THE PRESENT PERFORMANCE AND FUTURE UPGRADE OF THE KEKB ELECTRON LINAC K. Furukawa∗, the KEK Electron Linac Group and the Linac Commissioning Group, High Energy Accelerator Research Organization (KEK),

The KEKB linac injects 8-GeV electrons and 3.5-GeV positrons into the KEKB asymmetric collider rings de-signed for the B-physics study. The KEKB has recorded the highest luminosity records to which the linac con-tributes with an advanced operational stability. In order to further improve the luminosity, the new schemes of dual-bunch injection and continuous injection were studied and have been adopted. It is also planned to upgrade KEKB for a luminosity of 1035/cm2/s with exchanged beam ener-gies (3.5-GeV electrons and 8-GeV positrons). Upgraded linac is being designed and studied with a higher accelera-tion gradient and others to realize such a super B factory.