Imaging performances of the DRAGO gamma camera

In this work, we present the results of the experimental characterization of the DRAGO gamma camera. This camera is based on a monolithic array of 77 Silicon Drift Detectors (SDDs), with a total active area of 6.7 cm2, coupled to a single CsI(Tl) scintillator crystal, 5 mm thick. The use of an array of SDDs provides high quantum efficiency for the detection of the scintillation light together with a very low electronics noise. A very compact detection module based on the use of integrated readout circuits has been developed. Performances achieved in gamma-ray imaging using this camera are here reported. When imaging a 0.2 mm collimated 57Co source (122 keV) over different points of the active area, a spatial resolution ranging between 0.25 and 0.5 mm has been measured. The depth of interaction capability of the detector, thanks to a maximum likelihood reconstruction algorithm here adopted, has been also investigated by imaging a collimated beam tilted to an angle of 45° with respect to the scintillator surface.