A new approach to position sensitive gamma-ray spectrometry

A new type of gamma-ray imaging technique which employs digital focusing optics is proposed. This involves producing a real and diminished image of an interaction, from a small fraction of the scintillation photons, by means of a converging lens and an image intensifier/optical detector assembly. The remaining photons collected by light pipes and photomultiplier tubes coupled to the edge of the crystal. Thus pulse height and positional information are both retrieved. The calculations in the energy range 100-700 keV indicate that with a small degradation in energy resolution (5-10%), a spatial resolution of 1-1.5 mm is well within the capabilities of such an approach. A feasibility study using 28 keV x-rays and a 2 mm thick NaI(Tl) crystal ascertain the role of a lens system in the improvement of image resolution. (author)