Present status of the KEK electron/positron injector linac

In the KEK electron/positron injector linac, we have pursued a simultaneous injection scheme for four different rings over the past year, while continuing normal frequent injections to all the rings without any serious troubles. In the course of machine studies, a common optics for three beams of KEKB 8-GeV electron, 3.5-GeV positron and PF 2.5-GeV electron was found and has been established by verifying real injections to three rings. The event system, which allows a pulse-to-pulse beam mode switching at the maximum rate of 20 msec, has been fully tested in various situations as well as the beam monitor system. Based on these successful results, we started simultaneous injections to three rings in April this year with a typical injection pattern of 12.5 pps for the KEKB two rings and 0.5 pps for the PF ring. Detailed operation status in the simultaneous injection mode as well as the usual operation statistics in FY2008 is reported. (author)