Kofu, Maiko; Yamamuro, Osamu*
Journal of the Physical Society of Japan, 89(5), p.051002_1 - 051002_12, 2020/05
The behavior of hydrogen in metals has attracted much attention in fundamental and applied research areas for many decades. Among metals, palladium is remarkable in that it can absorb large quantities of hydrogen, and hydrogen atoms are highly mobile in the fcc Pd lattice. The dynamics of hydrogen in Pd have been investigated by means of neutron spectroscopy which is the best tool to provide insights into microscopic dynamics of hydrogen atoms. In this article, we review recent and historical neutron scattering works to facilitate the latest understanding of the hydrogen dynamics in bulk and nanometer-sized Pd hydrides.
Kawasaki, Ikuto; Kobata, Masaaki; Fujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Nakamura, Ai*; Iha, Wataru*; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*
Journal of the Physical Society of Japan, 89(4), p.044704_1 - 044704_6, 2020/04
Nakamura, Masahiko; Kutsukake, Kenichi; Matsuda, Makoto
JAEA-Technology 2019-022, 20 Pages, 2020/03
The JAEA Tokai tandem accelerator (an electrostatic accelerator) has the advantage that it can accelerate an ion beam with proportional energy to its acceleration voltage. Therefore the control of an ion beam energy can be automated when the control of the acceleration voltage can be automated by using the scaling operation system: an electromagnetics proportion of optical device parameters, and the ganged control system: a synchronized controlling related devices in the JAEA Tokai Tandem accelerator control system. We should improve several devices to achieve the automatic control of the accelerator voltage. Especially, the positioning system of the corona probe which adjusts the acceleration voltage had to be automated. However the original corona probe was difficult to be applied to the automation by its poor control system and low positioning precision. We have developed the new corona probe which improved defects of the original one. The new corona probe has an automatic and high precision positioning system and enhanced maintainability by new control system, new driven system and new position detection system. We describe about the development of the new corona probe in detail.
Kirihara, Yoichi; Nakashima, Hiroshi; Sanami, Toshiya*; Namito, Yoshihito*; Itoga, Toshiro*; Miyamoto, Shuji*; Takemoto, Akinori*; Yamaguchi, Masashi*; Asano, Yoshihiro*
Journal of Nuclear Science and Technology, 57(3-4), p.444 - 456, 2020/03
no abstracts in English
Ito, Keita*; Yasutomi, Yoko*; Zhu, S.*; Nurmamat, M.*; Tahara, Masaki*; Toko, Kaoru*; Akiyama, Ryota*; Takeda, Yukiharu; Saito, Yuji; Oguchi, Tamio*; et al.
Physical Review B, 101(10), p.104401_1 - 104401_8, 2020/03
Takahashi, Osamu*; Shibui, Yohei*; Xu, P. G.; Harjo, S.; Suzuki, Tetsuya*; Tomota, Yo*
Quantum Beam Science (Internet), 4(1), p.16_1 - 16_15, 2020/03
Yamashita, Takayuki; Morooka, Satoshi; Harjo, S.; Kawasaki, Takuro; Koga, Norimitsu*; Umezawa, Osamu*
Scripta Materialia, 177, p.6 - 10, 2020/03
Safety Division, J-PARC Center
JAEA-Review 2019-043, 147 Pages, 2020/02
This annual report describes the activities on radiation safety and general safety in Japan Proton Accelerator Research Complex (J-PARC) in FY 2018. Activities on radiation safety such as radiation control in each facility, environmental monitoring, individual monitoring, maintenance of monitoring instruments and other activities on radiation matters are represented, and activities of general safety such as safety committees, meetings, lectures, trainings and periodical checks are described. In addition, activities on promotion of safety culture and the technological developments and research on safety issues are also summarized in each separate section.
Zhang, Z,*; Wang, H.*; Yoshikawa, Hirofumi*; Matsumura, Daiju; Hatao, Shuya*; Ishikawa, Satoshi*; Ueda, Wataru*
ACS Applied Materials & Interfaces, 12(5), p.6056 - 6063, 2020/02
Yoshimoto, Masahiro; Yamazaki, Yoshio; Nakanoya, Takamitsu; Saha, P. K.; Kinsho, Michikazu
EPJ Web of Conferences (Internet), 229, p.01001_1 - 01001_7, 2020/02
In the 3-GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted thick Hybrid type Boron-doped Carbon (HBC) stripper foil for the multi-turn H charge-exchange injection. The HBC stripper foil developed at KEK has been successfully demonstrated to improve the foil lifetime significantly. Early manufacturing process of the stripper foil in the J-PARC had been carried out in following two steps: foil fabrication in KEK Tsukuba-site and foil preparation in JAEA Tokai-site. However, to proceed with the foil manufacturing in a same place efficiently, the carbon discharge arc-evaporation system for HBC stripper foil was removed from the Tsukuba-site and relocated in the Tokai-site. After reassembling of the carbon discharge arc-evaporation system, performance evaluation tests of new HBC foil which are produced at the JAEA Tokai site (J-HBC) are implemented at the TIARA facility of QST-Takasaki. As results of argon beam irradiation for lifetime evaluation, components analysis with RBS method, and impurity evaluation with micro-PIXE method, we can verify that the J-HBC foil performs pretty much equally to the original HBC foil. After the irradiation test by using 400MeV H beam in the J-PARC RCS, user operation by using the J-HBC foil was successfully demonstrated for 10 days.
Hamon, 30(1), p.45 - 50, 2020/02
no abstracts in English
Sugiyama, Masaaki*; Inoue, Rintaro*; Nakagawa, Hiroshi; Saio, Tomohide*
Hamon, 30(1), p.16 - 25, 2020/02
Neutron has distinct features as a scattering probe to analyze structure and dynamics of biological macromolecules. The theme of this review is to try to describe how we did/do utilize them. And "How we should utilize them more effectively in the trend of integrative structural biology?" with solution scattering.
Hamon, 30(1), p.7 - 8, 2020/02
Safety review of JRR-3 under the New Regulatory Requirements was completed on 7th November 2018. Neutron beam will come back in early 2021 after reinforcement works of the roof of the reactor building, the peripheral structures like a stack, a cooling tower, and the experimental hall. The future of neutron sciences using the research reactor strongly depends on how many impacted researches using JRR-3 are achieved after restarting JRR-3. At this stage, we can learn a lot of things from the back numbers of HAMON.
Naoe, Takashi; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Wakui, Takashi; Wakai, Eiichi; Haga, Katsuhiro; Takada, Hiroshi
JPS Conference Proceedings (Internet), 28, p.081004_1 - 081004_6, 2020/02
The beam window of the mercury target vessel in J-PARC is severely damaged by the cavitation. The cavitation damage is a crucial factor to limit lifetime of the target because it increases with the beam power. Therefore, mitigating cavitation damage is an important issue to operate the target stably for long time at 1 MW. At J-PARC, to mitigate the cavitation damage: gas microbubbles are injected into mercury for suppressing pressure waves, and double-walled structure with a narrow channel of 2 mm in width to form high-speed mercury flow (4m/s) has been adopted. After operation, the beam window was cut to inspect the effect of the cavitation damage mitigation on inner wall. We optimized cutting conditions through the cold cutting tests, succeeding in cutting the target No.2 (without damage mitigation technologies) smoothly in 2017, and target No.8 with damage mitigation technologies. In the workshop, progress of cavitation damage observation for the target vessel will be presented.
Naoe, Takashi; Harjo, S.; Kawasaki, Takuro; Xiong, Z.*; Futakawa, Masatoshi
JPS Conference Proceedings (Internet), 28, p.061009_1 - 061009_6, 2020/02
At the J-PARC, a mercury target vessel made of 316L SS suffers proton and neutron radiation environment. The target vessel also suffers cyclic impact stress caused by the proton beam-induced pressure waves. The vessel suffers higher than 4.510 cyclic loading during the expected service life of 5000 h. We have investigated fatigue strength 316L SS up to gigacycle in the previous studies. The cyclic hardening and softening behavior were observed. In this study, to evaluate the cyclic hardening/softening behavior, the dislocation densities of specimens were measured using the neutron diffraction method at the MLF BL-19. The result showed that the dislocation density of a 316L SS was increased with increasing the number of loading cycles. By contrast, in the case of cold-rolled 316L SS, annihilation and re-accumulation of dislocation by cyclic loading were observed. In the workshop, result of neutron diffraction measurement will be introduced with the progress of fatigue test.
Takada, Hiroshi; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 28, p.081003_1 - 081003_7, 2020/02
At the Japan Proton Accelerator Research Complex (J-PARC), the pulsed spallation neutron source has been in operation with a redesigned mercury target vessel from October 2017 to July 2018, during which the operational beam power was restored to 500 kW and the operation with a 1-MW equivalent beam was demonstrated for one hour. The target vessel includes a gas-micro-bubbles injector and a 2-mm-wide narrow mercury flow channel at the front end as measures to suppress the cavitation damage. After the operating period, it was observed that the cavitation damage at the 3-mm-thick front end of the target vessel could be suppressed less than 17.5 m.
Wakui, Takashi; Wakai, Eiichi; Kogawa, Hiroyuki; Naoe, Takashi; Hanano, Kohei; Haga, Katsuhiro; Takada, Hiroshi; Shimada, Tsubasa*; Kanomata, Kenichi*
JPS Conference Proceedings (Internet), 28, p.081002_1 - 081002_6, 2020/02
A mercury target vessel of J-PRAC is designed with a triple-walled structure consisting of the mercury vessel and a double-walled water shroud with internal and external vessels. During the beam operation at 500 kW in 2015, small water leakages from a water shroud of the mercury target vessel occurred twice. Design, fabrication and inspection processes were improved based on the lessons learned from the target failures. The total length of welding lines at the front of the mercury target vessel decreases drastically to approximately 55% by adopting monolithic structure cut out from a block of stainless steel by the wire-electrical discharge machining. Thorough testing of welds by radiographic testing and ultrasonic testing was conducted. The fabrication of the mercury target vessel #8 was finished on September 2017 and the beam operation using it started. Stable beam operation at 500 kW has been achieved and it could experience the maximum beam power of 1 MW during a beam test.
Metoki, Naoto; Aoki, Dai*; Griveau, J.-C.*; Otsuki, Junya*
Journal of the Physical Society of Japan, 89(2), p.024707_1 - 024707_6, 2020/02
The pseudo triplet ground state in the heavy-fermion superconductor NpPdAl was concluded. The magnetic susceptibility can be reproduced by the singlet ground state with the main component of and the first excited doublet dominated by at ,K. The magnetization curve can be explained from the effective local hamiltonian for pseudo spin =1 with () equivalent to the quadrupole operator . The specific heat can be described with the Kondo model normalized to give the entropy R, corresponding to the pseudo triplet state. The derived Kondo temperature ,K comparable to the level splitting ,K indicates the contribution of the excited doublet to the possible multi-channel Kondo effect.
Nomura, Takuji*; Yamamoto, Yuji*; Yoshii, Kenji
Journal of the Physical Society of Japan, 89(2), p.024704_1 - 024704_10, 2020/02
We report a mean-field theoretical study of a triangular magnet NiGaS. Using the localized Wannier functions obtained from a band calculation, the most stable magnetic state was found to be spiral with the incommensurate structure, consistent with the result from neutron diffraction. The Ni-site Coulomb interaction was not strong (U about 2 eV). The spin value at the Ni site was also not so large about 1.1 mb. These results mean that the hybridization between Ni and S may play an important role. The dynamical spin correlation function was found to in accord with the results from neutron scattering.
Journal of the Physical Society of Japan, 89(2), p.025001_1 - 025001_2, 2020/02
Good correspondence of the and - coupling scheme can be realized in the -electron states of the heavy-fermion superconductor NpPdAl and the isostructural family. The rare-earth and actinide elements are under a common strong uniaxial point charge potential with tetragonal point symmetry . The systematic development of the -electron states can be understood in the coupling scheme of configuration (the number of electrons ). We can find the corresponding states in - coupling scheme with three -orbitals , and determined from CePdAl with configuration.