Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.
Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Amekura, Hiroshi*; Toulemonde, M.*; Narumi, Kazumasa*; Li, R.*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Ishikawa, Norito; Okubo, Nariaki; et al.
Scientific Reports (Internet), 11(1), p.185_1 - 185_11, 2021/01
We report the track formation of 10 nm in diameter in silicon irradiated with 6 MeV C, i.e., much lower energy than the previously reported energy threshold.
Miura, Hikaru*; Kuribara, Yuichi; Yamamoto, Masayoshi*; Sakaguchi, Aya*; Yamaguchi, Noriko*; Sekizawa, Oki*; Nitta, Kiyofumi*; Higaki, Shogo*; Tsumune, Daisuke*; Itai, Takaaki*; et al.
Scientific Reports (Internet), 10, p.11421_1 - 11421_9, 2020/07
Li, R.*; Narumi, Kazumasa*; Chiba, Atsuya*; Hirano, Yu*; Tsuya, Daiju*; Yamamoto, Shunya*; Saito, Yuichi*; Okubo, Nariaki; Ishikawa, Norito; Pang, C.*; et al.
Nanotechnology, 31(26), p.265606_1 - 265606_9, 2020/06
We report the elongation of embedded Au nanoparticles (NPs) in three different matrices under irradiations of 4 MeV C ions and 200 MeV Xe ions. Large elongation of Au NPs was observed for crystalline indium tin oxide (ITO) under both 4 MeV C and 200 MeV Xe irradiation. The ITO layer preserved the crystallinity even after large elongation was induced. This is the first report of the elongation of metal NPs in a crystalline matrix.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Sasaki, Hirokazu*; Nishikubo, Hideo*; Nishida, Shinsuke*; Yamazaki, Satoshi*; Nakasaki, Ryusuke*; Isomatsu, Takemi*; Minato, Ryuichiro*; Kinugawa, Kohei*; Imamura, Akihiro*; Otomo, Shinya*; et al.
Furukawa Denko Jiho, (138), p.2 - 10, 2019/02
no abstracts in English
Goto, Yuichi; Yamamoto, Masahiko; Kuno, Takehiko; Inada, Satoshi
Nihon Hozen Gakkai Dai-15-Kai Gakujutsu Koenkai Yoshishu, p.489 - 492, 2018/07
Radioactive liquid waste from the Tokai Reprocessing Facility Analytical Laboratory is temporarily stored in intermediate waste storage tank by using receiving valves. Then, the liquid waste is transferred to liquid treatment facility by using liquid feed valves. The deterioration of the gasket part of these valves (leakage of waste liquid) was confirmed in 2004. Since then, the material of gaskets was changed from polyethylene to Teflon. In 2016, the gaskets were replaced by periodical update. Therefore, physical properties of used gaskets were investigated, and the relevance between radioactive level and degradation degree was evaluated.
Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Haller, E. E.*; et al.
Journal of the Physical Society of Japan, 87(3), p.033704_1 - 033704_5, 2018/03
Kijima, Yuichi; Yamamoto, Yoichi; Oda, Tetsuzo
JAEA-Technology 2017-028, 33 Pages, 2018/01
The International Noble Gas Experiment related to monitoring network for radioactive noble gas (xenon) has been carried out all over the world, as part of the International Monitoring System (IMS) of CTBT. Thirty IMS radionuclide stations including the Takasaki station in Japan are monitoring radioxenon. The past measurement results show that several stations often detect radioxenon and the major emission source of these radioxenon is medical radioisotope production facilities. And nuclear power plants and medical institutions used radioxenon for nuclear medicine diagnosis, and so on are also considered as the possible sources of radioxenon, and it is therefore important to understand the background behavior of radioxenon originated from above facilities for enhancement of monitoring capability for nuclear tests. The international joint measurement was conducted in 2012 by the Preparatory Commission for the CTBT Organization, US Pacific Northwest National Laboratory, Japan Chemical Analysis Center and JAEA at the Ohminato site of JAEA Aomori Research and Development Center in Mutsu city, Aomori, as part of investigation on radioxenon background in East Asia region. In 2014, the additional measurement was carried out at the same place for further investigation. A high sensitive Transportable Xenon Laboratory developed by PNNL was used for this measurement. This paper describes the outline and the results of the joint measurement conducted in 2012 and 2014.
Goto, Yuichi; Yamamoto, Masahiko; Kuno, Takehiko; Surugaya, Naoki
Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.31 - 34, 2016/07
Chloroprene rubber gaskets are often used to seal the glove box body and its panels. Such gaskets are deformed with compressive pressure and its elastic restoring force keeps sealing property. Therefore, gaskets play an important role in glove box sealing. However, physical properties of those used in glove box have not reported so far. In this study, hardness, elongation, tensile strength and compression set are investigated and its sealing performances are evaluated. The gaskets samples are taken from the glove box, which is used for 37 years. It is found that hardness, elongation and tensile strength of gaskets are changed due to the aging but its values are within the specification of chloroprene rubber. Also, the compression-set is less than the value that sealing performance is decreased. The results show that even the gaskets are used for long time, it has the property to keep sealing performances of glove box.
Kijima, Yuichi; Yamamoto, Yoichi
Nihon Genshiryoku Gakkai-Shi ATOMO, 58(3), p.156 - 160, 2016/03
JAEA has built and operated two radionuclide stations and a certified laboratory for monitoring of radionuclide out of facilities of the International Monitoring System (IMS) under the CTBT National Operation System of Japan. JAEA also has developed and operated the National Data Center for analysis and evaluation of radionuclide observation data obtained from the IMS station. In this paper, we explain the outline of the CTBT and the CTBT activities of JAEA, and introduce two examples of detection of some anthropogenic radionuclides including the monitoring case for the DPRK's 3rd nuclear test in February 2013 from all observational results obtained from the CTBT radionuclide stations in Japan.
Ayame, Junko; Sugiyama, Kenji; Takashita, Hirofumi; Yamamoto, Ryuichi
JAEA-Review 2015-016, 182 Pages, 2016/02
Nuclear Fuel Cycle Engineering Laboratories (NCL) of JAEA has held the explanatory meetings in Ibaraki prefecture since May 2011 in order to transmit factual information and reduce the excessive anxiety about radiation risk. Applying to our past risk communication process to the explanatory meetings, we built a process of interactivity between participants and our staff for the meetings. We incorporated the participants' needs into the meetings, and, as far as possible, we had interactive two-way communication so that the meetings were not one-way and persuasive but promote mutual understanding. According to the opinions and the results of questionnaire survey that were received from the participants, it became evident that the interactive explanatory meetings were effective in reducing participants' anxiety. This report explains the risk communication process for carrying out the explanatory meeting, and shows the activities of the meetings, questions and opinions from the participants, and questionnaire results that NCL implemented.
Sugiyama, Kenji; Ayame, Junko; Takashita, Hirofumi; Yamamoto, Ryuichi
JAEA-Review 2015-013, 75 Pages, 2016/02
JAEA has held public meetings on radiation and its health effects mainly for parents of students in kindergartens, elementary schools, and junior high schools in Fukushima prefecture after the Fukushima nuclear accident. These meetings are held based on our experience of practicing risk communication activities for a decade in JAEA with local residents. Questionnaires were collected after the meetings. By analyzing questionnaires, we confirmed that interactive communication is effective in increasing participants' understanding and in decreasing their anxiety. Risk communication study office supported the staff members of the meetings providing information such as participants' questions in the past meetings. To provide information, we made a homepage and held the orientation for the staff members Questionnaires of the staff members were also collected and analyzed after the public meetings.
Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi*; Yamamoto, Hideaki; Saito, Kimiaki
Radiation Protection Dosimetry, 167(1-3), p.340 - 343, 2015/11
Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Yamamoto, Seiichi*; Toshito, Toshiyuki*; Komori, Masataka*; Morishita, Yuki*; Okumura, Satoshi*; Yamaguchi, Mitsutaka; Saito, Yuichi; Kawachi, Naoki; Fujimaki, Shu
Annals of Nuclear Medicine, 29(3), p.268 - 275, 2015/04
Yoshimura, Kazuya; Onda, Yuichi*; Sakaguchi, Aya*; Yamamoto, Masayoshi*; Matsuura, Yuki*
Journal of Environmental Radioactivity, 139, p.370 - 378, 2015/01
Miyamoto, Nobuyoshi*; Shimasaki, Kotaro*; Yamamoto, Kosuke*; Shintate, Morio*; Kamachi, Yuichiro*; Bastakoti, B. P.*; Suzuki, Norihiro*; Motokawa, Ryuhei; Yamauchi, Yusuke*
Chemistry; A European Journal, 20(46), p.14955 - 14958, 2014/11