Introducing GPU backend of BLonD to longitudinal beam simulations for J-PARC synchrotrons

Adachi, Kyosuke; Tamura, Fumihiko; Nomura, Masahiro; Shimada, Taihei; Miyakoshi, Ryosuke*; Okita, Hidefumi; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.

JPS Conference Proceedings (Internet), 45, p.011121_1 - 011121_8, 2026/06

https://journals.jps.jp/doi/10.7566/JPSCP.45.011121

no abstracts in English

Beam dynamics studies of cavity failures for the initial operation phase of the ESS superconducting linac

Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Miyamoto, Ryoichi*; Milas, N.*; Eshraqi, M.*

Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.58 - 62, 2026/04

The European Spallation Source (ESS) superconducting proton linac is currently undergoing commissioning. During the initial operation phase, the final beam energy will be about 800 MeV, reaching a 2 MW power. High reliability and availability are crucial for the success of the ESS science programs and thus operations will be maintained even with failures of main linac components such as cavities and quadrupoles, as long as ~50 percent of the intended power can be achieved. To this end, we developed beam optics strategies to address failures in the cavities of the superconducting linac. Due to the constraints in the RF cavity amplitudes, we implemented a modified version of standard cavity compensation techniques. The results indicated that this strategy enables beam recovery that meets the beam quality specifications, thereby enhancing the availability of the ESS linac.

J-PARC LINAC 50 Hz operation verification study

Kondo, Yasuhiro; Chimura, Motoki; Cicek, E.*; Fukui, Yuji*; Futatsukawa, Kenta*; Fuwa, Yasuhiro; Goto, Rikuto*; Hirano, Koichiro; Ishikawa, Masaki*; Ito, Takashi; et al.

Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.124 - 129, 2026/03

https://www.pasj.jp/web_publish/pasj2025/proceedings/PDF/FRO6/FRO601.pdf

Various upgrade plans of the J-PARC linac are underway, and repetition-rate doubling project is one of the most important part. Currently, the linac supplies a 400~MeV H ion beam to the 3~GeV synchrotron (RCS) at a repetition rate of 25~Hz. However, to deliver the beam to both RCS and proton-beam irradiation facility under planning, it is necessary to raise the repetition rate from 25~Hz to 50~Hz. Prior to construction of the beamline to the irradiation facility, we conducted a verification of the 50~Hz operation of all the linac apparatus simultaneously within the current operational limits in May 2025. And also, the verification of the 50~Hz operation of the particle counter system, which is one of the most important safety device of the J-PARC accelerator, was conducted. As a result, any significant problems were not found out, and it is now ready for the upcoming 50~Hz-beam acceleration demonstration. This paper describes this details of the demonstration of the 50~Hz operation, without beam acceleration, of the J-PARC linac.

Horonobe Underground Research Laboratory Project Investigation report for the 2024 fiscal year

Nakayama, Masashi; Ishii, Eiichi; Aoyagi, Kazuhei; Hayano, Akira; Murakami, Hiroaki; Ono, Hirokazu; Takeda, Masaki; Fukatsu, Yuta; Mochizuki, Akihito; Ozaki, Yusuke; et al.

JAEA-Review 2025-042, 136 Pages, 2025/12

JAEA-Review-2025-042.pdf:12.95MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe-cho in Hokkaido, north Japan. In the fiscal year 2024, we continued R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". These are identified as key R&D on challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near-field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100C" were addressed for "Demonstration of repository design options". The validation of a method for assessing permeability using the Ductility Index and a method for estimating the state of in-situ ground pressure from hydraulic perturbation tests were investigated as part of the study "Understanding of buffering behaviour of sedimentary rock to natural perturbations". In FY2024, we continued construction of the East Access Shaft and the Ventilation Shaft, and construction of these shafts were completed to a depth of 500 m. After the completion of the East Access Shaft, excavation of the West Access Shaft and 500 m gallery has began. As of the end of FY2024, excavation progress is as follows, the East Access Shaft and the Ventilation Shaft were 500 m depth, the West Access Shaft was 472 m depth, 500 m gallery was 112.9 m, respectively. In the Horonobe International Project (HIP), Management Board and Joint Task Meeting was held at the Horonobe URL in June 2024 to review the progress of construction of galleries and preparations of experiments. Task Meetings to review the implementation plan for in-situ testing and analysis were also held. HIP will be implemented in two phases: Phase 1 (from FY2022 to FY2024) and Phase 2 (from FY2025 to FY2028), the research results of Phase 1 were compiled in FY2024.

Phase space measurements of 90 mA and 52.5 keV H ion beam at J-PARC frontend

Shibata, Takanori*; Nammo, Kesao*; Shinto, Katsuhiro; Okoshi, Kiyonori; Kawai, Isao*; Kitamura, Ryo; Morishita, Takatoshi; Kondo, Yasuhiro; Sato, Yoichi*

Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.514 - 516, 2025/11

https://doi.org/10.18429/JACoW-IPAC2025-MOPM082

no abstracts in English

Horonobe Underground Research Laboratory Project; Investigation program for the fiscal year 2025

Nakayama, Masashi; Ishii, Eiichi; Hayano, Akira; Aoyagi, Kazuhei; Murakami, Hiroaki; Ono, Hirokazu; Takeda, Masaki; Mochizuki, Akihito; Ozaki, Yusuke; Kimura, Shun; et al.

JAEA-Review 2025-027, 80 Pages, 2025/09

JAEA-Review-2025-027.pdf:6.22MB

The Horonobe Underground Research Laboratory Project is being pursued by the Japan Atomic Energy Agency to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2025, we continue R&D on "Study on near-field system performance in geological environment" and "Demonstration of repository design options". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", we continue to obtain data from the full-scale engineered barrier system performance experiment, and work on the specifics of the full-scale engineered barrier system dismantling experiment. As for "Demonstration of repository design options", the investigation, design, and evaluation techniques are to be systemized at various scales, from the tunnel to the pit, by means of an organized set of evaluation methodologies for confinement performance at these respective scales. Preliminary borehole investigations will be conducted within a 500 m gallery, with the objectives of obtaining rock strength and rock permeability data, as well as surveying the extent of the excavation damaged zone surrounding the test tunnel via tomographic analysis. A planning study for the in-situ construction test will be conducted to investigate the construction of backfill material and watertight plugs. The volume of water inflow associated with the excavation of the 500 m gallery will be observed, and its magnitude will be compared with the range of water inflow predicted in the analysis. The test plan to determine the extent of the excavation damaged zone around the pit, which is planned to be constructed in the 500 m gallery, will be studied to determine the in-situ excavation damaged zone. In addition, the investigation and evaluation methods for the amount of water inflow from fractures and the extent of the excavation damaged zone around the pit will be organized. Concerning the construction and maintenance of the subsurface facilities, excavation of the West Access Shaft and the 500 m gallery will continue. It is anticipated that the construction of the facilities will be completed by the end of the fiscal year 2025. In addition, we continue R&D on the following three tasks in the Horonobe International Project; Task A: Solute transport experiment with model testing, Task B: Systematic integration of repository technology options, and Task C: Full-scale engineered barrier system dismantling experiment.

A New concept of Mu- conversion search

Kawamura, Naritoshi; Kitamura, Ryo; Kanda, Sotaro*; Matoba, Shiro*; Mibe, Tsutomu*; Fukuyama, Takeshi*; Mimura, Yukihiro*; Uesaka, Yuichi*

Proceedings of Science (Internet), 480, p.074_1 - 074_6, 2025/07

https://doi.org/10.22323/1.480.0074

Benchmarking GPU backend of longitudinal simulation code BLonD

Adachi, Kyosuke; Tamura, Fumihiko; Nomura, Masahiro; Shimada, Taihei; Miyakoshi, Ryosuke*; Okita, Hidefumi; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.543 - 546, 2024/10

https://www.pasj.jp/web_publish/pasj2024/proceedings/PDF/THP0/THP003.pdf

no abstracts in English

Applying a deep generative model to mountain plot images

Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Okita, Hidefumi; Miyakoshi, Ryosuke*; Seiya, Kiyomi*; Yoshii, Masahito*; Omori, Chihiro*; Hara, Keigo*; Hasegawa, Katsushi*; et al.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.85 - 88, 2024/10

https://www.pasj.jp/web_publish/pasj2024/proceedings/PDF/THOT/THOT02.pdf

no abstracts in English

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.