Development of radiation hard silicon sensors for the CBM Silicon Tracking System using simulation approach

The Silicon Tracking System (STS) is a key detector of the CBM experiment planned at the Facility for Antiproton and Ion Research (FAIR). It has to reconstruct the trajectories of hundreds of charged particles created in heavy-ion collisions at typical beam energies of 25 GeV/nucleon. Radiation hard sensors and fast read out electronics are needed to match the interaction rates of up to 10 MHz. A low-mass detector system is required for a momentum measurement with about 1% resolution. First double-sided silicon microstrip detector prototypes with 50 μm strip pitch developed together with CiS, Germany have been characterized in the laboratory using radioactive sources. For the development of further prototype sensors, 3-dimensional device and process simulation tools have been used. They allow estimating the current and capacitance behavior of the sensor as well as its key parameters e.g. charge collection efficiency and interestrip isolation. The high-radiation environment in the CBM experiment results in a particle fluence through the STS of up to 10¹⁵ 1-MeV n_eq/cm² in a few years of operation. We present the simulation results and measurements of double-sided silicon microstrip detectors after neutron irradiation. Analog microcables are an essential component of the detector. Their careful design is necessary for the low material budget and lowest possible noise performance of the readout electronics. Simulations performed with the package RAPAEL have been validated using a well studied geometry of the cable and compared with results obtained using a different package.