Silicon Drift Detectors and CUBE Preamplifiers for High-Resolution X-ray Spectroscopy

Abstract

In this work we present the results of the experimental characterization of Silicon Drift Detectors (SDDs) readout by CUBE preamplifiers for X-ray spectroscopy measurements. One specific goal of the work was to characterize SDDs of different sizes cooled at low temperature in view of their use in the upgrade of the SIDDHARTA nuclear physics experiment. Beside the target application, the results of this work are also of interest for a more extended use of the SDDs in other X-ray spectroscopy applications. The SDDs have been designed as single units with square shape of different areas, $64$ mm $^{2}$ ( $8~\hbox{mm} \times 8~\hbox{mm}$ ) and $144 $ mm $^{2}$ ( $12~\hbox{mm} \times 12~\hbox{mm}$ ), and also as monolithic array of $3 \times 3$ elements of the $8~\hbox{mm} \times 8~\hbox{mm}$ unit (total area $26~\hbox{mm} \times 26~\hbox{mm}$ ). The read-out of the SDDs is based on a CMOS (Complementary Metal Oxide Semiconductor) preamplifier (CUBE) both for the single unit and for the $3 \times 3$ array. For the readout of the array, an Application Specific Integrated Circuit (ASIC) has been used. An energy resolution better than 124 eV at the ${\rm Mn} - {\rm K}\alpha $ line has been measured with a $64 $ mm $^{2}$ SDD cooled at the temperature of 50 K. The energy resolution remains good ( $ eV) also at short shaping time (250 ns) thanks to the noise feature of the CUBE preamplifier. Results of measurements on SDDs of different format and also on arrays of SDDs are presented in this work.