Modeling and design of portable Compton gamma-ray cameras

Compton cameras have certain applications requiring portability. Camera designs which improve the portability of these devices by using room-temperature semiconductor and position-sensitive scintillation detectors have been investigated. Models have been developed and tested for the angular image resolution and energy resolution of the camera. A critical component of the models is a Monte Carlo code for simulating the light collection in the position-sensitive scintillator. Model testing has been accomplished with measurements made using a simplified camera having only one room-temperature Si(Li) detector and one position-sensitive NaI(Tl) detector. The model accurately matches measured resolutions over the energy range from 0.66 to 2.75 MeV. The efficiency and time resolution of the portable camera designs have also been investigated. The models predict the angular image resolution for a camera based on room-temperature Si(Li) and NaI(Tl) detectors to be between 9 and 5 degrees for incident photons from 0.5 to 3.0 MeV. The resolution of a camera with a CsI(Tl) detector in place of the NaI(Tl) is predicted to improve the resolution to between 7 and 4 degrees in this energy range