Single Shot Coherence Properties of the Free-Electron Laser SACLA in the Hard X-ray Regime

摘要

We measured the coherence properties of the free-electron laser SACLA on a single shot basis at an X-ray energy of 8?keV. By analysing small-angle X-ray scattering speckle patterns from colloidal dispersions we found a degree of transverse coherence of β_t = 0.79 ± 0.09. Taking detector properties into account, we developed a simulation model in oder to determine the degree of coherence from intensity histograms. Finally we calculated a coherence time of τ_c = 0.1?fs and a pulse duration of 5.2?fs which corresponds with previous predictions.