Erlangen 2018 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 25: Poster Session I

A 25.42: Poster

Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal

Grazing-Incidence XUV Split-Delay Unit for the FLASH2 Reaction Microscope — •Florian Trost¹, Kirsten Schnorr¹, Sven Augustin¹, Georg Schmid¹, Severin Meister¹, Hannes Lindenblatt¹, Yifan Liu¹, Thomas Wodzinski², Barbara Keitel², Elke Ploenjes-Palm², Markus Braune², Marion Kuhlmann², Stefan Düsterer², Rolf Treusch², Thomas Pfeifer¹, Claus Dieter Schröter¹, and Robert Moshammer¹ — ¹Max-Planck-Institut für Kernphysik, Heidelberg — ²DESY, Hamburg

In order to perform XUV pump-probe experiments on small quantum systems such as atomic targets or small molecules and clusters, a new direct-focussing XUV split-and-delay optics was designed, installed and commissioned as part of the permanent reaction microscope user endstation at FLASH2. A planar mirror, which is divided into two halves geometrically, splits an incoming XUV pulse into two parts and introduces a variable temporal delay between them. An off-axis ellipsoidal mirror then focuses the XUV pulses into the gas target of the reaction microscope.

The focus position and the optical aberrations of the FEL beam were measured using a wavefront sensor. We identified the influence of position and rotation of the mirrors on the different aberrations. A focus size of 3 micrometer in diameter was obtained. The new direct-focussing XUV optics decreases background from scattered light compared to our previous back-reflecting geometry due to single passage through the interaction region and because of the smaller focus size.