Lyotropic polymer liquid crystal coating; Enabling lamellar ion-conduction pathways for superior C-Rate performance in NCM523 cathodes

Marium, M.*; Aoki, Kentaro*; He, Y.*; Yamamoto, Katsuhiro*; Suwansoontorn, A.*; Ikuta, Seiya*; Hara, Mitsuo*; Nagano, Shusaku*; Nagao, Yuki*; Nishikawa, Kei*; et al.

ACS Applied Energy Materials (Internet), 8(22), p.16589 - 16600, 2025/11

https://doi.org/10.1021/acsaem.5c02323

Development of the beam separation test device to evaluate the electric field of non-destructive electrostatic septum

Nagayama, Shota; Kinsho, Michikazu; Harada, Hiroyuki; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Shimogawa, Tetsushi*; Sato, Atsushi*

Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1025 - 1028, 2025/11

https://doi.org/10.18429/JACoW-IPAC2025-TUPB028

Slow extraction method of synchrotrons is used in nuclear and particle physics experiments, radiation therapy, and many other applications. In the slow extraction process, beam loss at the septum electrode, which separates the extracted beam from the circumferential side, induces activation and damage to the device. To solve this problem, we have devised an electric field measurement device named "Beam separation test device" to evaluate the two-dimensional electric field distribution of the nondestructive electrostatic septum that we are developing. The device consists of a prototype septum, horizontal and vertical wire scanners, and an electron gun installed on a movable stage fixed to a drive unit. This device measures the electric field by injecting an electron beam into the electric field and measuring the bending angle of the beam orbit. In developing this device, an additional optics system was designed to make a narrow electron beam to improve the measurement accuracy of the electric field distribution. In addition, we designed a beam dump that reduces secondary electron emission by utilizing energy loss when particles collide with materials. According to calculations of secondary electron emission, this beam dump can reduce secondary-emission into the chamber by up to 98%.

State-of-the-art beam loss minimization at high-intensity beam operation of the 3 GeV rapid cycling synchrotron at the Japan Proton Accelerator Research Complex

Saha, P. K.; Harada, Hiroyuki; Tamura, Fumihiko; Okabe, Kota; Yoshimoto, Masahiro; Shobuda, Yoshihiro; Okita, Hidefumi; Kojima, Kunihiro; Nakanoya, Takamitsu; Hatakeyama, Shuichiro; et al.

Physical Review Accelerators and Beams (Internet), 28(7), p.074201_1 - 074201_23, 2025/07

https://doi.org/10.1103/tbyh-jcq3

Transverse asymmetry of individual rays in the La()La reaction

Okuizumi, Mao*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.

Physical Review C, 111(3), p.034611_1 - 034611_6, 2025/03

https://doi.org/10.1103/PhysRevC.111.034611

Adsorption isotherm and kinetics of diffusion of water accumulated between polypropylene thin film and Si substrate; Neutron reflectivity investigation

Miyazaki, Tsukasa*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Takenaka, Mikihito*; Nakanishi, Yohei*; Shibata, Motoki*; Aoki, Hiroyuki; Yamada, Norifumi*; et al.

Colloids and Surfaces A; Physicochemical and Engineering Aspects, 701, p.134928_1 - 134928_8, 2024/11

https://doi.org/10.1016/j.colsurfa.2024.134928

Neutron reflectivity study on the adsorption layer of polyethylene grown on Si substrate

Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Shibata, Motoki*; Nakanishi, Yohei*; Arakawa, Masato*; Takenaka, Mikihito*; Kida, Takumitsu*; Tokumitsu, Katsuhisa*; Tanaka, Ryo*; et al.

Langmuir, 40(30), p.15758 - 15766, 2024/07

https://doi.org/10.1021/acs.langmuir.4c01584

Reduction of accident occurrence frequencies by taking safety measures for defense-in-depth level 4 in a sodium-cooled fast reactor

Nishino, Hiroyuki; Kurisaka, Kenichi; Naruto, Kenichi*; Gondai, Yoji; Yamamoto, Masaya

Mechanical Engineering Journal (Internet), 11(2), p.23-00409_1 - 23-00409_15, 2024/04

https://doi.org/10.1299/mej.23-00409

The effectiveness evaluation of safety measures against severe accident is necessary for restart of experimental sodium-cooled fast reactor Joyo in Japan. These safety measures correspond to those in defense-in-depth (DiD) level 4. In the previous study, a level-1 probabilistic risk assessment (PRA) at power was performed to calculate frequencies of the accident sequences of failure of safety measures in DiD level 1 to 3, to identify dominant accident sequence groups, and to identify dominant accident sequence for selecting important accident sequences in each accident sequence group which are needed for implementing the effectiveness evaluation of safety measures in DiD level 4. Based on this, the present study implemented level-1 PRA at power to show quantitatively reduction of those occurrence frequency by the safety measure in the DiD level 4. As the result, the frequency of each accident sequence group decreased significantly, and total frequency of the accident sequence groups decreased to about 1E-6 /reactor-year which is about 1/1000 times the one estimated in the previous study. The protected loss of heat sink was the largest contributor in all the accident groups and a dominant accident sequence in each accident group was also identified in this study.

Beam separation experiment with prototype non-destructive electrostatic septum and study for device improvement

Nagayama, Shota; Harada, Hiroyuki; Shimogawa, Tetsushi*; Sato, Atsushi*; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.526 - 530, 2023/11

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/WEP1/WEP19.pdf

We have been developing "Non-destructive electrostatic septum" for a slow extraction. This septum has multiple electrodes placed around the region without the beam hitting and separate the beam by its electric field. To evaluate its electric field, we have built a prototype septum and a test machine, which consists of an electron gun and monitors. This test machine can measure the electric field indirectly by using a narrow electron beam. The experiment results of prototype septum is good agreement with the calculation one. However, this electric field distribution is not enough to separate the beam. A step function-like electric field distribution is ideal for the beam separation with minimal negative effect on the beam. We have studied to improve the electrode configuration to match the beam shape. In this paper, we present the result of the electric field measurements and the septum improvement. Additionally, we describe the future plan of this development.

1-MW beam operation at J-PARC RCS with minimum beam loss

Saha, P. K.; Harada, Hiroyuki; Okabe, Kota; Okita, Hidefumi; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yoshimoto, Masahiro; Hotchi, Hideaki*

Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.147 - 152, 2023/10

https://doi.org/10.18429/JACoW-HB2023-TUA4I2

Demonstration of a kicker impedance reduction scheme with diode stack and resistors by operating the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Shobuda, Yoshihiro; Harada, Hiroyuki; Saha, P. K.; Takayanagi, Tomohiro; Tamura, Fumihiko; Togashi, Tomohito; Watanabe, Yasuhiro; Yamamoto, Kazami; Yamamoto, Masanobu

Physical Review Accelerators and Beams (Internet), 26(5), p.053501_1 - 053501_45, 2023/05

https://doi.org/10.1103/PhysRevAccelBeams.26.053501

At the Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC), theoretical predictions have indicated that the kicker-impedance would excite the beam-instability. A 1 MW beam with large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) through suppression of the beam instabilities by choosing the appropriate machine parameters. However, we require other high-intensity and high-quality smaller emittance beams (than the 1 MW beam) for the Main Ring (MR). Hence, we proposed a scheme for suppressing the kicker-impedance by using prototype diodes and resistors, thereby demonstrating the effect on the kicker impedance reduction. However, the J-PARC RCS must be operated with a repetition rate of 25 Hz, which urged us to consider special diodes that are tolerant to heating. After developments, we have demonstrated that the special diodes with resistors can suppress the beam instability by reducing the kicker impedance. Enhanced durability of the prototype diodes and resistors for the 25 Hz operation was also realized. Moreover, the new diodes and the resistors have negligible effect on the extracted beam from the RCS. From a simulation point of view, the scheme can be employed for at least 5 MW beam operation within the stipulated specifications.