Present and future Anger cameras based on Silicon Drift Detectors

Silicon drift detectors (SDDs) have recently shown to be a competitive device for the readout of scintillator with respect to conventional photodetectors like photomultiplier tubes, thanks to their high quantum efficiency and low electronics noise. In particular, arrays of SDDs could represent an interesting photodetector to be employed in the development of Anger cameras with high position resolution. Recently, we have developed the DRAGO camera, which is a high-resolution Anger camera based on a monolithic array of 77 SDDs, with an active area of 6.7 cm², coupled to a scintillator crystal. The performances achieved in gamma-ray imaging using this camera are first reported in this work. According to the achieved results, we are now designing a new Anger camera, in the framework of the HICAM project, composed by 100 SDDs of 1 cm² each in a 10times10 cm² format. This camera is foreseen to be employed in application mainly for human imaging where high-position resolution and camera compactness are of primary interest. The main issues of the design of this camera as well as the results of Montecarlo simulations of its performances are presented in this work. As a basic unit for this camera, we have experimentally characterized the electronics noise and gamma-ray performances, when coupled to a scintillator, of a SDD of 1 cm² of active area. This device shows excellent performances in terms of electronics noise with moderate cooling achieved by a Peltier element.