Recent progress with Cadmium Zinc Telluride (CZT) radiation sensors grown by the traveling heater method (THM) at Kromek is reported. Large volume monolithic pixelated detectors, 40×40×15 mm<sup>3</sup> have been fabricated with good initial gamma spectroscopy response (< 2.5% energy resolution at 662 keV at room temperature without correction). After depth of interaction (DOI) correction, detector performance with < 1% energy resolution at 662 keV at room temperature has been obtained on pixelated 22×22×15 mm<sup>3</sup> CZT detector. For medical imaging applications, 20×20×6 mm<sup>3</sup> pixelated detectors exhibits < 3% energy resolution at 122 keV without correction. These results have been achieved via our proprietary THM crystal growth in combination with our robust device fabrication technique. Examples of progress in other areas of CZT development for gamma spectroscopy and imaging applications such as 40×40×5 mm<sup>3</sup> cross-strip device for PET and Kromek’s general-purpose SPECT camera will also be presented.
One electrode configuration frequently used in CZT detectors is the cross-strip pattern. The cathode-to-anode signal ratio (C/A) can be used to estimate the position of photon interaction in the direction perpendicular to the electrode plane. In addition, C/A is used to calibrate for the depth-dependent anode signal. Based on the design configuration of the electrode widths with respect to the CZT thickness, their measured energy spectrum varies due to the small pixel effect and charge trapping. In this work we evaluate the effect of a poor cathode energy resolution on the depth of interaction correction and anode signal recovery.