Integration and first operation of the Gotthard-II detector at European XFEL

Gotthard-II (G-II) is a 1-D silicon microstrip hybrid detector developed by the Paul Scherrer Institut within the framework of a collaboration agreement with the European XFEL. The ASIC features a dynamic gain switching architecture, in order to cope with the luminosity of European XFEL, and a 12-bit analog-to-digital converter with a sampling/conversion rate of more than 18 MS/s as well as a Static random-access memory, making it capable of matching the European XFEL pulse train structure, thus acquiring up to 2700 images at 4.5 MHz per burst. The sensor's strip pitch can be either of 50 mu m or 25 mu m , for a total of 1280 or 2560 output channels per detector, respectively, with a spectral sensitivity that allows either X-ray detection (optimized in the 5-20 keV range) or visible light detection. Its exceptionally good compliance with the European XFEL beam conditions will make G-II the most widely employed detector across the facility, with a total of 29 modules of different flavors that will be installed in scientific instruments and beam diagnostic setups. Although the detector will be predominantly used for spectroscopic measurements it will have a variety of other applications, including X-ray diffraction/emission/absorption experiments, relative pulse arrival time monitoring (of fundamental importance for pump-probe experiments), spectral diagnostics, and beam quality monitoring, with the possibility for the detector itself to generate a veto patterns for the large area MHz framerate pixel detectors employed at the scientific instruments, such as AGIPD, LPD and DSSC. In this paper, an overview of G-II detector technology and its usage at the European XFEL will be presented; the focus will then move on towards the process of detector integration in the European XFEL control system, data acquisition, and data correction infrastructure, highlighting its challenges. Finally, an overview of the first results obtained at scientific instruments will be given.