Detection performance of SI GaAs detectors for nuclear medicine

This collaboration has already obtained encouraging results about the performance of 200 and 600 mm thick semiinsulating GaAs detectors, in terms of charge collection efficiency (c.c.e.), detection efficiency and imaging capabilities, to be used as single photon counting detectors with photons in the radiographic energy range. The possible use of such detectors in nuclear medicine implies detection of more energetic photons, up to the 140 keV of the 99mTc source; thus efficient detectors must be thicker than those previously studied. In this paper, we present the results of the investigation of electrical and detection properties (spectra, c.c.e., energy resolution) of a series of detectors, whose thickness ranges from 200 to 1000 um, when irradiated with radioactive sources over the energy range used in nuclear medicine.