Watanabe, Masari*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Ueno, Wataru*; Matsui, Kazuki*; Goto, Takayuki*; Hagihara, Masato
Physical Review B, 105(5), p.054414_1 - 054414_12, 2022/02
Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Authelet, G.*; et al.
Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03
The structures of the neutron-rich Co isotopes were investigated via () knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Level schemes were reconstructed using the coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations suggests coexistence of spherical and deformed shapes at low excitation energies in the Co isotopes.
Elekes, Z.*; Kripk, *; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.
Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01
The nuclear structure of the Ni nucleus was investigated by (,) reaction using a NaI(Tl) array to detect the deexciting prompt rays. A new transition with an energy of 2227 keV was identified by and coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.
Matsui, Masanori*; Komatsu, Kazuki*; Ikeda, Emi*; Sano, Asami; Goto, Hirotada*; Yagi, Takehiko*
American Mineralogist, 96(5-6), p.854 - 859, 2011/05
Neutron powder diffraction analyses of -Al(OD) revealed that the crystals are orthorhombic with space group 222, but not as reported previously by X-ray diffraction data. The initial lattice parameters and the atomic positions of both Al and O were taken from previous X-ray structural analyses for the structure, while the H atom positions were determined using ab initio calculations. The -Al(OH) structure possesses one relatively long and two short O-H...O hydrogen bonds. Ab initio calculations are also used to find that -Al(OH) with space group 222 transforms to another high pressure polymorph with space group at around 67 GPa, and that the two short hydrogen bonds in -Al(OH) become both symmetric through the transformation, in which the protons are located at the midpoints of the O...O hydrogen bonds.
Oketani, Kazuki*; Nara, Yoshitaka*; Matsui, Hiroya; Fujii, Hirokazu*
no journal, ,
For the geological disposal of radioactive wastes, it is important to understand the long-term migration of radionuclides. The network of fractures and pores in a rock mass, which have a role as the pathway of the fluid flow of materials, may change due to sealing of a material in the long term. We measured changes in hydraulic conductivity of crystalline rock mass using water mixed with clays sampled from a fault in the Mizunami Underground Research Laboratory, Japan Atomic Energy Agency. This result indicates that permeability of in-situ rock mass is possible to decrease by fracture filling with a clay material in a fault.
Watanabe, Masao; Nakajima, Taro*; Inamura, Yasuhiro; Matsui, Kazuki*; Kanda, Tomoki*; Nomoto, Tetsuya*; Oishi, Kazuki*; Kawamura, Yukihiko*; Saito, Hiraku*; Tamatsukuri, Hiromu; et al.
no journal, ,
In recent years, due to advances in precision measurement technology in pulsed magnetic fields, a novel magnetic state was discovered in a strong magnetic field. We constructed a measurement environment that can comprehensively explore the reciprocal lattice space under magnetic fields up to 14 Tesla by combining the long-pulse magnetic field generated by the supercapacitor and pulsed neutrons at J-PARC. This equipment can generate a magnetic field that is sufficiently longer than the time width (about 10 milliseconds) of the multi-wavelength neutron pulse passing through the sample. This method was used to investigate the magnetic phase transition in the frustrated magnet CuFeO.