Monte Carlo techniques in X-ray analytics with synchrotron radiation

Monte Carlo techniques are powerful tools to simulate the interaction of electromagnetic radiation with matter. One of the most widespread simulation program packages is Geant4. But it is not evident which accuracy can be obtained by a simulation. In this work, results of experiments using monochromatized synchrotron radiation in the X-ray regime are quantitatively compared to the results of simulations using Geant4. For the quantitative measurements a cadmium telluride detector was used, that had been fully characterized and calibrated in the laboratory of PTB at the electron storage ring BESSY II. For the simulations the detector was modeled with high accuracy. Whereas for most set-ups good agreement of experimental and simulation results was observed, for some orientations a dominant Rayleigh-scattered contribution was observed only for the simulations. For small scattering angles, prominent deviations were observed, which were caused by diffraction in the experiments. As a complementary perspective ray tracing techniques shall be further developed for the optimization of X-ray optics based on highly oriented pyrolytic graphite (HOPG) mosaic crystals.