Preliminary study on protection of synchrotron radiation damage in CEPC main ring

Abstract

The Circular Election–Positron Collider has been proposed by Institute of High Energy Physics (IHEP, CAS). The beam in the main ring with energy up to 120 GeV would produce intense synchrotron radiation (SR) with photon energy up to several MeV. Without shielding, this radiation would be harmful to the accelerator components. To clarify the radiation damage, analyze the source of SR, and design the shielding system to protect the accelerator. The theoretical formula has been used to estimate the spectrum and distribution of SR. Several ways of designing or shielding vacuum chamber with different geometries and various materials are put forward to protect sensitive facility components. The Monte Carlo program FLUKA has been introduced to calculate cumulative dose and heat deposition in all designing cases. The SR in CEPC main ring would be harmful to the coil used in dipole magnets. The design based on LEP with aluminum and lead would need 23 mm lead to make the coil safe. The design based on LEP with copper would need 28 mm of outer copper. And the copper chamber and lead shield design would need 16 mm of Lead. The theoretical formula has been used in source generation of Monte Carlo program to get the distribution of SR in CEPC main ring. The program was also used to simulate SR problems in the vacuum chamber with designs of different geometries and materials. Among these designs, the elliptical pipe with lead shield is preferred in CEPC.