Vacuum and leak test of the thermal insulation vacuum chamber of the SuperKEKB QCS cryostats
宗 占国, 大内 徳人, 有本 靖, 大木 俊征, 青木 和之, 王 旭東 （KEK）； 遠藤 友成 （(株)日立テクノロジーアンドサービス）
Abstract:The SuperKEKB superconducting magnet cryostats have been used for the accelerator operation for about 28 000 hours. The cryostat vacuum chamber requires a vacuum level of < 1.0E-2 Pa for thermal performance of multilayer insulation and this paper reports the monitored vacuum levels of room and cryogenic temperature with the accelerator operation. During the accelerator’s long shutdown, a comprehensive helium leak test was performed to each connection part of the cryostats and the leak test results will be presented in this paper.