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Figure 3
Flux (photons s−1 0.1% BW−1) as a function of energy for the undulator harmonics of the undulator U23 calculated using SPECTRA 9.0.2 (Tanaka & Kitamura, 2001BB61) at 29.3 m from the source within a 1 mm × 1 mm (35.7 µrad × 35.7 µrad) aperture. This corresponds to the theoretical available flux after the second high-heat-load slit system of the beamline. In order to protect the first monochromator crystal of the HRPD beamline branch the slits are never opened larger than 1 mm × 1 mm. The calculated flux values are used as a starting value for the ray-tracing calculation in SHADOW after the first high-heat-load slit system. The energy spectrum of U23 has a gap between 15.2 keV of the first and 25.6 keV of the third harmonic (minimum gap of 10 mm). Fixed energies of 25.6, 42.7, 60.0 and 77.1 keV used at the beamline are highlighted by the open circles at the end of the third, fifth, seventh and ninth harmonic and correspond to maximum flux reachable at the minimum gap of ∼10 mm.

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ISSN: 1600-5775
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