Statistical Analysis of X-ray Speckle at the NSLS

TL;DR

This paper analyzes the statistical properties of X-ray speckle from a disordered aerogel to assess beam coherence and photon rates at a synchrotron source, revealing discrepancies with expected coherence and photon flux.

Contribution

It provides a quantitative assessment of the coherence and photon flux at a specific beamline using speckle analysis, highlighting deviations from theoretical expectations.

Findings

Coherence at the beamline is within 35% of expected values.

The coherent photon rate is about half of the predicted based on source brilliance.

Speckle analysis can effectively evaluate beam coherence and photon flux.

Abstract

We report a statistical analysis of the static speckle produced by illuminating a disordered aerogel sample by a nominally coherent x-ray beam at wiggler beamline X25 at the National Synchrotron Light Source. The results of the analysis allow us to determine that the coherence delivered to the X25 hutch is within 35% of what is expected. The rate of coherent photons is approximately two times smaller than expected on the basis of the X25 wiggler source brilliance.