CDTE ARRAY SPECTROMETERS FOR X-RAY AND GAMMA-RAY ASTRONOMY

Our knowledge of the hard-X- and soft-gamma-ray sky obtained in the la st few years by satellite missions and in particular by SIGMA has demo nstrated that in this energy range the next generation of instruments must provide both good imaging over a large field of view and fine spe ctroscopy over a large energy band. Currently, a possible answer to th ese requirements may be offered by instruments based on position-sensi tive detectors (PSD) constructed of modular arrays of CdTe microspectr ometers. CdTe is a room temperature compound semiconductor with high Z that can be grown in large pure crystals and then cut so as produce s mall spectroscopic devices. By packing these elements into arrays, it is possible to construct highly segmented detectors sensitive from app roximately 10 keV to a few MeV. Due to the intrinsic characteristics o f these CdTe microspectrometers, such a PSD would offer fine spatial r esolution (down to a few millimetres) and good spectroscopic performan ce (E/DELTAE > 50 for E = 500 keV). We present experimental results ob tained from CdTe microdetectors with various geometrical shapes and si zes. Furthermore, we outline a possible coded-mask telescope design ba sed on a CdTe PDS together with an evaluation of the achievable sensit ivity.