The physics aim of the Compressed Baryonic Matter (CBM) experiment is to explore the phase diagram of strongly interacting matter at highest net baryon densities and moderate temperatures in the range reachable with AA collisions between 2-45AGeV, initially 2-14AGeV (SIS 100).
The Silicon Tracking System (STS) is the central detector for charged particle tracking and momentum determination. It is designed to be operated at high occupancy at collision rates up to 10MHz. It is planned to reach the track reconstruction efficiency of 95%. The momentum resolution is expected to be around 1.5%. To achieve these goals, double-sided ouble-metal silicon sensors with a pitch of 58um are employed. The sensors are mounted on light-weight carbon ladders, forming 8 tracking stations. The read-out electronics is kept outside of the detector acceptance. The self-triggering read-out electronics is connected with the silicon micro-strip sensors through the multi-line micro-cables. The resulting material budget is about 1%X0 per station. The entire system is going to be operated in a thermal enclosure to maintain constant temperature below -5C. Before the mass production of the silicon sensors, several studies are performed with prototypes, such as electrical and optical inspection, measurements with the radioactive sources and beam tests of the sensors and the read-out electronics. Particularly, we study the possible impact of the severe radiation environment (10^14 1MeVneq cm-2) to the sensor performance.
The STS project is realised in cooperation of institutes from Germany, Poland, Russia and Ukraine. This presentation is given on behalf of the CBM Collaboration.