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Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.
Science, 333(6046), p.1128 - 1131, 2011/08
Times Cited Count:131 Percentile:95.14(Multidisciplinary Sciences)A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.
Fujimura, Akio*; Yasui, Yukio*; Igawa, Naoki; Yoshida, Yukihiko*; Ishigaki, Toru*; Kono, Yohei*; Kittaka, Shunichiro*; Sakakibara, Toshiro*
no journal, ,
Magnetic phase diagram was investigated by the specific heat measurement and magnetic structure has been studied by using neutron diffraction for CsCuMoO with CuO ribbon chains. We found that this material showed antiferromagnetic transition at T = 1.85 K under 0 magnetic field. The difference in magnetic and crystal structure between CsCuMoO and RbCuMoO are discussed.
Fujimura, Akio*; Yasui, Yukio*; Kono, Yohei*; Kittaka, Shunichiro*; Sakakibara, Toshiro*; Igawa, Naoki; Matsukawa, Takeshi*; Yoshida, Yukihiko*; Hoshikawa, Akinori*; Ishigaki, Toru*
no journal, ,
The magnetic behavior and magnetic structure of ACuMoO (A=Rb, Cs) with CuO ribbon chains have been studied by using specific heat measurement and neutron diffraction method. CsCuMoO showed collinear-antiferromagnetic structure analyzed by the neutron diffraction. The relation between magnetic behavior and magnetic for those materials are discussed.
Yasui, Yukio*; Fujimura, Akio*; Omori, Kiyoshi*; Igawa, Naoki; Matsukawa, Takeshi*; Yoshida, Yukihiko*; Hoshikawa, Akinori*; Ishigaki, Toru*
no journal, ,
The magnetic structure of CsCuMoO has been studied by using the neutron powder diffraction. Cu spins collinearly ordinate along the axis and we found that this material has ferromagnetic structure in ribbon chains and antiferromagnetic structure between ribbon chains. Those results indicate that the magnetic structure is strongly inflected with ferromagnetic . In this presentation, the detail of magnetic structure of this material will be discussed.
Yasui, Yukio*; Fujimura, Akio*; Omori, Kiyoshi*; Igawa, Naoki; Matsukawa, Takeshi*; Yoshida, Yukihiko*; Hoshikawa, Akinori*; Ishigaki, Toru*
no journal, ,
The magnetic structure of CsCuMoO with CuO ribbon chains have been studied by using the neutron powder diffraction. The magnetic reflections were observed below = 1.85 K and all of the magnetic reflections overlapped Bragg reflections. Considering that these are 16-Cu ions in the unit cell, CsCuMoO has the collinear-antiferromagnetic structure.