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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：43 Percentile：96.93(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.
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 173, 2012/01
Three electrostatic accelerators of TIARA were operated smoothly in FY 2010, and all the planned experiments were carried out except those canceled by users or the impact of Great East Japan Earthquake on March 11, 2011. On the other hand, Saturday operation for experiments was carried out after October on the Global Nuclear-Human Resource Development Initiative. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2116, 2367 and 1800 hours, respectively, which were similar to those of usual years. Regarding the single-ended accelerator, the generator in the high-voltage terminal failed and was replaced with new one. A switching magnet was installed for a new branch beam line of the ion implanter. As to the tandem accelerator, In ion was generated and accelerated at intensity of 500 nA.
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
JAEA-Review 2010-065, JAEA Takasaki Annual Report 2009, P. 181, 2011/01
Three electrostatic accelerators of TIARA were operated smoothly in FY 2009, and all the planned experiments were carried out except those canceled by users. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2100, 2416 and 1866 hours, respectively. Regarding the single-ended accelerator, the radio frequency oscillator of the ion source mounted in high-voltage terminal and the sequencer for control of the SB beam line failed, and they were replaced. The oven controller of Freeman ion source of the ion implanter was renewed. As to the tandem accelerator, Mn ion was successfully generated and accelerated with intensity of 150 nA.
Chiba, Atsuya; Uno, Sadanori; Yamada, Keisuke; Yokoyama, Akihito; Agematsu, Takashi; Yokota, Wataru; Kitano, Toshihiko*; Takayama, Terumitsu*; Kanai, Shinji*; Orimo, Takao*; et al.
Dai-23-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.119 - 122, 2010/11
Operation times of each accelerator are keeping the same level as in recent 10 years, Tandem accelerator, Single-ended and Ion implanter amounted to about 2,000, 2,500 and 1,900 hours, respectively. In the last fiscal year, we succeeded in maintaining the terminal voltage of the tandem accelerator to high stability for long periods by exchanging the material of a corona-probe needle to the tungsten (NPS Co.). In the ion-implanter, the oven control system equipped with the Freeman ion source was renewed. There was no trouble to affect on the machine-time in the last fiscal year, so the all planned experiments were carried out.
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 175, 2009/12
Three electrostatic accelerators of TIARA were operated smoothly in FY 2008, and all the planned experiments were carried out except those canceled by users. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2009, 2426 and 1882 hours, respectively. Regarding the tandem accelerator, the control system was renewed, and the unstable acceleration voltage caused by mechanical vibration reduced by adjusting the driving mechanism of the pellet chains. The SF
gas for the single-ended accelerator was purified, and its storage tank was repainted. As to the ion implanter, Bi
ion, which was requested by users, was successfully generated and accelerated with intensity of 0.5
A.
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Mizuhashi, Kiyoshi; et al.
JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 191, 2008/11
Three electrostatic accelerators were operated smoothly in FY 2007, and all the planned experiments were carried out except those canceled by users. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 1949, 2437 and 1900 hours. The high-pressure residual gas of SF is leaking from the SF gas handling system of the tandem accelerator. The most amount of the leak comes out when the accelerator tank pressure is high. Therefore, in order to reduce the leak by lowering the residual gas pressure, a pipe was installed to carry the gas in the high-pressure part of the system for the accelerator to the low-pressure storage tank. As to the ion implanter, Pb ion, which was requested by users, was successfully generated using oven method and accelerated with intensity of 1.5 A.
Mizuhashi, Kiyoshi; Uno, Sadanori; Okoshi, Kiyonori; Chiba, Atsuya; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Sakai, Takuro; Yokota, Wataru; et al.
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 197, 2007/02
Three electrostatic accelerators were almost operated smoothly for various experiments in FY 2005. The yearly operation time of each accelerator amounts to 1974, 2359.9, 1859.9 hour for the tandem, the single-ended and the ion implanter, respectively. Main trouble was a short circuit of a part of the ion source in the single-ended accelerator. This lets to the suspension of operation for fifteen days. As features in FY 2005, the generation of the power cut by thunderbolts and large earthquakes were abounding. By this natural force, the Turbo-molecular pump was broken, experiment was interrupted and then the inspection of accelerator facility was carried out every time. New beam acceleration and improvement of each accelerator were carried out.
Mizuhashi, Kiyoshi; Uno, Sadanori; Okoshi, Kiyonori; Chiba, Atsuya; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sakai, Takuro; Sato, Takahiro; Yokota, Wataru; et al.
JAEA-Review 2005-001, TIARA Annual Report 2004, P. 371, 2006/01
no abstracts in English
Sakakibara, Yasuhide; IKEDA, Hiroshi; Yokota, Yoshio; Kitabata, Takuya; Yamaguchi, Toshihiko
JNC TN4200 2004-001, 317 Pages, 2004/08
JNC-TN4200-2004-001.pdf:24.97MB
None
Yamawaki, Michio*; Suzuki, Atsushi*; Yokota, Toshihiko*; Luo, G.*; Yamaguchi, Kenji*; Hayashi, Kimio
Proceedings of 1st Information Exchange Meeting on Basic Studies on High-Temperature Engineering, p.357 - 364, 1999/09
no abstracts in English
Mizuhashi, Kiyoshi; Uno, Sadanori; Okoshi, Kiyonori; Chiba, Atsuya; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Sakai, Takuro; Yokota, Wataru; et al.
no journal, ,
no abstracts in English
Mizuhashi, Kiyoshi; Uno, Sadanori; Okoshi, Kiyonori; Chiba, Atsuya; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Yokota, Wataru; Kitano, Toshihiko*; et al.
no journal, ,
no abstracts in English
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Mizuhashi, Kiyoshi; et al.
no journal, ,
no abstracts in English
Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
no journal, ,
Three electrostatic accelerators of TIARA were operated smoothly in FY 2009, and all the planned experiments were carried out except those canceled by users. The yearly operation time of the tandem accelerator, the single-ended accelerator and the ion implanter amounted to 2100, 2416 and 1866 hours, respectively. Regarding the tandem accelerator, the voltage probe needle made of tungsten was replaced with that of nickel-plating metal, and a initial stability of high voltage was maintained for 500 hours as a result. The radio frequency oscillator of the ion source mounted in high-voltage terminal of the single-ended accelerator and the sequencer for control of one of beam line failed and renewed. The superannuated oven controller of Freeman ion source of the ion implanter was replaced with new one. An ion beam of Mn was newly developed with intensity of 150 nA in order to expand ion species for the tandem accelerator.
Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Agematsu, Takashi; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Yokota, Wataru; et al.
no journal, ,
The yearly operation time of three electrostatic accelerators at TIARA of Japan Atomic Energy Agency in 2010 was the tandem accelerator, the ion implanter and the single-ended accelerator amounted to 2,116, 1,800 and 2,367 hours, respectively. The tandem accelerator operated smoothly in this year, but stop times by trouble of the ion implanter and the single-ended accelerator was 1 and 2 times, respectively. Three electrostatic accelerators did not have damage when the Tohoku Earthquake occurred on March 11, 2011. However, these accelerators were not able to operate during the planned power outage by Tokyo Electric Power Company (TEPCO). The tandem accelerator accelerated ion beam of In, which gave intensity of 500 nA with stability. Additionally, the ion implanter generated maximum 400 nA at ion beam of Gd, which was used in experiments for the users.
