose distributions in a phantom irradiated by a certain mono-energetic source can be deduced through its graphical user interface (GUI). In this study, we extended DynamicMC to be used in combination with the PHITS by providing it with a higher flexibility for dynamic movement for a less sophisticated anthropomorphic phantom. We anticipate that the present work and the developed open-source tools will be in the interest of nuclear radiation physics community for research and teaching purposes.

Journal Articles

Recent improvements of the Particle and Heavy Ion Transport code System; PHITS version 3.33

Sato, Tatsuhiko; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shinichiro; Kai, Takeshi; Matsuya, Yusuke; Matsuda, Norihiro; Hirata, Yuho; et al.

Journal of Nuclear Science and Technology, 61(1), p.127 - 135, 2024/01

 Times Cited Count:8 Percentile:99.39(Nuclear Science & Technology)

The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo radiation transport code that can simulate the behavior of most particle species with energies up to 1 TeV (per nucleon for ions). Its new version, PHITS3.31, was recently developed and released to the public. In the new version, the compatibility with high-energy nuclear data libraries and the algorithm of the track-structure modes have been improved. In this paper, we summarize the upgraded features of PHITS3.31 with respect to the physics models, utility functions, and application software introduced since the release of PHITS3.02 in 2017.

Journal Articles

Experimental and computational verifications of the dose calculation accuracy of PHITS for high-energy photon beam therapy

Kuga, Naoya*; Shiiba, Takuro*; Sato, Tatsuhiko; Hashimoto, Shintaro; Kuroiwa, Yasuyoshi*

Journal of Nuclear Science and Technology, 61(1), p.136 - 145, 2024/01

 Times Cited Count:1 Percentile:63.33(Nuclear Science & Technology)

This study aims to verify the accuracy of PHITS in terms of photon and electron transport and provide essential data for its application in clinical dosimetry in high-energy photon beam therapy. Percentage depth dose (PDD), beam profiles, and output factor (OPF) in a water phantom with various field sizes created by a Clinac 21EX linear accelerator were measured using an ionization chamber. Experimental setups were precisely reproduced by PHITS version 3.24, and the percentage differences (%Diff) between the measured and calculated data were evaluated. The average %Diff of PDDs obtained from PHITS and measurement were within 10% and 2% in the build-up and fall-off regions, respectively. For beam profiles, the average %Diff in the plateau region was within 3%; the differences between the calculated and measured distances from the central axis to 50% dose level were within 2 mm. These differences were lower than their tolerance levels. The consistency between the PHITS and EGSnrc was better; their %Diff was within 1% in most cases. The concurrence between the PHITS and measurement shown in this study demonstrates the potential clinical application of PHITS in high-energy photon beam therapy, given its similar dose calculation accuracy compared with EGSnrc.

Journal Articles

ICRU Report 98, Stochastic nature of radiation interactions; Microdosimetry

Braby, L. A.*; Conte, V.*; Dingfelder, M.*; Goodhead, D. T.*; Pinsky, L. S.*; Rosenfeld, A. B.*; Sato, Tatsuhiko; Waker, A. J.*; Guatelli, S.*; Magrin, G.*; et al.

Journal of ICRU, 23(1), p.1 - 168, 2023/12

This report provides a comprehensive description of the basic concepts and theories, computational and experimental procedures, and applications of microdosimetry.

Journal Articles

Atmospheric ionizations by solar X-rays, solar protons, and radiation belt electrons in September 2017 space weather event

Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Sato, Kaoru*; Tsutsumi, Masaki*; Tanaka, Yoshimasa*; Ogawa, Yasunobu*; Sato, Tatsuhiko

Space Weather, 21(12), p.e2023SW003651_1 - e2023SW003651_11, 2023/12

 Times Cited Count:0 Percentile:0.01(Astronomy & Astrophysics)

Comprehensive understandings of their global impact on the atmosphere require whole pictures of spatio-temporal distributions of the ionization due to them. We estimate the altitude profiles of the ionization rate during the space weather event occurred in September 2017 by using the Particle and Heavy Ion Transport code System (PHITS) with input of the particle fluxes obtained by satellites. The estimates are then compared with measurements of the ionization altitude, ionization intensity, and electron density by the radars in the polar region such as the PANSY radar at Syowa Station and the EISCAT in Tromso, Norway. We conclude that the PHITS simulation results reproduce those ionizations measured by ground-based instruments with inputs of observed ionization sources by satellites within a factor of 2.

Journal Articles

Sharing the latest science with all people; Development and promotion of the PHITS code

Sato, Tatsuhiko

Oyo Butsuri, 92(11), p.684 - 687, 2023/11

Development and promotion of the PHITS code will be introduced.

Journal Articles

Fetal and maternal atomic bomb survivor dosimetry using the J45 pregnant female phantom series; Considerations of the kneeling and lying posture with comparisons to the DS02 system

Domal, S. J.*; Correa-Alfonso, C. M.*; Paulbeck, C. J.*; Griffin, K. T.*; Sato, Tatsuhiko; Funamoto, Sachiyo*; Cullings, H. M.*; Egbert, S. D.*; Endo, Akira; Hertel, N. E.*; et al.

Health Physics, 125(4), p.245 - 259, 2023/10

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

The RERF Working Group on Organ Dose (WGOD) has established the J45 (Japan 1945) series of high-resolution voxel phantoms, which were derived from the UF/NCI series of hybrid phantoms and scaled to match mid-1940s Japanese body morphometries. In this present study, we present the J45 pregnant female phantoms in both a kneeling and lying posture, and assess the dosimetric impact of these more anatomically realistic survivor models in comparisons to current organ doses given by the DS02 system. For the kneeling phantoms facing the bomb hypocenter, organ doses from bomb source photon spectra were shown to be overestimated by the DS02 system by up to a factor of 1.45 for certain fetal organs and up to a factor of 1.17 for maternal organs. For lying phantoms with their feet in the direction of the hypocenter, fetal organ doses from bomb source photon spectra were underestimated by the DS02 system by factors as low as 0.77 while maternal organ doses were overestimated by up to a factor of 1.38. Results from this study highlight the degree to which the existing DS02 system can differ from organ dosimetry based upon 3D radiation transport simulations using more anatomically realistic models of those survivors exposed during pregnancy while in a kneeling or lying position.

Journal Articles

Development of an electron track-structure mode for arbitrary semiconductor materials in PHITS

Hirata, Yuho; Kai, Takeshi; Ogawa, Tatsuhiko; Matsuya, Yusuke*; Sato, Tatsuhiko

Japanese Journal of Applied Physics, 62(10), p.106001_1 - 106001_6, 2023/10

 Times Cited Count:2 Percentile:66.71(Physics, Applied)

Optimization of semiconductor detector design requires theoretical analysis of the process of radiation conversion to carriers (excited electrons) in semiconductor materials. We, therefore, developed an electron track-structure code that can trace an incident electron trajectory down to a few eV and simulate many excited electron productions in semiconductors, named ETSART, and implemented it into PHITS. The accuracy of ETSART was validated by comparing calculated electron ranges in semiconductor materials with the corresponding data recommended in ICRU Report 37 and obtained from another simulation code. The average energy required to produce a single excited electron (epsilon value) is an important value that describes the characteristics of semiconductor detectors. Using ETSART, we computed the epsilon values in various semiconductors and found that the calculated epsilon values cannot be fitted well with a linear model of the band-gap energy. ETSART is expected to be useful for initial and mechanistic evaluations of electron-hole generation in undiscovered materials.

Journal Articles

A Terrestrial SER Estimation Methodology Based on Simulation Coupled With One-Time Neutron Irradiation Testing

Abe, Shinichiro; Hashimoto, Masanori*; Liao, W.*; Kato, Takashi*; Asai, Hiroaki*; Shimbo, Kenichi*; Matsuyama, Hideya*; Sato, Tatsuhiko; Kobayashi, Kazutoshi*; Watanabe, Yukinobu*

IEEE Transactions on Nuclear Science, 70(8, Part 1), p.1652 - 1657, 2023/08

 Times Cited Count:0 Percentile:0.01(Engineering, Electrical & Electronic)

Single event upsets (SEUs) caused by neutrons is a reliability problem for microelectronic devices in the terrestrial environment. Acceleration tests using white neutron beam provide realistic soft error rates (SERs), but only a few facilities can provide white neutron beam in the world. If single-source irradiation applicable to diverse neutron source can be utilized for the evaluation of the SER in the terrestrial environment, it contributes to solve the shortage of beam time. In this study, we investigated the feasibility of the SER estimation in the terrestrial environment by any one of these measured data with the SEU cross sections obtained by PHITS simulation. It was found that the SERs estimated by our proposed method are within a factor of 2.7 of that estimated by the Weibull function. We also investigated the effect of simplification which reduce the computational cost in simulation to the SER estimation.

536 (Records 1-20 displayed on this page)