Performance evaluation of an advanced XRF elemental mapping system featuring a novel ring-shaped monolithic array of silicon drift detectors

This paper introduces an ultra-fast x-ray fluorescence (XRF) spectrometer based on a novel ring-shaped Semiconductor Drift Detector (SDD) and on a novel readout and processing electronics and discusses its performance. The new detector is based on 4 independent "droplef' type SDDs monolithically integrated on the same chip. The detector shape optimizes the collection angle of the fluorescence radiation. The x-ray excitation beam is focused on the sample by means of a polycapillary lens through the hole cut in the center of the detector. The "droplet" type SDD is characterized by a better energy resolution and a better peak-to-valley ratio with respect to the ones of "conventional" SDDs. The energy resolution is of the order of 140 eV FWHM on the Mn Ka line with 1 mu s shaping time at - 15 degrees C and the peak-to-valley ratio is of the order of 6000. In order to fully exploit the detection rate performance of this detector we have developed a novel read-out electronic unit with selectable shaping time and on-board histogramming capability.