  We studied the properties of chromium compensated GaAs when coupled to charge
integrating ASICs as a function of detector temperature, applied bias and x-ray
tube energy. The material is a photoresistor and can be biased to collect
either electrons or holes by the pixel circuitry. Both are studied here.
Previous studies have shown substantial hole trapping. This trapping and other
sensor properties give rise to several non-ideal effects which include an
extended point spread function, variations in the effective pixel size, and
rate dependent offset shifts. The magnitude of these effects varies with
temperature and bias, mandating good temperature uniformity in the sensor and
very good temperature stabilization, as well as a carefully selected bias
voltage.
