A Comprehensive Hard X-/Soft Gamma-ray Imaging Syst. for Astro. using APD Arrays

A critically important region of the electromagnetic spectrum is the hard X-ray/soft gamma-ray band from 10 KeV to a few MeVs. In this band, a wealth of astrophysical processes occur in an even greater diversity of astrophysical objects and phenomena, both on a compact and diffuse scale. Surprisingly, for such a pivotal region of the spectrum, the high energy sky is still quite unexplored in that the number of sources detected is still too small to allow a comprehensive study of the various phenomena involved. An instrument used for planetary scientific investigations is an X-ray/ gamma-ray spectrometer; it must be lightweight, stable, reliable, rugged, and long-lived. Radiation Monitoring Devices, Inc. (RMD) proposes to develop an innovative detector with a matrix of CsI(Tl) scintillators coupled to an array of avalanche photodiodes (APDs). Such a detector can be integrated into an imaging spectrometer to achieve improved angular resolution using a shadow-casting technique with the use of one or two-coded apertures. The improved angular resolution in the hard X-ray and gamma-ray regime will enable the studying of spatial and temporal development of solar flares, repeating gamma-ray bursters, and hard X-ray transients.