Cooled CdZnTe detectors for X-ray astronomny

Recent results combining thermoelectrically cooled CdZnTe detectors with a low-noise Pentafet preamplifier are presented. Cooling between -30 degrees C and -40 degrees C reduces the leakage current of the detectors and allows the use of a pulsed reset preamplifier and long shaping times, significant ly improving the energy resolution. Mn K-alpha X-rays at 5.9 keV have been observed with a resolution of less than 280 eV FWHM and a peak to backgroun d of more than 200:1. The Fano factor of the material has been estimated at 0.11 +/- 0.012 at -40 degrees C. The detector requirement for X-ray astron omy will be a photon-counting imaging spectrometer. A 16 x 16 element, bump bonded pixel detector is described and results from a prototype silicon ar ray presented. The detector is constructed with ASIC amplifiers with a syst em noise of <25 electrons rms and should give an energy resolution comparab le to the Pentafet results presented here. (C) 1999 Elsevier Science B.V. A ll rights reserved.