High stability X-ray spectroscopy system with on-chip front-end in charge amplifier configuration

This paper presents the performance of a two-chip detector system based on a silicon drift detector and on a charge amplifier, part of the latter being integrated in the detector chip. The two-chip system is intended for high-resolution X-ray spectroscopy experiments in which stability of operation is mandatory to avoid on-line calibration procedures. Experimental measurements have been carried out to test the stability of the whole system with a quantitative analysis of the gain stability obtained by comparing X-ray spectra taken at different operating conditions, varying the temperature and/or the detector bias. A gain variation of less than 0.4% has been obtained at extreme operating conditions. The problems and critical aspects of the two-chip charge amplifier solution are discussed.