Characterization of a digital ASIC readout system for 11×11 pixelated TlBr detectors

Thallium bromide (TlBr) is being investigated for use as room temperature semiconductor gamma-ray spectrometers because of its wide band gap (2.68 eV) and high stopping power. When cooled to -20°C, performance of better than 1% FWHM at 662 keV has been observed on 5×5×5 mm3 pixelated TlBr detectors. Currently, each of nine anode pixels (in a 3 × 3 array) is read out individually through separate preamplifiers, limiting the number of pixels that can practically be used. VAD_UM digital application specific integrated circuit (ASIC) is currently used to read out signals from an array of 11×11 pixel anodes on each 3D CdZnTe detector. This work applies the same digital ASIC to TlBr by designing and building a compact system capable of reading out a larger detector (12mm × 12mm × 5mm as opposed to the current 5mm × 5mm × 5mm) while keeping the detector cooled for stable operation. We present an initial characterization of the system, including operating performance and power consumption used to keep the detector at various temperatures.