Spectroscopic performances of 16 x 16 pixel CZT imaging hard-X-ray detectors

Cadmium zinc telluride (CZT) pixel detectors show very good spectral and spatial resolution and are suitable for use in compact hard-X-ray sensors operated without cryogenics. One of the most appealing astrophysical applications is their use as focal-plane detectors for multilayer hard-X-ray telescopes operating in the (10-80) keV energy band. This paper reports experimental results obtained from two 16 x 16 pixellated CZT detectors (10 × 10 × 1 mm³ and 10 × 10 × 2 mm³ single crystals) with 450 μm pixel operated at room temperature using standard commercial read-out electronics. We have investigated about energy resolution and material properties of both detectors. Both arrays gave similar results showing an energy resolution less than 5% at 59.5 keV and a good material uniformity. The good energy resolution of both detectors demonstrates as the pixellated anode structure reduces (small pixel effect) the incomplete charge collection due to severe hole trapping typically present in CZT crystals. A calibration curve, obtained using three different energies, shows a linear response of the detectors.