|Recent Developments for the Improved Bunch Arrival Time Monitors at FLASH and for the European XFEL
|At today's free-electron lasers, pump-probe experiments and seeding schemes put high demands on the timing stability of electron bunches. At FLASH and the upcoming European XFEL a reliable and precise arrival time detection down to the femtosecond level has to cover a broad range of bunch charges, which may even change from 1 nC down to 20 pC within a bunch train. At FLASH, the new bunch arrival time monitor has to cope with the special operation mode where the MHz repetition rate bunch train is separated into two segments for FLASH1 and FLASH2 beam lines. Each of the two segments will exhibit individual timing jitter characteristics since they are generated from two different injector lasers and can be accelerated with individual energy gain settings. This operation mode places high demands on both, the hardware and the required servers for the bunch arrival time monitor, with regard to automated control and exception handling. In this paper, we describe the adapted electro-optical subsystem and show latest results from the newly implemented read-out electronics based on the MTCA.4 platform.