High Z Semiconductor Gamma-Ray Detector for Nuclear Non-Proliferation

There is a critical need for low cost, high performance gamma-ray detectors for identification and localization of special nuclear materials (SNM) such as plutonium and weapons grade uranium. Cadmium zinc telluride (Cd1-xZnxTe or & quot;CZT & quot;) has emerged as the leading room temperature semiconductor gamma ray detector. However, despite decades of research and recent improvements in crystal growth and processing techniques, the yield of device grade CZT is low. To meet the needs of homeland security a lower cost alternative to CZT is desirable. In the search for semiconductors that have potential for higher intrinsic detection efficiency than CZT and potentially lower cost, lead-containing chalcogenides have been identified as promising candidates. These materials have several favorable properties for room temperature gamma-ray detection including high Z (due to Pb), wide band gap (1.6 eV to 2.8 eV range) and can exhibit high electron mobility and no ionic conductivity. The goal of the proposed project is to investigate growth of high quality crystals of PbGa2Se4 and then implement advanced detector designs based on such detectors. Commercial Applications and Other Benefits: In addition to nuclear non-proliferation, nuclear medicine, computed tomography and non-destructive testing are other applications where high performance, less expensive spectrometers will have beneficial applications. One medical application that RMD already takes part in is the production of surgical probes used for localizing radiopharmaceutical uptake. These tools have become part of a technique (sentinel node biopsy) that minimizes the debilitating nature of removing lymph nodes in monitoring the spread of breast cancer. As this technique has become more accepted for breast cancer, other treatment areas have been considered such as monitoring PET isotopes (emitting at 511 keV) which have greater specificity to cancer sites. A high energy emission presents a challenging probe design because of scattering and lack of efficiency. New large PbGa2Se4 detectors capable of scatter rejection would be a very welcome solution if available