CERBEROS — Beam detector for pion experiments at GSI

A beam detector with self-triggering capabilities for experiments with secondary pion beams at the HADES¹ spectrometer at GSI Darmstadt has been developed. The device should allow for an event-based reconstruction of the momentum of the secondary pion beam that has a momentum spread of about 8%. The pion momentum will be reconstructed from its position in the X-Y plane 18m and 3m upstream from the actual experiment target for each beam particle. The challenging issue is to achieve an accuracy of momentum measurement in the permille range for each individual pion for beam intensity of 10⁸ part/5 s spill. The beam detector consists of two double-sided radiation hard silicon strip sensors and n-XYTER² ASIC readout. The latter with its self-triggering architecture and built-in data buffers, together with the expected homogeneous distribution of the particles over the active detector area allows for continuous beam monitoring and profiling without any loose of data. The current status of the development, performance of the system and results obtained in the laboratory with radioactive sources and with proton beams will be presented in this talk.