The AMS silicon tracker readout: Performance results with minimum ionizing particles

First results for the AMS silicon tracker readout performance are presented. Small 20.0×20.0×0.300 mm 3 silicon microstrip detectors were installed in a 50 GeV electron beam at CERN. The detector readout consisted of prototypes of the tracker data reduction card equipped with a 12-bit ADC and the tracker frontend hybrid with VA_hdr readout chips. The system performance is assessed in terms of signal-to-noise, position resolution, and efficiency.