Test of prototype modules of the CBM Silicon Tracking System in a proton beam at COSY

The prototype Silicon Tracking System comprised two stations based on double-sided silicon microstrip, ultrathin readout cables, and self-triggering readout electronics (Fig. 2-left). The detectors SPID-CBM02 originate from a cooperation with CiS, Erfurt, and have 256 orthogonal strips per side with 50 μm strip pitch. The detectors were assembled into boards at SE SRTIIE, Kharkov, Ukraine. The readout boards developed at GSI are based on the selftriggering n-XYTER chip. Numerous improvements as compared to the in-beam test of 2009 [2] were introduced on hardware and software levels. By implementing proper shielding and grounding techniques the electronic noise was reduced to about 600 e−, which is now dominated by the preamplifier noise. The n-XYTER temperature was stabilized with water cooling, which abated the problem of the baseline drift significantly. In addition, an automatic baseline calibration was implemented in the data acquisition software and run between the beam spills. A detector control application based on the