Recent Upgrades of the Bunch Arrival Time Monitors at FLASH and European XFEL

In modern free electron laser facilities like FLASH and European XFEL a high resolution intra train bunch arrival time measurement is mandatory, providing a crucial information for the beam based feedback system. At FLASH and European XFEL a reliable arrival time detection with a resolution better than 0.1% is required for a broad range of bunch charges, from 1 nC down to 20 pC. The system developed is based on electro-optical sampling where an ultra-short pulsed laser is employed. Several bunch arrival time monitors (BAM) were developed and are since 2012 in operation at the FLASH facility. A major upgrade involved the development of new hardware and software based on the MTCA standard. Special operation mode at both facilities includes the possibility to subdivide the bunch train in up to three segments, each with different bunch energy and charge, causing variation of the time jitter within the bunch train itself. A further upgrade includes the measurement of the arrival time and application of delay correction for each of the three segments. In this poster, we describe the development, installation and commissioning of the hardware, firmware and software of the new system