Coded Mask Imaging with CZT Detectors
J. L. Matteson, W. A. Heindl, E. Kalemci, R. E. Rothschild, T. R. Skelton
P. L. Hink, K. R. Slavis
Coded mask imagers based on CZT detectors are under
consideration for future high energy X-ray astronomy
missions. UCSD and WU have developed a prototype
crossed strip CZT detector that operates from ~ 10 - 300
keV with 500 micron spatial resolution and few keV
energy resolution. This was combined with a MURA coded
mask to form a laboratory coded mask imager, in which
the detector resolution oversampled the mask unit cell
by a factor of 2.6. Images were made with 41 keV X-rays
to study the detector's spatial accuracy and the
system's modulation transfer, sensitivity, image
accuracy, and systematic effects. Results were
excellent. The detector exhibited high spatial accuracy
and strip-to-strip (and pixel-to-pixel) selectivity, and
the modulation transfer was essentially 100 percent.
Correlation images showed a strong peak, 76 s, due
to the X-ray source, which had a width and shape in
agreement with expectations. The off-source image was
flat and had fluctuations that were agreement with
counting statistics. Any systematic effects were
limited to less than 0.5 percent of the source. These
results were obtained without any "flat fielding"
corrections, such as irregularities in detector spatial
accuracy or effective area. In light of these result,
coded mask imagers based on CZT detectors should be able
to provide high quality images with large dynamic range,
as will be necessary for future deep surveys of the high
energy X-ray sky.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.