Laser spectroscopy of the ^2S_1/2-^2P_1/2 , ^2P_3/2 transitions in stored and cooled relativistic C 3+ ions

The ^2S_1/2-^2P_1/2 and ^2S_1/2-^2P_3/2 transitions in Li-like carbon ions stored and cooled at a velocity of β≈ 0.47 in the experimental storage ring (ESR) at the GSI Helmholtz Centre in Darmstadt have been investigated in a laser spectroscopy experiment. Resonance wavelengths were obtained using a new continuous-wave UV laser system and a novel extreme UV (XUV) detection system to detect forward emitted fluorescence photons. The results obtained for the two transitions are compared to existing experimental and theoretical data. A discrepancy found in an earlier laser spectroscopy measurement at the ESR with results from plasma spectroscopy and interferometry has been resolved and agreement between experiment and theory is confirmed.