LUMINOSITY IMPROVEMENT AT PEP-II BASED ON OPTICS MODEL AND BEAM-BEAM SIMULATION ∗

Since the beginning of this year, we have made significant improvements in the machine optics at PEP-II. As a result, the specific luminosity increased nearly 20%. The largest luminositygain actually came fromminimizing nonlinear chromatic effects and running both rings much closer to the half integer resonance in the horizontal plane.