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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:30 Percentile:96.87(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.
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
Times Cited Count:233 Percentile:99.74(Multidisciplinary Sciences)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.
Kitabatake, Satomi*; Ushiroda, Tota*; Hirayama, Ryoichi*; Furusawa, Yoshiya*; Funayama, Tomoo; Yokota, Yuichiro; Okahata, Yoshio*; Ito, Atsushi*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 86, 2015/03
Biological effects of high-LET radiation could be understood in terms of the ion track structure. Therefore the evaluation of the contribution of both core and penumbra regions to biological effects is an important issue for the study of high-LET effects. In the present study, we developed a protocol to make a uniform DNA sheet with insoluble nature in aqueous solution, and explored the applicability to the detection of 8-OHdG distributions after heavy-ion irradiation. Water-insoluble DNA sheet was irradiated with proton and neon ion beams at JAEA-Takasaki. After irradiation DNA samples were incubated with an 8-OHdG antibody followed by with a second antibody containing a fluorescence probe. The preliminary results indicated that upon ion irradiation randomly distributed dot-like fluorescence was observed, suggesting that these dots may be from incident ions.
Suzuki, Masayuki; Kiriyama, Hiromitsu; Nakai, Yoshiki*; Okada, Hajime; Daito, Izuru; Bolton, P.; Daido, Hiroyuki; Kondo, Kiminori; Kawanishi, Shunichi; Kagebayashi, Yoshio*; et al.
Proceedings of Conference on Lasers and Electro-Optics and The Quantum Electronics and Laser Science Conference (CLEO/QELS 2010) (CD-ROM), 2 Pages, 2010/05
We have demonstrated efficient second harmonic generation (SHG) of high energy fundamental Nd:YAG laser pulse energy of the multi-joule (J) level at 10-Hz using high optical quality top-seeded solution growth CsBO (TSSG-CBO) crystal. SHG output energy of 1.2 J is obtained with a conversion efficiency of 60%. These results indicate that CBO is a good candidate material for high energy SHG of Nd-doped lasers at the several J level or more with high repetition rate.
Suzuki, Masayuki; Kiriyama, Hiromitsu; Nakai, Yoshiki; Okada, Hajime; Daito, Izuru; Kagebayashi, Yoshio*; Yokota, Toshio*; Bolton, P.; Daido, Hiroyuki; Kawanishi, Shunichi
Optics Communications, 283(3), p.451 - 453, 2010/02
Times Cited Count:0 Percentile:0(Optics)We have demonstrated efficient frequency doubling of high energy fundamental Nd:YAG laser pulse energy of the multi-J level at a high repetition rate using high optical quality top-seeded solution growth CsBO (TSSG-CBO) crystal. Second-harmonic (532 nm) generation (SHG) output energy of 12 W at 10 Hz is obtained with a conversion efficiency of 60% The numerical calculation SHG efficiency agrees well with the measured results. These results indicate that CBO is a good candidate material for high energy SHG of Nd-doped lasers at the several J level or more with high repetition rate.
Sakakibara, Yasuhide; IKEDA, Hiroshi; Yokota, Yoshio; Kitabata, Takuya; Yamaguchi, Toshihiko
JNC TN4200 2004-001, 317 Pages, 2004/08
None
Yanagihara, Satoshi; Oshima, Soichiro; Sukegawa, Takenori; Tanabe, Norio*; Takaya, Junichi*; Kiuchi, Yoshio*; Yokota, Shuichi*
Nihon Genshiryoku Gakkai-Shi, 43(5), p.493 - 502, 2001/05
Times Cited Count:1 Percentile:12.05(Nuclear Science & Technology)no abstracts in English
JRR-2 Control Office; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Morozumi, Minoru; Kambayashi, Yuichiro; Shitomi, Hajimu; Kokanezawa, Takashi; et al.
JAERI 1027, 57 Pages, 1962/09
no abstracts in English
JRR-2 Operations Office; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Haginoya, Kinichi; Kohayakawa, Toru; Yamaki, Jikei; Yokota, Mitsuo; Horiki, Oichiro; et al.
JAERI 1024, 79 Pages, 1962/08
no abstracts in English
JRR-2 Critical Experiments Group; Kambara, Toyozo; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Morozumi, Minoru; Kambayashi, Yuichiro; Shitomi, Hajimu; Kokanezawa, Takashi; et al.
JAERI 1025, 62 Pages, 1962/03
no abstracts in English
Wada, Seiichi; Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Yokota, Yuichiro; Matsumoto, Yoshihisa*; Oto, Takayo*; Hosoi, Yoshio*; Suzuki, Norio*; Hamada, Nobuyuki*; et al.
no journal, ,
Clustered DNA damages induced by high LET heavy ions are thought non-repairable or difficult to repair. However, much less is known about the reparability of clustered DNA damages. The major DNA repair pathway in mammalian cells is non-homologous end joining (NHEJ). In this study we investigated NHEJ pathway by exposure to high LET heavy ions, by analyzing responses of Ku to DNA damage induced by high LET heavy ions. pGFP and pGFP-Ku80 were transfected into xrs-5 cells (mutated in Ku80). Cells were irradiated with rays and ion beams (LET=2.7-1610 keV/m) at TIARA JAERI-Takasaki. Survival rates were measured by colony formation assay. To examine DNA damage and NHEJ pathway induced by heavy ion beams, H2AX and GFP signal on the nuclei were observed. Xrs5-GFP-Ku80 cells were radioresistant to rays and all ion beams, in comparison with xrs5-GFP cells. When the inactivation cross section was calculated to evaluate lethal effects per one particle, the difference of inactivation cross section between xrs5-GFP cells and xrs5-GFP-Ku80 cells became smaller with increasing LET. GFP and H2AX foci on the nuclei co-localized from 10 to 30 min after C (108 keV/m) and Ne ion (321 keV/m) irradiation. While GFP foci were observed for 10 min after Ar ion (1610 keV/m) irradiation, were not observed for 20 min. The difference of LET of ion beams influenced NHEJ responses.
Wada, Seiichi; Funayama, Tomoo; Matsumoto, Yoshihisa*; Oto, Takayo*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Yokota, Yuichiro; Kakizaki, Takehiko; Hosono, Yoshio*; Suzuki, Norio*; et al.
no journal, ,
no abstracts in English
Suzuki, Masayuki; Kiriyama, Hiromitsu; Nakai, Yoshiki; Okada, Hajime; Daito, Izuru; Kagebayashi, Yoshio*; Yokota, Toshio*; Bolton, P.; Daido, Hiroyuki; Kawanishi, Shunichi
no journal, ,
A second harmonic generation (SHG) of Nd:YAG or Nd:glass is typically utilizing to pump the Ti:sapphire chirped-pulse amplification laser system for realizing a high intensity pulse laser. CsBO (CBO) crystal has a potential to obtain the high energy SHG because the effective nonlinear coefficient and damage threshold are high. In this presentation, we have demonstrated efficient frequency doubling of high energy fundamental Nd:YAG laser pulse energy of the 1.2 J with a conversion efficiency of 60% at a 10 Hz using high optical quality top-seeded solution growth CBO (TSSG-CBO) crystal. These results indicate that TSSG-CBO is a good candidate material for high energy SHG of Nd-doped lasers at the several J level with high repetition.
Suzuki, Masayuki; Kiriyama, Hiromitsu; Nakai, Yoshiki; Okada, Hajime; Daito, Izuru; Kagebayashi, Yoshio*; Yokota, Toshio*; Bolton, P.; Daido, Hiroyuki; Kondo, Kiminori; et al.
no journal, ,
no abstracts in English
Takir, D.*; Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; et al.
no journal, ,
JAXA spacecraft and sample return mission Hayabusa2 has arrived at the near-Earth asteroid 162173 Ryugu, which is classified a primitive carbonaceous object. Here we report recent results of near-infrared spectrometer (NIRS3) on the Hayabusa2 spacecraft. The observations provide direct measurements of the surface composition of Ryugu and context for the returned samples. NIRS3 has detected a weak and narrow absorption feature centered at 2.72 micrometer across entire observed surface. This absorption feature is attributed to the presence of OH-bearing minerals. The NIRS3 observations also revealed that Ryugu is the darkest object to be observed up-close by a visiting spacecraft. The intensity of the OH feature and low albedo are consistent with thermally-and/or shock-metamorphosed, and/or carbon-rich space-weathered primitive and hydrated carbonaceous chondrites.