5V, High Gain, High Sensitivity Photomultiplier Detector

The gamma ray spectrometers used for nuclear physics research at national laboratories are expensive, bulky, and limited in maximum count rate and other performance measures. Scintillators would be a viable alternative, provided that conventional glass photomultiplier tubes could be replaced with a high quantum efficiency, UV sensitive solid state detector that operates at low voltage, has low noise, and provides active areas of at least 5 cm2. To date, no silicon-based detector meets these needs. This project will develop a novel silicon nanowire ,Si-NW, photodetector that is ideally matched to the scintillator requirements, offering high quantum efficiency, low bias voltage, large sensitive areas, a large gain-bandwidth product, ruggedness, and low cost. In Phase I, the feasibility of the wafer-scale Si-NW fabrication process was demonstrated. This achievement along with earlier data on the UV photo response, gain, and excess noise of experimental Si-NW detectors demonstrated the feasibility of the concept. Phase II will develop full-scale photodetectors with active areas of 1-5cm2, integrate the photodetectors with stateof the art LaBr3:Ce scintillator crystals to produce fully functional gamma instruments, and deliver the instruments to a cooperating national laboratory for testing. Commercial Applications and Other Benefits as described by the awardee: In addition to the application for nuclear physics research, the new gamma ray detectors should become key tools for the nuclear power industry for use in monitoring reactors and the nuclear fuel cycle, for industrial non-destructive testing, and for the medical PET scan market. Compact, rugged, low-voltage gamma detectors also would be essential for homeland security and the global war on terror