Present status of J-PARC MUSE

Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Natori, Hiroaki*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Tampo, Motonobu*; Kawamura, Naritoshi*; Teshima, Natsuki*; et al.

Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03

https://doi.org/10.1088/1742-6596/2462/1/012033

Electrical resistance measurement techniques for metal hydrides under high-pressure H conditions & electrical transport and structural properties of FeH

Matsuoka, Takehiro*; Hirao, Naohisa*; Oishi, Yasuo*; Shimizu, Katsuya*; Machida, Akihiko; Aoki, Katsutoshi

Koatsuryoku No Kagaku To Gijutsu, 21(3), p.190 - 196, 2011/09

https://doi.org/10.4131/jshpreview.21.190

We present the newly developed electrical resistance measurement technique for metal hydrides compressed in high-pressure H and the first successful simultaneous measurements of electrical resistance and X-ray diffraction of FeH at high pressures and low temperatures. The electrical resistivity showed a sharp increase with the formation of iron-hydride FeH () at 3.5 GPa. The '-phase of FeH was found to be metallic up to 25.5 GPa. The vs. curves up to 16.5 GPa approximately follow Fermi-liquid law below 25 K. However, was found to be better fitting at 25.5 GPa. This change can be related to the previously reported ferromagnetism collapse at corresponding pressures.

Spins and parities of astrophysically important S states from Si(He, )S

Setoodehnia, K.*; Chen, A. A.*; Komatsubara, Tetsuro*; Kubono, Shigeru*; Binh, D. N.*; Carpino, J. F.*; Chen, J.*; Hashimoto, Takashi*; Hayakawa, Takehito; Ishibashi, Yoko*; et al.

Physical Review C, 83(1), p.018803_1 - 018803_4, 2011/01

https://doi.org/10.1103/PhysRevC.83.018803

The structure of proton-unbound S states strongly determines the thermonuclear P(, )S reaction rate at temperatures characteristic of explosive hydrogen burning in classical novae and type I X-ray bursts. Specifically, the rate had been previously predicted to be dominated by two low-lying, unobserved, levels in the =4.7-4.8 MeV region, with spin and parity assignments of 3 and 2. In recent experimental work, two candidate levels were observed with energies of 4.699 MeV and 4.814 MeV, but no experimental information on their spins and parities was obtained. We have performed an in-beam -ray spectroscopy study of S with the Si(He, )S reaction. The spin and parities were inferred from a comparison to the known decay schemes of the corresponding mirror states.

Generation and application of ultrahigh monochromatic X-ray using high-quality FeBO single crystal

Mitsui, Takaya; Seto, Makoto; Kikuta, Seishi*; Hirao, Naohisa*; Oishi, Yasuo*; Takei, Fumihiko*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Higashitaniguchi, Satoshi*; Masuda, Ryo*

Japanese Journal of Applied Physics, Part 1, 46(2), p.821 - 825, 2007/02

https://doi.org/10.1143/JJAP.46.821

Ultrahigh monochromatic 14.4 keV X-rays with a narrow bandwidth of 15.4 neV were generated successfully with a high counting rate of 12,000 counts/s at the undulator beamline (BL11XU) of SPring-8. It was achieved by combining an intense X-ray from the third generation synchrotron radiation facility SPring-8 and pure nuclear Bragg scattering of a very highquality FeBO perfect single crystal at the Nel temperature. We describe the detailed study of the beam characteristics and some performance test experiments of energy-domain synchrotron radiation Mssbauer spectroscopy, including a highpressure experiment using a diamond anvil cel.

Structural properties and phase transition of hole-orbital-ordered (CHNH)CuCl studied by resonant and non-resonant X-ray scatterings under high pressure

Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Murakami, Yoichi; Shobu, Takahisa*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Oishi, Yasuo*

Physical Review B, 72(1), p.014123_1 - 014123_10, 2005/07

https://doi.org/10.1103/PhysRevB.72.014123

The effects of hydrostatic pressure on a structure and the corresponding resonant X-ray scattering (RXS) spectrum have been investigated for the hole-orbital-ordered compound (CHNH)CuCl. We have found a structural phase transition at Pc=4 GPa. The reduction of the Jahn-Teller distortion (JTD) toward Pc is also ascertained by structural analyses. The gradual change in the color of the crystal is also observed in connection with the structural change near Pc. We experimentally confirmed that the RXS intensity comes from the polarization of the density of states of px and py symmetries, which is mainly dominated not by the on-site 3d-4p Coulomb interaction but by the JTD of the CuCl octahedron. The RXS study under a high pressure shows no striking change as JTD is suppressed by the application of pressure. On the other hand, the RXS intensity becomes zero above Pc. The results indicate that the local environment of the Cu ion markedly changes. Two possible structures above Pc are proposed.

Determination of low-pressure crystalline-liquid phase boundary of SnI

Fuchizaki, Kazuhiro*; Fujii, Yasuhiko*; Oishi, Yasuo*; Omura, Ayako*; Hamaya, Nozomu*; Katayama, Yoshinori; Okada, Taku

Journal of Chemical Physics, 120(23), p.11196 - 11199, 2004/06

https://doi.org/10.1063/1.1751397

The location of the liquidus in the low-pressure crystalline phase of SnI was determined utilizing X-ray diffraction measurements under pressures up to approximately GPa. The liquidus is not well fitted to a monotonically increasing curve such as Simon's equation, but breaks near GPa and then becomes almost flat. The results are compared to those from molecular dynamics simulations. Ways to improve the model potential adopted in the simulations are discussed.

Volume collapse transition in TmTe; Competition between strong correlation and - hybridization at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; Taguchi, Munetaka*; Oishi, Yasuo*; Matsumura, Takashi*; Ishii, Hirofumi*; Hiraoka, Nozomu*; Cai, Y.*

no journal, , 

Structural and valence changes of europium hydride induced by application of high-pressure H

Matsuoka, Takehiro*; Shimizu, Katsuya*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Yoda, Yoshitaka*; Mitsui, Takaya; Masuda, Ryo; Machida, Akihiko; Aoki, Katsutoshi; et al.

no journal, , 

Europium-hydride EuH exposed to high-pressure H conditions has been studied by X-ray diffraction and Mssbauer spectroscopy measurements up to 50 GPa using synchrotron radiation. We report new structural and valence transitions, Pnma(x=2, divalent) P63/mmc(x=2, 7.2-8.7GPa) I4/m(x2, 8.7-9.7 GPa) I4/mmm(x2, 9.7 GPa, trivalent). The phase of I4/mmm having trivalent character is a small distortion from cubic fcc structure which has been commonly observed for -phase of all other trivalent rare-earth metal hydrides. Our study clearly demonstrates the first observation of -phase of EuH and suggest that the material is no longer an irregular member of the rare earth metal hydrides RH systems.