STATUS OF KEKB AND UPGRADE PLAN TO SUPERKEKB

KEKB is an electron-positron two-ring collider for the leading B meson factory. It consists of an 8 GeV electron ring (HER) and a 3.5 GeV positron ring (LER) and their injector linac. It has been operated since December 1998, and has recently marked the peak luminosity of 17.12 /nb/s. This peak luminosity is obtained under the crabready beam optics having the robust operating condition by some efforts to solve the optics problems. We are aiming more luminosity improvement after the crab cavity installation. Further the major upgrade plan for SuperKEKB is expected to achieve 400 /nb/s keeping the baseline of the original proposal. This paper describes the recent status of KEKB and upgrade plans for SuperKEKB.