Demonstration of shape analysis of neutron resonance transmission spectrum measured with a laser-driven neutron source

Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Lan, Z.*; Wei, T.*; et al.

Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09

https://doi.org/10.1038/s41598-024-72836-8

Degradation of a lithium cobalt oxide cathode under high voltage operation at an interface with an oxide solid electrolyte

Ito, Kotaro*; Tamura, Kazuhisa; Shimizu, Keisuke*; Yamada, Norifumi*; Watanabe, Kenta*; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*

RSC Applied Interfaces (Internet), 1(4), p.790 - 799, 2024/04

https://doi.org/10.1039/D3LF00251A

LiCoO is widely used as a cathode material in lithium-ion batteries. However, the reversible capacity of LiCoO at high voltage is not well known because of the oxidative degradation of the electrolyte. In this study, a thin-film all-solid-state battery was fabricated with epitaxially grown LiCoO cathode and LiPO solid electrolyte as a model battery that operates stably at high voltages, ranging up to 4.6 V, without drastic degradation. However, the charge-discharge capacities of the battery decreased with cycling at 4.7 V. synchrotron X-ray diffraction studies revealed that LiCoO was deactivated via a change in its crystal structure to O1 type, with narrow interlayer distances, at 4.7 V. The reduced distance between the interlayers in the O1 structure possibly prevents the re-intercalation of Li ions, leading to irreversibility.

Stable photoelectrochemical reactions at solid/solid interfaces toward solar energy conversion and storage

Watanabe, Kenta*; Horisawa, Yuhei*; Yoshimoto, Masataka*; Tamura, Kazuhisa; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*

Nano Letters, 24(6), p.1916 - 1922, 2024/02

https://doi.org/10.1021/acs.nanolett.3c03982

Electrochemistry has extended from reactions at solid/liquid interfaces to those at solid/solid interfaces. In this study, we achieve the stable photoelectrochemical reaction at the semiconductor-electrode/solid-electrolyte interface in Nb-doped anatase-TiO (a-TiO:Nb)/LiPO (LPO)/Li all-solid-state cell. The oxidative currents of a-TiO:Nb/LPO/Li increase upon light irradiation when a-TiO:Nb is located at a potential that is more positive than its flat-band potential. The photoelectrochemical reaction at the semiconductor/solid-electrolyte interface is driven by the same principle as that at semiconductor/liquid-electrolyte interfaces. Thus, we extend photoelectrochemistry to all-solid-state systems composed of solid/solid interfaces.

Reducing the effect of noise generated from stepper motor for H0 collimator in J-PARC RCS

Fujiyama, Hiroki*; Takahashi, Hiroki; Okabe, Kota; Ito, Yuichi*; Hatakeyama, Shuichiro; Suzuki, Takahiro*; Otsu, Satoru*; Yamakawa, Ryuto*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.529 - 531, 2023/01

http://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/WEP0/WEP010.pdf

Stepper motors are used for mechanical drive in collimators and wire scanner monitors of J-PARC accelerators. Many of these drive unit hardware have been used since the beginning of J-PARC construction, and it is necessary to take measures against aging deterioration. Therefore, we started updating the motor and control system from around 2017. However, when the stepper motor was updated to the current product in the RCS H0 collimator, a malfunction occurred. This is because the drive unit control system cannot correctly recognize the state of the LS (limit switch) due to the noise generated by the motor driver, which hinders the operation. When the noise generated from the old and new stepper motors was measured in a simple test environment for confirmation, it was found that the current product was clearly larger. As a countermeasure, when the wiring of the stepper motor, which was bundled in a single multi-core cable, was separated into separate cables for the power system and LS signal system, the noise level was reduced to about 1/10 and normal operation was restored. I was able to. In this case, we report on noise countermeasures for the RCS H0 collimator drive unit.

Response characteristics of a lithium glass scintillator for gamma-ray and neutron

Lee, J.; Ito, Fumiaki*; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Koizumi, Mitsuo; Hori, Junichi*; Terada, Kazushi*

Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2022/11

no abstracts in English

Solidification pressures and ages recorded in mafic microgranular enclaves and their host granite; An Example of the world's youngest Kurobegawa granite

Suzuki, Kota*; Kawakami, Tetsuo*; Sueoka, Shigeru; Yamazaki, Ayu*; Kagami, Saya; Yokoyama, Tatsunori; Tagami, Takahiro*

Island Arc, 31(1), p.e12462_1 - e12462_15, 2022/09

https://doi.org/10.1111/iar.12462

Demonstration of a neutron resonance transmission analysis system using a laser-driven neutron source

Hironaka, Kota; Ito, Fumiaki*; Lee, J.; Koizumi, Mitsuo; Takahashi, Tone; Suzuki, Satoshi*; Yogo, Akifumi*; Arikawa, Yasunobu*; Abe, Yuki*

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

Neutron resonance transmission analysis (NRTA) is a method for non-destructive measurement of nuclear material by using a time-of-flight (TOF) technique with a pulsed neutron source. For NRTA system to carry out the short-distance TOF measurements with high resolutions, a short-pulsed neutron source is required. Laser-driven neutron sources (LDNSs) is very suitable as such a neutron source because of its short pulse width. Moreover, the compactness of the laser system is also expected due to the remarkable development of laser technology in recent years. In the present study, we have developed a technology for applying LDNS to the NRTA system and conducted the demonstration experiment using the LFEX laser at Osaka University to investigate the feasibility of the system. In this experiment, we successfully observed the neutron resonance peaks of indium and silver samples.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Development of measurement and analysis techniques in X-ray photoelectron spectroscopy; From NAP-HARPES to 4D-XPS

Toyoda, Satoshi*; Yamamoto, Tomoki*; Yoshimura, Masashi*; Sumida, Hirosuke*; Mineoi, Susumu*; Machida, Masatake*; Yoshigoe, Akitaka; Suzuki, Satoru*; Yokoyama, Kazushi*; Ohashi, Yuji*; et al.

Vacuum and Surface Science, 64(2), p.86 - 91, 2021/02

https://doi.org/10.1380/vss.64.86

We have developed measurement and analysis techniques in X-ray photoelectron spectroscopy. To begin with, time-division depth profiles of gate stacked film interfaces have been achieved by NAP-HARPES (Near Ambient Pressure Hard X-ray Angle-Resolved Photo Emission Spectroscopy) data. We then have promoted our methods to quickly perform peak fittings and depth profiling from time-division ARPES data, which enables us to realize 4D-XPS analysis. It is found that the traditional maximum entropy method (MEM) combined with Jackknife averaging of sparse modeling in NAP-HARPES data is effective to perform dynamic measurement of depth profiles with high precision.

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

https://doi.org/10.1126/science.aav7432

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.