Relativistic effects on resonant interactions between electrons and highly charged ions

We report measurements of resonant processes in electron collisions with very highly charged heavy ions made using an electron beam ion trap. By measuring the ion abundance ratio in the trap at the equilibrium condition as a function of electron energy, we have observed resonant processes such as dielectronic recombination and resonant excitation double autoionization very clearly. Remarkable relativistic effects due to the generalized Breit interaction have been clearly shown in dielectronic recombination for highly charged heavy ions