Diagnostics of polarization purity of x-rays by means of Rayleigh scattering

TL;DR

This paper presents a method to diagnose the polarization purity of synchrotron X-ray radiation using Rayleigh scattering, highlighting how tiny polarization impurities significantly influence scattered light polarization.

Contribution

It introduces two novel diagnostic techniques for assessing synchrotron radiation polarization purity, one based on polarization measurements and theoretical calculations, and another on combined polarization and cross section measurements.

Findings

Tiny polarization impurities affect scattered light polarization significantly.

The proposed methods enable precise diagnostics of polarization purity.

The second method is independent of theoretical transition amplitude calculations.

Abstract

The synchrotron radiation is commonly known to be completely linearly polarized when observed in the orbital plane of the synchrotron motion. Under actual experimental conditions, however, the degree of polarization of the synchrotron radiation may be lower than the ideal 100%. We demonstrate that even tiny impurities of polarization of the incident radiation can drastically affect the polarization of the elastically scattered light. We propose to use this effect as a precision tool for the diagnostics of the polarization purity of the synchrotron radiation. Two variants of the diagnostics method are proposed. The first one is based on the polarization measurements of the scattered radiation and relies on theoretical calculations of the transition amplitudes. The second one involves simultaneous measurements of the polarization and the cross sections of the scattered radiation and is independent of theoretical amplitudes.