Recombination measurements of the heaviest ions

Dielectronic recombination and radiative recombination have been studied fo r several lithium-like ions (Au76+, Pb79+ Bi80+ and U89+) as well as for hy drogen-like Bi82+ and completely stripped Bi83+. Experiments were performed at the electron cooler of the storage ring ESR of the Gesellschaft fur Sch werionenforschung (GSI) in Darmstadt. In the dielectronic recombination spe ctra analyzed so far for the lithium-like ions, 2s(1/2) --> 2p(1/2) excitat ions with capture of the free electron into Rydberg states with n greater t han or equal to 20 and 2s(1/2) --> 2p(3/2) excitations with capture into n = 5 (uranium) and n=6 (gold, lead, bismuth) are observed. These measurement s provide a stringent test of atomic structure and recombination theory for high-Z heavy-ions. In particular, the extrapolation of the 2p(1/2)nl(j) se quence (n greater than or equal to 20) to the series limit renders possible to extract the 2s(1/2) --> 2p(1/2) Lamb-shift in lithium-like high-Z ions at an expected accuracy level which can test QED theory.