101. A micro channel-cut crystal X-ray monochromator for a self-seeded hard X-ray free-electron laser.
- Author
-
Osaka T, Inoue I, Kinjo R, Hirano T, Morioka Y, Sano Y, Yamauchi K, and Yabashi M
- Subjects
- Diamond chemistry, Electrons, Equipment Design, Silicon chemistry, X-Rays, Lasers, Optics and Photonics instrumentation
- Abstract
A channel-cut Si(111) crystal with a channel width of 90 µm was developed for achieving reflection self-seeding in hard X-ray free-electron lasers (XFELs). With the crystal a monochromatic seed pulse is produced from a broadband XFEL pulse generated in the first undulator section with an optical delay of 119 fs at 10 keV. The small optical delay allows a temporal overlap between the seed optical pulse and the electron bunch by using a small magnetic chicane for the electron beam placed between two undulator sections. Peak reflectivity reached 67%, which is reasonable compared with the theoretical value of 81%. By using this monochromator, a monochromatic seed pulse without broadband background in the spectrum was obtained at SACLA with a conversion efficiency from a broadband XFEL pulse of 2 × 10
-2 , which is ∼10 times higher than the theoretical efficiency of transmission self-seeding using a thin diamond (400) monochromator.- Published
- 2019
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