Synchrotron Beam Polarization Factor

The polarization factor, Pol, takes into account the variation in scattering intensity caused by the beam polarization, as can be anticipated because elastic scattering is forbidden along the polarization direction of the incident beam. Synchrotron sources typically produce X-ray beams that are linearly polarized in the horizontal plane. Most synchrotron-based scattering measurements are performed with the scattering angle measured in the vertical plane, so that P= 1. For horizontal scattering spectrometers with a horizontally-polarized beam, the polarization factor is P = cos(2 ). A number of spectrometers scan the detector in both the vertical and horizontal planes. 

Most of the current optics using Synchrotron Radiation diffracts in the vertical plane and thus is sensitive to vertical bouncing of the beam. The horizontal optical plane of the dispersive scheme combines this extra advantage which helps to keep superior energy resolution since the orbit seems to show a better stability in the horizontal direction. Owing to the horizontal polarization of S.R., one must consider the cos (20) attenuation factor which reduces the Darwin width of the crystal. This results in a lower reflectivity and an improved energy resolution as well. 

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