Regular Article

Angular distribution and polarization of X-ray radiation in highly charged He-like ions: hyperfine-induced transition

¹ School of Science, Hunan University of Technology, Zhuzhou 412007, P.R. China
² Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, P.R. China
³ College of Science, National University of Defense Technology, Changsha 410073, P.R. China

^a e-mail: chenzhanbin008@qq.com
^b e-mail: dongcz@nwnu.edu.cn

Received: 9 February 2018
Received in final form: 4 April 2018
Published online: 5 June 2018

Abstract

The angular distribution and polarization properties of the X-rays produced by the hyperfine-induced transition are investigated within a fully relativistic distorted-wave approximation. The calculations are performed for the 1s2p_3∕2 ³P₂F_i = 3/2 → 1s^{2 1}S₀F_f = 1/2 component of the Kα₁ decay for highly charged He-like ¹¹⁹Sn⁴⁸⁺ and ²⁰⁷Tl⁷⁹⁺ ions with nuclear spin I = 1/2 following impact excitations by an un-polarized and a completely longitudinally-polarized electron beam, respectively. The Breit interaction and mutipole mixing between the leading M2 decay and the hyperfine-induced E1 decay corrections to both linear and circular polarizations of the emitted X-ray radiations are evaluated. All these effects are found to be significant and may potentially explain the disagreement between the theories and experiments related to the polarization properties of the X-ray radiation.