Monte Carlo simulation of a multiple CsI bar detector for gamma-ray astronomy

We present the results from a Monte Carlo simulation of a prototype of the imager proposed for the gamma-ray satellite experiment INTEGRAL. The instrument is based on a two layer CsI(Tl) detector position sensitive in all three dimensions that will be coupled with a coded aperture mask placed ∼ 4 m from the scintillator. The Monte Carlo simulations have been performed using both the GEANT3 and EGS4 packages. In this article we present Monte Carlo estimates the three key detector features: detection efficiency for ensuring good sensitivity in the MeV region, energy resolution, and polarisation capability for increasing the possible astrophysical studies. For these two last points in particular, the new possibilities offered by the 3D position sensitivity of the detector are investigated.