Design studies for an all-scintillator Compton telescope

We are designing an all-scintillator Compton gamma imager to be used in criminal and security investigations involving radioactive threat material. We have chosen solid scintillator for the active volumes of both the scatter and absorber detectors and propose using one of four different materials for the scatter detector: LaBr3, NaI, CaF2 and PVT. We have investigated how well these materials will perform as scatter detectors using two simulation packages, BEAMnrc/EGSnrc and Geant4. We have simulated gamma rays incident on the four materials and examined the probability of single-Compton events and photoelectric absorption events, the angle of the Compton-scattered gamma ray and the Compton energy spectrum. We present a comparison of the BEAMnrc/EGSnrc and Geant4 results. In all studies, we find the simulation packages to be in good agreement.