Ultra-fast XRF spectrometer based on a novel high-performance ring-shaped semiconductor drift detector

An ultra-fast XRF spectrometer based on a novel ring-shaped semiconductor drift detector (SDD) and on a novel readout and processing electronics is introduced and its performance is discussed. The new detector is based on 4 independent "droplet" type SDDs monolithically integrated on the same chip. The detector shape optimizes the collection angle for the fluorescence radiation. The excitation X-ray 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 130 eV on the Mn Kalpha line with 1 mus shaping time at -20degC and the peak-to-valley ratio is of the order of 6000. In order to fully exploit the detection rate performances of this detector we have developed a novel read-out electronic unit. This unit allows the shaping time selection between 150 ns (high rate measurements) and 450 ns (high resolution measurements). Thanks to the on-board histogramming capability a total count-rate higher than 3 Mcounts/s can be reached on the four SDDs