XRF spectrometers based on monolithic arrays of silicon drift detectors:: Elemental mapping analyses and advanced detector structures

We present a novel X-ray Fluorescence (XRF) spectrometer based on a ring-shaped monolithic array of silicon drift detectors (SDDs) with a hole laser-cut in the center and we show some examples of its application in elemental mapping analyzes. The X-ray excitation beam, focused by a polycapillary X-ray lens in a small and intense spot, reaches the sample going through the central hole of the detector chip. This geometry allows the collection of a large fraction of the fluorescence emitted by the sample and the reduction of the distance between the sample and the detector and, therefore of air absorption. These features, together with the high detection rate of the SDDs shorten the scanning time in elemental mapping. Some application examples of the new spectrometer in different research fields, from archaeometry to biology, are shown. Moreover, the paper introduces a new topology of the multi-element detector based on four SDDs monolithically integrated in a Silicon chip and surrounding a hole cut in its center. The structure of the four SDDs has been specifically designed to obtain very high energy-resolution and peak-to-background ratio. The first experimental results obtained with this detector are presented. It will equip a future version of the XRF spectrometer.