Observation of the 2p3/2→2s1/2 intra-shell transition in He-like uranium

We present the first observation of the 1s2p 3P2→1s2s 3S1 transition in He-like uranium. The experiment was performed at the internal gas-jet target of the ESR storage ring at GSI exploiting a Bragg crystal spectrometer and a germanium solid-state detector. Using the 1s22p 2P3/2→1s22s 2S1/2 transition in Li-like uranium as reference and the deceleration capabilities of the ESR storage ring, we obtained the first evaluation of the energy of an intra-shell transition for a He-like heavy ion.