Stability and Characteristics of Large CZT Coplanar Electrode Detectors

The single polarity charge sensing method based on coplanar grid electrodes has demonstrated promising results on CZT detectors having volumes of ~1 cm. This paper presents the performance of two coplanar grid CZT detectors having dimensions of 1.5 1 5 1.0 cm2, among the largest CZT spectrometers that have been reported. Energy resolutions of 2.3% and 2.0% full-width half-maximum were obtained on the two detectors at 662 keV using simple analog techniques. Further improvement is achievable with depth sensing and digital pulse processing techniques. Other detector characteristics, critical to practical application of these devices, are reported here. This includes the stability of detector response over a period of several months and the variation of detector performance in environments having high gamma radiation fluxes and a range of counting rates.