The Simulation of the CMS Silicon Tracker

The CMS Tracker is the largest all silicon tracking detector ever built. It consists of 201m^2 of silicon strip detectors, already assembled, and 1m^2 of silicon pixel detectors expected to be assembled by Fall 2007. A total of 1,440 pixel and 15,148 microstrip modules are mounted in several substructures for a total of about 66 million and 9 million readout channels, respectively. The physics analysis potential of CMS depends on the accuracy of the simulation of such a complex device. The fast shaping times of the electronics and the signal degradation due to the radiation damage caused by the large flux of particles produced in the LHC collisions are a challenge for the simulation. The accuracy of the predicted space point resolution depends on the ability to correctly model several factors: the diffusion of charges in the 4T magnetic field of CMS, the delta ray emission, the inter-strip capacitance, the collected charge and the noise. In addition, a detailed description of the positioning of the detectors is demanded. The large number of channels with locally mounted electronics requires power and cooling. The large amount of passive material causes multiple scattering, nuclear interactions, electron bremsstrahlung and photon conversions, whose precise simulation demands an accurate evaluation of the passive material budget.