Cooled CdZnTe detectors for X-ray astronomy

Recent results combining thermoelectrically cooled CdZnTe detectors with a low-noise Pentafet preamplifier are presented. Cooling between −30°C and −40°C reduces the leakage current of the detectors and allows the use of a pulsed reset preamplifier and long shaping times, significantly improving the energy resolution. Mn Kα X-rays at 5.9 keV have been observed with a resolution of less than 280 eV FWHM and a peak to background of more than 200:1. The Fano factor of the material has been estimated at 0.11±0.012 at −40°C. The detector requirement for X-ray astronomy will be a photon-counting imaging spectrometer. A 16×16 element, bump bonded pixel detector is described and results from a prototype silicon array presented. The detector is constructed with ASIC amplifiers with a system noise of <25 electrons rms and should give an energy resolution comparable to the Pentafet results presented here.