Ultra high flux 2-D CdZnTe monolithic detector Arrays for x-ray imaging applications

The performance of 2-D CdZnTe monolithic detector arrays designed for high flux x-ray imaging applications was studied. For the first time we have obtained 5 X 10(6) counts/s/mm(2) count-rate for a CdZnTe, pixelated detector array. This count-rate is more than. twice the highest count-rate ever achieved using a CdZnTe detector array. Such excellent performance was demonstrated for more than 600 individual CdZnTe detector arrays. The 2-D CdZnTe monolithic arrays were 16 x 16 pixel devices with. 0.4 mm x 0.4 mm area pixels on a 0.5 mm pitch and were fabricated using 8.7 mm x 8.7 mm x 3.0 mm CdZnTe single crystals grown by the high-pressure, electro-dynamic gradient freeze technique. The CdZnTe detector arrays were bonded to a ceramic substrate with the Z-bond (TM) technique. This enabled performance testing of the individual detector arrays before bonding to the read-out ASIC chip. The detector arrays were characterized in a custom designed test system. The measurement and data acquisition system consisted of a 16 x 16 pin probe head and 256-channel read-out electronics controlled by a host PC. We utilized our 8-channel fast bipolar ASIC chip and computer controlled, 120 kVp x-ray source. In order to measure the true throughput of the CdZnTe devices a counts correction method was developed and implemented that compensates for the. counting system non-linearity caused by pile-up and amplifier shaping time effects. Survey of detector array performance as a function of CdZnTe charge transport properties showed that the maximum achievable count-rate of these detectors strongly depends on the hole charge transport properties of the crystals.