Characterization of an ASIC front-end electronics dedicated to the Silicon Drift Detectors

Large-area multi-anode Silicon Drift Detectors (SDDs) have X-ray imaging and spectroscopic characteristics that make them extremely attractive in the perspective of their applications to the field of space astrophysics and in instruments for medical diagnostic imaging. We describe here, in a few words, two developing applications concerning both these application fields. Nevertheless, the aim of this paper is to describe the characterisation of an ASIC suitably developed for coupling with SDDs. Notwithstanding the 1D nature of the SDD when the event time is not known, an algorithm that exploits the charge diffusion to reconstruct the position of the photon absorption point also along the drift direction (that is, the one formally not position-sensitive) was developed. So the SDD has the actual 2D imaging capability with both the spatial and energy resolution. The ASIC was developed specifically to account for these detector characteristics and to improve them. The structure of the ASIC and the 2D imaging method will be described and the characterization of the first prototypes of the ASIC will be exposed in terms of the energy resolution and noise. Finally preliminary tests of the ASIC will be shown.