Development of a detector based on Silicon Drift Detectors for gamma-ray spectroscopy for astronomy applications

This work deals with the development of a new gamma detector based on Silicon Drift Detectors (SDDs) to read out large (3"×3") LaBr₃:Ce scintillators for gamma-ray spectroscopy for astronomy applications, an activity supported by European Space Agency (ESA). SDDs, characterized by high quantum efficiency and low electronic noise, are good candidates in applications with a wide energy range of gamma rays to be detected from 150keV to 15MeV. A first prototype is under development with the aim to achieve an energy resolution of 3% FWHM at 662 keY. The SDDs are designed as monolithic arrays of 3×3 units, each one of an active area of 8 mm × 8 mm (total array area of 26 mm × 26 mm).To cover the large surface of the 3"×3" LaBr3:Ce scintillator the modules are expected to be arranged in a 3×3 matrix, for a total of 81 SDDs read out by a custom developed electronics. In this work we will report on the design issues of this detector and on the first experimental results obtained in gamma-ray spectroscopy with a 1"×1" LaBr₃:Ce scintillator.