Recent progress in thallium bromide detectors for X- and gamma-ray spectroscopy

Recent progress in the development of room-temperature TlBr detectors is pr esented. Higher-performance TlBr detectors have been fabricated from high-p urity TlBr crystals grown by the traveling molten zone method. The TlBr cry stals have exhibited large mobility-lifetime products of 2.6 x 10(-4) and 3 .7 x 10(-5) cm(2)/V for electrons and holes, respectively. An energy resolu tion of 29.8 keV (5.8%) FWHM has been recorded for 511 keV gamma -rays with a TlBr detector at room temperature. Timing properties of the TlBr detecto rs have been studied by recording the coincidence timing spectra between a TlBr detector and a BaF2 scintillator coupled to a photomultiplier tube. Ti ming resolution of 21.3 ns FWHM has been measured for 511 keV positron anni hilation gamma -rays from a Na-22 source. By using a single TlBr detector i n current mode, an X-ray CT scanner system of a first-generation type has b een developed. The performance of the system has been evaluated by observin g tomographic images. Images with good spatial resolution have been obtaine d by the scanner with the TlBr detector. (C) 2001 Elsevier Science B.V. All rights reserved.