Silicon photomultiplier-based Compton Telescope for Safety and Security

A Compton gamma imager has been designed for use in consequence management operations and in security investigations. The imager uses solid inorganic scintillator, known for robust performance in field survey conditions, and was constrained in overall size by the requirement that it be operable from a variety of platforms, and person transportable among them. In order to introduce minimal dead material in the path of the incoming and scattered gamma rays, custom silicon photomultipliers (SiPMs), with a thin glass substrate, were used to collect the scintillation light from the scatter layers. To move them out of the path of the gamma rays, preamplification electronics for the silicon photomultiplers were located a distance from the imager. This imager, the Silicon photomultiplier Compton Telescope for Safety and Security (SCoTSS) is able to provide a one-degree image resolution in a 90° field of view for a 10 mCi point source 40 m distant, within about one minute, for photopeak energies ranging from 344 keV to 1274 keV. Here, we present a comprehensive performance study of the SCoTSS imager.