Design and Construction of a Test-Stand for the Split and Delay Line at the European XFEL

TL;DR

This paper details the design, construction, and initial validation of a test-stand for the Split and Delay Line at the European XFEL, enabling ultra-fast X-ray experiments with femtosecond precision.

Contribution

It introduces a novel test-stand setup for the SDL at the European XFEL, including mechanical, electronic, and vacuum system integration, and demonstrates successful assembly and validation.

Findings

Successful assembly of the SDL test-stand

Initial validation under ultra-high vacuum conditions

Achieved femtosecond temporal separation for experiments

Abstract

This work presents the design and construction of a test-stand for the Split and Delay Line (SDL) at the European X-ray Free Electron Laser (XFEL) in Hamburg, Germany. The advancements in Free Electron Laser technology have now made it possible to investigate ultra-fast dynamics in materials science, biology, chemistry, etc. In the SDL, an incident free electron laser pulse is split into two parts by a beam splitter: one half travels along the upper branch, and the other half travels along the lower branch. These two pulses can either merge again in the collinear mode or travel along different optical paths toward the sample in the inclined mode. This setup achieves a temporal separation of a few femtoseconds between the X-ray pulse pairs, which is crucial for ultra-fast X-ray pump-probe experiments investigating rapid dynamics. This report provides detailed documentation of the mechanical and electronic configuration of the test-stand, vacuum testing, the manufacturing of supporting cables, and the challenges encountered during the project. Finally, the SDL was successfully assembled and initially validated under ultra-high vacuum (UHV) operating conditions.