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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.
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：259 Percentile：99.73(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.
Iwata, Takahiro*; Kitazato, Kohei*; Abe, Masanao*; Otake, Makiko*; Arai, Takehiko*; Arai, Tomoko*; Hirata, Naru*; Hiroi, Takahiro*; Honda, Chikatoshi*; Imae, Naoya*; et al.
Space Science Reviews, 208(1-4), p.317 - 337, 2017/07
Times Cited Count：54 Percentile：71.62(Astronomy & Astrophysics)NIRS3: The Near Infrared Spectrometer is installed on the Hayabusa2 spacecraft to observe the target C-type asteroid 162173 Ryugu at near infrared wavelengths of 1.8 to 3.2 micrometer. It aims to obtain reflectance spectra in order to detect absorption bands of hydrated and hydroxide minerals in the 3 micrometer-band. We adopted a linear-image sensor with indium arsenide (InAs) photo diodes and a cooling system with a passive radiator to achieve an optics temperature of 188 K, which enables to retaining sufficient sensitivity and noise level in the 3 micrometer wavelength region. We conducted ground performance tests for the NIRS3 flight model (FM) to confirm its baseline specifications. The results imply that the properties such as the signal-to-noise ratio (SNR) conform to scientific requirements to determine the degree of aqueous alteration, such as CM or CI chondrite, and the stage of thermal metamorphism on the asteroid surface.
Shibata, Keiichi; Nakagawa, Tsuneo; Fukahori, Tokio; Iwamoto, Osamu; Ichihara, Akira; Iwamoto, Nobuyuki; Kunieda, Satoshi; Otsuka, Naohiko; Katakura, Junichi; Watanabe, Yukinobu*; et al.
Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.2, p.727 - 732, 2008/05
General- and special-purpose JENDL data files are being produced in cooperation with the Japanese Nuclear Data Committee. We have developed nuclear model codes to improve the quality of MA and FP data. In the FP region, we obtained global coupled-channel optical model parameters, which can be applied to neutron- and proton-induced reaction data up to 200 MeV. These parameters are used for statistical model calculation. Resolved resonance parameters of MA and FP nuclei were updated to improve the low-energy behavior of the cross sections by using recent measurements. As a follow-up of JENDL-3.3, which was released in 2002, covarainces of several nuclei were estimated for a study on ADS. Concerning special-purpose files, the compilation of the 2007 versions of JENDL High Energy File and Photonulcear Data Files is in the final stage.
Ca
Cu
O
superconductorTokiwa, Kazuyasu*; Mikusu, Satoshi*; Higemoto, Wataru; Nishiyama, Kusuo*; Iyo, Akira*; Tanaka, Yasumoto*; Kotegawa, Hisashi*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Watanabe, Tsuneo*
Physica C, 460-462(2), p.892 - 895, 2007/09
Times Cited Count：3 Percentile：17.87(Physics, Applied)Zero- and longitudinal-field muon-spin rotation (ZF-
SR and LF-SR) measurements were carried out on a multi-layered HgBaCaCuO (Hg-1245) superconductor with 
of 108 K. With decreasing temperature, the observed ZF-SR function changed from a Gaussian-type to an exponential-type below 60 K and zero field muon precession was also observed below 45 K. These SR signals are attributed to the development of the antiferromagnetic ordering in inner CuOplanes with a low carrier concentration. These results seem to indicate clear evidence that antiferromagnetism microscopically coexists with superconductivity in the Hg-1245 superconductor below 60 K.
Igashira, Masayuki*; Watanabe, Yukinobu*; Fukahori, Tokio; Okumura, Keisuke; Katakura, Junichi; Chiba, Satoshi; Shibata, Keiichi; Yamano, Naoki*; Nakagawa, Tsuneo; Odano, Naoteru*; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(1), p.85 - 96, 2007/03
This technical note summarizes research activities on nuclear data carried out by Japanese Nuclear Data Committee (JNDC) during the fiscal years of 2003 and 2004. During this period, the nuclear data files for special purposes (JENDL-HE-2004 and JENDL-PD-2004) were released. Other activities are described: analysis of post nuclear fuel irradiation experiments, nuclear chart and nuclear data evaluation for astrophysics.
Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.
Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11
Times Cited Count：669 Percentile：96.97(Nuclear Science & Technology)Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for 
U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.
Kawai, Masayoshi*; Nakagawa, Tsuneo; Watanabe, Takashi*; Nakajima, Yutaka*; Zukeran, Atsushi*; Matsunobu, Hiroyuki*; Sugi, Teruo*; Chiba, Satoshi
Journal of Nuclear Science and Technology, 38(4), p.261 - 269, 2001/04
no abstracts in English
Nakagawa, Tsuneo; Watanabe, Takashi*; *
JAERI-Data/Code 97-050, 103 Pages, 1997/12
JAERI-Data-Code-97-050.pdf:2.73MB
no abstracts in English
Watanabe, Katsutoshi; Hamada, Shozo; Kodaira, Tsuneo; Hishinuma, Akimichi
ASM Conference on Welding and Joining Science and Technology, p.615 - 619, 1997/03
no abstracts in English
Watanabe, Katsutoshi; Shindo, Masami; Nakajima, Hajime; Koikegami, Hajime*; Higuchi, Makoto*; Nakanishi, Tsuneo*; Sahira, Kensho*; Marushichi, Koki*; Takeiri, Toshiki*; Saito, Teiichiro*; et al.
JAERI-Research 97-009, 62 Pages, 1997/02
JAERI-Research-97-009.pdf:4.82MB
no abstracts in English
Watanabe, Katsutoshi; Jitsukawa, Shiro; Hamada, Shozo; Kodaira, Tsuneo; Hishinuma, Akimichi
Fusion Engineering and Design, 31, p.9 - 15, 1996/00
Times Cited Count：6 Percentile：50.18(Nuclear Science & Technology)no abstracts in English
Nakagawa, Tsuneo; Shibata, Keiichi; Chiba, Satoshi; Fukahori, Tokio; Nakajima, Yutaka; ; Kawano, Toshihiko*; Kanda, Yukinori*; Osawa, Takaaki*; Matsunobu, Hiroyuki*; et al.
Journal of Nuclear Science and Technology, 32(12), p.1259 - 1271, 1995/12
Times Cited Count：497 Percentile：99.95(Nuclear Science & Technology)no abstracts in English
Watanabe, Katsutoshi; Nakajima, Hajime; Koikegami, Hajime*; Higuchi, Makoto*; Nakanishi, Tsuneo*; Saito, Teiichiro*; Takatsu, Tamao*
JAERI-Research 95-001, 58 Pages, 1995/01
JAERI-Research-95-001.pdf:4.31MB
no abstracts in English
Watanabe, Katsutoshi; Nakajima, Hajime; Saito, Teiichiro*; Takatsu, Tamao*; Koikegami, Hajime*; Higuchi, Makoto*; Nakanishi, Tsuneo*; Sahira, Kensho*; Marushichi, Koki*; Takeiri, Toshiki*
JAERI-Research 94-046, 50 Pages, 1994/12
JAERI-Research-94-046.pdf:2.23MB
no abstracts in English
Watanabe, Katsutoshi; Nakajima, Hajime; Sahira, Kensho*; Marushichi, Koki*; Takeiri, Toshiki*; Saito, Teiichiro*; Takatsu, Tamao*; Nakanishi, Tsuneo*; Koikegami, Hajime*; Higuchi, Makoto*
Proc. of the 2nd JAERI Symp. on HTGR Technologies; Oct. 21
23,1992,Oarai,Japan (JAERI-M 92-215), p.560 - 574, 1993/01
no abstracts in English
Watanabe, Katsutoshi; Sahira, Kensho*; Takatsu, Tamao*; Nakanishi, Tsuneo*; Higuchi, Makoto*; Nakajima, Hajime
Computer Aided Innovation of New Materials,II, p.1491 - 1494, 1993/00
no abstracts in English
Kawai, Masayoshi*; Iijima, Shungo*; Nakagawa, Tsuneo; Nakajima, Yutaka; Sugi, Teruo; Watanabe, Takashi*; Matsunobu, Hiroyuki*; *; *
Journal of Nuclear Science and Technology, 29(3), p.195 - 213, 1992/03
no abstracts in English
Nakagawa, Tsuneo; Kawai, Masayoshi*; Iijima, Shungo*; Matsunobu, Hiroyuki*; Watanabe, Takashi*; Nakajima, Yutaka; Sugi, Teruo; *; *; *; et al.
Nuclear Data for Science and Technology, p.939 - 941, 1992/00
no abstracts in English
Watanabe, Katsutoshi; Nakajima, Hajime; Sahira, Kensho*; Marushichi, Koki*; Takeiri, Toshiki*; Saito, Teiichiro*; Takatsu, Tamao*; Nakanishi, Tsuneo*; Koikegami, Hajime*; Higuchi, Makoto*
Tainetsu Kinzoku Zairyo Dai-123-Iinkai Kenkyu Hokoku, 33(2), p.227 - 242, 1992/00
no abstracts in English
