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Journal Articles

Positron annihilation study of tungsten exposed to low-energy deuterium plasma

Hirade, Tetsuya; Furuta, Hikaru*; Torikai, Yuji*; Fujimura, Yuki; Michishio, Koji*

JJAP Conference Proceedings (Internet), 9, p.011106_1 - 011106_7, 2023/00

Positron annihilation lifetime (PAL) measurements by use of a positron source of $$^{22}$$Na were performed for polycrystalline ITER-grade tungsten samples exposed to low-energy deuterium plasma. The energy of deuterium plasma was low and then it was expected that it would affect just near-surface region. However, we obtained the longer mean positron annihilation lifetime in the tungsten samples exposed to the low-energy deuterium plasma than the virgin tungsten samples. Moreover, almost same longer values were obtained even on the other (no exposed) side of the samples, although the thickness of the samples were about 2 mm. Although, there has been no report of observation of defect formation by existence of hydrogen or deuterium in tungsten, the results indicated that deuterium existence in tungsten can be one of reasons of defects formation.

Journal Articles

Spatial distribution and preferred orientation of crystalline microstructure of lead-bismuth eutectic

Ito, Daisuke*; Sato, Hirotaka*; Odaira, Naoya*; Saito, Yasushi*; Parker, J. D.*; Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi

Journal of Nuclear Materials, 569, p.153921_1 - 153921_6, 2022/10

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

Journal Articles

Observation of topological Hall torque exerted on a domain wall in the ferromagnetic oxide SrRuO$$_3$$

Yamanouchi, Michihiko*; Araki, Yasufumi; Sakai, Takaki*; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi

Science Advances (Internet), 8(15), p.eabl6192_1 - eabl6192_6, 2022/04

 Times Cited Count:2 Percentile:79.1(Multidisciplinary Sciences)

In a ferromagnetic Weyl metal SrRuO$$_3$$, a large effective magnetic field $$H_mathrm{eff}$$ exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of $$H_mathrm{eff}$$ to current density exhibits nonmonotonic temperature dependence and surpasses those of conventional spin-transfer torques and spin-orbit torques. This enhancement is described well by topological Hall torque (THT), which is exerted on a DW by Weyl electrons emerging around Weyl points when an electric field is applied across the DW. The ratio of the $$H_mathrm{eff}$$ arising from the THT to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques reported in metallic systems, showing that the THT may provide a better way for energy-efficient manipulation of magnetization in spintronics devices.

Journal Articles

Investigation of radioactive samples for neutron capture reaction measurements using energy-resolved neutron imaging

Segawa, Mariko; Toh, Yosuke; Kai, Tetsuya; Kimura, Atsushi; Nakamura, Shoji

Annals of Nuclear Energy, 167, p.108828_1 - 108828_5, 2022/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

A Multi-technique tomography-based approach for non-invasive characterization of additive manufacturing components in view of vacuum/UHV applications; Preliminary results

Grazzi, F.*; Cialdai, C.*; Manetti, M.*; Massi, M.*; Morigi, M. P.*; Bettuzzi, M.*; Brancaccio, R.*; Albertin, F.*; Shinohara, Takenao; Kai, Tetsuya; et al.

Rendiconti Lincei. Scienze Fisiche e Naturali, 32(3), p.463 - 477, 2021/09

 Times Cited Count:1 Percentile:13.6(Multidisciplinary Sciences)

Journal Articles

Observation of Eu adsorption band in the CMPO/SiO$$_{2}$$-P column by neutron resonance absorption imaging

Miyazaki, Yasunori; Watanabe, So; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori; Kai, Tetsuya; Parker, J. D.*

JPS Conference Proceedings (Internet), 33, p.011073_1 - 011073_7, 2021/03

Neutron resonance absorption imaging was adapted to observe the Eu band adsorbed in the CMPO/SiO$$_{2}$$-P column for minor actinide recovery by extraction chromatography. Several wet columns were prepared by either light water or heavy water and compared with the dry column to evaluate the neutron transmission. The neutron transmission spectra showed that 45% was transmitted through the dry column while 20% and 40% were transmitted through the wet columns of light water and heavy water, respectively. The results indicated that heavy water is more applicable than light water to observe the Eu adsorption band in the CMPO/SiO$$_{2}$$-P column.

Journal Articles

Microstructure distribution of Japanese sword cross sections analyzed by the diffractometer TAKUMI at J-PARC

Oikawa, Kenichi; Harjo, S.; Pham, A. H.*; Kawasaki, Takuro; Morito, Shigekazu*; Kiyanagi, Yoshiaki*; Shinohara, Takenao; Kai, Tetsuya; Oba, Takuya*; Ito, Masakazu*

JPS Conference Proceedings (Internet), 33, p.011062_1 - 011062_6, 2021/03

Journal Articles

Visualization of the boron distribution in core material melting and relocation specimen by neutron energy resolving method

Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken

JPS Conference Proceedings (Internet), 33, p.011075_1 - 011075_6, 2021/03

Journal Articles

Feasibility study of PGAA for boride identification in simulated melted core materials

Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.

JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03

In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).

Journal Articles

Behavior of tritium release from a stainless vessel of the mercury target as a spallation neutron source

Kasugai, Yoshimi; Sato, Koichi; Takahashi, Kazutoshi*; Miyamoto, Yukihiro; Kai, Tetsuya; Harada, Masahide; Haga, Katsuhiro; Takada, Hiroshi

JPS Conference Proceedings (Internet), 33, p.011144_1 - 011144_6, 2021/03

A spallation neutron source with a mercury target has been in operation at the Materials and Life Science Experimental Facility of J-PARC since 2008. The target vessel made of stainless steel is required to be exchanged periodically due to radiation damage etc. In this presentation, tritium gas release observed in the first series of exchange work in 2011 and the analytical results will be shown.

Journal Articles

Upgrade history and present status of the general control system for the Materials and Life Science Experimental Facility at J-PARC

Sakai, Kenji; Oi, Motoki; Haga, Katsuhiro; Kai, Tetsuya; Nakatani, Takeshi; Kobayashi, Yasuo*; Watanabe, Akihiko*

JPS Conference Proceedings (Internet), 33, p.011151_1 - 011151_6, 2021/03

For safely and efficiently operating a spallation neutron source and a muon target, a general control system (GCS) operates within Materials and Life Science Experimental Facility (MLF), GCS administers operation processes and interlocks of many instruments for various operation statuses. It consists of several subsystems such as an integral control system (ICS), interlock systems (ILS), shared servers, network system, and timing distribution system (TDS). Although GCS is an independent system that controls the target stations, it works closely with the control systems of other facilities in J-PARC. Since the first beam injection in 2008, GCS has operated stably without any serious troubles after modification based on commissioning for operation and control. Then, significant improvements in GCS such as upgrade of ICS by changing its framework software and function enhancement of ILS were proceeded until 2015, in considering sustainable long-term operation and maintenance. In recent years, many instruments in GCS have replaced due to end of production and support of them. In this way, many modifications have been proceeded in the entire GCS after start of beam operation. Under these situation, it is important to comprehend upgrade history and present status of GCS in order to decide its upgrade plan for the coming ten years. This report will mention upgrade history, present status and future agenda of GCS.

Journal Articles

Study of neutron-nuclear spin correlation term with a polarized Xe target

Sakai, Kenji; Oku, Takayuki; Okudaira, Takuya; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Hayashida, Hirotoshi*; Kakurai, Kazuhisa*; Shimizu, Hirohiko*; Hirota, Katsuya*; et al.

JPS Conference Proceedings (Internet), 33, p.011116_1 - 011116_6, 2021/03

In neutron fundamental physics, study of correlation term $${bf s}cdot{bf I}$$ of a neutron spin $${bf s}$$ and a target nuclear spin $${bf I}$$ is important because $${bf s}cdot{bf I}$$ term interferes to parity non-conserving (PNC) and time reversal non-conserving terms. For this study, a xenon (Xe) is an interesting nucleus because it has been observed an enhancement of PNC effect around neutron resonance peaks, and polarizes up to $$ sim 10^{-1}$$ by using a spin exchange optical pumping (SEOP) method. We would plan to develop a polarized Xe gas target with a compact in-situ SEOP system, and to study $${bf s}cdot{bf I}$$ term by utilizing epithermal neutron beams supplied from a high intense pulsed spallation neutron source. As the first step, we attempted to measure neutron polarizing ability caused by $${bf s}cdot{bf I}$$ term at a 9.6 eV s-wave resonance peak of $$^{129}$$Xe at BL10 in MLF, by detecting change $$Delta R$$ of ratio between neutron transmissions with the polarized and unpolarized Xe target. After demonstrating that our apparatus could detect small change ($$Delta R_{rm DB} , {approx},10^{-2}$$) of neutron transmissions caused by Doppler broadening effect, a signified value of $$Delta R$$ has been obtained as preliminary results. For analyzing the obtained $$Delta R$$ in detail, we are improving our nuclear magnetic resonance and electron paramagnetic resonance systems for evaluating Xe polarization independently of neutron beams.

Journal Articles

Measurement of Doppler broadening of prompt gamma-rays from various zirconium- and ferro-borons

Tsuchikawa, Yusuke; Kai, Tetsuya; Abe, Yuta; Oishi, Yuji*; Sun, Y.*; Oikawa, Kenichi; Nakatani, Takeshi; Sato, Ikken

Nuclear Instruments and Methods in Physics Research A, 991, p.164964_1 - 164964_5, 2021/03

 Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)

Peak shape analysis was performed for the energy spectra of Doppler-broadened prompt $$gamma$$-rays generated by neutron capture reactions with various boride or boron samples. Significant differences were observed between nonmetallic and metallic borides. Minor differences between the peak shapes of prompt $$gamma$$-rays from zirconium- and ferro-borons were evaluated by a peak fitting method. The identification of zirconium- and ferro-borons and other types of borides was estimated.

Journal Articles

Neutron Bragg-edge transmission imaging for microstructure and residual strain in induction hardened gears

Su, Y. H.; Oikawa, Kenichi; Shinohara, Takenao; Kai, Tetsuya; Horino, Takashi*; Idohara, Osamu*; Misaka, Yoshitaka*; Tomota, Yo*

Scientific Reports (Internet), 11, p.4155_1 - 4155_14, 2021/02

 Times Cited Count:9 Percentile:77.48(Multidisciplinary Sciences)

Journal Articles

Development of three-dimensional distribution visualization technology for boron using energy resolved neutron-imaging system (RADEN)

Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

Journal Articles

Development of event-type neutron imaging detectors at the energy-resolved neutron imaging system RADEN at J-PARC

Parker, J. D.*; Harada, Masahide; Hayashida, Hirotoshi*; Hiroi, Kosuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Nakatani, Takeshi; Oikawa, Kenichi; Segawa, Mariko; Shinohara, Takenao; et al.

Materials Research Proceedings, Vol.15, p.102 - 107, 2020/05

Journal Articles

The Energy-resolved neutron imaging system, RADEN

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Nakatani, Takeshi; Segawa, Mariko; Hiroi, Kosuke; Su, Y. H.; Oi, Motoki; Harada, Masahide; Iikura, Hiroshi; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

 Times Cited Count:33 Percentile:95.93(Instruments & Instrumentation)

Journal Articles

Applications of the energy-resolved neutron imaging system, RADEN

Kai, Tetsuya; Shinohara, Takenao; Matsumoto, Yoshihiro*

Kensa Gijutsu, 25(2), p.1 - 5, 2020/02

no abstracts in English

Journal Articles

Pulsed neutron imaging based crystallographic structure study of a Japanese sword made by Sukemasa in the Muromachi period

Oikawa, Kenichi; Kiyanagi, Yoshiaki*; Sato, Hirotaka*; Omae, Kazuma*; Pham, A.*; Watanabe, Kenichi*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Kai, Tetsuya; Harjo, S.; et al.

Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02

Journal Articles

Feasibility study of two-dimensional neutron-resonance thermometry using molybdenum in 316 stainless-steel

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

Materials Research Proceedings, Vol.15, p.149 - 153, 2020/02

414 (Records 1-20 displayed on this page)