A Solid State Directional Gamma Detector

A solid-state gamma-ray detector has been developed which exhibits directionality. Four PIN diode detectors are backed with Pb and arranged in a square array which exhibits an angular response to gamma rays. The high-Z material provides directionality and also enhances the sensitivity of the detectors to high-energy gammas by means of the x-ray fluorescence accompanying photon interactions in the backing. The array responses are used to identify the quadrant containing the source and obtain the radiation level. Ratios of the counting rates in opposite pairs of detectors are used to determine the angular position of the source within the quadrant.