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Tamii, Atsushi*; Pellegri, L.*; Sderstrm, P.-A.*; Allard, D.*; Goriely, S.*; Inakura, Tsunenori*; Khan, E.*; Kido, Eiji*; Kimura, Masaaki*; Litvinova, E.*; et al.
European Physical Journal A, 59(9), p.208_1 - 208_21, 2023/09
no abstracts in English
Nanjo, Kotaro; Ishikawa, Jun; Sugiyama, Tomoyuki; Pellegrini, M.*; Okamoto, Koji*
Journal of Nuclear Science and Technology, 59(11), p.1407 - 1416, 2022/11
Times Cited Count:5 Percentile:90.16(Nuclear Science & Technology)Suzuki, Hakuto*; Zhao, G.*; Okamoto, Jun*; Sakamoto, Shoya*; Chen, Z.-Y.*; Nonaka, Yosuke*; Shibata, Goro; Zhao, K.*; Chen, B.*; Wu, W.-B.*; et al.
Journal of the Physical Society of Japan, 91(6), p.064710_1 - 064710_5, 2022/06
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)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.
Kondo, Masahiro*; Yoshimoto, Tatsuya*; Ishikawa, Jun; Okamoto, Koji*
Hozengaku, 15(4), p.79 - 85, 2017/01
no abstracts in English
Yoshimoto, Tatsuya*; Ishikawa, Jun; Okamoto, Koji*; Maruyama, Yu
Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 5 Pages, 2014/11
Kubota, Masato; Yamada, Hiroyuki*; Nakao, Hironori*; Okamoto, Jun*; Yamasaki, Yuichi*; Sawa, Akihito*; Murakami, Yoichi*
Japanese Journal of Applied Physics, 53(5S1), p.05FH07_1 - 05FH07_5, 2014/05
Times Cited Count:2 Percentile:8.89(Physics, Applied)Okamoto, Jun*; Nakao, Hironori*; Yamasaki, Yuichi*; Wadachi, Hiroki*; Tanaka, Arata*; Kubota, Masato; Horigane, Kazumasa*; Murakami, Yoichi*; Yamada, Kazuyoshi*
Journal of the Physical Society of Japan, 83(4), p.044705_1 - 044705_6, 2014/04
Times Cited Count:8 Percentile:55.49(Physics, Multidisciplinary)Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo*; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi*; Tanaka, Arata*; et al.
Hoshako, 22(4), p.202 - 209, 2009/07
no abstracts in English
Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi; Tanaka, Arata*; et al.
Physical Review Letters, 100(24), p.247202_1 - 247202_4, 2008/06
Times Cited Count:39 Percentile:82.23(Physics, Multidisciplinary)no abstracts in English
Okane, Tetsuo; Takeda, Yukiharu; Okamoto, Jun*; Mamiya, Kazutoshi*; Okochi, Takuo; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Ochiai, Akira*; et al.
Journal of the Physical Society of Japan, 77(2), p.024706_1 - 024706_6, 2008/02
Times Cited Count:15 Percentile:64.43(Physics, Multidisciplinary)Okamoto, Jun*; Okane, Tetsuo; Saito, Yuji; Terai, Kota*; Fujimori, Shinichi; Muramatsu, Yasuji*; Yoshii, Kenji; Mamiya, Kazutoshi*; Koide, Tsuneharu*; Fujimori, Atsushi; et al.
Physical Review B, 76(18), p.184441_1 - 184441_5, 2007/11
Times Cited Count:34 Percentile:76.91(Materials Science, Multidisciplinary)CaSrRuO, which is ferromagnetic for Sr concentration x 0.3, has been studied by X-ray magnetic circular dichroism (XMCD) in Ru 3 and O 1 core-level X-ray absorption. XMCD signals appear at x 0.3 and monotonically increases with x in the ferromagnetic phase. While the monotonic increase of the XMCD signals with x is of a typical Stoner-type, the absence of appreciable change in the spectral line shapes of both the Ru 3 and O 1 XMCD spectra indicate that the itinerant-electron ferromagnetism in CaSrRuO is influenced by strong electron correlation.
Suzuki, Shigeru*; Matsubara, Eiichiro*; Komatsu, Takuya*; Okamoto, Yoshinori*; Kanie, Kiyoshi*; Muramatsu, Atsushi*; Konishi, Hiroyuki; Mizuki, Junichiro; Waseda, Yoshio*
Corrosion Science, 49(3), p.1081 - 1096, 2007/03
Times Cited Count:32 Percentile:80.51(Materials Science, Multidisciplinary)X-ray diffraction measurements of a small amount of samples extracted from wet corrosion products freshly formed on a pure iron and iron-2 mass% silicon surfaces have been conducted using synchrotron radiation. The results showed that -FeOOH was formed on the outer side of wet corrosion products formed on the pure iron by sodium chloride solution, while -FeOOH, -FeOOH, FeO, and green rusts were formed on the inner side. In comparison to the case of the pure iron, a significant formation of -FeOOH was observed in the iron-silicon alloy. Furthermore, in-situ diffraction measurements by a conventional X-ray source were conducted for analyzing corrosion products formed on the pure iron and iron-silicon alloy surfaces by cyclic exposure to wet and dry atmospheres. The results obtained by the diffraction and diffraction measurements on the corrosion products were consistent.
Ishida, Yukiaki*; Hwang, J. I.*; Kobayashi, Masaki*; Takeda, Yukiharu; Mamiya, Kazutoshi*; Okamoto, Jun*; Fujimori, Shinichi; Okane, Tetsuo; Terai, Kota*; Saito, Yuji; et al.
Applied Physics Letters, 90(2), p.022510_1 - 022510_3, 2007/01
Times Cited Count:23 Percentile:64.27(Physics, Applied)no abstracts in English
Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Okamoto, Jun*; Mamiya, Kazutoshi*; Muramatsu, Yasuji*; Fujimori, Atsushi; Ochiai, Akira*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.105 - 106, 2006/08
no abstracts in English
Okane, Tetsuo; Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Takeda, Yukiharu; Saito, Yuji; Muramatsu, Yasuji*; Fujimori, Atsushi*; Haga, Yoshinori; Yamamoto, Etsuji; et al.
Journal of the Physical Society of Japan, 75(2), p.024704_1 - 024704_5, 2006/02
Times Cited Count:12 Percentile:58.31(Physics, Multidisciplinary)no abstracts in English
Okamoto, Jun*; Fujimori, Shinichi; Okane, Tetsuo; Fujimori, Atsushi*; Abbate, M.*; Yoshii, Shunsuke*; Sato, Masatoshi*
Physical Review B, 73(3), p.035127_1 - 035127_6, 2006/01
Times Cited Count:2 Percentile:12.61(Materials Science, Multidisciplinary)We have performed photoemission and soft X-ray absorption studies of pyrochlore-type Ru oxides, namely, the filling-control system SmCaRuO and the bandwidth-control system SmBiRuO, which show insulator-to-metal transition with increasing Ca and Bi concentration, respectively. Core levels and the O 2 valence band in SmCaRuO show almost the same amount of monotonous upward energy shifts with Ca concentration, which indicates that the chemical potential is shifted downward due to hole doping. The Ru 4 band in SmCaRuO is also shifted toward the Fermi level () with hole doping and the density of states (DOS) at increases. The core levels in SmBiRuO, on the other hand, do not show clear energy shifts except for the Ru 3 core level, whose line shape change also reflects the increase of metallic screening with Bi concentration. We observe pronounced spectral weight transfer from the incoherent to the coherent parts of the Ru band with Bi concentration, which is expected for a bandwidth-control Mott-Hubbard system. The increase of the DOS at is more abrupt in the bandwidth-control SmBiRuO than in the filling-control SmCaRuO, in accordance with a recent theoretical prediction. Effects of charge transfer between the Bi 6 band and the Ru 4 band are also discussed.
Kobayashi, Masaki*; Ishida, Yukiaki*; Hwang, J. I.*; Mizokawa, Takashi*; Fujimori, Atsushi*; Mamiya, Kazutoshi*; Okamoto, Jun*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; et al.
Physical Review B, 72(20), p.201201_1 - 201201_4, 2005/11
Times Cited Count:140 Percentile:96.08(Materials Science, Multidisciplinary)no abstracts in English
Hwang, J. I.*; Ishida, Yukiaki*; Kobayashi, Masaki*; Hirata, Gen*; Takubo, Ko*; Mizokawa, Takashi*; Fujimori, Atsushi; Okamoto, Jun; Mamiya, Kazutoshi*; Saito, Yuji; et al.
Physical Review B, 72(8), p.085216_1 - 085216_6, 2005/08
Times Cited Count:64 Percentile:87.9(Materials Science, Multidisciplinary)no abstracts in English
Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji*; Yoshii, Kenji; Fujimori, Atsushi*; Tanaka, Arata*; Abbate, M.*; et al.
Physical Review B, 71(10), p.104401_1 - 104401_5, 2005/03
Times Cited Count:20 Percentile:61.99(Materials Science, Multidisciplinary)The antiferromagnetic-to-ferromagnetic transition in SrFeCoO (0.15) induced by Co doping has been studied by magnetic circular X-ray dichroism. The orbital and spin magnetic moments of the Fe and Co 3 states under the magenetic field of 2 T are found to show different dependences: The spin polarization of Fe 3 gradually increases with Co concentration; On the other hand, a large spin polarization of Co 3 is induced already in the antiferromagnetic phase, indicating that the Co moment is nearly fully alligned already in the antiferromagnetic phase. This suggests that the alignment of the Fe magnetic moment in SrFeCoO is induced by interaction with doped Co magnetic moment. Possible formation of ferromagnetic Co rich region is discussed.