Sensitivity of gamma-ray source detection using 3D-position-sensitive semiconductor detectors

Three-dimensional-position-sensitive semiconductor detectors provide both the energy and the locations of each gamma-ray interaction. From these data, Compton-imaging methods can reconstruct the source distribution around the detector as a function of energy. Known isotopes are detected using the generalized likelihood ratio test (GLRT), and the performance is presented as a function of false-alarm probability for the cases of known and unknown background intensity. In addition, the localization performance is presented using two different algorithms as a function of measurement time for a point source in background using experimental data from a 20 mm × 20 mm × 15 mm CdZnTe detector. The effect of energy resolution on detection performance is also noted. Imaging information is hence used along with spectroscopic information to improve the search for a hidden source.