%0 journal article
%@ 1367-2630
%A Blumenhagen, K.-H., Fritzsche, S., Gassner, T., Gumberidze, A., Maertin, R., Schell, N., Seipt, D., Spillmann, U., Surzhykov, A., Trotsenko, S., Weber, G., Yerokhin, V.A., Stoehlker, T.

%D 2016
%J New Journal of Physics
%N 10
%P 103034 
%R doi:10.1088/1367-2630/18/10/103034
%T Polarization transfer in Rayleigh scattering of hard x-rays
%U https://doi.org/10.1088/1367-2630/18/10/103034
10 
%X We report on the first elastic hard x-ray scattering experiment where the linear polarization characteristics of both the incident and the scattered radiation were observed. Rayleigh scattering was investigated in a relativistic regime by using a high-Z target material, namely gold, and a photon energy of 175 keV. Although the incident synchrotron radiation was nearly 100% linearly polarized, at a scattering angle of $\theta =90^\circ $ we observed a strong depolarization for the scattered photons with a degree of linear polarization of $+0.27 \% \pm 0.12 \% $ only. This finding agrees with second-order quantum electrodynamics calculations of Rayleigh scattering, when taking into account a small polarization impurity of the incident photon beam which was determined to be close to 98%. The latter value was obtained independently from the elastic scattering by analyzing photons that were Compton-scattered in the target. Moreover, our results indicate that when relying on state-of-the-art theory, Rayleigh scattering could provide a very accurate method to diagnose polarization impurities in a broad region of hard x-ray energies.