view article
Figure 4
Probability density distributions of transverse pointing-angle fluctuations at the entrance to the SPB/SFX instrument of the European XFEL. Histograms show the distribution of pointing deviations after centering on the inter-train, intra-train and single-shot mean angles (virtual references), where κ denotes the kurtosis of the intra-train pointing-angle distributions. Shot-to-shot pointing-angle measurements reflect the spatial averaging of discrete speckle displacements derived from finite detector sampling. As the intrinsic single-shot pointing uncertainty is substantially smaller than the effective discretization interval of the estimator, the inter-train distributions exhibit an apparent multi-peak structure. Gaussian mixture models of order ng are therefore used to capture the underlying envelope of these distributions and estimate their overall range and variance.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 33| Part 5| September 2026|
https://doi.org/10.1107/S1600577526005898
Follow J. Synchrotron Rad.
Sign up for e-alerts
E-alerts
Follow J. Synchrotron Rad. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS