Locating a gamma source can be done by a variety of methods, ranging from rotating shields, to inter-detector shadowing, to Compton and Coded aperture imaging. Directional information is usually available in spectra from detector arrays, but the information is often ignored. Compton data from an array can be exploited to yield precise source locations, but that technique is slow. Processing data from occlusion, or mutual detector shadowing, is less precise, but much faster. Instruments currently implementing an occlusion method tend to focus only on azimuthal angles, but with some modification the technique can be extended to estimate elevation angles as well. We present a generalization of the occlusion method for estimating both azimuthal and elevation angles to a source, and calibration of the method involves singular value decomposition. The method works even for ill-chosen detector array geometries, and we show results from several detector systems.
|