Low Power, Room Temperature Systems for the Detection and Identification of Radionuclides from Atmospheric Nuclear Test.

摘要

For half a century, CdZnTelCdTe has been investigated for producing radiation detectors. Albeit some success, detector performance and production yield issues remain. Most importantly, the basic science about the factors limiting the detector property and production yield is not understood. The goal of this program is to experimentally and theoretically understand these limiting factors. In addition, techniques will be developed to remove these factors. In this program, 160 CZT crystals have been grown to achieve the program goal. It is discovered that Cd vacancies and Te antisites (Te at Cd sites) are the two major defects that limit the performance of the CZT/CdTe detectors. The introduction of Zn in to the crystals is one way to reduce the density of Te antisites. A process to reduce Cd vacancies has been developed for the growth of CTZ crystals. Zn has been introduced into the crystals to reduce the densities of the Te antisites. Using these approaches, CTZ with Zn contents of 0%, 4%, 10%, 15%, and 20% have been produced and detectors have been fabricated. The best detectors are produced in CZT grown with 10% Zn and 1.5% excess Te. The resolution of 57Co 122keV peak is less than 5% at room temperature.