High resolution CdZnTe pixel detectors with VLSI readout

CdZnTe pixel detectors with a custom VLSI readout, are being developed at Caltech/JPL for use in focusing hard X-ray telescopes. We have recently tested several prototype detector assemblies, each consisting of a 2 mm thick CdZnTe pixel detector indium bump bonded to our VLSI readout chip. A complete pulse height analysis chain is located directly below each 680 by 650 /spl mu/m pixel and includes a preamplifier, shaping amplifiers, and a peak stretcher/discriminator. Here we report on the first fully functional operation of these detector/VLSI hybrids. Using an Am/sup 241/ source, collimated to illuminate a single pixel, excellent energy resolution of 670 eV FWHM was measured for the 59.5 keV-line at -10 C, with electronic noise of only 340 eV FWHM. Illumination with an uncollimated source was performed to assess the uniformity of pixel response and to exercise the readout chip's ability to process multiple pixel events arising from X-rays interacting above pixel boundaries. The imaging capability of the detector was demonstrated using a tungsten slit mask.