Sun, YP (reprint author), Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.
BEPC II, the upgrading project of the Beijing Electron-Positron Collider (BEPC), has been designed with a luminosity of 10(33) cm(-2) s(-1) at the t-charm energy regime. To increase the operating luminosity of the BEPC II, a low momentum compaction factor collision mode has been studied. At the same time, the dynamic aperture of this mode has been calculated since it may not be enough as a result of the sextupole strength increasing. The corresponding luminosity of this mode is calculated through beam-beam simulations.