Neutron measurement in the accelerator tunnel of J-PARC Rapid Cycling Synchrotron

Yamamoto, Kazami; Hatakeyama, Shuichiro; Otsu, Satoru*; Matsumoto, Tetsuro*; Yoshimoto, Masahiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.494 - 498, 2021/10

J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) provides more than 700 kW proton beam to the neutron target. In order to investigate the influence of the radiation, we intend to evaluate the radiations such as the neutron and gamma-rays, which are generated due to the proton beam loss. If the amount of beam loss is excessive, it becomes difficult to identify the individual neutron and gamma ray. Therefore, we investigated the signal rate of the extraction point of RCS. Preliminary result indicated that we can enough distinguish the neutron and gamma-ray by the liquid scintillator.

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

https://doi.org/10.1140/epjti/s40485-021-00067-6

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 1.6310 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 4.0810. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

J-PARC 3-GeV RCS; 1-MW beam operation and beyond

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

Journal of Instrumentation (Internet), 15(7), p.P07022_1 - P07022_16, 2020/07

https://doi.org/10.1088/1748-0221/15/07/P07022

no abstracts in English

J-PARC RCS; High-order field components inherent in the injection bump magnets and their effects on the circulating beam during multi-turn injection

Hotchi, Hideaki; Harada, Hiroyuki; Takayanagi, Tomohiro

Journal of Physics; Conference Series, 1350, p.012102_1 - 012102_5, 2019/11

https://doi.org/10.1088/1742-6596/1350/1/012102

The Residual dose distribution and worker doses in J-PARC 3GeV rapid cycling synchrotron

Yamamoto, Kazami

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.333 - 337, 2019/07

https://www.pasj.jp/web_publish/pasj2019/proceedings/PDF/WEPH/WEPH021.pdf

J-PARC 3GeV Synchrotron (RCS) started beam commissioning in 2007. The beam commissioning has been continued to increase the beam power for users. In a high-intensity hadron accelerator such as J-PARC, it is essentially important to reduce the activation due to beam loss and to suppress the exposure of workers. For this purpose, RCS has continued to study and countermeasure for the causes of beam loss from the initial stage of beam commissioning. At present, stable user operation is continuing at 500 kW. This value is half the design beam power of 1 MW, and the residual doses are being maintained enough small so that the maintenance work does not be hindered. In this report, we will introduce the history and measures of the residual doses in RCS so far, and the situation of the exposure dose of workers during maintenance work.

The Fast measurement of the monitors data with the beam synchronized tag in J-PARC

Hatakeyama, Shuichiro*; Yamamoto, Kazami; Yoshimoto, Masahiro; Hayashi, Naoki

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.789 - 793, 2019/07

https://www.pasj.jp/web_publish/pasj2019/proceedings/PDF/THPI/THPI025.pdf

The J-PARC Rapid Cycling Synchrotron (RCS) accelerates 400 MeV LINAC beams up to 3 GeV, and distributes them to the Materials Life Science Experiment Facility (MLF) and the Main Ring Synchrotron (MR) in 25 Hz cycle. To prevent radiation damages from the beam loss and also to detect failures of machines an interlock mechanism called the Machine Protection System (MPS) is introduced. If the beam is stopped by the MPS we should recover it quickly for the users of experiment facilities. The MPS related to the beam dynamics is usually diagnosed by beam loss monitors (BLM), beam position monitors (BPM) and current transformers (CT). Data of these monitors should be distinguished MLF or MR since the parameters for the magnet and the RF systems are different between MLF and MR. We confirmed validity of the method to distinguish the beam destination by using the information of the beam synchronized tag from the reflective memory (RFM) when taking the monitor data in 25 Hz.

Study on beam dynamics of high intensity proton beam and mitigation of beam loss in J-PARC RCS

Hotchi, Hideaki

FAS Dayori (Internet), (18), p.20 - 26, 2019/06

http://www.heas.jp/lecture/fas.html

no abstracts in English

Operation status of J-PARC rapid cycling synchrotron

Yamamoto, Kazami; Kamiya, Junichiro

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.2020 - 2023, 2019/06

https://doi.org/10.18429/JACoW-IPAC2019-TUPTS036

The 3 GeV rapid cycling synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Experimental Facility and Main Ring synchrotron. In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have conducted a beam study to achieve high-power operation with less loss. In addition, we have also maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last Japan fiscal year.

Pulse-by-pulse switching of operational parameters in J-PARC 3-GeV RCS

Hotchi, Hideaki; Watanabe, Yasuhiro; Harada, Hiroyuki; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yoshimoto, Masahiro

Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1041 - 1044, 2018/06

https://doi.org/10.18429/JACoW-IPAC2018-TUPAL018

1 MW beam tuning for beam loss mitigation in the J-PARC 3 GeV RCS

Hotchi, Hideaki; Harada, Hiroyuki; Kato, Shinichi; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; Watanabe, Yasuhiro; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.61 - 65, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/MOOM/MOOM03.pdf

After the RF power supply upgrade, the J-PARC 3-GeV RCS restarted a 1-MW beam test in October 2015. In the beam test in October, we successfully removed longitudinal beam loss by beam loading compensation as well as minimized space-charge induced beam loss by injection painting. In addition, in this beam test, beam instability was also well suppressed by controlling the tune and the chromaticity. Furthermore, in the following beam test, the transverse painting area was successfully expanded by introducing both quadrupole correctors and anti-correlated painting scheme, by which a foil scattering part of beam loss during charge-exchange injection was further reduced. By these recent efforts, the 1-MW beam operation is now estimated to be established within a permissible beam loss level. This paper presents recent progresses of 1-MW beam tuning with particular emphasis on our approaches to beam loss issues.