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Journal Articles

Improvement of the longitudinal phase space tomography at the J-PARC synchrotrons

Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Saha, P. K.; Yoshii, Masahito*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Hasegawa, Katsushi*; et al.

Journal of Physics; Conference Series, 2687(7), p.072005_1 - 072005_7, 2024/01

Longitudinal phase space tomography is an effective measurement tool for acquiring the longitudinal phase space distribution. For the J-PARC synchrotrons, tomography, which can take into account the beam dynamics such as longitudinal space charge effect and nonlinearity, is desired, as the beam power increases. In this study, for the J-PARC synchrotron, the CERN's tomography, which employs the hybrid algorithm that can consider the beam dynamics for reconstruction, is introduced and benchmarked. The benchmark results show that the CERN's tomography has the ability to measure the longitudinal phase space distribution accurately, in the high-power beam operation at the J-PARC synchrotrons.

Journal Articles

Summary of the working group C on accelerator systems

Machida, Shinji*; Huang, H.*; Saha, P. K.

Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.670 - 674, 2023/12

Journal Articles

Consideration of high intensity single bunch acceleration in J-PARC RCS

Tamura, Fumihiko; Okita, Hidefumi; Hotchi, Hideaki*; Saha, P. K.; Meigo, Shinichiro; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Seiya, Kiyomi*; Sugiyama, Yasuyuki*; et al.

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.64 - 68, 2023/11

The J-PARC 3GeV synchrotron (RCS) provides high intensity proton beams to the Materials and Life Science Experimental Facility (MLF) and the Main Ring (MR). The harmonic number (h) of the RCS is 2 and the RCS normally accelerates two bunches. For some experiments at the MLF, a single bunch is preferred. In this case, one of the rf bucket is filled with protons and the other is empty. Therefore the beam intensity is halved. If the RCS can accelerate with h=1, the intensity per bunch can be doubled, enabling to provide single bunch beams to the MLF with the maximum intensity. This possibly increases the MR beam power by injecting high intensity single bunches eight times. In this presentation, we report mainly on the consideration of h=1 acceleration in the RCS by longitudinal simulations.

Journal Articles

Status of the laser stripping of H$$^{-}$$ beam at J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.59 - 63, 2023/11

Journal Articles

Challenge to charge exchange with pure carbon foil in the J-PARC 3GeV synchrotron

Nakanoya, Takamitsu; Yoshimoto, Masahiro; Saha, P. K.; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.937 - 941, 2023/11

In the J-PARC 3GeV Rapid Cycling Synchrotron (RCS), the 400MeV H$$^{-}$$ beam is changed to H+ beam by a charge exchange foil and accelerated to 3GeV. So far, RCS had used two types of charge exchange foil. One is the HBC (Hybrid Boron mixed Carbon) foil and the other is the Kaneka GTF (Graphene Thin Film). HBC foil is a patented deposition method developed at KEK for the stable production of thick carbon foil. Initially, the RCS used HBC foil produced atKEK. However, in 2017, JAEA had started HBC foil production and has been using it since then. Recently, we have succeeded in depositing thick pure carbon foil, which had been considered difficult to produce by the arc deposition method. As a new challenge, this pure carbon foil was used in the user operation from March 2023. As a result, Pure carbon foils showed less deformation and more stable charge exchange performance than HBC and GTF.

Journal Articles

A Kicker impedance reduction scheme with diode stack and resistor at the RCS in J-PARC

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

Proceedings of 68th ICFA Advanced Beam Dynamics Workshop on High Intensity and High Brightness Hadron Beams (HB2023) (Internet), p.162 - 169, 2023/10

At the 3-GeV Rapid Cycling Synchrotron (RCS) within the Japan Proton Accelerator Research Complex (J-PARC), kicker impedance causes beam instability. A 1-MW beam with a large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) by suppressing beam instabilities without the need for a transverse feedback system - simply by turning off the sextuple magnets. However, we require other high-intensity and high-quality beams with smaller emittances for the Main Ring (MR). To address this, we proposed a scheme for suppressing the kicker impedance using a diode stack and resistors, which effectively reduces beam instability. Importantly, these devices have a negligible effect on the extracted beam from the RCS.

Journal Articles

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

Journal Articles

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

 Times Cited Count:0 Percentile:0.02(Physics, Nuclear)

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.

Journal Articles

Recent results of beam loss mitigation and extremely low beam loss operation of J-PARC RCS

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

Journal of Physics; Conference Series, 2420, p.012040_1 - 012040_7, 2023/01

Journal Articles

Status of POP demonstration of 400 MeV H$$^{-}$$ laser stripping at J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.272 - 276, 2023/01

Journal Articles

Recent usage status of charge-exchange stripper foil for 3GeV synchrotron of J-PARC

Nakanoya, Takamitsu; Yoshimoto, Masahiro; Saha, P. K.; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.629 - 633, 2023/01

In the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS), a 400 MeV H- beam injected from the linac is exchange to an H+ beam by a charge exchange foil and accelerated to 3 GeV. The charge exchange foils mainly used in the RCS are HBC foil (Hybrid Boron mixed Carbon stripper foil), which are made by adding a small amount of boron to carbon rods and using them as electrodes by the arc deposition method. Since 2018, foils produced by JAEA have been used for user operation. So far, no major problems have occurred due to the foils. Meanwhile, the beam power of the RCS has been gradually increased from 500 kW to 830 kW since 2018. As beam power increases, the foil issues were identified to achieve the RCS design power of 1 MW. In this paper, we will report on the recent foil usage status and issue in the user operation.

Journal Articles

Achievement of low beam loss at high-intensity operation of J-PARC 3 GeV RCS

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

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1 - 5, 2023/01

Journal Articles

Results of 1-MW operation in J-PARC 3 GeV rapid cycling synchrotron, 2

Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio; Nomura, Masahiro; Suganuma, Kazuaki; Fujirai, Kosuke; Kamiya, Junichiro; Nakanoya, Takamitsu; Hatakeyama, Shuichiro; Yoshimoto, Masahiro; et al.

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.277 - 281, 2023/01

The J-PARC 3GeV Rapid Cycling Synchrotron (RCS) is aiming to provide the proton beam of very high power for neutron experiments and the main ring synchrotron. We have continued the beam commissioning and the output power from RCS have been increasing. In recent years, we have been trying continuous supply of 1-MW high-intensity beam, which is the design value, to a neutron target. We tried to operate continuously for over 40 hours in June 2020. However, some trouble occurred and the operation was frequently suspended. In June 2021, we tried again 1-MW operation but it was suspended due to deterioration of the cooling water performance. Last summer shutdown period, we recovered performance of the cooling water system and retried in this June. In the final case, the outside temperature became extremely high. We could not keep 1-MW power, whereas 600 kW beam was delivered in stable.

Journal Articles

$$beta^-$$ decay of exotic P and S isotopes with neutron number near 28

Tripathi, V.*; Bhattacharya, S.*; Rubino, E.*; Benetti, C.*; Perello, J. F.*; Tabor, S. L.*; Liddick, S. N.*; Bender, P. C.*; Carpenter, M. P.*; Carroll, J. J.*; et al.

Physical Review C, 106(6), p.064314_1 - 064314_14, 2022/12

 Times Cited Count:2 Percentile:47.44(Physics, Nuclear)

no abstracts in English

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:5 Percentile:81.82(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Laser stripping for 1.3 GeV H$$^{-}$$ beam at the SNS

Gorlov, T.*; Aleksandrov, A.*; Cousineau, S.*; Liu, Y.*; Oguz, A. R.*; Kay, M.*; Saha, P. K.

Proceedings of the 2022 North American Particle Accelerator Conference (NAPAC 2022) (Internet), p.702 - 704, 2022/08

Journal Articles

Recent progress of laser stripping POP demonstration study at J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.656 - 660, 2021/10

Journal Articles

Initiatives to address the lifetime improvement of HBC stripper foil for 3GeV synchrotron of J-PARC

Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10

no abstracts in English

Journal Articles

Foil hits reduction by minimizing injection beam size at the foil in J-PARC RCS

Saha, P. K.; Yoshimoto, Masahiro; Okabe, Kota; Harada, Hiroyuki; Tamura, Fumihiko; Hotchi, Hideaki*

Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.590 - 593, 2021/08

Journal Articles

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki

EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07

The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63$$times$$10$$^{-5}$$ variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.08$$times$$10$$^{-5}$$. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

176 (Records 1-20 displayed on this page)