Design characteristics of a low-energy gamma-ray imager for future space missions

The performance characteristics and detailed design of a position sensitive γ-ray detector, constructed from an array of CsI(Tl) scintillation elements viewed by individual photodiodes, is discussed on the basis of a series of laboratory tests. The imager matrix is configured as a two layer arrangement of position sensitive detectors and has a number of modes of operation including single site events in the upper layer and Compton scatter events between the two layers. The spectral range of operation, detection efficiency and energy resolution are assessed in terms of the dimensions of the matrix elements, their optical properties, and the detailed design of the front-end electronics.