Last Updated: 15 June 1995
The purpose of the SVT is to extend STAR tracking to the lowest achievable momenta and to identify short lived particles decaying before they reach the inner layers of the TPC. The SVT therefore needs to be as close as possible to the primary vertex while maintaining a reasonable radial coverage. It must also have an excellent position resolution to permit accurate tracking and vertexing and it should be as light a mass as achievable to minimize scattering of particles, gamma-ray conversion and the generation of background within the detector. In addition, the detector must also handle large occupancy although the number of electronic channels should be limited to minimize the cost. Semi-conductor drift detector technology has been shown to permit excellent spatial resolution, to handle quite large particle occupancy and to require a small fraction of the number of electronic channels of an equivalent spatial resolution pixel detector. The inherent slow readout time of semi-conductor drift detectors is still a factor of 10 smaller than the TPC drift time and therefore does not impose any limitations on the experiment. Solid state drift detectors appear to be the optimal technology for a STAR microvertex detector. Table I gives summary information for the SVT.
Table: Description of the proposed Silicon Vertex Tracker for STAR.