Design of the movable collimator for background suppression for the CEPC

Abstract The Circular Electron Positron Collider (CEPC) is a proposed electron-positron collider to be operated at unprecedented high energy and luminosity. To reduce background noise from spent particles, a movable collimator system has been devised. This study presents a comprehensive design of the movable collimator for the CEPC, addressing the challenges posed by its high energy and luminosity. The interaction between synchrotron radiation, background particles, and the collimator was thoroughly investigated. Several aspects, including optimization of synchrotron radiation load, thermodynamic design, and structural impedance of the collimator, are considered. Additionally, the study examines the impact of key geometric parameters on the collimator's performance, providing valuable guidance for optimizing its performance with different requirement.