Polarization of Parametric X Radiation

Abstract

Polarization properties of parametric x radiation (PXR) produced by ${E}_{0}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}80.5\mathrm{MeV}$ electrons interacting with a $13\ensuremath{\mu}\mathrm{m}$ thick silicon crystal have been investigated. The direction and the degree of the linear polarization of PXR observed at about 20\ifmmode^\circ\else\textdegree\fi{} with respect to the electron beam direction were determined by means of a novel method exploiting directional information of the photoelectric effect in a charge coupled device consisting of $6.8\ifmmode\times\else\texttimes\fi{}6.8\ensuremath{\mu}\mathrm{m}$ pixels. Comparison of the results with a newly derived theoretical expression exhibits very good agreement if on top of the basic interaction process underlying PXR effects decreasing the polarization are taken into account.