Point-source detection using energy and imaging information from 3D-position-sensitive semiconductor detectors

Three-dimensional-position-sensitive semiconductor detectors provide both the energy and the locations of each gamma-ray interaction in the detector. From these data, Compton-imaging methods can reconstruct the source distribution around the detector as a function of energy. Automated detection and identification methods have been developed to use this combined energy and imaging information to detect the presence of point sources of radiation in a background environment with an unknown energy spectrum and a uniform spatial distribution, as well as to identify the nuclide, localize its position, and estimate the source strength. Experimental performance was better than the commercial software Genie 2000 (Canberra) that uses only spectral information. Performance for all methods is shown as a function of false-alarm probability using experimental data collected on a 20 mm × 20 mm × 15 mm CdZnTe detector.