Leakage Currents and Capacitances of Thick CZT Detectors

TL;DR

This paper investigates the dark currents and capacitances in thick CZT detectors, analyzing their impact on readout noise and energy resolution, with measurements and calculations to inform detector design improvements.

Contribution

It provides detailed measurements and analysis of dark currents and capacitances in 0.5 cm CZT detectors, highlighting their effects on readout noise and detector performance.

Findings

Dark currents and capacitances significantly influence readout noise.

Pixel-pixel and pixel-cathode noise coupling can further affect performance.

Quantitative estimates of noise contributions inform detector optimization.

Abstract

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 8x8 anode pixels on a surface of 2 cm x 2 cm. Using the NCI ASIC from Brookhaven National Laboratory 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 coupling.