SRS VMM readout for Gadolinium GEM-based detector prototypes for the NMX instrument at ESS

We report on further development and application of a general purpose readout system, the Scalable Readout System (SRS). The SRS was introduced by the RD51 collaboration in 2009 in a common effort. Several front-end Application Specific Integrated Circuits (ASICs) were implemented in the system, of which the APV25 is most commonly used. Recently, we implemented the VMM ASIC, developed to read out detectors of the ATLAS New Small Wheel. We developed hardware components as well as FPGA firmware and computer software. With this latest implementation called SRS VMM, other groups intend to perform experiments and detector R&D.; In our application targeted at the NMX macromolecular diffractometer, one of the instruments foreseen at the European Spallation Source (ESS), SRS VMM was used to read out prototype detectors. Small scale versions were successfully tested at neutron sources and a full scale version was constructed. In those test beams, the feasibility of the detector and readout electronics design could be demonstrated