Recent progress on practical materials study by Bragg edge imaging at J-PARC

Oikawa, Kenichi; Su, Y. H.; Kiyanagi, Ryoji; Kawasaki, Takuro; Shinohara, Takenao; Kai, Tetsuya; Hiroi, Kosuke; Harjo, S.; Parker, J. D.*; Matsumoto, Yoshihiro*; et al.

Physica B; Condensed Matter, 551, p.436 - 442, 2018/12

https://doi.org/10.1016/j.physb.2017.12.038

Study of the magnetization distribution in a grain-oriented magnetic steel using pulsed polarized neutron imaging

Hiroi, Kosuke; Shinohara, Takenao; Hayashida, Hirotoshi*; Parker, J. D.*; Su, Y. H.; Oikawa, Kenichi; Kai, Tetsuya; Kiyanagi, Yoshiaki*

Physica B; Condensed Matter, 551, p.146 - 151, 2018/12

https://doi.org/10.1016/j.physb.2018.05.013

Phonon dynamics of NaI investigated by G() analysis

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 551, p.351 - 354, 2018/12

BB2017-0467.pdf:0.48MB

https://doi.org/10.1016/j.physb.2017.12.057

The dynamic structure function in real space G() is deduced from the dynamical structure factor S() which can be obtained from inelastic neutron scattering measurement. In this study, we applied the G() analysis to NaI which is a typical alkali halide crystal. The optic and acoustic phonons of NaI are widely separated in energy because the difference in mass between the constituent atoms is large. These characteristic properties certainly help us to evaluate the G() features associated with the phonon modes. We measured the S() for NaI powder using the Fermi chopper spectrometer 4SEASONS at J-PARC, and converted S() into G() by newly developed software which utilizes the maximum entropy method. Our analysis clearly demonstrated the G() of TO mode oscillates out of phase with that of LA mode, which is physically reasonable. Further analyses will be given in the presentation.

Characteristics of the 2012 model lithium-6 time-analyzer neutron detector (LiTA12) system as a high efficiency detector for resonance absorption imaging

Kai, Tetsuya; Sato, Setsuo*; Hiroi, Kosuke; Su, Y. H.; Segawa, Mariko; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Shinohara, Takenao; Oikawa, Kenichi; et al.

Physica B; Condensed Matter, 551, p.496 - 500, 2018/12

https://doi.org/10.1016/j.physb.2017.11.086

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

https://doi.org/10.1016/j.physb.2017.12.037

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

Current status of a polarized neutron reflectometer "SHARAKU" in J-PARC

Soyama, Kazuhiko; Aoki, Hiroyuki; Yamazaki, Dai; Miyata, Noboru*; Akutsu, Kazuhiro*; Hanashima, Takayasu*; Kasai, Satoshi*; Suzuki, Junichi*

no journal, , 

Spatial scale dependence of diffusion process in glass-forming liquids

Kofu, Maiko; Faraone, A.*; Tyagi, M.*; Nagao, Michihiro*; Yamamuro, Osamu*

no journal, , 

The self-diffusion of molecules in a liquid is basically governed by Fick's law. It is known that the self-part of the van Hove correlation function is written as the Gaussian function with respect to and decays exponentially with time (Debye relaxation). In the case, the relaxation time obeys the relation . In glass-forming materials, however, the relaxation process is often described by the non-Debye KWW function, . A natural question arises as to whether the relation is valid for the non- Debye diffusion process. To address this issue, we have investigated in detail the -dependence of the relaxation times for two different types of liquid, a molecular liquid (3-methylpentane) and an ionic liquid (C4mimTFSI). The measurements were done using neutron spin echo, backscattering and chopper spectrometers at NIST. Two crossover points were clearly found. The first crossover can be due to coupling with structural relaxation and the second one is Gaussian to non-Gaussian transition. This is the first clear experimental evidence for the two crossover.

Neutron scattering instruments of the MLF Spectroscopy Group at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakamura, Mitsutaka; Shibata, Kaoru; Kawakita, Yukinobu; Matsuura, Masato*; Endo, Hitoshi*; Seto, Hideki*; Ito, Shinichi*; Nakajima, Kenji; et al.

no journal, , 

Single crystal neutron diffraction study of a crystalline-state photoisomerization in a 3-cyanopropyl cobaloxime complex

Ohara, Takashi; Kiyanagi, Ryoji; Oikawa, Kenichi; Kawasaki, Takuro; Kaneko, Koji; Tamura, Itaru; Nakao, Akiko*; Hanashima, Takayasu*; Munakata, Koji*

no journal, ,