Electron trapping variations in single-crystal pixelated HgI2 gamma-ray spectrometers

The characteristics of thick (∼6 mm) HgI₂ room-temperature gamma-ray detectors having 4 small pixel anodes are investigated. Spectra for the different anodes (overall and for individual interaction depths) are presented. The mu-tau product for electrons was measured to study the variations of electron transport within a single HgI₂ crystal. By using the single polarity charge sensing with depth sensing, the μ_eτ_e was estimated to vary from ∼9×10^-4 cm²/V to 7×10^-3 cm²/V. Individual pixels have the ability to produce spectra with resolutions less than 3% at 662 keV. Some effects of electron detrapping and hole transport are also discussed.