Three-Dimensional High-Resolution Gamma Ray Detector for RIA

79011S In nuclear physics research, gamma-ray spectroscopy with fast exotic beams allows for the measurement of calculable quantum-mechanical observables with beam rates as low as a few particles per second. To obtain good experimental data, gamma-ray detectors must have good energy and spactial resolution. Combining these detector attributes is difficult, and results in very expensvie and problematic experimental stations. This project will develop a high resolution, room temperture, gamma-ray detector that will address these concerns. The depth of gamma-ray interaction will be obtained from the ratio of the cathode signal, which depends on the drift of both electrons and holes, and the signal of the anode pixel, which depends on electrons only. The output will provide a three-dimensitonal identification of the event location, information critical to the new generation of experimental gamma ray detection systems. Phase I will test an acquisition system for full detector readout from a large number of pixels on a pixilated solid state detector. The system will be based on a previously-developed multichannel detector readout integrated circuit (IC). Detector performance for gamma rays from 122 keV to 662 keV will be demonstrated. Finally the design specification for the detector and for an optimized new readout IC will be developed. Commercial Applications and Other Benefits as described by the awardee: In addition to Nuclear Physics applications, the detector system should find a market as a general-purpose detector for industries employing nuclear techniques. Potential applications of national importance include systems designed for: medical imaging, radioactive materials monitoring, baggage and cargo inspection, NDI and NDE, nuclear weapons treaty verification, and explosives and contraband detection using gamma backscatter detectors.