Influence of the photon beam position on incident SR intensity at SXMCD endstation

TL;DR

This study investigates how small shifts in photon beam position at the SXMCD endstation influence the synchrotron radiation intensity and polarization, proposing a new method to estimate the circular polarization degree based on absorption measurements.

Contribution

It introduces a novel approach to estimate the circular polarization degree of synchrotron radiation using absorption data from gold mesh measurements at different beam positions.

Findings

Absorption intensity follows a Gaussian distribution with beam position changes.

The ratio of SR passing through upper and lower apertures varies monotonously with beam position.

A new method for estimating SR circular polarization degree is proposed.

Abstract

A small fluctuation of the photon beam position will affect the characteristics of the synchrotron radiation (SR) intensity and polarization when it enters the end-station through the related beamline. In this paper, by changing the electron orbit equilibrium position in the vertical direction, we have measured the corresponding changes in the absorption strength of the SR with a gold mesh in different chopper aperture positions. It is found that for three aperture positions, the absorption intensity of the gold mesh shows a good Gaussian distribution as the photon beam position moves, while the ratio of the SR intensity passing through the upper and lower apertures shows a monotonous variation. This suggests a new method for estimating the circular polarization degree of SR originating from the bending magnet based on our current measurement.