Determining the energy-dependent X-ray flux variation of a synchrotron beamline using Laue diffraction patterns

Although the spectrum originating from a superconducting bending magnet is quasi-continuous, it shows important intensity variations through its spectral range. A method to determine the incident energy-dependent flux variation based on the comparison between observed intensities and the calculated intensities of a well known structure (calcite) is presented here. It is found that the measured flux is highly sensitive to the use of correct Debye-Waller factors for the atoms of the standard crystal. By using the measured flux curve, it was possible to unambiguously index the Laue diffraction pattern of a trigonal crystal structure in its hexagonal setting. This is a crucial but difficult first step for the determination of strain and stress in materials with this symmetry, such as quartz, Mg, Ti, Zn etc.