SpeAR_XFEL

X-ray free-electron-lasers generate laser pulses based on the principle of self-amplification of spontaneous emission. This allows for continuous tuning of the X-ray radiation wavelength and leads to the emission of a train of ultrashort, more precisely a few hundred femtoseconds long, X-ray spikes. However, the principle of self- amplification of spontaneous emission has some drawbacks, which have to be overcome to study well-defined measurements relying on precise knowledge of the activation signal. Only if parameters such as stochastically varying shot intensities, separations, durations as well as photon energies are known, the potential of ultrafast and nonlinear measurements can be fully exploited. To achieve knowledge about the underlying parameters, temporal and spectral characteristics of X-ray pulses have to be examined utilizing real-time analysis techniques.

To receive the required characteristics, the main objective during the project SpeAR_XFEL is to design and construct a novel, angle-resolved electron multi-time-of-flight spectrometer with individually variable retardation voltage and high energy resolution for XUV and X-ray-triggered ultrafast measurement. For this purpose, suitable online analysis techniques based on machine learning methods have to be developed.

Tasks of Intelligent Embedded Systems regarding this project are:

• Development of suitable analysis techniques to cope with the load of measured data.
• Consideration of correlations within individual data sets of the angle-dependent detection and therefore distill the most general information from the experiment using, e.g., machine learning techniques.
• This should result in an implementation of an online X-ray characterization tool based on deep learning methods.

Cooperation partners during this project are:

• TU Dortmund, Zentrum für Synchrotronstrahlung (DELTA)
• Universität Kassel, Institut für Physik und CINSaT
• European X-Ray Free-Electron Laser Facility GmbH
• Helmholtz Zentrum Berlin, BESSY II