An analytical model for fluorescent and scattering X-ray beam monitor designing

Abstract

All the beamlines at modern synchrotron facilities are equipped with X-ray Beam Intensity or Position Monitors. Among those monitors, a relatively simple device is aiming at measuring the X-ray fluorescence and the X-ray scattering (elastic and inelastic) signal emitted from a thin foil with a punctual detector, a combination of several punctual detectors or a 2D detector. To improve the design of this kind of monitor, an analytical simulation has been developed to estimate the recording signal intensity according to the foil, the detector and the beam parameters. The mains X-ray interaction with matter processes involved in these monitors are simulated and several parameters of the incident X-ray beam are taken into account such as its intensity, energy, size and polarization. Furthermore, in contrast to the complex and time-consuming Monte-Carlo method, this analytical simulation is performed in few seconds and is implemented in a user-friendly interface. In order to validate our tool, the simulated results were compared to a series of measurements performed on the METROLOGIE beamline of the SOLEIL synchrotron. The differences with the experimental results are less than 30% by using a metallic foil and less than 50% with a Kapton® foil. The performances of our tool in term of accuracy, computation time and ease of use are perfectly adapted for the design of X-ray monitors based on an X-ray fluorescence and scattering foil.