Leakage currents and capacitances of thick CZT detectors

The quality of cadmium zinc telluride (CZT) detectors is steadily improving. For state of the art detectors, readout noise is thus becoming an increasingly important factor for the overall energy resolution. In this contribution, we present measurements and calculations of the dark currents and capacitances of 0.5 cm thick CZT detectors contacted with a monolithic cathode and 8times8 anode pixels on a surface of 2times2 cm². Using the NCI ASIC from Brookhaven National lab as an example, we estimate the readout noise caused by the dark currents and capacitances. Furthermore, we discuss possible additional readout noise caused by pixel-pixel and pixel-cathode noise cross- coupling.