The silicon vertex detector of HERA-B

HERA-B is an experiment to study CP violation in the B system using an internal target at the DESY HERA proton ring(820 GeV). The main goal is to measure the asymmetry in the "gold plated" decays of B-0, B-0 --> J/psi K-s(0) yielding a measurement of the angle beta of the unitarity triangle. From the semileptonic decay channels of the b, (b) over bar -hadron produced in association with the B-0, (B) over bar(0) can be used to tag the flavor of the B-0. The purpose of the Vertex Detector System is to provide the track coordinates for reconstructing the J/psi --> e(+)e(-), mu(+)mu(-) secondary decay vertices and the impact parameters of all tagging particles.