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![[Figure 2]](vl5005fig2mag.jpg)
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Figure 2
The positioning of several Si(111) analyser crystals on a logarithmic-spiral curve optimizes the paths of the beams coming from the centre O of this curve which impact with the same angle Ψ the middle of each analyser crystal; in this figure the crystals are tilted with a 1° pitch and the corresponding beam paths through this LogSpiral MAD filter are represented. (a) To avoid interception/cutting of beams coming from the sample, the maximum length of the crystals l and their spacing i are imposed by the lowest energy accepted by this rigid MAD system, here 9.5 keV, which corresponds to l = 26 mm and i = 8 mm for a sample-to-analyser distance D = 460 mm, and allow simultaneous measurements with an angular step of 1° and a beam width of 4.6 mm. (b) At higher energies, the same crystal size and spacing leads to a decrease in the width of the beams analysed to 1.6 mm at 37.78 keV. (c) This LogSpiral curved analyser surface can be realized either by a single thin curved crystal or by several crystals supported on a fixed and rigid dedicated curved surface. |
![[Figure 2]](vl5005fig2.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
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