Abstract
A Monte Carlo algorithm has been developed to calculate the instrumental profile function of a powder diffraction synchrotron beamline. Realistic models of all optical elements are implemented in a ray-tracing software. The proposed approach and the emerging paradigm have been investigated and verified for several existing X-ray powder diffraction beamlines. The results, which can be extended to further facilities, show a new and general way of assessing the contribution of instrumental broadening to synchrotron radiation data, based on ab initio simulations.
Highlights
Most techniques in synchrotron radiation experiments, involving either soft or hard X-rays, extract the physical information by measuring radiation scattering, in terms of an intensity signal versus photon energy, detection position or angle, etc
The general principle is the simulation of the interaction between the photon beam generated by SHADOW and a capillary filled with a known crystal or standard, generating a diffracted photon beam and continuing the ray-tracing along the optical elements found in the beam path from specimen to detector
In order to check the quality of the simulation, a line profile analysis (LPA) with real samples was performed both with the measured instrumental profile function (IPF) and with
Summary
Most techniques in synchrotron radiation experiments, involving either soft or hard X-rays, extract the physical information by measuring radiation scattering, in terms of an intensity signal versus photon energy, detection position or angle, etc. Many experimental techniques base their success on a data analysis where the experimental results are compared with a model including the physics of the scattering phenomenon (absorption, diffraction, etc.), as well as a model of the broadening of instrument and detector caused by their non-ideality. Most data analysis routines include an approximate broadening, e.g. via convolution with Gaussians of adjustable breadth, with the only constraint of keeping the effect within a ‘reasonable’ range of values. Simulation tools in charge of modelling the beamline source and optics usually stop at the sample, providing information on beam size, divergence, energy spread and sometimes polarization or coherence. We show here that this is possible for illustrating how a beamline works and to obtain quantitative information on the instrumental functions, which could be used in data analysis
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