CdZnTe pixel detectors with a custom VLSI readout, are being developed at C
altech/JPL for use in focusing hard X-ray telescopes. We have recently test
ed several prototype detector assemblies, each consisting of a 2 mm thick C
dZnTe pixel detector indium bump bonded to our VLSI readout chip. A complet
e pulse height analysis chain is located directly below each 680 by 650 mu
m pixel and includes a preamplifier, shaping amplifiers, and a peak stretch
er/discriminator. Here we report on the first fully functional operation of
these detector/VLSI hybrids. Using an Am-241 source, collimated to illumin
ate a single pixel, excellent energy resolution of 670 eV FWHM was measured
for the 59.5 keV line at -10C, with electronic noise of only 340 eV FWHM.
Illumination with an uncollimated Am-241 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.