Test beam studies of a silicon microstrip vertex detector

We have studied the operation of a three plane system of 50 micron pitch silicon microstrip detectors in a highly relativistic pion beam. A larger system, of similar design, will be used as a charm decay detector in a fixed target experiment at Fermilab (E691) which will study production from a photon beam with energy up to 250 Gev and intensity of approximately 5 x 105 per sec. The rate of e+e- pairs passing through the silicon planes will be of the order 5 x 105 per sec. The hadronic interactions will have an average charge multiplicity in the range 6 to 8 contained in a cone of + or - 100 mrad. To achieve high efficiency and good two particle resolution in this environment, we have chosen to use discriminator readout of every strip