A compact-rigid multi-analyser for energy and angle filtering of high-resolution X-ray experiments. Part 1. Principles and implementation

Prat, A.; Hodeau, J.-L.

doi:10.1107/S160057752201116X

Figure 4
Optimization of the curvature of crystal sheets to realize Laue mode analysers; along its curvature, at every 1°, the diffraction planes of these thin curved crystals are symbolized by a large plane with the corresponding direction of its incident X-ray beam. (a) Examples of crystal plane orientations for positioning the thin Si single-crystal sheet in a transmission MAD system. (b) Beam paths from two sources at 7 keV and 9 keV (green and purple, respectively) arriving on the Si(111) planes of two single-crystal sheets which have ideal curvatures for 7 keV and 9 keV, respectively; the origins of these representations have been translated so that the midpoints of the two curved crystal sheets are coincident. (b′) Zoom-in on the directions and impacts of the beams at the upper ends of the single-crystal sheet which enlarge the most important curvature difference existing between 7 keV and 9 keV (green and purple), an energy range close to that of a Cu Kα₁ X-ray source. (c) Beam paths coming from these two different energy sources 7 keV and 9 keV, positioned to be filtered by Si(111) planes of a single-crystal sheet having its curvature determined for 9 keV in both cases; the purple curve represents the ideal paths of the 9 keV beams filtered by a MAD system having an ideal curvature for 9 keV, the blue curve represents the paths of the 7 keV beams filtered by a MAD system having a modified curvature corresponding to 9 keV filtering and corrected due to a δD optimization of the sample-to-MAD-system distance. (c′) Enlargement showing this variation δD in the distance of the sample from the MAD system which can modify and reduce the deviations of the Bragg angle Θ_A of the beams on this curved crystal of the MAD filter and can allow a wider angular range of filtering, as discussed in the text and in Fig. 5

. (c′′) Zoom-in on the impact of these 7 and 9 keV beams, at the upper ends of the single-crystal sheet with curvatures determined for 9 keV ideally and with the modification due to a small δD variation of the sample-to-MAD-system distance.

JOURNAL OF
SYNCHROTRON
RADIATION

ISSN: 1600-5775

Volume 30| Part 1| January 2023| Pages 111-125

https://doi.org/10.1107/S160057752201116X

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