Beam-beam study in BEPC mini-/spl beta/ scheme

For performing mini-/spl beta/ colliding on Beijing Electron Positron Collider (BEPC), high RF voltage is supplied for shortening the bunch length, but beam experiments show that high RF voltage results in the luminosity decrease. The conclusions of detailed study are that, for BEPC, the averaging over the betatron phase during the collision has occurred. The ratio of bunch length over beta function at interaction point is too small, and the mitigating of averaging over the betatron phase causes the luminosity decreases.