Chapter 23 - Cryogenic System for BEPCI SRF Cavity IR Quadrupole and Detector Solenoid Magnets

Abstract

This chapter summarizes the progress in cryogenics of the BEPCII project. Beijing Electron-Positron Collider Upgrade (BEPCII) requires three types of superconducting facilities, including one pair of superconducting radio frequency (SRF) cavities, one pair of interaction region quadrupole magnets, and one detector solenoid magnet. The cryo-plant for BEPCII has a total cooling capacity of 1 kW at 4.5K, which is composed of two separate helium refrigerators of 500 W each. The two refrigerators comprise the same gas storage and recovery system. The cryogenic facilities of the BEPCII cryoplant are distributed over four areas; the first colliding hall, the second colliding hail, the compressor hall, and the gas tank farm. The BESIII detector solenoid magnet and a pair of interaction region quadrupole magnets are located in the first colliding hall. The two SRF cavities are located in the second colliding hall. The two colliding halls are in a distance of 100 meters. The mechanical fabrication of the cryogenic system is to be conducted in China with some imported components such as the refrigerators and cryogenic valves.