X-ray Thomson scattering in warm dense matter

The scattering of photons in plasmas is an important diagnostic tool. Especially, the region of warm dense matter can be probed by X-ray Thomson scattering. The scattering cross-section is related to the dynamic structure factor \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$S(k,\omega)$\end{document}. We improve the standard treatment of the scattering on free electrons within the random phase approximation (RPA) by including collisions. The dielectric function is calculated in the Born-Mermin approximation. The inclusion of collisions modifies the dynamic structure factor significantly in the warm dense matter regime. We conclude that a theoretical description beyond the RPA is needed to derive reliable results for plasma parameters from X-ray Thomson scattering experiments.