Characterization of TlBr gamma detector based on electrical charge and Cherenkov light analysis

Abstract

Thallium Bromide (TlBr) semiconductors have been extensively studied for their potential as room-temperature gamma-ray detectors, owing to their advantageous material properties. Recent advancements have demonstrated that timing performance in TlBr detectors can be enhanced by incorporating Cherenkov photon detection during gamma-ray interactions. In this study, TlBr detector (5 × 5 × 5 mm3) was investigated through a combined analysis of electrical charge and Cherenkov light signals. The depth of interaction (DoI) correction applied to the trapezoidal filter output yielded significant improvements in energy resolution, reducing it from 5.6% to as low as 2.51% FWHM at 511 keV and from 4.6% to as low as 1.94% FWHM at 662 keV, within specific C/A ratio ranges. The drift time, ranging from 2 to 30 μs, was found to be proportional to the C/A ratio, covering 4 to 9 photoelectrons. Furthermore, a time resolution of 511 ps was achieved at 6 photoelectrons, based on the FWHM of the time difference distribution in coincidence measurements at 511 keV using a 22Na source. These results highlight the potential of TlBr detectors for achieving high energy and timing resolution in gamma detection, particularly for Compton-PET systems.