320x240 GaAs pixel detectors with improved X-ray imaging quality

We report on gain and offset corrections for GaAs X-ray pixel detectors, wh ich were hybridised to silicon CMOS readout integrated circuits (ROICs). Th e whole detector array contains 320 x 240 square-shaped pixels with a pitch of 38 mum. The GaAs pixel detectors are based on semi-insulating and VPE g rown substrates. The ROIC operates in the charge integration mode and provi des snapshot as well as real time video images. Previously we have reported that the image quality of semi-insulating GaAs pixel detectors suffer from local variations in X-ray sensitivity. We have now developed a method to c ompensate for the sensitivity variations by applying suitable offset and ga in corrections. The improvement in image quality is demonstrated in the mea sured signal-to-noise ratio of flood exposure images. (C) 2001 Elsevier Sci ence B.V. All rights reserved.