A Directional Gamma Radiation Spectrometer Based on Pixelated CZT Arrays and Coded Mask Apertures

The Government is deploying a growing number of radiation detectors at U.S. borders, ports of entry and other key locations, intended to assist in the detection of a potential terrorist's nuclear explosive device or radiological dispersal device. The most widely deployed radiation detector products today are radiation "pagers". Such products are unable to differentiate between natural radiation, and legitimate and clandestine radioactive materials, resulting in a disturbingly high incidence of false positives. As a result, there is a need for a portable device that can provide radionuclide identification and spatial localization. We report on the demonstration of a potentially low-cost, portable radiation sensor that provides radionuclide spectral information as well as spatial information and orientation about nuclear sources. Sensors based on this technology will allow personnel in the field to locate and positively identify potentially threatening radioactive materials while reducing the number of false alarms. Combined with isotopic identification software, it has the capability to differentiate radioactive sources as potentially dangerous or likely benign while also providing source direction, distance, and size information. It is based on high-resolution pixel array CZT detectors, new multichannel detector readout ASICs, coded mask apertures, and novel software. Data will be provided on device design and performance.