A compact‐rigid multi‐analyser for energy and angle filtering of high‐resolution X‐ray experiments. Part 2. Efficiency of a single‐crystal‐comb

• Published in: Journal of synchrotron radiation Vol. 30; no. 1; pp. 126 - 136
• Main Authors: Hodeau, J.-L., Prat, A., Boudet, N., Blanc, N., Arnaud, S., Hazemann, J.-L., Lahéra, E., Proux, O., Jacquet, M., Autran, P.-O., Dejoie, C., Martinetto, P.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.01.2023; John Wiley & Sons, Inc
• Subjects: Collimators; compact-rigid multi-analyser; Crystals; Cultural heritage; Cultural resources; Diffraction; Efficiency; Filtration; heterogeneous materials; high-resolution powder diffraction; Instrumentation and Detectors; Laboratories; multi-analyser-diffraction filtering; Physics; Radiation sources; Research Papers; Synchrotron radiation; Synchrotrons; compact-rigid multi-analyser; heterogeneous materials; high-resolution powder diffraction; multi-analyser-diffraction filtering
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S1600577522011250

Diffraction instruments using filtering by one or several analyser crystals exist since the 1980s and 1990s at synchrotron radiation sources, but, due to its low efficiency, this filtering is little used on laboratory sources. In order to overcome this limitation, the efficiency of a small diffraction filtering multi‐analyzer block (MAD block) realized with a `single‐crystal‐comb' curved on a rigid support is demonstrated here. The geometry of this curved surface is logarithmic spiral and is optimized to allow multi‐filtering over a relatively important diffraction angular range and to be also applicable over an X‐ray spectral range. The efficiency of such a small rigid‐compact MAD block consisting of this single‐crystal‐comb generating 20–50 Si(111) single‐crystal blades, associated with a block of Soller collimators, is demonstrated. The angle between each crystal is 0.1°, so the measurement range of the comb is 2–5°. The geometry of this system has been optimized for operation with a synchrotron X‐ray source over an energy range of 22 keV to 46 keV and could be used with laboratory X‐ray sources (Ag Kα1, 22.1 keV). This MAD block complements and exploits the qualities of the `photon‐counting' detectors which have very low intrinsic noise. Their joint efficacy is supported by powder pattern measurements of a LaB6 reference sample and of several heterogeneous samples of cultural heritage materials, carried out at 22 keV on the D2AM beamline at the ESRF. Their signal‐to‐noise ratio is excellent (1000/1) and allows the detection thresholds of the measurements (from 3–1% to 0.1%) to detect minor phases in the studies of `real' heterogeneous materials to be drastically improved. The efficiency of a small multi‐analyser block of diffraction filtering, formed by a `single‐crystal‐comb' curved on a logarithmic spiral rigid support that allows 20–50 filtering measurements in parallel, is discussed and tested on a reference powder and on complex samples. It gives an excellent signal‐to‐noise ratio (1000/1) and drastically improves the detection thresholds of measurements (from 3–1% to 0.1%) to detect minor phases in studies of `real' heterogeneous materials.