  We report on the construction and laboratory testing of pixellated CZT
detectors mounted in a flip-chip, tiled fashion and read out by an ASIC, as
required for proposed hard X-ray astronomy missions. Two 10 mm x 10 mm x 5 mm
detectors were fabricated, one out of standard eV Products high-pressure
Bridgman CZT and one out of IMARAD horizontal Bridgman CZT. Each was fashioned
with a 4 x 4 array of gold pixels on a 2.5 mm pitch with a surrounding guard
ring. The detectors were mounted side by side on a carrier card, such that the
pixel pitch was preserved, and read out by a 32-channel VA-TA ASIC from IDE AS
Corp. controlled by a PC/104 single-board computer. A passive shield/collimator
surrounded by plastic scintillator encloses the detectors on five sides and
provides a ~40deg field of view. Thus this experiment tests key techniques
required for future hard X-ray survey instruments. The experiment was taken to
Ft Sumner, NM in May 2000 in preparation for a scientific balloon flight aboard
the joint Harvard-MSFC EXITE2/HERO payload. Although we did not receive a
flight opportunity, and are currently scheduled to fly in September 2000, we
present our calibration data in the flight configuration together with data
analysis techniques and simulations of the expected flight background spectrum.

Astrophysics