Spectroscopic performance of pixellated thallium bromide detectors

The purpose of this study is to evaluate spectroscopic performance of pixellated thallium bromide (TIBr) radiation detectors. Pixellated TIBr detectors have been fabricated from TIBr crystals grown by the traveling molten zone (TMZ) method with zone-refined materials. Charge transport properties of the crystals were measured by performing the Hecht analysis. The TIBr crystals have exhibited the mobility-lifetime product of around 10(-3) cm(2)/V for electrons, which is three times larger than the previously reported value. The pixellated TIBr detectors with similar to 2 mm thickness have 4 pixellated electrodes (0.57 mm x 0.57 mm each) on the anode surface. In order to evaluate the spectroscopic performance, the detectors have been tested with Co-57, Cs-137, and Co-60 gamma-ray sources at room temperature. The TIBr detector 1.9 mm thick has demonstrated energy resolutions of 6.7 keV (5.5%) and 22.3 keV (3.4%) for 122 and 662 keV gamma-rays, respectively. Full-energy peaks of 1.17 and 1.33 MeV gamma-rays from the Co-60 source have also been detected with the detector.