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Takei, Hayanori
Journal of Nuclear Science and Technology, 45 Pages, 2025/06
The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system combines a subcritical nuclear reactor with a high-power superconducting proton linear accelerator (JADS-linac). One of the factors limiting the advancement of the JADS-linac is beam trips, which often induce thermal cycle fatigue, thereby damaging the components in the subcritical core. The average beam current of the JADS-linac is 32 times higher than that of the linear accelerator (linac) of the Japan Proton Accelerator Research Complex (J-PARC). Therefore, according to the development stage, comparing the beam trip frequency of the JADS-linac with the allowable beam trip frequency (ABTF) is necessary. Herein the beam trip frequency of the JADS-linac was estimated through a Monte Carlo program using the reliability functions based on the operational data of the J-PARC linac. The Monte Carlo program afforded the distribution of the beam trip duration, which cannot be obtained using traditional analytical methods. Results show that the frequency of the beam trips with a duration exceeding 5 min must be reduced to 27% of the current J-PARC linac level to be below the ABTF.
Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio
JAEA-Technology 2024-026, 123 Pages, 2025/03
JAEA-Technology-2024-026.pdf:14.22MB
Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.
Iwai, Takeo*; Tokanai, Fuyuki*; Soda, Hikaru*; Harada, Hiroyuki
Kasokuki, 21(4), p.381 - 386, 2025/01
no abstracts in English
Kamiya, Junichiro; Morohashi, Yuko
Kurin Tekunoroji, 35(1), p.39 - 42, 2025/01
no abstracts in English
Kojima, Kunihiro; Harada, Hiroyuki; Tamura, Fumihiko; Okita, Hidefumi; Chimura, Motoki; Saha, P. K.
Progress of Theoretical and Experimental Physics (Internet), 2025(1), p.013G01_1 - 013G01_19, 2025/01
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)A comprehensive study on the random resonances was conducted to mitigate beam losses and ensure sufficient tunability of the operating point for further beam power ramp-up in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex. Low-intensity beam studies revealed considerable excitation of the half-integer random resonance. This half-integer random resonance was successfully compensated using trim quadrupole magnets without exciting other higher-order resonances. By implementing a conventional theoretical procedure based on resonance driving terms, we identified the leakage field from extraction magnets as the primary source of the error field driving the random resonance. High-intensity beam studies confirmed that our resonance compensation approach substantially mitigated beam loss in higher-tune regions, making it highly effective in improving operating point tunability.
Yamada, Ippei; Kamiya, Junichiro
Review of Scientific Instruments, 95(12), p.123308_1 - 123308_11, 2024/12
Times Cited Count：1 Percentile：39.80(Instruments & Instrumentation)A gas-sheet beam profile monitor enabling non-destructive two-dimensional profile measurements of a high-intensity beam by capturing an image of a beam-induced fluorescence was developed. For quantitative profile measurements, the monitor's response function comprising, e.g., the gas sheet density distribution and the detector's sensitivity distributions must be experimentally clarified because the monitor output is a converted profile with the response function. A response function measurement method was devised based on the beam-profile-measurement method formula of the monitor. The response function was obtained by injecting a thin electron beam into the developed monitor and scanning its center position in transverse. The measured response function was evaluated by the J-PARC 3 MeV, 60 mA H
beam profile measurement. The 2-D beam profile was successfully reconstructed with the measured response function within the 2.74% residual of the least-squares method and 6.01% experimental statistic deviation. The projected 1-D profiles agreed well with those measured using a wire-scanning-type profile monitor.
from 3-GeV protons and 
Hg with the 
Bi(n,xn) reactionsSugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio
JAEA-Conf 2024-002, p.162 - 167, 2024/11
A neutron energy spectrum is important for shielding design at an Accelerator-Driven System facility (1.5-GeV p + Lead Bismuth Eutectic). A similar spectrum can be obtained at J-PARC (3-GeV proton + Hg). To check the validity of the unfolding, the unfolding with the Bi(n,xn) reactions and the response functions (JENDL/HE-2007 and TALYS) was applied. In our poster, we present the derivation of the spectrum and comparison with the spectrum with a Time-of-Flight technique.
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
no abstracts in English
Chimura, Motoki
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1064 - 1069, 2024/10
no abstracts in English
Yamamoto, Kazami; Nakano, Hideto; Matsumoto, Tetsuro*
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.741 - 745, 2024/10
To accumulate a high-intensity beam in the Rapid Cycling Synchrotron (RCS), the H
beams from the linac converted into protons and injected into the RCS. In this process, a certain amount of the beam is not converted, and it leads to the injection dump. Since the secondary particles are constantly produced inside the dump due to this waste beam, we have studied if those secondary particles can be used as an irradiation test. In this report, we compare the results of calculations using PHITS/DCHAIN codes and measurements using a germanium-semiconductor detector after activating a bismuth-209 sample.
Meigo, Shinichiro; Yamaguchi, Yuji; Iwamoto, Hiroki
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.32 - 37, 2024/10
no abstracts in English
Kitamura, Ryo; Fuwa, Yasuhiro; Kuriyama, Yasutoshi*; Miyao, Tomoaki*
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.233 - 234, 2024/10
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.525 - 528, 2024/10
A decade has elapsed since the radio frequency (RF)-driven negative hydrogen (H) ion source initiated operation at J-PARC. In the 2023/2024 campaign, a single RF-driven H ion source has generated H beams with a beam current of 60 mA, which enabled the J-PARC linac to inject them into the 3 GeV rapid cycling synchrotron (RCS) with a beam current of 50 mA. The continuous operation time of the ion source reached exceeding 4,900 hours in this campaign, which signifies a notable enhancement in operational longevity in comparison to the preceding longest campaign in 2022/2023, which spanned 4,412 hours. This paper provides the operational status of the RF-driven H ion source during this campaign and the current status of the J-PARC-made antenna, which is currently under development.
Kojima, Kunihiro; Harada, Hiroyuki; Chimura, Motoki; Saha, P. K.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.118 - 122, 2024/10
Further beam power ramp-up going beyond the design output beam power of 1 MW is proceeding in the J-PARC RCS. In MW-class rings, the residual radioactivity accompanying the beam loss strictly limits the available beam power. While the current beam loss is mitigated to 0.1% level at the designed beam power, further beam loss mitigation prepared for the beam power ramp-up is required. The resonance crossing of the tune spread can cause unallowable beam loss. Since the beam power ramp-up definitely extends the space-charge-induced tune spread, the sufficiently wide stability region in the betatron tune map must be secured for low beam loss. We conducted low-intensity beam studies on the half-integer random resonances that likely have significant effects on the width of the stability region. Thanks to the simplification coming from the mitigation of the space-charge force, the successful compensation of the resonance is realized by using the trim quadrupole magnets. In the high-intensity beam studies, the resonance compensation was found to be beneficial in extending the stability region.
Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Fuwa, Yasuhiro; Tongu, Hiromu*; Hayano, Hitoshi*; Geng, R. L.*
Journal of Instrumentation (Internet), 19(9), p.P09037_1 - P09037_15, 2024/09
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Fuwa, Yasuhiro; Terunuma, Nobuhiro*
IEEE Transactions on Applied Superconductivity, 34(5), p.4004005_1 - 4004005_5, 2024/08
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)We are developing a correction magnet for charged particle beams using permanent magnets. By rotating the rod of the permanent magnet that generates the magnetic field, the magnetic field can be changed to bipolarity. To verify the principle of this bi-polarity change, a prototype was built, and its performance was evaluated. The performance evaluation of the prototype machine revealed that the inhomogeneity of the remanent magnetization of the permanent magnet has a significant effect on the multipole component. To suppress this effect, a compensating magnet with additional anisotropic intermediate poles is being considered.
Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Fuwa, Yasuhiro
IEEE Transactions on Applied Superconductivity, 34(5), p.4904504_1 - 4904504_4, 2024/08
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)A permanent magnet can be used to generate an axisymmetric uniform magnetic field over a long distance. To satisfy Ampere's law, which states that the line-integral value of the magnetic field is zero, a magnetic field region of opposite polarity appears somewhere along the axis while maintaining uniformity in a certain range along the axis. Using this configuration, a magnetic field generator for a Faraday rotation device for laser light was fabricated. This device has a large bore of 30 mm in diameter to handle ultra-high-power lasers and can hold a large crystal disc for Faraday rotation. The irregularity in the central plane is less than 1% within the bore diameter. This configuration can also be applied to long axisymmetric beam transport magnets. This technique can be extended to control the gradient of the magnetic field distributions, such as the focusing field of a klystron.
Takei, Hayanori
Journal of Nuclear Science and Technology, 61(8), p.1075 - 1088, 2024/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)In the proton linear accelerator (linac), the proton beam is unexpectedly interrupted due to the electrical discharge originating from the radio frequency, failure of the device/equipment, or other factors. Do these beam trips occur randomly? Conventionally, it has been implicitly assumed that beam trips occur randomly. In this study, we investigated whether beam trips in the linac of the Japan Proton Accelerator Research Complex (J-PARC) occur randomly to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained using the Kaplan-Meier estimation, a reliability engineering methods. Using this reliability function, the randomness of beam trips was examined. Analysis of five-year operational data for five subsystems of the J-PARC linac showed that beam trips occurred randomly in some subsystems. However, beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, the primary subsystems of the proton linac.
