The silicon vertex tracker of NA60

The NA60 experiment at CERN studies the production of open charm and prompt dimuons in collisions of high energy protons or heavy ions with target nuclei. The physics program relies on the precise measurement of the charged particles´ positions and momenta at the vertex. Tracking starts already a few centimeters away from the target in a radiation tolerant silicon detector placed in a 2.5 T dipole magnetic field. During several weeks of running in 2003 and 2004, this vertex tracker was exposed to high levels of inhomogeneously distributed radiation. In this paper we describe the construction, operation and performance of this novel, LHC-era detector.