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Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Natori, Hiroaki*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Tampo, Motonobu*; Kawamura, Naritoshi*; Teshima, Natsuki*; et al.
Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03
Times Cited Count：0 Percentile：0.2(Physics, Applied)Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：1 Percentile：22.72(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Nishimura, Shoichiro*; Torii, Hiroyuki*; Fukao, Yoshinori*; Ito, Takashi; Iwasaki, Masahiko*; Kanda, Sotaro*; Kawagoe, Kiyotomo*; Kawall, D.*; Kawamura, Naritoshi*; Kurosawa, Noriyuki*; et al.
Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08
Times Cited Count：13 Percentile：83.13(Optics)
ReWatanabe, Hiroshi*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Andreyev, A. N.; Hashimoto, Takashi*; Kondev, F. G.*; Lane, G. J.*; Litvinov, Yu. A.*; Liu, J. J.*; Miyatake, Hiroari*; et al.
Physics Letters B, 814, p.136088_1 - 136088_6, 2021/03
Times Cited Count：4 Percentile：46.8(Astronomy & Astrophysics)Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：8 Percentile：56.2(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count：13 Percentile：99.06(Quantum Science & Technology)Ebisuzaki, Toshikazu*; Wada, Satoshi*; Saito, Norihito*; Fujii, Takashi*; Nishimura, Akihiko
Reza Kenkyu, 45(10), p.664 - 665, 2017/10
no abstracts in English
Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count：7 Percentile：90.97(Physics, Atomic, Molecular & Chemical)Sato, Katsutoshi*; Nishikino, Masaharu; Kawachi, Tetsuya; Shimokawa, Takashi*; Imai, Takashi*; Teshima, Teruki*; Nishimura, Hiroaki*; Kando, Masaki
Journal of Radiation Research, 56(4), p.633 - 638, 2015/07
Times Cited Count：1 Percentile：6.94(Biology)While X-ray laser is expected to be widely applied to biomedical studies, this has not been achieved to date and its biological effects such as DNA damage have not been evaluated. As a first step for its biological application, we developed a culture cell irradiation system using laser-plasma soft X-ray laser and investigated whether the soft X-ray laser is able to induce the DNA double strand breaks (DSBs) in living cells or not. The human adenocarcimona cell line A549 was irradiated with the soft X-ray laser at a photon energy of 89 eV and then the repair focus formation of the DSBs was assessed by immunofluorescence staining with anti-phosphorylated DNA-PKcs antibody. As a result, the phosphorylated DNA-PKcs foci were clearly identified even with just a single shot of the soft X-ray laser. In this study, we successfully demonstrated for the first time that soft X-ray laser at 89 eV induced the DNA double strand breaks in living cells.
Ito, Chikara; Naito, Hiroyuki; Oba, Hironori; Saeki, Morihisa; Ito, Keisuke; Ishikawa, Takashi; Nishimura, Akihiko; Wakaida, Ikuo; Sekine, Takashi
Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07
A high-radiation resistant optical fiber has been developed in order to investigate the interiors of the reactor pressure vessels and the primary containment vessels of the Fukushima Daiichi Nuclear Power Station. The radiation resistance of an optical fiber was improved by increasing the amount of hydroxyl up to 1000 ppm in pure silica fiber. The improved image fiber consists of common cladding and a large number of fiber cores made from pure silica that contains 1000 ppm hydroxyl. The transmissive rate of an infrared image was not affected after the irradiation of 1 MGy. We have developed the fiber-coupled LIBS system to detect plasma emission efficiently in near-infrared region. In addition, we have performed a 
ray dose rate measurement using an optical fiber of which scintillator is attached to the tip. As a result, the concept of applicability of a probing system using the high-radiation resistant optical fibers has been confirmed.
Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03
Nishikino, Masaharu; Sato, Katsutoshi; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Imazono, Takashi; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.301 - 306, 2011/12
Temporal sequences of physical and physicochemical stage of actions in biological systems irradiated with energetic radiation take place with in the order of picoseconds. The short duration of laser produced plasma source could be used as a new source in contrast to conventional X-ray sources in investigating the mechanism of the affect of radiation on biological cells. We have started to develop a focused X-ray beam irradiation system for use in studying radiobiological effects on cells, and demonstrated a preliminary study of radiation effect on culture cells irradiated with laser produced plasma Ka X-rays and the X-ray laser.
Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12
This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.
Okano, Yasushi; Kobayashi, Noboru*; Ogawa, Takashi; Oki, Shigeo; Naganuma, Masayuki; Okubo, Tsutomu; Mizuno, Tomoyasu; Ogata, Takanari*; Ueda, Nobuyuki*; Nishimura, Satoshi*
JAEA-Research 2009-025, 105 Pages, 2009/10
JAEA-Research-2009-025.pdf:10.45MB
A metal fuel core has specific features on high heavy metal density, hard neutron spectrum, and efficient neutron utilization. Enlarged applicable design envelops would improve core performances and features: higher breeding ratio, compacted reactor core, and, smaller amount of Pu-fissile inventory. A joint study on "Reactor Core and Fuel Design of Metal Fuel Core of Sodium Cooled Fast Reactor" by Japan Atomic Energy Agency and Central Research Institute of Electric Power Industry has been conducted during Japanese fiscal years of 2007 and 2008. This report shows the results on (1) the study on applicable design ranges of metal fuel specifications, (2) the study on conceptual core designs for high breeding ratio, and (3) the safety study on metal fuel core designed in the Fast Reactor Cycle Technology Development (FaCT) Project.
Saito, Yuya; Tanai, Kenji; Kikuchi, Hirohito*; Hirai, Takashi*; Nishimura, Mayuka*
JAEA-Research 2008-010, 35 Pages, 2008/03
JAEA-Research-2008-010.pdf:15.56MB
Site with the potential to adversely affect the performance of the disposal system should be avoided by site selection in Japan. On the other hand, according to Atomic Energy Commission, the possibility to occur the natural and artificial events suddenly should be examined. So it is important to examine about the critical state of the engineering barrier system (EBS) when if the fault move across the EBS. And this study helps to be understood by the nation. In this paper, we examined the influence of the velocity of fault movement by the model test, and tried to improve the precision of the simulation analysis. Test results showed that the total pressure of the buffer inside was about 20% decreased when the velocity was a one-tenth. And it is important to set the permeability of the near-field rock appropriately when simulating the behavior of the buffer material affected by fault movement.
-H)Ru complex derived from H
Ogo, Seiji*; Kabe, Ryota*; Uehara, Keiji*; Kure, Bunsho*; Nishimura, Takashi*; Menon, S. C.*; Harada, Ryosuke*; Fukuzumi, Shunichi*; Higuchi, Yoshiki*; Ohara, Takashi; et al.
Science, 316(5824), p.585 - 587, 2007/04
Times Cited Count：228 Percentile：99.49(Multidisciplinary Sciences)A novel dinuclear nickel-ruthenium complex with a bridging hydrido ligand, a Ni(-H)Ru complex, was obtained from the reaction of a dinuclear NiRu aqua complex with dihydrogen (H) in water under ambient conditions. The structure of the Ni(-H)Ru complex was unequivocally determined by neutron analysis. This is the first crystal structure of (six-coordinated Ni)(-H)M (M=transition metal atoms) that is similar to the core structure of the proposed active form of the [NiFe]hydrogenase.
Isobe, Mitsutaka*; Toi, Kazuo*; Matsushita, Hiroyuki*; Goto, Kazuyuki*; Suzuki, Chihiro*; Nagaoka, Kenichi*; Nakajima, Noriyoshi*; Yamamoto, Satoshi*; Murakami, Sadayoshi*; Shimizu, Akihiro*; et al.
Nuclear Fusion, 46(10), p.S918 - S925, 2006/10
Times Cited Count：30 Percentile：69.47(Physics, Fluids & Plasmas)no abstracts in English
Honda, Akira; Kato, Takashi; Tateishi, Tsuyoshi*; Imakita, Tsuyoshi*; Masuda, Kaoru*; Kato, Osamu*; Nishimura, Tsutomu*
Zairyo To Kankyo, 55(10), p.458 - 465, 2006/10
Migration of radioactive material can be affected by the redox condition and the concentration of ligands in the repository of radioactive waste. It is possible that radioactive waste contains nitrate which can affect the migration behavior of radioactive nuclides by both changing the redox condition of the environment and acting as a ligand. On the other hand, several researchers observed the reduction of nitrate ions in ammonia due to the iron. Ammonia has a potential to ligand for radioactive nuclides. Nitrate can also affect the rate of hydrogen gas evolution accompanied by metal corrosion through changing the rest potential of metal by its oxidizing nature. Carbon steel was, therefore, immersed in an aqueous solution of sodium nitrate in a closed system for observing both the chemical interaction between metal and nitrate, and the effect of nitrate on the hydrogen gas evolution rate. The experimental pH range of the solution was 10.0-13.5 which corresponds to the pH range of pore fluid of cementitious material. The cathodic current density shows a Tafel equation type potential dependency in the aqueous solution containing nitrate or nitrite. In spite of the acceleration of cathodic reaction due to the existence of nitrate, the corrosion rates of carbon steel were not accelerated in the nitrate solutions. This fact suggests that the system is controlled by the anodic reaction. The nitrate reduction accompanied by the corrosion of carbon steel is considered to be a series reaction such as nitrate nitrite ammonia. The nitrate reduction reaction compete with the water reduction reaction within the anodic controlled condition, therefore nitrate strongly reduced the hydrogen evolution rate. The generation rates of ammonia were independent of the concentration of nitrate.
Nishimura, Mayuka; Tanai, Kenji; Takaji, Kazuhiko*; Hirai, Takashi*; Shiratake, Toshikazu*
JAEA-Research 2006-036, 82 Pages, 2006/06
JAEA-Research-2006-036.pdf:4.09MB
In order to evaluate the long term mechanical behavior of the Enginnered Barrier System (EBS), it is essential to set suitable parameters of constitutive models of the buffer material. In this report, the parameters of the Sekiguchi-Ohta model and the Adachi-Oka model are examined. The results are as follows; it is impossible to set the sole parameter which can evaluate both the deformation and the stress of the buffer material. But when selecting a suitable parameter for the object of evaluation, the mechanical behavior of buffer material can be approximately described. On the other hand, the range of the secondary consolidation coefficient of the bentonite ore is estimated to corroborate to the viscous parameter of the buffer material, using a natural analogue study. Finally, the mechanical behavior of the buffer material is analyzed using these parameters, and the maximum amount of settling of the overpack is estimated.
Tanai, Kenji; Jintoku, Takashi*; Kikuchi, Hirohito*; Nishimura, Mayuka; Matsumoto, Kazuhiro*; Aoyanagi, Shigeo; Yui, Mikazu
JAEA-Research 2006-035, 32 Pages, 2006/06
JAEA-Research-2006-035.pdf:3.46MB
In order to contribute to the safety standards and guidelines which a regulator decides, state-of the art assessment method is investigated and summarized in the table about performance guarantee contents of buffer material related to the mechanical support and protection of the overpack and rock matrix, and the retardation of radionuclide. In addition, examples of the assessment tool are described. In this report, summary of (1) basic properties of bentonite, including swelling properties, mechanical properties and hydraulic properties, (2) long-term behavior of bentonite, including creep deformation, penetration into host rock, erosion and alteration, (3) gas permeability, (4) colloid filtration and (5) mechanical stability of the near-field is described. Check points, assessment methods (based on the data obtained from the experimental results, the estimation value obtained from empirical equations and database, and the modeling calculations) and latest results of these R&D programs were also summarized.
