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C ions based on first-principles calculationsSekikawa, 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：0.19(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.
C level structure by 
-ray spectroscopyHosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08
Times Cited Count：14 Percentile：66.39(Physics, Multidisciplinary)Level structure of the C hypernucleus was precisely determined by means of -ray spectroscopy. We identified four -ray transitions via the C
reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet 
was measured to be 
(stat)
(syst)keV from the direct 
transition. Excitation energies of the 
and 
states were measured to be 
, keV and 
, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of 
hypernuclei.
Ide, Takayuki*; Kawai, Yusuke*; Handa, Hiroyuki*; Fukidome, Hirokazu*; Kotsugi, Masato*; Okochi, Takuo*; Enta, Yoshiharu*; Kinoshita, Toyohiko*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.
Japanese Journal of Applied Physics, 51(6), p.06FD02_1 - 06FD02_4, 2012/06
Times Cited Count：7 Percentile：30.34(Physics, Applied)Hanada, Masaya; Kojima, Atsushi; Tanaka, Yutaka; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; et al.
Fusion Engineering and Design, 86(6-8), p.835 - 838, 2011/10
Times Cited Count：13 Percentile：69.55(Nuclear Science & Technology)Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D
beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D beams for 100s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490-500 keV have been successfully produced at a beam current of 1-2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of 
1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.
Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; Kazawa, Minoru; et al.
AIP Conference Proceedings 1390, p.536 - 544, 2011/09
Times Cited Count：7 Percentile：84.66(Physics, Atomic, Molecular & Chemical)no abstracts in English
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08
Times Cited Count：51 Percentile：88.28(Physics, Fluids & Plasmas)Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m
for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 
2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.
Naoe, Takashi; Futakawa, Masatoshi; Shobu, Takahisa; Wakui, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*; Kawai, Masayoshi*
Journal of Nuclear Science and Technology, 45(7), p.698 - 703, 2008/07
Times Cited Count：12 Percentile：61.64(Nuclear Science & Technology)Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by micro-jets and/or shock waves which are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique which consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts.
Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Kikuchi, Kenji; Kogawa, Hiroyuki; Ikeda, Yujiro; Kawai, Masayoshi*; Kurishita, Hiroaki*; Konashi, Kenji*
Journal of Nuclear Materials, 343(1-3), p.154 - 162, 2005/08
Times Cited Count：10 Percentile：56.65(Materials Science, Multidisciplinary)For decoupled and poisoned moderator, a thermal neutron absorber, i.e., decoupler, is located around the moderator to give neutron beam with a short decay time. A B4C decoupler is already utilized, however, it is difficult to use in a MW class source because of He void swelling and local heating by (n,a) reaction. Therefore, a Ag-In-Cd (AIC) alloy which gives energy-dependence of macroscopic neutron cross section like that of B
C was chosen. However, from heat removal and corrosion protection points of view, AIC is needed to bond between an Al alloy (A6061-T6), which is the structural material of a moderator. An AIC plate is divided into a Ag-In (15wt%) and Ag-Cd (35wt%) plate to extend the life time, shorten by burn up of Cd. We performed bonding tests by HIP (Hot Isostatic Pressing). We found out that a better HIP condition was holding at 803 K, 100 MPa for 1 h for small test pieces (f20mm). Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 20 MPa, which is less than that of the design stress.
Kawano, Toshihiko*; Matsunobu, Hiroyuki*; Murata, Toru*; Zukeran, Atsushi*; Nakajima, Yutaka*; Kawai, Masayoshi*; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Osawa, Takaaki*; et al.
JAERI-Research 2003-026, 53 Pages, 2003/12
JAERI-Research-2003-026.pdf:2.48MB
New evaluations of neutron nuclear data for Uranium, Plutonium, and Thorium isotopes which are essential for applications to nuclear technology were carried out for the Japanese Evaluated Nuclear Data Library, JENDL-3.3. The objectives of the current release of JENDL were to fix several problems which have been reported for the previous version, to improve the accuracy of the data, and to evaluate covariances for the important nuclides. Quantities in JENDL-3.2 were extensively re-evaluated or replaced by more reliable values. The heavy nuclide data in JENDL-3.3 were validated with several benchmark tests, and it was reported that the current release gave a good prediction of criticalities.
Kawai, Masayoshi*; Furusaka, Michihiro*; Kikuchi, Kenji; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Li, J.*; Sugimoto, Katsuhisa*; Yamamura, Tsutomu*; Hiraoka, Yutaka*; Abe, Katsunori*; et al.
Journal of Nuclear Materials, 318, p.35 - 55, 2003/05
R&D works for MW class solid target composed of tungsten to produce pulsed intense neutron source has been made in order to construct a future scattering facility. Three methods were investigated to prevent corrosion of tungsten from water; those are hipping, brazing and electric coating in molten salt bath. Hipping condition was optimized to be 1500 degree C in the previous work: here small punch test shows highest load for crack initiation of hipped materials at the boundary of W/Ta. The basic techniques for the other two methods were developed. Erosion test showed that uncovered W is susceptible of flowing water velocity. At high velocity w is easy to be eroded. For solid target design slab type and rod type targets were studied. As long as the optimized neutron performance is concerned, 1MW solid target is better than mercury target.
Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.
Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11
Times Cited Count：669 Percentile：96.97(Nuclear Science & Technology)Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for 
U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.
Kawai, Masayoshi*; Nakagawa, Tsuneo; Watanabe, Takashi*; Nakajima, Yutaka*; Zukeran, Atsushi*; Matsunobu, Hiroyuki*; Sugi, Teruo*; Chiba, Satoshi
Journal of Nuclear Science and Technology, 38(4), p.261 - 269, 2001/04
no abstracts in English
Kawano, Toshihiko*; Matsunobu, Hiroyuki*; Murata, Toru*; Zukeran, Atsushi*; Nakajima, Yutaka*; Kawai, Masayoshi*; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Osawa, Takaaki*; et al.
Journal of Nuclear Science and Technology, 37(4), p.327 - 334, 2000/04
no abstracts in English
U,U,
U,
Pu,
Pu,and 
PuKawano, Toshihiko*; Matsunobu, Hiroyuki*; Murata, Toru*; Zukeran, Atsushi*; Nakajima, Yutaka*; Kawai, Masayoshi*; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Osawa, Takaaki*; et al.
JAERI-Research 2000-004, p.76 - 0, 2000/02
JAERI-Research-2000-004.pdf:2.39MB
no abstracts in English
Nakagawa, Tsuneo; Shibata, Keiichi; Chiba, Satoshi; Fukahori, Tokio; Nakajima, Yutaka; ; Kawano, Toshihiko*; Kanda, Yukinori*; Osawa, Takaaki*; Matsunobu, Hiroyuki*; et al.
Journal of Nuclear Science and Technology, 32(12), p.1259 - 1271, 1995/12
Times Cited Count：498 Percentile：99.95(Nuclear Science & Technology)no abstracts in English
Kawai, Masayoshi*; Iijima, Shungo*; Nakagawa, Tsuneo; Nakajima, Yutaka; Sugi, Teruo; Watanabe, Takashi*; Matsunobu, Hiroyuki*; *; *
Journal of Nuclear Science and Technology, 29(3), p.195 - 213, 1992/03
no abstracts in English
Nakagawa, Tsuneo; Kawai, Masayoshi*; Iijima, Shungo*; Matsunobu, Hiroyuki*; Watanabe, Takashi*; Nakajima, Yutaka; Sugi, Teruo; *; *; *; et al.
Nuclear Data for Science and Technology, p.939 - 941, 1992/00
no abstracts in English
Futakawa, Masatoshi; Naoe, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*; Kawai, Masayoshi*
no journal, ,
no abstracts in English
Tanikawa, Ryusuke*; Sakaguchi, Norihito*; Watanabe, Seiichi*; Kinoshita, Hiroshi*; Kokawa, Hiroyuki*; Kawai, Masayoshi*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
