Development of CdZnTe X-ray detectors at DSRI

An overview of the development of CdZnTe X-ray detectors at the Danish Spac e Research Institute is presented. Initiated in the beginning of 1996, the main motivation at that time was to develop focal plane detectors for the n ovel type of hard X-ray telescopes, which are currently under study at DSRI . With the advent of the Danish Micro Satellite program it was, however, re cognised that this type of detector is very well suited for two proposed mi ssions (eXCALIBur, AXO). The research at DSRI has so far been concentrated on the spectroscopic properties of the CZT detector. At DSRI we have develo ped a technique, which, with the use of microstrip electrodes, is able to c ompensate for the signal loss caused by trapping of positive charge carrier s. This technique leads to a dramatic improvement of the achievable energy resolution, even for crystals of poor quality. With the technique, hole tra pping has now little influence and the spectrum displays a pronounced Gauss ian peak at 661 keV with a width (FWHM) of 6.9 keV. Also a small peak produ ced by CdTe escape events can now be observed. At the same time, no events have to be rejected. (C) 2000 Elsevier Science B.V. All rights reserved.