EXPERIMENTAL CHARACTERIZATION OF PEP-II LUMINOSITY AND BEAM-BEAM PERFORMANCE∗

The beam-beam performance of the PEP-II B-Factory has been studied by simultaneously measuring the instan-taneous luminosity, the horizontal and vertical e+ and e− beam sizes in the two rings, and the spatial extent of the luminous region as extracted from BaBar dilepton data. These quantities, as well as ring tunes, beam lifetimes and other collider parameters are recorded regularly as a func-tion of the two beam currents, both parasitically during routine physics running and in a few dedicated accelerator physics experiments. They are used to quantify and im-prove the PEP-II beam-beam performance