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" x2" and 3" x3") LaBr3 scintillators. We report on the development of a new single SDD prototype, with 8x8 mm(2) 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 Fe-55 source we achieved an energy resolution of 140eV and 12geV, respectively, at -20 degrees C and -43 degrees 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.