Some Studies on Increasing the Luminosity of BEPCⅡ

Abstract: BEPCⅡ, the upgrading project of the Beijing Electron-Positron Collider (BEPC), has been designed with a luminosity of 10³³cm^－2.s^－1 at the τ-charm energy region. According to the beam-beam simulation results, the luminosity of BEPCⅡ~with a crossing collision angle of 11mrad is about 0.50×10³³cm^－2.s^－1 with the original operation mode at the working point of 6.53/5.58. To increase the operating luminosity of the BEPCⅡ, a low momentum compaction factor (α_P) collision mode has been studied which can increase the luminosity to 0.54×10³³cm^－2.s^－1. If the bunch length of the low α_P mode is reduced from 1.5cm to 1.2cm, a mode with vertical beta function at IP equal to 1.2cm could push the luminosity to 0.828×10³³cm^－2.s^－1 at the working points 6.53/5.56.