Performance of semi-insulating gallium arsenide X-ray pixel detectors withcurrent-integrating readout

First images are presented from tests of a semi-insulating gallium arsenide X-ray imaging detector, flip-chip bonded to a current integrating CMOS rea dout chip. The detector is designed for applications in synchrotron X-ray i maging. The X-ray sensing part of the detector consists of a 150 mum thick GaAs photodiode containing an array of 92 x 100 pixels, each 150 mum by 150 mum in size. Operating the device at -20 degreesC we have obtained a map o f detector dark current, which is typically in the range 0.4 pA to 0.8 pA/p ixel. We have also obtained images of the detector response to a collimated X-ray beam. (C) 2001 Elsevier Science B.V. All rights reserved.