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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.
Ota, Yukihiro; Nakai, Noriyuki; Nakamura, Hiroki; Machida, Masahiko; Inotani, Daisuke*; Ohashi, Yoji*; Koyama, Tomio*; Matsumoto, Hideki*
Physical Review B, 81(21), p.214511_1 - 214511_6, 2010/06
Times Cited Count：32 Percentile：75.43(Materials Science, Multidisciplinary)An extension of the Ambegaokar-Baratoff relation to a superconductor-insulator-superconductor (SIS) Josephson junction with multiple tunneling channels is derived. Applying the resultant relation to a SIS Josephson junction formed by an iron-based (five-band) and a single-band Bardeen-Cooper-Schrieffer (BCS) type superconductors, a theoretical bound of the Josephson critical current (
) multiplied by the resistance of the junction (
) is given. We reveal that such a bound is useful for identifying the pairing symmetry of iron-pnictide superconductors. One finds that if a measured value of 
is smaller than the bound then the symmetry is 
-wave, and otherwise 
-wave without any sign changes. In addition, we stress that temperature dependence of is sensitive to the difference of the gap functions from the BCS type gap formula in the above heterojunction.
Tobita, Noriyuki; Okada, Takashi; Kashiro, Kashio; Matsumoto, Masaki; Watahiki, Masatoshi; Nakata, Keiji*; Gonnokami, Kiyomi*
JNC TN8430 2004-001, 125 Pages, 2004/12
JNC-TN8430-2004-001.pdf:143.53MB
An event that a pre-filter burned on fire took place in the glove box dismantlement facility of Plutonium Production Facility, on April 21, 2003. The direct cause of this event was considered to be sparks generated by an abrasive wheel cutter, some of which reached the pre-filter and eventually burned the pre-filter. Further investigation revealed that there exist other deficiencies those of which formed indirect causes of the event, such as the wheel cutter was used without protective cover and adequate shield against sparks was not installed during the operation. To prevent similar event in the future, following corrective actions were introduced. Wheel cutter will not be used without protective cover; Incombustible pre-filter will be used; Shield will be place at the front of the pre-filter. We have conducted series of experimental tests in order to evaluate and confirm the validity of these corrective actions as well as determine the cause of the fire. This report present the results of these tests.
Shimomura, Yasuo; Tsunematsu, Toshihide; Yamamoto, Shin; Maruyama, So; Mizoguchi, Tadanori*; Takahashi, Yoshikazu; Yoshida, Kiyoshi; Kitamura, Kazunori*; Ioki, Kimihiro*; Inoue, Takashi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 78(Suppl.), 224 Pages, 2002/01
no abstracts in English
Suzuki, Yoshio; Kushida, Noriyuki; Yamagishi, Nobuhiro; Minami, Takahiro; Matsumoto, Nobuko; Nakajima, Kohei; Nishida, Akemi; Matsubara, Hitoshi; Tian, R.; Hazama, Osamu; et al.
no journal, ,
no abstracts in English
Suzuki, Yoshio; Kushida, Noriyuki; Yamagishi, Nobuhiro; Nakajima, Kohei; Minami, Takahiro; Matsumoto, Nobuko; Aoyagi, Tetsuo; Nakajima, Norihiro; Iba, Katsuyuki*; Hayashi, Nobuhiko; et al.
no journal, ,
no abstracts in English
s-wave in iron-pnictide superconductorsOta, Yukihiro; Nakai, Noriyuki; Nakamura, Hiroki; Machida, Masahiko; Inotani, Daisuke*; Ohashi, Yoji*; Koyama, Tomio*; Matsumoto, Hideki*
no journal, ,
An enormous amount of studies has been devoted to the identification of the pairing symmetry in iron-based superconductors. In the paper, we focus on a heterotic (multiband) superconductor- insulator-(single-band)superconductor junction. First, we derive the Amgegaokar-Baratoff relation. We evaluate a theoretical lowerbound of 
for s-wave without sign change, which may correspond to a upper bound for s-wave. Next, we discuss how a fluctuation of relative phases between multiple gaps and the pairing symmetry correct the Shapiro step, e.g., the step height and the step position. On the basis of these results, we propose a conventional and direct method to identify the s-wave symmetry.
Ota, Yukihiro; Machida, Masahiko; Nakai, Noriyuki; Nakamura, Hiroki; Koyama, Tomio*; Matsumoto, Hideki*
no journal, ,
In order to examine pairing symmetry and application potential of iron-pnictide superconductors, Josephson junctions including the new type of superconductors have been intensively examined. In particular, recent experimental achievements indicate the necessity of further theoretical investigations for how multiple tunneling contributions and the sign change between the superconducting gaps reflect the basic Josephson effects. In this paper, we theoretically examine a product and a Shapiro step in a heterotic SIS junction between conventional s-wave and iron-pnictide superconductors as a typical example of Josephson junctions with multiple tunneling channels. Then, we show that they are good probe to identify the pairing symmetry of the iron-pnictide superconductors.
-wave in iron-based superconductorsOta, Yukihiro; Nakai, Noriyuki; Nakamura, Hiroki; Machida, Masahiko; Inotani, Daisuke*; Ohashi, Yoji*; Koyama, Tomio*; Matsumoto, Hideki*
no journal, ,
An enormous amount of studies has been devoted to the identification of the pairing symmetry in iron-based superconductors. We show a theory of Josephson junctions with multi-gap superconductors. We focus on a heterotic (multi-band)superconductor- insulator-(one-band)superconductor junction. We derive the Ambegaokar-Baratoff relation. We evaluate a lower bound of for -wave without sign change, which may correspond to a upper bound for -wave. Next, we discuss how a fluctuation of relative phases between the gaps and the symmetry modify the Shapiro step. Thus, we propose a direct method to identify -wave.
Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Matsumoto, Hiroshi*; Yoshioka, Masakazu*; Matsumoto, Noriyuki*; Kumada, Hiroaki*; Matsumura, Akira*; Sakurai, Hideyuki*; Hiraga, Fujio*; Kiyanagi, Yoshiaki*; et al.
no journal, ,
no abstracts in English
Matsumoto, Hiroshi*; Suzuki, Fumiko*; Sugawara, Hirotaka*; Yoshioka, Masakazu*; Higashi, Yasuo*; Matsumoto, Noriyuki*; Hasegawa, Kazuo; Kondo, Yasuhiro; Uchida, Kazuhide*; Kurokawa, Shinichi*
no journal, ,
