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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
Times Cited Count：58 Percentile：96.23(Astronomy & Astrophysics)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.
Ti
during hydrogen cyclingKim, H.*; Sakaki, Koji*; Saita, Itoko*; Enoki, Hirotoshi*; Noguchi, Kazuo*; Machida, Akihiko; Watanuki, Tetsu; Nakamura, Yumiko*
International Journal of Hydrogen Energy, 39(20), p.10546 - 10551, 2014/07
Times Cited Count：14 Percentile：32.47(Chemistry, Physical)The effect of the vanadium content on the cyclic stability of V-Ti binary alloys was investigated. VTi, 
0.2 and 0.5 samples were hydrogenated and dehydrogenated at 410 K and 553 K respectively, for more than 100 times. During hydrogen cycling, reduction in the reversible hydrogen storage capacity was clearly observed from both samples. In addition, the shape of the pressure-composition-isotherm curves was significantly altered over the testing cycle period; the absorption and desorption plateaus got markedly inclined and the hysteresis became evidently smaller. We found that even after the hydrogen storage capacity of VTi was significantly reduced, at low enough temperature VTi was able to absorb hydrogen as much as it did at the first cycle.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
Noguchi, Koji; Yasuo, Kiyoshi; Seto, Nobuhiko; Iwasaki, Shogo; Inami, Shinichi
no journal, ,
At the Tokai reprocessing plant, release of the low radioactive fluid to the ocean is carried out using sea release facilities. It was confirmed that there was a leak point on the sea release facilities. Therefore, check and investigation were performed and the leak point was identified. The leak part was cut and the part was then collected to investigate the cause of the leak. As a result, it was estimated that the leak occurred after the pipe was mechanically damaged and a successive change occurred on the part. For this leak point, a series of works for the cause investigation was carried out in detail, the repair work was performed, and preventive measures were taken against recurrences. This paper describes the summary of the sea release facilities, the situation of the outbreak of the leak, and the process that confirmed the leak point.
Sato, Hiroyuki; Iigaki, Kazuhiko; Shimizu, Atsushi; Noguchi, Hiroki; Sakaba, Nariaki; Asano, Koji*; Oyama, Sunao*; Onishi, Hiroyuki*; Suyama, Kazumasa*; Usui, Yukinori*
no journal, ,
no abstracts in English
