Annealing as Grown Large Volume CdZnTe (10%) Single Crystals for Increased Spectral Resolution

Large-volume CdZnTe detectors would improve radiation detection capabilities in support of the nonproliferation of nuclear weapons. However, the spectroscopic performance of current, large-volume Cadmium 10% Zinc Telluride, Cd0.9Zn0.1Te, (CZT) detectors is not sufficient for detection scenarios requiring reliable radioisotope identification. The deficiency has been linked to the cumulative effect of tellurium precipitates (secondary phases) presented in CZT single-crystal. The random nature of the interaction prevents the use of any electronic or digital charge correction techniques, without a significant reduction in the detector efficiency. This project will develop a heat treatment for CZT crystals to eliminate the tellurium precipitates. The careful control of the temperatures and atmosphere of the annealing process will chemically convert the tellurium precipitates without disturbing the crystalline structure. Commercial Applications and other Benefits as described by the awardee: The new process should provide a low cost method to provide unprecedented radioisotope identification capabilities. The widespread use of these detectors should aid in tracking the production and transport of nuclear materials.