High Efficiency, High Speed Gamma Ray Detectors

In this project, high quantum efficiency, fast (<20 nsec) silicon avalanche photodiode (APD) detectors, needed for Nuclear Physics research, will be optimized for the blue (e.g., 340-400 nm) optical radiation emitted by scintillators under gamma irradiation. The APDs have been designed to be highly manufacturable, with low dark count rates, high uniformity, and nanosecond-scale temporal response. In Phase I, through a set of orthogonal designed experiments, pixellated silicon APD arrays will be optimized for gamma detection applications. The design also will be optimized for obtaining high yields and, concomitantly, low cost. In Phase I, monolithically-integrated pulse-processing electronics will be designed; prototypes will be coupled with existing 2.5 GHz, low noise (20 erms) amplifiers; and the characteristics of the device, with and without coupling to LaBr3, will be measured. In Phase II, full performance and reliability testing of an integrated gamma camera will be performed. Commercial Applications and other Benefits as described by the awardee: Improvements in scintillator/APD detector design and manufacture, and in digital signal processing, would be valuable in supporting both national health and homeland security. These instruments not only could image and localize a radioactive source of interest, but also identify nuclear threats in the midst of legitimate sources found in commerce and in the environment. In addition, the detector systems could be deployed to support stockpile stewardship, nuclear safeguards and monitoring, and advance SPECT and PET medical instruments.