Hannover 2016 – scientific programme
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K: Fachverband Kurzzeitphysik
K 4: Poster
K 4.5: Poster
Tuesday, March 1, 2016, 16:30–19:00, Empore Lichthof
A split-and-delay unit for the European XFEL: Enabling hard x-ray pump/probe experiments at the HED instrument — •Sebastian Roling1, Karen Appel2, Stefan Braun3, Peter Gawlitza3, Harald Sinn2, Frank Wahlert1, Ulf Zastrau2, and Helmut Zacharias1 — 1Westfälische Wilhelms-Universität Münster — 2European XFEL GmbH, Hamburg — 3Fraunhofer IWS, Dresden
For the High Energy Density (HED) instrument at the SASE2 - Undulator at the European XFEL an x-ray split-and-delay unit (SDU) is built covering photon energies from hν = 5 keV up to hν = 24 keV. This SDU will enable time-resolved x-ray pump / x-ray probe experiments as well as sequential diffractive imaging on a femtosecond to picosecond time scale. Further, direct measurements of the temporal coherence properties will be possible by making use of a linear autocorrelation.The x-ray FEL pulses will be split by a sharp edge of a silicon mirror coated with Mo/B4C and W/B4C multilayers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. Because of the different incidence angles, the path lengths of the beams will differ as a function of wavelength. Hence, maximum delays between ±1.0 ps at hν = 24 keV and up to ±23 ps at hν = 5 keV will be possible. Measurements of the reflectance of the multilayer coatings have been performed at the ESRF yielding a maximum reflectance of the Mo/B4C coating of R = 0.85.