Development of an ultra-low-power X-ray-photon-resolving imagingdetector array

摘要

We report on progress to develop and demonstrate CZT and Si hybrid detector arrays for future NASA missions in X-ray and Gamma-ray astronomy. The primary goal for these detectors is consistent with the design concept for the EXIST mission1 and will also be appropriate for other NASA applications and ground-based projects. In particular we target science instruments that have large aperture (multiple square meters) and therefore require a low power ROIC (readout integrated circuits) design (＜ 10 microwatt per pixel in quiescent mode). The design also must achieve good energy resolution for single photon detection for X-rays in the range 5-600 keV with a CZT sense layer and 2-30 keV with a Si sense layer. The target CZT arrays are 2 cm × 2 cm with 600 micron square-shaped pixels. The low power smart pixel detects rare X-ray hits with an adjustable threshold setting. A test array of 7 x 5 pixels with a 5 mm thick CZT sense layer demonstrates that the low power pixel can successfully detect X-rays with ～50 readout noise electrons RMS.