Hannover 2016 – wissenschaftliches Programm

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K: Fachverband Kurzzeitphysik

K 4: Poster

K 4.5: Poster

Dienstag, 1. März 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.