MEASUREMENT OF THE LINEAR-POLARIZATION OF PARAMETRIC X-RADIATION

The linear polarization of Parametric X-radiation (PXR) produced by 80 .5 MeV electrons in a 13 mu m thick silicon single crystal has been an alyzed by means of a novel method of polarimetry exploiting directiona l information of the photoeffect in a charge coupled device consisting of 1.3 x 10(6) square pixels of 6.8 mu m. The experiment was carried out at the Darmstadt superconducting linear accelerator S-DALINAC prov iding a low-emittance electron beam. The linear polarization of the (2 2 0) reflection observed in eight narrow angular bins between 20 degr ees and 21 degrees with respect to the electron beam direction is cons istent with complete local linear polarization. The orientation of the polarization plane, within measurement errors of typically 10 degrees , varies over the diffraction pattern in such a way as to be expected from kinematical theory. The result of this experiment is in contradic tion to the only other PXR polarization measurement performed so far. (C) 1998 Elsevier Science B.V. All rights reserved.