PEP-II and KEKB Operational Status

The present two B-Factories, PEP-II at SLAC in California and KEKB at KEK in Tsukuba, Japan, operate at the Upsilon 4S and have reached parameter levels unprecedented for e+e- colliders. They have provided very large data samples for their respective particle detectors, BaBar and BELLE. Luminosity has exceeded 1.5 x 10
³⁴
/cm
²
/s. Beam currents have reached 2.5 A with 1600 positron bunches spaced by 4 nsec. Continuous injection with the detectors taking data has added significantly to data collection rates by about 40%. Bunch-by-bunch feedback systems damp strong longitudinal and transverse coupled bunch instabilities. The beam-beam interaction has allowed high tune shift levels even in the presence of parasitic crossing and crossing angle effects. Both B-Factory colliders have significant near term luminosity improvement programs.