Measurements of the Beam-Beam Interaction at PEP-II

The beam-beam interaction is one of the performance limitations at PEP-II. The peak luminosity in PEP-II has reached 3.4x1033/cm2/s with 693 bunches with a positron current of 1.6 A and an electron current of 0.84 A. The beam-beam tune shift limits have exceeded 0.06 horizontally and 0.03 vertically. A model of the luminosity with current using the measured beam sizes has been developed. Studies are underway to increase theluminosity toward 1034/cm2/s and beyond by increasing the number of bunches, raising the beam currents, lowering the betas at the interaction points, and shortening the bunch lengths[1]