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 3.4 /spl times/ 10/sup 33//cm/sup 2//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 the luminosity toward 10/sup 34//cm/sup 2//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.