Recent Upgrade on Muon Target at J-PARC

Authors

Shunsuke Makimura¹^,²^,*, Shiro Matoba¹^,³, Hikaru Sunagawa¹^,³, Naritoshi Kawamura¹^,³, Koichiro Shimomura¹^,³, Yoshinori Fukao¹^,², Yusuke Uchiyama¹^,², Kaoru Inoue¹^,², Satoshi Mihara¹^,², Makoto Yoshida¹^,², Masami Iio¹^,⁴, Naoyuki Sumi¹^,⁴, Yutaka Nagasawa⁵, Masahiro Onoi⁵, Hiroyuki Shidara⁶, Kenta Kurihara⁷, and Masakazu Takahashi⁷

Affiliations

¹J-PARC Center, Tokai, Ibaraki 319-1195, Japan

²Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki 305-0801, Japan

³Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan

⁴Applied Research Laboratory, KEK, Tsukuba, Ibaraki 305-0801, Japan

⁵Metal Technology Co. Ltd., Ebina, Kanagawa 243-0424, Japan

⁶Metal Technology Co. Ltd., Aisho, Shiga 529-1202, Japan

⁷Metal Technology Co. Ltd., Toki, Gifu 509-5142, Japan

Journal

Published Date

6/12/26

DOI

Abstract

A pulsed muon beam has been generated by a 3-GeV 333-microA proton beam on a muon target made of graphite at J-PARC, Materials and Life Science Experimental Facility (MLF). The first muon beam was successfully generated in 2008, and 300-kW proton beam has been operated by a fixed target till 2014. To extend the lifetime, a muon rotating target, in which the radiation damage is distributed to a wider area, had been developed. The muon rotating target #1 was installed in 2014 and operated for five years until 2019. The rotating target #2 has stably operated at 950 kW until now in 2024. Simultaneously, in the COMET experiment to explore the muon-electron conversion process, 8 GeV proton beam with an intensity of 3.2 kW in Phase 1 and 56 kW in Phase 2 will irradiate targets in a superconducting solenoid magnet. In this presentation, the recent upgrade of the muon target at J-PARC MLF MUSE, the COMET target will be introduced.