부산대학교 도서관

We present a spectroscopic system constituted by a Silicon Drift Detector (SDD) coupled to a CMOS charge sensitive preamplifier, named SIRIO, specifically designed to reach ultimate low noise levels. The SDD, with an active area of $\hbox{13~mm}^2$, has been manufactured by optimizing the production processes in order to reduce the anode current, successfully reaching current densities between $\hbox{17~pA/cm}^2$ and $\hbox{25~pA/cm}^2$ at $ + \hbox{20}~^\circ {\rm C}$ for drift fields ranging from 100 V/cm to 500 V/cm. The preamplifier shows minimum intrinsic noise levels of 1.27 and 1.0 electrons r.m.s. at $+\hbox{20}~^{\circ}{\rm C}$ and $-\hbox{30}~^{\circ}{\rm C}$, respectively. At room temperature ($ + 20^\circ {\rm C}$) the $^{55}{\rm Fe}$ 5.9 keV and the pulser lines have 136 eV and 64 eV FWHM, respectively, corresponding to an equivalent noise charge of 7.4 electrons r.m.s.; the noise threshold is at 165 eV. The energy resolution, as measured on the pulser line, ranges from 82 eV FWHM (9.4 electrons r.m.s.) at $ + \hbox{30}~^\circ {\rm C}$ down to 29 eV FWHM (3.3 electrons r.m.s.) at $ - \hbox{30}~^\circ {\rm C}$.