New development of Silicon Drift Detectors for gamma-ray spectroscopy

In this work, we report on a new development of Silicon Drift Detectors (SDDs) for gamma-ray spectroscopy for astronomy applications, within a research project supported by the European Space Agency. The final goal of the development is the realization of monolithic arrays of SDDs which will be assembled to readout large (2″×2″ and 3″×3″) LaBr3 scintillators. We report on the development of a new single SDD prototype, with 8×8 mm² active area, produced at FBK semiconductor laboratories. For the readout of the SDD signals,we have adopted a CMOS charge preamplifier (CUBE) recently developed at Politecnico di Milano. This preamplifier has allowed to achieve state-of-the-art noise performance using a relatively standard SDD technology process. A quantum efficiency of about 80% has been measured on the SDD at the emission wavelengths of LaBr3 (360–380 nm). In first experimental measurements irradiating the SDD, without scintillator, with a ⁵⁵Fe source we achieved an energy resolution of 140eV and 129eV, respectively, at −20°C and −43°C. By coupling the SDD with a LaBr3 scintillator (9mm diameter), we have measured an energy resolution of 5.6% FWHM and 2.6% FWHM respectively at 122keV and 662keV.