Linear polarization of x rays due to dielectronic recombination into highly charged ions

Synopsis The linear polarization of x rays produced by dielectronic recombination into highly charged ions was for the first time measured at an electron beam ion trap using a newly developed Compton polarimeter. The experimental results open a possibility for diagnostics of anisotropies of hot plasmas. We also demonstrate a high sensitivity of the x-ray polarization to the Breit interaction.