TEST-RESULTS OF GAAS STRIP DETECTORS IN HIGH-ENERGY PARTICLE BEAMS

The first GaAs strip detector constructed in Aachen has been tested at CERN in a high energy particle beam in August and September 1994. The detector had a pitch of 200 mu m and was made of a 508 mu m thick Fre iberger SI-GaAs wafer. Using the low noise Viking preamplifier chip [1 ] a signal to noise ratio of 13 was obtained at normal beam incidence for a bias voltage of 450V. Signal to noise ratios up to 26 were achie ved depending on bias voltage and beam angle. Furthermore the spatial resolution of the GaAs detector was measured to be 72 mu m without any correction for multiple scattering.