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Journal Articles

The Energy-resolved neutron imaging system, RADEN

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

 Times Cited Count:1 Percentile:100(Instruments & Instrumentation)

Journal Articles

A Simplified Cluster Analysis of Electron Track Structure for Estimating Complex DNA Damage Yields

Matsuya, Yusuke; Nakano, Toshiaki*; Kai, Takeshi; Shikazono, Naoya*; Akamatsu, Ken*; Yoshii, Yuji*; Sato, Tatsuhiko

International Journal of Molecular Sciences (Internet), 21(5), p.1701_1 - 1701_13, 2020/03

Among various DNA damage induced after irradiation, clustered damage composed of at least two vicinal lesions within from 10 to 20 base pairs is recognized as fatal damage to human tissue. Such clustered damage yields have been evaluated by means of computational approaches; however, the simulation validity has not been sufficiently made yet. Meanwhile, the experimental technique to detect clustered DNA damage has been evolved in the recent decades, so both approaches with simulation and experiment get used to be available for investigating clustered damage recently. In this study, we have developed a simple model for estimating clustered damage yield based on the spatial density of ionization and electronic excitation events obtained by the PHITS code, and compared the computational results to the experimental clustered damage coupled with base damage (BD) measured by gel electrophoresis and atomic force microscopy. The computational results agreed well with experimental fractions of clustered damage of strand breaks (SB) and BD, when the yield ratio of BD/SSB is assumed to be 1.3. From the comparison of complex DNA double-strand break coupled with BDs between simulation and experimental data, it was suggested that aggregation degree of the events along electron track reflects the complexity of DNA damage. The resent simulation enables to quantify the type of clustered damage which cannot be measured in in vitro experiment, which succeeded in interpreting the experimental detection efficiency for clustered BD.

Journal Articles

Verification of dose estimation of Auger electrons emitted from Cu-64 using a combination of FNTD measurements and Monte Carlo simulations

Kusumoto, Tamon*; Matsuya, Yusuke; Baba, Kentaro*; Ogawara, Ryo*; Akselrod, M. S.*; Harrison, J.*; Fomenko, V.*; Kai, Takeshi; Ishikawa, Masayori*; Hasegawa, Sumitaka*; et al.

Radiation Measurements, 132, p.106256_1 - 106256_4, 2020/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Internal radiation therapy with Cu-64 concentrates energy deposition in tumor cells by virtue of released Auger electrons with low energy. In our previous study, we have attached the solutions at the surface of Fluorescent Nuclear Track Detector (FNTD) and succeeded in measuring the absorbed doses of Auger electrons registered in FNTD. However, because there are several types of radiation emitted from the source, i.e., beta rays, positron etc., the contribution degree of Auger electron to energy concentration remain uncertain. In this study, we quantitatively analyzed the spatial dose distribution in the FNTD based on Monte Carlo simulation with PHITS and GEANT4, and evaluated high dose deposited by Auger electrons. The dose distribution calculated by the PHITS code is exactly equivalent to that by Geant4. Also, the simulations are well agreement with experimental results. If the contribution of Auger electrons is ignored, the significantly high absorbed dose proximal to the source is not properly reduced. These findings demonstrate that Auger electrons work very effectively to kill cancer cells proximal to Cu-64 source while minimizing damage effects on normal cells distal to the source.

Journal Articles

Depth profiles of energy deposition near incident surface irradiated with swift heavy ions

Ogawa, Tatsuhiko; Ishikawa, Norito; Kai, Takeshi

Nuclear Instruments and Methods in Physics Research B, 461, p.272 - 275, 2019/12

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

Heavy ion irradiation, which deposits energy locally in materials, is widely used to study new material modification and radiation-induced damage. So far, radial distribution of energy deposition by heavy ions were well studied. By contrast, depth profile of energy deposition was usually assumed to be uniform but the energy deposition near the incident surface is likely suppressed because the delta-rays are pushed by the incident heavy ions. In this study, spatial distribution of energy deposition in the materials exposed to heavy ions is calculated by using a track structure simulation code RITRACKS. The result showed that energy deposition is suppressed in the first 2 nm of water and that beyond 2 nm is uniform. This result can be applied to the materials other than water by scaling with electron density. It is indicated that reactor fuel pins damaged by fission products and the materials modified by heavy ions receive less energy deposition and less radiation effect in the first 2 nm.

Journal Articles

Modeling of yield estimation for DNA strand breaks based on Monte Carlo simulations of electron track structure in liquid water

Matsuya, Yusuke; Kai, Takeshi; Yoshii, Yuji*; Yachi, Yoshie*; Naijo, Shingo*; Date, Hiroyuki*; Sato, Tatsuhiko

Journal of Applied Physics, 126(12), p.124701_1 - 124701_8, 2019/09

 Times Cited Count:4 Percentile:21.8(Physics, Applied)

Biological effects after ionizing radiation exposure arise from initial DNA strand breaks. DNA damage can be estimated from the simulation with both track structure analysis and diffusion of free radicals; however, the simulation is a time-consuming process. In this study, we present a simple model for estimating yields of strand breaks based only on spatial patterns of inelastic interactions (i.e., ionization and electronic excitation) generated by electrons, which are evaluated by PHITS code without considering the production and diffusion of free radicals. In this model, the number of events per track and that of the two events pair within 3.4 nm (corresponding to 10 base pair) were stochastically sampled for calculating SSB and DSB yields, respectively. The calculated results agreed well with other simulations and experimental data on DSB yield and yield ratio of DSB/SSB for the exposure to mono-energetic electrons. The present model also can demonstrate the relative biological effectiveness at the DSB endpoint for various photon exposures. This study indicated that the spatial pattern of inelastic events composed of ionization and electronic excitation is sufficient to obtain the impact of electrons on initial induction to DNA strand break.

Journal Articles

Gamma-ray glow preceding downward terrestrial gamma-ray flash

Wada, Yuki*; Enoto, Teruaki*; Nakamura, Yoshitaka*; Furuta, Yoshihiro; Yuasa, Takayuki*; Nakazawa, Kazuhiro*; Morimoto, Takeshi*; Sato, Mitsuteru*; Matsumoto, Takahiro*; Yonetoku, Daisuke*; et al.

Communications Physics (Internet), 2(1), p.67_1 - 67_9, 2019/06

 Times Cited Count:3 Percentile:23(Physics, Multidisciplinary)

JAEA Reports

Biosphere assessment methodology commonly applicable to various disposal concepts

Kato, Tomoko; Fukaya, Yukiko*; Sugiyama, Takeshi*; Nakai, Kunihiro*; Oda, Chie; Oi, Takao

JAEA-Data/Code 2019-002, 162 Pages, 2019/03

JAEA-Data-Code-2019-002.pdf:2.78MB

The radioactive waste generated from Fukushima Daiichi nuclear power station (FDNPS) accident have features such as wide range of radioactivity level (from low to high) and huge amount etc. It would be necessary for the waste from the FDNPS accident to develop suitable disposal concept and to be disposed safely and reasonably. When considering such appropriate disposal concepts in site-generic phase, it is necessary to appropriately develop models and parameters depending on the disposal concepts, such as disposal depth and specification of engineered barrier. In addition, it is desirable to evaluate the safety of repository with common models and parameters independent on the disposal concepts. In the safety assessment of disposal, it is useful to show the difference in performance of repository with "dose" as an indicator of safety assessment. Biosphere model and parameter set and flux-to-dose conversion factors calculated using them are originally dependent on the disposal concepts. However, the biosphere models and the parameter set in safety assessment of near-surface disposal, sub-surface disposal and geological disposal are prepared in each case, and are different according to the age and purpose of the discussion. In this study, an example of biosphere model and parameter-set of groundwater sceinario commonly applicable to various disposal concepts were shown, to calculate flux-to-dose conversion factors, as common indicators independent to disposal concept. And, a set of flux-to-dose conversion factors was also calculated by using the commonly available biosphere model and parameter set. By applying the flux-to-dose conversion factors, it is possible to compare the performance of disposal concepts to the waste generated from FDNPS accident, focusing on the parts depending on the disposal concepts.

JAEA Reports

Progress of general control system for Materials and Life Science Experimental Facility at J-PARC

Sakai, Kenji; Oi, Motoki; Takada, Hiroshi; Kai, Tetsuya; Nakatani, Takeshi; Kobayashi, Yasuo*; Watanabe, Akihiko*

JAEA-Technology 2018-011, 57 Pages, 2019/01

JAEA-Technology-2018-011.pdf:4.98MB

For safely and efficiently operating a spallation neutron source and a muon target, a general control system (GCS) operates within Materials and Life Science Experimental Facility (MLF). GCS administers operation processes and interlocks of many instruments. It consists of several subsystems such as an integral control system (ICS), interlock systems (ILS), shared servers, network system, and timing distribution system (TDS). Although GCS is an independent system that controls the target stations, it works closely with the control systems of the accelerators and other facilities in J-PARC. Since the first beam injection, GCS has operated stably without any serious troubles after modification based on commissioning for operation and control. Then, significant improvements in GCS such as upgrade of ICS by changing its framework software and function enhancement of ILS were proceeded until 2015. In this way, many modifications have been proceeded in the entire GCS during a period of approximately ten years after start of beam operation. Under these situation, it is important to comprehend upgrade history and present status of GCS in order to decide its upgrade plan. This report summarizes outline, structure, roles and functions of GCS in 2017.

Journal Articles

Recent progress of radiation physicochemical process (third part)

Kai, Takeshi; Yokoya, Akinari*; Fujii, Kentaro*; Watanabe, Ritsuko*

Hoshasen Kagaku (Internet), (106), p.21 - 29, 2018/11

It is thought to that the biological effects such as cell death or mutation are induced by complex DNA damage which are formed by several damage sites within a few nm. As the prediction of complex DNA damage at an electron track end, we report our outcomes. These results indicate that DNA damage sites comprising multiple nucleobase lesions with a single strand breaks can be formed by multiple collisions of the electrons within 1 nm. This multiple damage site cannot be processed by base excision repair enzymes. Pre-hydrated electrons can also be produced resulting in an additional base lesion over a few nm from the multi-damage site. This clustered damage site may be finally converted into a double strand break. These DSBs include another base lesion(s) at their termini that escape from the base excision process and which may result in biological effect. Our simulation is useful to reveal phenomena involved in radiation physico-chemistry as well as the DNA damage prediction.

Journal Articles

Spatial resolution test targets made of gadolinium and gold for conventional and resonance neutron imaging

Segawa, Mariko; Oikawa, Kenichi; Kai, Tetsuya; Shinohara, Takenao; Hayashida, Hirotoshi*; Matsumoto, Yoshihiro*; Parker, J. D.*; Nakatani, Takeshi; Hiroi, Kosuke; Su, Y.; et al.

JPS Conference Proceedings (Internet), 22, p.011028_1 - 011028_8, 2018/11

Journal Articles

Occupation sites and valence states of Co dopants in (La, Co)-codoped M-type Sr ferrite; $$^{57}$$Fe and $$^{59}$$Co nuclear magnetic resonance studies

Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Ueda, Hiroaki*; Tanioku, Yasuaki*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Takao, Kenta*; Shimoda, Aiko*; et al.

Physical Review B, 98(6), p.064403_1 - 064403_10, 2018/08

 Times Cited Count:4 Percentile:48.81(Materials Science, Multidisciplinary)

To specify preferential occupation sites of Co substituents and to clarify charge and spin states of Co ions in (La, Co)-cosubstituted hexagonal magnetoplumbite-type (M-type) Sr ferrite, $$^{57}$$Fe and $$^{59}$$Co nuclear magnetic resonance (NMR) spectra are measured under zero and external magnetic fields using powdered and single crystalline specimens. To a considerable degree, the charge compensation between La$$^{3+}$$ and Co$$^{2+}$$ works in the equal (La, Co)-codoped case, where more than half of the Co ions are considered to be present in the minority spin $$4f_1$$ sites at the center of the oxygen tetrahedra, with the $$S$$ = 3/2 state carrying a small orbital moment owing to spin-orbit interaction. The remaining small number of high-spin Co$$^{2+}$$ ($$S$$ = 3/2, $$L$$ = 1) ions with unquenched orbital moments would be distributed to the other octahedral $$12k$$, $$2a$$, and $$4f_2$$ sites.

Journal Articles

Features of particle and heavy ion transport code system (PHITS) version 3.02

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:153 Percentile:0.01(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.

Journal Articles

A Significant role of non-thermal equilibrated electrons in the formation of deleterious complex DNA damage

Kai, Takeshi; Yokoya, Akinari*; Ukai, Masatoshi*; Fujii, Kentaro*; Toigawa, Tomohiro; Watanabe, Ritsuko*

Physical Chemistry Chemical Physics, 20(4), p.2838 - 2844, 2018/01

 Times Cited Count:7 Percentile:32.45(Chemistry, Physical)

It is thought that complex DNA damage which induces in radiation biological effects is formed at radiation track end. Thus, the earliest stage of water radiolysis at the electron track end was studied to predict DNA damage. These results indicate that DNA damage sites comprising multiple nucleobase lesions with a single strand breaks can therefore be formed by multiple collisions of the electrons within three base pairs (3bp) of a DNA strand. This multiple damage site cannot be processed by base excision repair enzymes. However, pre-hydrated electrons can also be produced resulting in an additional base lesion more than 3bp away from the multi-damage site. This clustered damage site may be finally converted into a double strand break (DSB) when base excision enzymes process the additional base lesions. These DSBs include another base lesion(s) at their termini that escape from the base excision process and which may result in biological effects such as mutation in surviving cells.

Journal Articles

Modern radiation chemistry (Applications), 16; Computer simulation study of initial process of radiation biological effect

Watanabe, Ritsuko*; Kai, Takeshi; Hattori, Yuya*

Radioisotopes, 66(11), p.525 - 530, 2017/11

To understand the mechanisms of radiation biological effects, modeling and simulation studies are important. In particular, simulation approach is powerful tool to evaluate modeling of mechanisms and the relationship among experimental results in different spatial scale of biological systems such as DNA molecular and cell. This article summarizes our approach to evaluate radiation action on DNA and cells by combination of knowledge in radiation physics, chemistry and biology. It contains newly theoretical approach to estimate physico-chemical process of DNA damage induction in addition to typical method of DNA damage prediction. Outline of the mathematical model for dynamics of DNA damage and cellular response is also presented.

Journal Articles

Recent improvements of particle and heavy ion transport code system: PHITS

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:2 Percentile:8.34

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 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.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Journal Articles

Reliability estimation of neutron resonance thermometry using tantalum and tungsten

Kai, Tetsuya; Hiroi, Kosuke; Su, Y.; Shinohara, Takenao; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Segawa, Mariko; Nakatani, Takeshi; Oikawa, Kenichi; et al.

Physics Procedia, 88, p.306 - 313, 2017/06

 Times Cited Count:2 Percentile:10.17

Journal Articles

Features of PHITS version 2.88

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.

Journal Articles

Benchmark study of the recent version of the PHITS code

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:22 Percentile:1.03(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.

Journal Articles

Dynamic behavior of secondary electrons produced by a high-energy electron in liquid water

Kai, Takeshi; Yokoya, Akinari*; Fujii, Kentaro*; Watanabe, Ritsuko*

Yodenshi Kagaku, (8), p.11 - 17, 2017/03

It is thought to that the biological effects such as cell death or mutation are induced by complex DNA damage which are formed by several damage sites within a few nm. We calculated dynamic behavior of secondary electrons produced by primary electron and positon of high energy in water whose composition ratio is similar to biological context. The secondary electrons induce the ionization or electronic excitation near the parent cations. The decelerated electrons about 10% are distributed to their parent cations by the attractive Coulombic force. From the results, we predicted the following formation mechanism for the complex DNA damage. The electrons ejected from DNA could induce the ionization or the electronic excitation within the DNA. The electrons attracted by the Coulombic force are pre-hydrated in water layer of the DNA. The pre-hydrated electrons could induce to the DNA damage by dissociative electron transfer. As the results, the complex DNA damage with 1 nm could be formed by the interaction of not only the primary electron or positon but also the secondary electrons.

262 (Records 1-20 displayed on this page)