COSMIC: a multi-scatter Compton telescope sky-monitor for low-energy gamma-ray astronomy

The study of highly transient low-energy gamma-ray sources such as active galaxies, X-ray binaries, soft gamma-ray repeaters and gamma-ray bursts offers unique insight into the astrophysics of extreme physical processes. Sensitive all-sky monitoring of low-energy gamma rays is therefore highly desirable. Development of next-generation instrumentation is technically challenging since a combination of large effective collection area, wide field-of-view and good angular resolution is required. Recent advances in position-sensitive detectors and associated electronics have made it possible to consider a multi-scatter Compton telescope as an all-sky monitor for energies in the range ~30 keV to a few MeV. We have performed simulations of various configurations of such an instrument and find that it can provide a substantial improvement over current sky monitors in this energy regime