Ultra Low Noise Silicon Drift Detector and CMOS Front-End for X-Ray Spectroscopy with Less than 100 eV Energy Resolution at Room Temperature

We present a spectroscopic system constituted by a Silicon Drift Detector (SDD) coupled to a CMOS charge preamplifier specifically designed for ultimate low noise levels. The upper limit of the SDDs-based system operating temperature is presently determined by the detector current density at the anode, ranging from 1 nA/cm2 down to 200 pA/cm2 at room temperature for typical and best devices and by the noise of the Front-End Electronics at short shaping times. For these limits usually SDD operates at temperature between -20 C and -50 C. Our SDDs has been manufactured by optimizing the production processes in order to reduce the anode current, successfully reaching a current density of 28 pA/cm2 at room temperature. The preamplifier has a noise level of less than 4 electrons r.m.s. at room temperature and short shaping times. With this system it was possible to reach at +21C with a pulser line width of only 74 eV FWHM (8.6 electrons r.m.s.), a noise threshold of 190 eV and to acquire a 55Fe spectrum with 141 eV FWHM at 5.9 keV