DIFFUSION OF POLARIZED PHOTONS IN THE FRAME OF THE TRANSPORT-THEORY

In the frame of the multiple applications of synchrotron radiation X-ray spectrometry (SRXRS), a detailed description of the transport of polarized photons in condensed media is of utmost importance. The effect of polarization requires four parameters to describe an X-ray beam in place of the single intensity of the models without polarization. Further, the state of polarization changes every time the photon undergoes a scattering event. Accordingly, a proper description of photon transport including polarization effects, here represented with the Stokes parameters, involves a system of four coupled equations of transfer. In this paper, the system of transport equations, describing the diffusion of X-ray photons (including polarization effects) in a homogeneous target of infinite thickness, is solved. An iterative solution, universally valid for all the interactions in the X-ray regime, is obtained. The solution is applied, e.g. to study Rayleigh scattering of (initially) unpolarized X-rays. The first and second order Rayleigh intensities are compared with similar terms computed with a scalar model using a kernel with averaged polarization, in order to quantify the influence of including, rigorously, polarization in the prediction of multiple scattering intensities of the Rayleigh effect.