This work focuses on the 3. Results and discussion characterization of 10 x 10 x 1 0 mm(3) THM-grown CdZnTe detector-grade crystals that have been post-growth annealed to remove the secondary phases (SPs). All three detectors showed an average energy resolution of similar to 1.63% for a small guarded pixel with 3.5 min diameter, measured using Cs-137-662 keV with an average peak-to-Compton ratio of 2.7. The characterization showed vestiges of SPs and micro-twins present in some of the crystals indicating that the SPs prior to annealing were large and had size in the range of 100-500 mu m. The various detectable structural features, such as micron twins, strains and sub-micron level of Te inclusions seemed to have little or no influence in the radiation spectrometer performance of the detectors; this is possibly because they are either having low density or electrically inactive. (C) 2009 Elsevier B.V. All rights reserved.