Radiative recombination of highly charged ions with polarized electrons

Abstract

We present a theoretical study of the radiative recombination (RR) of heavy highly charged ions with arbitrary (longitudinally and transversely) polarized electrons. In order to investigate how the spin state of incident electrons affects the linear polarization of emitted photons, we apply the density matrix theory and solutions of the relativistic Dirac equation. Explicit analytical expressions are obtained for the dependencies of the differential cross section and the polarization Stokes parameters of RR photons on the components of the incident electrons polarization vector. Detailed calculations of the degree of linear polarization and the tilt angle that characterizes the orientation of the polarization axis are carried out for radiative recombination with bare ${\mathrm{U}}^{92+}$ and ${\mathrm{Xe}}^{54+}$ ions for different polarization states of the incoming electrons. Based on the results of these calculations, we argue that the linear polarization of RR photons is very sensitive to the spin state of an electron target, and this sensitivity can be easily observed with the help of modern Compton polarization detectors.