Detectors for high resolution gamma-ray imaging based on a single CsI(Tl) scintillator coupled to an array of silicon drift detectors

Silicon Drift Detectors (SDDs) coupled to scintillators have been recently employed successfully in gamma-ray detection. The low value of output capacitance of a SDD allows to reach a lower electronics noise with respect to a conventional silicon photodiode. Detectors based on array of SDDs are of particular interest for gamma-ray imaging. A first prototype conceived for high-resolution imaging is based on a monolithic array of small SDDs (5 mm² each unit) with on-chip JFET. The first imaging results obtained with a seven elements array are here reported. For the realization of gamma detectors of larger active areas, SDDs of 30 mm² of area with external JFET, to be assembled in arrays have been produced. We present the experimental results obtained in the characterization of a single CsI(Tl)-SDD unit