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

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 1s2p3∕2 3P2F i = 3/2 → 1s2 1S0F 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.