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

M Vockert,S Litvinov,T Gaßner,S Fritzsche,A Gumberidze,F Nolden,G Weber,J Glorius,M Lestinsky,M S Sanjari,C Trageser,U Spillmann,A Surzhykov,S Trotsenko,Th Stöhlker,T Krings,C Kozhuharov,R Märtin,M Steck,U Popp,H Bräuning,Yu A Litvinov,S Hagmann,N Petridis,C Brandau,R Heß ,D Winters ,P.‐M Hillenbrand ,Sabrina Geyer ,Sebastian Heß

doi:10.1103/physreva.99.052702

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 U92+. 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.Received 22 February 2019DOI:https://doi.org/10.1103/PhysRevA.99.052702Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)PropertiesPolarizationTechniquesCompton scatteringRadiation detectorsAccelerators & BeamsAtomic, Molecular & Optical

Highlights

Radiative electron capture (REC) is known as the dominant electron-capture process in fast collisions of heavy, highly charged ions with light target atoms and has attracted a lot of attention since its discovery in the early 1970s [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]
The obtained data confirms that for medium-Z ions such as Xe, the radiative electron capture (REC) process is a source of highly polarized x rays which can be tuned with respect to the degree of linear polarization and the photon energy
P) + P cos2 (φ + φ), where P corresponds to the degree of linear polarization and φ accounts for a possible mismatch between the detector axis and the direction of the incident photon polarization

Summary

INTRODUCTION

Radiative electron capture (REC) is known as the dominant electron-capture process in fast collisions of heavy, highly charged ions with light target atoms and has attracted a lot of attention since its discovery in the early 1970s [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. The introduction of improved, highly segmented semiconductor detector systems has significantly extended the applicability of Compton polarimetry so that it can be regarded as a reliable tool in high-energy atomic physics [33] It is valuable for the study of subtle spin-dependent and relativistic effects in the realm of relativistic collisions involving ions at high Z [12,34,35]. In the present work we employ dedicated Compton polarimeters [36,37] developed by the SPARC Collaboration to provide REC (linear) polarization data with significantly increased precision compared to the previous study [23] This enables a test of state-of-the-art, fully relativistic theory complementary to studies of the photon angular distribution. We discuss for the case of mid-Z ions the REC process as a radiation source whose photon energy and degree of linear polarization is tunable over a broad range

THE EXPERIMENT

DATA ANALYSIS AND RESULTS

CONCLUSION