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Kabumoto, Hiroshi; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; Nakagawa, Sohei; Ikekame, Takuma; Kato, Yuta; Ishizaki, Nobuhiro; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1165 - 1169, 2024/10
no abstracts in English
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
Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Miyakoshi, Ryosuke*; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 769, 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.
Tamura, Fumihiko; Sugiyama, Yasuyuki*; Okita, Hidefumi; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.774 - 776, 2024/10
The 3GeV RCS of J-PARC accelerates proton beams with a maximum beam intensity of 8e13 ppp, utilizing the features of magnetic alloy (MA) cavities. The beam is extracted in a single turn by kicker magnets, and immediately after the beam is extracted, a short voltage jump occurs in the cavity. This is due to a delay in the voltage control feedback, which takes a certain amount of time to respond to the step-like decrease of beam current upon single-turn extraction. In a wideband (Q=2) MA cavity, this response delay is observed as a voltage jump. This voltage jump can cause damage to the cavity system if the voltage at the time of extraction is high. Therefore, we prepared a logic to suppress the output synchronously with the beam extraction as a function of the LLRF control system. The details of the function and test results are reported.
Sugita, Moe; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Shinozaki, Shinichi
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.730 - 732, 2024/10
no abstracts in English
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.205 - 209, 2024/10
The Japan Atomic Energy Agency (JAEA) designs a 30-MW CW proton linear accelerator (linac) as a key component for the accelerator-driven subcritical system (ADS) project, aimed at nuclear waste management. The low energy beam transport (LEBT) in JAEA-ADS uses charge neutralization to minimize space-charge effects, which are the primary cause of beam loss in high-power accelerators. During commissioning and power ramp-up, precise control of the duty cycle is required for safety and machine protection; thus, a chopper system will be installed to manage the beam power. The chopper is located at the LEBT, to facilitate the disposal of the excess beam power, but its operation will affect the charge neutralization producing beam transients that could lead to beam loss. To shed light on this, we created a beam optics model for the chopper using an analytic approach to determine the required characteristics like voltage and dimensions, which was confirmed through TraceWin simulations. Subsequently, we analyzed the chopper's impact on space-charge compensation to evaluate the beam transients in the LEBT. This study reports the design of the chopper and its effects on beam performance for the JAEA-ADS LEBT.
Meigo, Shinichiro; Yamaguchi, Yuji
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 858, 2024/10
no abstracts in English
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
Yamaguchi, Yuji; Meigo, Shinichiro; Yamazaki, Takayuki*
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.239 - 243, 2024/10
Fringe field of a secondary-particle capture solenoid magnet with three coils has been experimentally investigated placed at muon science facility in materials and life science experimental facility (MLF), J-PARC. To clarify relationship between the fringe field and excitation current of each coil and interference of fields by the coils, proton beam position changes in vertical direction were measured for 125(= 5
) combinations of excitation currents using a multi-wire profile monitor located in front of the final target of MLF. The measured position changes show that the field by the most upstream coil is non-linear with its current while the fields by other coils are linear and that the field can be enhanced by excitation of multiple coils. The non-linearity of the filed by the most upstream coil has been introduced to the proton beam orbit correction, which has been demonstrated.
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.
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
no abstracts in English
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.
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
Suganuma, Kazuaki; Sekiyama, Yoshio*; Honda, Tomoyuki*; Dei, Tatsumi; Suzuki, Katsuo; Fujirai, Kosuke; Suzuki, Hiroshi*; Nakata, Morihiro*; Hosokawa, Hideaki*; Watanabe, Yasuhiro; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.738 - 740, 2024/10
In the J-PARC accelerator, the inner surface of the copper tubes that make up most of the coolant pipes is corroded. Generally, additives are added to the coolant to prevent corrosion, but the accelerator is in a radiation environment and additives cannot be used in the coolant to avoid impurities in the coolant become polluted by radiation. For example, in materials research in the nuclear field, there is a lot of research on strong acidic or strong alkaline solutions and corrosion resistant materials, but there is little literature on corrosion protection studies of purified water and copper materials. In general, we believe this is because the use of purified water and copper together in a radiation environment is limited. Corrosion testing of purified water and copper materials is unique to accelerators. The use of a thin copper film was considered as a possible method. In this case, we report on the current status of a new initiative, testing with copper thin films.
