Optimization and inference of bin widths for histogramming inelastic neutron scattering spectra

Tatsumi, Kazuyoshi; Inamura, Yasuhiro; Kofu, Maiko; Kiyanagi, Ryoji; Shimazaki, Hideaki*

Journal of Applied Crystallography, 55(3), p.533 - 543, 2022/06

https://doi.org/10.1107/S1600576722003624

A data-driven bin-width optimization for the histograms of measured data sets based on inhomogeneous Poisson processes was developed in a neurophysiology study [Shimazaki & Shinomoto (2007). Neural Comput. 19, 1503-1527], and a successive study [Muto et al. (2019). J. Phys. Soc. Jpn, 88, 044002] proposed its application to inelastic neutron scattering (INS) data. In the present study, the results of the method on experimental INS time-of-flight data collected under different measurement conditions from a copper single crystal are validated. The extrapolation of the statistics on a given data set to other data sets with different total counts precisely infers the optimal bin widths on the latter. The histograms with the optimized bin widths statistically verify two fine-spectral feature examples in the energy and momentum transfer cross sections: (i) the existence of the phonon band gaps; and (ii) the number of plural phonon branches located close to each other. This indicates that the applied method helps in the efficient and rigorous observation of spectral structures important in physics and materials science like novel forms of magnetic excitation and phonon states correlated to lattice thermal conductivities.

Charge-density-wave order and multiple magnetic transitions in divalent europium compound EuAl

Kaneko, Koji; Kawasaki, Takuro; Nakamura, Ai*; Munakata, Koji*; Nakao, Akiko*; Hanashima, Takayasu*; Kiyanagi, Ryoji; Ohara, Takashi; Hedo, Masato*; Nakama, Takao*; et al.

Journal of the Physical Society of Japan, 90(6), p.064704_1 - 064704_6, 2021/06

https://doi.org/10.7566/JPSJ.90.064704

Multi-step magnetic transitions in EuNiIn

Ikeda, Shugo*; Kaneko, Koji; Tanaka, Yuki*; Kawasaki, Takuro; Hanashima, Takayasu*; Munakata, Koji*; Nakao, Akiko*; Kiyanagi, Ryoji; Ohara, Takashi; Mochizuki, Kensei*; et al.

Journal of the Physical Society of Japan, 89(1), p.014707_1 - 014707_7, 2020/01

https://doi.org/10.7566/JPSJ.89.014707

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.

Magnetic structure of divalent europium compound EuGa studied by single-crystal time-of-flight neutron diffraction

Kawasaki, Takuro; Kaneko, Koji; Nakamura, Ai*; Aso, Naofumi*; Hedo, Masato*; Nakama, Takao*; Ohara, Takashi; Kiyanagi, Ryoji; Oikawa, Kenichi; Tamura, Itaru; et al.

Journal of the Physical Society of Japan, 85(11), p.114711_1 - 114711_5, 2016/11

https://doi.org/10.7566/JPSJ.85.114711

SENJU; A New time-of-flight single-crystal neutron diffractometer at J-PARC

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

Journal of Applied Crystallography, 49(1), p.120 - 127, 2016/02

https://doi.org/10.1107/S1600576715022943

Microstructure and residual strain distribution in cast duplex stainless steel studied by neutron imaging

Su, Y.; Oikawa, Kenichi; Kawasaki, Takuro; Kai, Tetsuya; Shiota, Yoshinori*; Sato, Hirotaka*; Shinohara, Takenao; Tomota, Yo*; Harada, Masahide; Kiyanagi, Ryoji; et al.

JPS Conference Proceedings (Internet), 8, p.031015_1 - 031015_5, 2015/09

https://doi.org/10.7566/JPSCP.8.031015

In this study, neutron imaging experiment was performed using NOBORU, BL10 of MLF at J-PARC. Four kinds of cast duplex stainless steel with ferrite and austenite microstructure were studied here, which were produced by different casting method at different temperature. Firstly, two-dimensional scintillation detector using wavelength-shifting fibers with pixel size of 0.52 mm 0.52 mm and illuminated area 55 mm 55 mm was used for data collection. Then, measurement by Micro Pixel Chamber based neutron imaging detector having higher spatial resolution about 0.2 mm was conducted. Data analysis code RITS (Rietveld Imaging of Transmission Spectra) will be used for microstructure including crystalline phase, lattice strain, crystallite size, texture evaluation.

Instrument design and performance evaluation of a new single crystal neutron diffractometer SENJU at J-PARC

Oikawa, Kenichi; Kawasaki, Takuro; Ohara, Takashi; Kiyanagi, Ryoji; Kaneko, Koji; Tamura, Itaru; Nakamura, Tatsuya; Harada, Masahide; Nakao, Akiko*; Hanashima, Takayasu*; et al.

JPS Conference Proceedings (Internet), 1, p.014013_1 - 014013_5, 2014/03

https://doi.org/10.7566/JPSCP.1.014013

A new single crystal time-of-flight neutron diffractometer has been installed at BL18 of the Materials and Life Science Experimental Facility of J-PARC. The diffractometer "SENJU" was designed for precise crystal and magnetic structure analyses using a small crystal less than 1.0 mm under multiple extreme environments such as low-temperature and high-magnetic field. The first neutron beam was delivered to the sample position on March 5, 2012. Subsequently, the hardware and software of SENJU have been checked and confirmed that they worked fine. At the same time, diffraction experiments of several organic and inorganic crystals have been done using NaCl, C12A7, and so on. In these measurements, Bragg reflections in the high-Q region (d-spacing 0.5 ) were clearly observed and analyzed successfully. In this presentation, we will show the instrument design and performance evaluation of SENJU in detail.

Detector system of the single-crystal time-of-flight neutron diffractometer at J-PARC/MLF

Kawasaki, Takuro; Nakamura, Tatsuya; To, Kentaro; Hosoya, Takaaki*; Oikawa, Kenichi; Ohara, Takashi; Kiyanagi, Ryoji; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru; et al.

Nuclear Instruments and Methods in Physics Research A, 735, p.444 - 451, 2014/01

https://doi.org/10.1016/j.nima.2013.09.057

Single crystal neutron diffractometer under extreme condition

Tamura, Itaru; Oikawa, Kenichi; Takahashi, Miwako*; Kawasaki, Takuro*; Kimura, Hiroyuki*; Kiyanagi, Ryoji*; Ohara, Takashi; Kaneko, Koji; Kiyotani, Tamiko*; Arai, Masatoshi; et al.

no journal, , 

no abstracts in English