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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.
Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11
Times Cited Count:7 Percentile:28.09(Green & Sustainable Science & Technology)Moro, Takuya*; Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Nakayama, Tadachika*; Takeda, Masatoshi*; Yamada, Noboru*; Nishihata, Yasuo; Fukuda, Tatsuo; et al.
Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11
Times Cited Count:17 Percentile:66.65(Chemistry, Physical)Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Ferroelectrics, 512(1), p.92 - 99, 2017/08
Times Cited Count:14 Percentile:56.38(Materials Science, Multidisciplinary)Yamanaka, Satoru*; Kim, J.*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Yamada, Noboru*; et al.
Advanced Sustainable Systems (Internet), 1(3-4), p.1600020_1 - 1600020_6, 2017/04
no abstracts in English
Fujiwara, Satoru; Araki, Katsuya*; Matsuo, Tatsuhito; Yagi, Hisashi*; Yamada, Takeshi*; Shibata, Kaoru; Mochizuki, Hideki*
PLOS ONE (Internet), 11(4), p.e0151447_1 - e0151447_17, 2016/04
Times Cited Count:24 Percentile:65.34(Multidisciplinary Sciences)Kim, Y.*; Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Ogawa, Takashi*; Serizawa, Takeshi*; Tanaka, Hirohisa*; Baba, Masaaki*; Fukuda, Tatsuo; Yoshii, Kenji; et al.
Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07
Times Cited Count:18 Percentile:60.6(Chemistry, Physical)An innovative electro-thermodynamic cycle based on temporal temperature variations using pyroelectric effect has been presented. Practical energy is successfully generated in both synchrotron X-ray diffraction measurements under controlled conditions and real engine dynamometer experiments. The main generating origin is revealed as a combination of a crystal structure change and dipole change phenomenon corresponds to the temperature variation. In particular, the electric field induced 180 domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.
Asami, Itsuo*; Fukuta, Shiro*; Kuroyanagi, Satoru*; Yamada, Masato*; Hase, Yoshihiro; Yoshihara, Ryohei; Narumi, Issei
JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 78, 2009/12
no abstracts in English
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Nuclear Fusion, 47(10), p.S668 - S676, 2007/10
Times Cited Count:34 Percentile:73.8(Physics, Fluids & Plasmas)The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 510 m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.
Tsuchiya, Kunihiko; Hoshino, Tsuyoshi; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Terai, Takayuki*; Tanaka, Satoru*; Munakata, Kenzo*; Kato, Shigeru*; Uchida, Munenori*; et al.
Nuclear Fusion, 47(9), p.1300 - 1306, 2007/09
Times Cited Count:22 Percentile:60.59(Physics, Fluids & Plasmas)no abstracts in English
Oku, Takayuki; Yamada, Satoru; Shinohara, Takenao; Suzuki, Junichi; Mishima, Kenji*; Hirota, Katsuya*; Sato, Hiromi*; Shimizu, Hirohiko
Physica B; Condensed Matter, 397(1-2), p.188 - 191, 2007/07
Times Cited Count:5 Percentile:27.23(Physics, Condensed Matter)We have studied a neutron polarization method by means of a quadrupole magnet. By passing through the aperture of the quadrupole magnet (QM), positive and negative polarity neutrons are accelerated in opposite directions and spatially separated due to the magnetic field gradient. Then, by extracting one spin component, we can obtain a highly polarized neutron beam. Since polarized neutrons do not interact with any substances in this method, we can obtain the polarized neutron beam free from neutron attenuation. As a result of a cold neutron beam polarization experiment by using the QM, we obtained extremely high neutron polarization degree P0.999. In this paper, we show some experimental results of the neutron polarization experiment and discuss the application of the QM-based polarizing device to neutron scattering experiments.
Oku, Takayuki; Iwase, Hiroki; Shinohara, Takenao; Yamada, Satoru; Hirota, Katsuya*; Koizumi, Satoshi; Suzuki, Junichi; Hashimoto, Takeji; Shimizu, Hirohiko
Journal of Applied Crystallography, 40(s1), p.s408 - s413, 2007/04
Times Cited Count:26 Percentile:89.69(Chemistry, Multidisciplinary)Measuring efficiency and/or angular resolution of small-angle neutron scattering experiments can be improved by focusing neutrons on a detector plane. Thus, a magnetic focusing lens (MNL) have been installed into the SANS instrument, SANS-J-II, of JRR-3 in AEA for the focusing-geometry SANS (FSANS) experiments. The MNL is an extended Halbach-type permanent sextupole magnet. The inner diameter and length of the MNL are 35 mm and 1200 mm, respectively. As the MNL functions as the focusing lens only for the polarized neutron with positive polarity, the incident neutron polarization is set positive by using the supermirror polarizer and the two-coil spin flipper. The intensity distribution of the neutrons focused by the MNL at the detector position was measured by using a high-resolution photomultiplier-based scintillation detector. In this paper, the neutron focusing property of the focusing setup is investigated, and the performance of the FSANS instrument is discussed.
Tsuchiya, Kunihiko; Hoshino, Tsuyoshi; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Terai, Takayuki*; Tanaka, Satoru*; Munakata, Kenzo*; Kato, Shigeru*; Uchida, Munenori*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
no abstracts in English
Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03
The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 510m, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high and long pulse.
Arakawa, Kazuo; Oikawa, Masakazu*; Shimada, Hirofumi*; Kamiya, Tomihiro; Nakano, Takashi*; Yusa, Ken*; Kato, Hiroyuki*; Sato, Takahiro; Agematsu, Takashi; Kashiwagi, Hirotsugu; et al.
Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.279 - 281, 2007/00
no abstracts in English
Oku, Takayuki; Yamada, Satoru; Sasao, Hajime*; Suzuki, Junichi; Shinohara, Takenao*; Hirota, Katsuya*; Ikeda, Kazuaki*; Tsuzaki, Tsuyoshi*; Kiyanagi, Yoshiaki*; Furusaka, Michihiro*; et al.
Physica B; Condensed Matter, 385-386(2), p.1225 - 1228, 2006/11
Times Cited Count:10 Percentile:44.52(Physics, Condensed Matter)We have developed a magnetic neutron lens based on an extended Halbach-type permanent sextupole magnet with magnet pieces of NEOMAX-44H, -35EH and high saturation magnetization material, permendule. The aperture size of the magnet is 35 mm in diameter and the magnet length is 2,400 mm. The magnet generates a sextupole magnetic field with a gradient coefficient =10,600 T/m inside the aperture, where is a distance from the magnet center axis. To prevent neutrons from hitting and reflecting at the inner surface of the magnet, the surface is covered with cadmium (Cd) sheets and also Cd pinhole slits with size of 30 mm in diameter are positioned in series inside the magnet aperture, resulting in the effective diameter of 30 mm. The neutron focusing property of the magnet is investigated by using pulsed polarized neutrons. The obtained results are discussed with the precise simulation results. Its application to the focusing-geometry small-angle neutron scattering experiments is also discussed.
Isayama, Akihiko; Inagaki, Shigeru*; Watanabe, Kiyomasa*; Narushima, Yoshiro*; Sakakibara, Satoru*; Funaba, Hisamichi*; Ida, Katsumi*; Nagayama, Yoshio*; Yamada, Hiroshi*; Kawahata, Kazuo*; et al.
Plasma Physics and Controlled Fusion, 48(1), p.L45 - L55, 2006/04
Times Cited Count:12 Percentile:39.29(Physics, Fluids & Plasmas)no abstracts in English
Matsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Galatanu, A.; Yamamoto, Etsuji; Shishido, Hiroaki*; Yamada, Mineko*; Yamaura, Junichi*; Hedo, Masato*; Uwatoko, Yoshiya*; et al.
Journal of the Physical Society of Japan, 74(5), p.1552 - 1556, 2005/05
Times Cited Count:23 Percentile:72.2(Physics, Multidisciplinary)We have succeeded in growing a high-quality single crystal of UCuSi with the tetragonal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. UCuSi is found to order antiferromagnetically below = 106 K, and follows a successive ferromagnetic ordering at = 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the [001] direction (-axis) both in the antiferromagnetic and ferromagnetic phases, while the [100] direction (-axis) corresponds to the hard-axis in magnetization. The magnetization curve in the antiferromagnetic phase indicates a clear metamagnetic transition at a low field of about 1 kOe and changes smoothly into a ferromagnetic magnetization curve below = 100 K. The saturation moment is determined as 1.75/U at 2 K. The electronic specific heat coefficient is also determined as 20 mJ/Kmol.
Oku, Takayuki; Suzuki, Junichi; Sasao, Hajime*; Yamada, Satoru; Furusaka, Michihiro*; Adachi, Tomohiro*; Shinohara, Takenao*; Ikeda, Kazuaki*; Shimizu, Hirohiko
Physica B; Condensed Matter, 356(1-4), p.126 - 130, 2005/02
Times Cited Count:11 Percentile:45.52(Physics, Condensed Matter)We have developed a magnetic neutron lens (MNL) based on a sextupole magnet. A neutron beam, which is incident to the sextupole magnet, either converges or diverges depending on the neutron spin state. Small-angle neutron scattering in focusing geometry (FSANS) was proposed to improve the q-resolution and/or measuring efficiency. The MNL is considered to be the most suitable focusing device for FSANS experiments using a polarized neutron beam, since it focuses the polarized neutron beam free from neutron attenuation and scattering by substances. Recently, we have developed the MNLs with sufficiently large apertures and strong focusing power for FSANS experiments. In this study, we evaluate the focusing property of the MNLs for the polarized neutron beam, and performed FSANS experiments using the MNL. The obtained results are discussed.