Radiative electron capture as a tunable source of highly linearly polarized x-rays

TL;DR

This study demonstrates that radiative electron capture into the K shell of Xe ions produces highly linearly polarized x-rays, which can be tuned by adjusting photon energy and emission angle, confirmed by precise measurements and relativistic calculations.

Contribution

The paper provides the first precise polarization measurements of K-REC radiation from Xe ions and confirms its potential as a tunable source of polarized x-rays.

Findings

REC produces highly polarized x-rays for medium-Z ions like Xe.

Photon polarization can be tuned by energy and emission angle.

Measured polarization agrees with relativistic calculations.

Abstract

The radiative electron capture (REC) into the K shell of bare Xe ions colliding with a hydrogen gas target has been investigated. In this study, the degree of linear polarization of the K-REC radiation was measured and compared with rigorous relativistic calculations as well as with the previous results recorded for U$^{92+}$. Owing to the improved detector technology a significant gain in precision of the present polarization measurement is achieved compared to the previously published results. The obtained data confirms that for medium-Z ions such as Xe the REC process is a source of highly polarized x-rays which can easily be tuned with respect to the degree of linear polarization and the photon energy. We argue, in particular, that for relatively low energies the photons emitted under large angles are almost fully linear polarized.