The CZT X-ray imager on AXO

DSRI has initiated a development program of CZT X-ray and gamma ray detecto rs employing strip readout techniques. A dramatic improvement of the energy response was found operating the detectors as so-called drift detectors. F or the electronic readout, modern ASIC chips were investigated. Modular des ign and the low power electronics will make large area detectors using the drift strip method feasible. The performance of a prototype CZT system will be presented and discussed. One such detector system has been proposed for future space missions: The X-Ray Imager (XRI) on the Atmospheric X-ray Obs ervatory (AXO), which is a mission proposed to the Danish Small Satellite P rogram and is dedicated to observations of X-ray generating processes in th e Earth's atmosphere. Of special interest will be simultaneous optical and X-ray observations of sprites that are flashes appearing directly above an active thunderstorm system. Additional objective is a detailed mapping of t he auroral X-ray and optical emission. XRI comprises a coded mask and a 20 cm x 40 cm CZT detector array covering an energy range from 5 to 200 keV.