Report on the 21st Annual Meeting of Particle Accelerator Society of Japan

Iwai, Takeo*; Tokanai, Fuyuki*; Soda, Hikaru*; Harada, Hiroyuki

Kasokuki, 21(4), p.381 - 386, 2025/01

https://doi.org/10.50868/pasj.21.4_381

no abstracts in English

Study on the mitigation of the beam loss for further beam power ramp-up in J-PARC RCS

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

https://www.pasj.jp/web_publish/pasj2024/proceedings/PDF/THOA/THOA05.pdf

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.

Commitment to sustainable Particle Accelerator Society of Japan; First roundtable meeting for communication with students and companies/research institutions

Harada, Hiroyuki; Sakaue, Kazuyuki*; Otani, Masashi*; Soda, Hikaru*

Kasokuki, 20(4), p.332 - 335, 2024/01

https://doi.org/10.50868/pasj.20.4_332

In Japan, where the birthrate is declining, securing young people to lead the next generation is an important issue for all organisations. The Particle Accelerator Society of Japan has nearly 1,000 members with increasing up to now, but it is necessary to take measures for the future. Therefore, the Events Committee and the Activation Committee of the Society jointly organised "First Roundtable meeting for communication with students and companies/research institutions". The aim of this meeting was to increase opportunities to connect students and companies/research institutions, to help students resolve their concerns about the future through job, and to help secure human resources for community. This paper reports on this meeting and its future as a new initiative towards the sustainable academic society.

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

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/WEOB/WEOB5.pdf

Development of new data acquisition system for several beam monitors in J-PARC RCS

Yoshimoto, Masahiro; Takahashi, Hiroki; Harada, Hiroyuki; Chimura, Motoki; Fuwa, Yasuhiro; Hayashi, Naoki; Kuriyama, Yasutoshi*; Sawabe, Yuki*; Hatakeyama, Shuichiro*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 843, 2023/11

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/FRP0/FRP08.pdf

In the J -PARC 3GeV synchrotron accelerator (RCS), a new signal processing system for beam monitors is been developing to replace the existing system for the main beam monitors that monitor the stability of the accelerator: beam loss monitor, beam position monitor and beam current monitor. The new system will consist of a TAG server and an ADC module that can be used commonly for the three main monitors. The main design concepts of the new system are: (1) the TAG server divides various beam J-PARC tag information to each ADC module, (2) the ADC module converts acquisition data from beam monitors to digital signals by ADC and performs high-speed analysis by FPGA with switching analysis methods to suit each monitor, (3) the ADC module periodically outputs the analysis data with tag information by packing the signal processing data of all shots for about 10 seconds, and also outputs any one shot data on-demand, and (4) the raw waveform data, the latest four shots of FFT-related data in the process of analysis and bunch data for each cycle are stored in the internal memory of the ADC module, and the data can be read out as needed. In this presentation, we will report on the progress of the data acquisition test of tag information reading and beam monitor signals using the prototype under 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.

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

https://doi.org/10.1088/1742-6596/2420/1/012040

Study of non-destructive slow beam extraction method in particle accelerator

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

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.503 - 507, 2023/01

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/WEP0/WEP002.pdf

Synchrotron accelerators realize physics experiments and radiation cancer treatment using the slow extraction technique, in which beams are stored in the ring and gradually delivered. We have devised and are currently developing a "non-destructive electrostatic septum" based on a new method, which in principle cannot be solved by conventional methods and is a cause of equipment failure and output limitation. It is ideal to generate a force distribution similar to a staircase function with discontinuous gaps at the boundary. In this presentation, we will show the calculation method for optimizing the electrode and wire configuration to generate a Lorentz force with a distribution similar to a staircase function in vacuum, and the calculation results of the beam breakup due to the generated Lorentz force. The compact proof-of-principle machine developed for the ongoing demonstration of this method will also be introduced.

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

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TUP0/TUP003.pdf