Beam-beam effects in BEPCII

Abstract: We first introduce the design parameters of the Beijing Electron-Positron Collider II (BEPCII) and the simulation study of beam-beam effects during the design process of the machine. The main advances since 2007 are briefly introduced and reviewed. The longitudinal feedback system was installed to suppress the coupled bunch instability in January 2010. The horizontal tune decreased from 6.53 to 6.508 during the course of data taken in December, 2010. The saturation of the beam-beam parameter was found in 2011, and the vacuum chambers and magnets near the north crossing point were moved 15 cm in order to mitigate the long range beam-beam interaction. At the beginning of 2013, the beam-beam parameter achieved 0.04 with the new lower $\alpha_{p}$ lattice and the peak luminosity achieved 7 x 10$^{32}$ cm$^{-2}$ s$^{-1}$.