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Small-angle X-ray scattering using coherent undulator radiation at the ESRF.
D L Abernathy1, G Grübel, S Brauer
1European Synchrotron Radiation Facility, BP 220, 38043 Grenoble CEDEX, France.
Journal of Synchrotron Radiation
|May 12, 2006
Summary
A new method creates a high-flux X-ray beam for small-angle scattering, enhancing synchrotron experiments. This technique optimizes beam properties for advanced diffraction studies.
Area of Science:
- Synchrotron radiation science
- X-ray optics
- Materials science
Background:
- Small-angle X-ray scattering (SAXS) requires specific beam properties.
- Traditional methods may not achieve optimal flux and coherence for certain SAXS applications.
Purpose of the Study:
- To develop a simple method for generating a high-coherent-flux X-ray beam.
- To optimize beam characteristics for small-angle scattering studies at the Troika beamline.
Main Methods:
- Utilizing mirrors and filters to select specific energies from the undulator harmonic structure.
- Reducing the longitudinal coherence length to increase energy bandpass and intensity.
- Analyzing speckle patterns from an aerogel sample using a CCD camera to measure coherent properties.
Main Results:
- A high-flux beam (>10^9 photons/s) was produced at 8.2 keV with a 1.3% bandpass through a 5-micron pinhole.
- Speckle pattern analysis confirmed expected spatial autocorrelation widths.
- An apparent incoherent fraction was observed, reducing measured speckle contrast.
Conclusions:
- The developed method successfully produces a high-flux, partially coherent X-ray beam suitable for SAXS.
- The technique allows for optimization of beam conditions for diffraction experiments.
- Further characterization is needed to fully understand and mitigate the incoherent fraction.