Status of C-band accelerator module in the KEKB injector linac

For future energy upgrade of the KEKB injector linac, we have been developing a C-band accelerator module which can yield twice higher acceleration field gradient (42 MV/m) than the present S-band modules. This paper reports on a development of the sixth prototype accelerating section and recent performance of the C-band module which recorded an average field gradient of 45 MV/m.