Towards Efficiency and Count-Rate Enhancement of X-ray ARDESIA Spectrometer

The development of new generations of synchrotron light sources aims at increasing their beam in term of flux and brightness. To cope with extremely high-brilliance sources, fluorescence detectors must go beyond their nowadays maximum throughput while keeping almost unchanged the performance. This paper has been carried out within the framework of the ARDESIA (ARray of DEtectors for Spectroscopy and Imaging Applications) project, whose primary aim is to develop a spectrometer with count-rate capability for applications like Xray absorption spectroscopy (XAS) and X-ray fluorescence (XRF). ARDESIA is a Silicon Drift Detector (SDD)-based, multichannel X-ray spectrometer, optimized for synchrotron applications requiring a high-count rate (>1Mcps per channel) and a high-resolution (e.g. below 150 eV of Full Width Half Maximum at peaking times faster than 200 ns) for X-ray fluorescence detection. This paper describes improvements made for the ARDESIA spectrometer on detection efficiency and overall counting rate capability to better match requirements of synchrotron experiments. These improvements have been obtained by increasing the number of channels, from 4 to 16, and the SDD thickness from 450 μm to 800 μm and 1000 μm. The new detection module and the new complete spectrometer are described in detail. The first 16-channel detection module prototype has been developed with an average resolution of 128 eV at the Mn-Kα at long peaking times (i.e. > 2 μs) and 183.5 eV at short peaking time (i.e. 32 ns). Then, the qualification of the 4channel 1mm-thick detector at the PETRA (Positron-Elektron-Tandem-Ring-Anlage) P65 beamline in DESY (Deutsches Elektronen-Synchrotron) is reported.