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Irisawa, Ayumi*; Sakuma, Kazuyuki; Takeuchi, Yukio*; Taniguchi, Keisuke*; Onda, Yuichi*
KEK Proceedings 2023-2, p.29 - 33, 2023/11
no abstracts in English
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.
Noda, Akira*; Nakamura, Shu*; Iwashita, Yoshihisa*; Shirai, Toshiyuki*; Tongu, Hiromu*; Soda, Hikaru*; Daido, Hiroyuki; Mori, Michiaki; Kado, Masataka; Sagisaka, Akito; et al.
International Journal of Modern Physics B, 21(3&4), p.319 - 330, 2007/02
Laser ion production has been studied for downsizing of the accelerator dedicated for cancer therapy. For optimization of various parameters such as pre-pulse condition, target position, laser spot size on target, laser pulse width and so on, time of flight (TOF) measurement utilizing the detected signal by a plastic scintillation counter played an essential role for real time measurement. Protons up to 900 keV and 600 keV are produced from the thin foil targets of Ti 3 micron and 5 micron in thickness, respectively. Modification of the energy distribution of the laser-produced ions with Maxwell distribution by utilizing an RF electric field synchronized to the pulse laser, which is the rotation of the ion beam in the longitudinal phase space (phase rotation), has been demonstrated for the first time.
Matsukado, Koji*; Esirkepov, T. Z.; Kinoshita, Kenichi*; Daido, Hiroyuki; Utsumi, Takayuki*; Li, Z.*; Fukumi, Atsushi*; Hayashi, Yukio; Orimo, Satoshi; Nishiuchi, Mamiko; et al.
Physical Review Letters, 91(21), p.215001_1 - 215001_4, 2003/11
Times Cited Count：136 Percentile：95.25(Physics, Multidisciplinary)no abstracts in English
Konno, Chikara; Maekawa, Fujio; Oyama, Yukio; Uno, Yoshitomo; Wada, Masayuki*; Maekawa, Hiroshi; Ikeda, Yujiro; Takeuchi, Hiroshi
Fusion Technology 1998, 2, p.1263 - 1266, 1998/00
no abstracts in English
Sakamoto, Atsushi; Takeuchi, Masayuki; Ogino, Hideki; Koizumi, Kenji; Sawahata, Osamu*; Sakamoto, Yukio*; Akutsu, Koichi*
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Okamura, Nobuo; Sakamoto, Atsushi; Takeuchi, Masayuki; Koizumi, Kenji; Sakamoto, Yukio*
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Ohata, Fumikazu; Sakamoto, Atsushi; Takeuchi, Masayuki; Koizumi, Kenji; Sawahata, Osamu*; Sakamoto, Yukio*; Akutsu, Koichi*
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Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Ito, Kazuyuki*; Sekita, Satoshi*; Sakamoto, Yukio*; Akutsu, Koichi*
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Takeuchi, Masayuki; Sakamoto, Atsushi; Sano, Yuichi; Ito, Kazuyuki*; Sekita, Satoshi*; Sakamoto, Yukio*; Akutsu, Koichi*
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Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Ito, Kazuyuki*; Sekita, Satoshi*; Sakamoto, Yukio*; Akutsu, Koichi*
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Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Matsuura, Takanobu*; Sakamoto, Yukio*; Sekita, Satoshi*
no journal, ,
In the present study, cleaning performance for sludge in a centrifugal contactor was investigated experimentally. It was confirmed that the splay nozzle could reduce the volume of washing solution and cleaning time significantly, compared with the cleaning without spray nozzle.
Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Matsuura, Takanobu*; Sakamoto, Yukio*; Sekita, Satoshi*
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Nakano, Hiroko; Hirota, Noriaki; Takeuchi, Tomoaki; Shibata, Hiroshi; Nemoto, Tadahiro*; Hanamoto, Yukio*; Tsuchiya, Kunihiko
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Nakano, Hiroko; Hirota, Noriaki; Takeuchi, Tomoaki; Shibata, Hiroshi; Nemoto, Tadahiro*; Hanamoto, Yukio*; Tsuchiya, Kunihiko
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Taniguchi, Keisuke*; Takeuchi, Yukio*; Fujita, Kazuki*; Dohi, Terumi; Hayashi, Seiji*; Kuramoto, Takayuki*; Nomura, Naoki*; Aono, Tatsuo*
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In Fukushima Prefecture, although decontamination has been completed except for difficult-to-return areas, most of the forest has not been decontaminated yet. From the forest, radiocaesium may enter rivers and affect downstream areas. A survey was conducted in three forested watersheds of the Nanokazawa, Saruta, Nuno rivers located in Fukushima Prefecture to understand the amount and characteristics of radiocaesium flowing out. In each watershed, suspended solids (SS) were collected by a suspended sand sampler, water was collected every few months, and the water level and flow rate were measured. After freeze-drying the SS sample, the concentration of suspended Cs-137 was measured by a germanium semiconductor detector. The water sample was filtered through a membrane filter with a pore size of 0.45 
m, then the dissolved Cs-137 was collected by the solid-phase extraction disk method or AMP coprecipitation method, and the dissolved Cs-137 concentration was measured by a germanium semiconductor detector. The ranges of dissolved Cs-137 concentration in FY2019 were 69-190 mBq/L in the Saruta River, 9.7-16 mBq/L in the Nanokazawa river, and ND-3.2 mBq/L in the Nuno River. In the poster, we will also present the results of SS measurements and flow observations.
Takeuchi, Yukio*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Yoshita, Hirofumi*; Fujita, Kazuki*; Takahashi, Yusuke*; Kuramoto, Takayuki*; Nomura, Naoki*; Hagiwara, Hiroki; Dohi, Terumi; et al.
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