The Storage Rings at the GSI Helmholtz Center, e.g. ESR (see figure above), offer world-wide unique opportunities for laser spectroscopy. Here, highly charged ions of heavy elements – for example hydrogen-like bismuth (charge state 82+) – can be produced and stored. The huge magnetic fields of the nucleus and the closely bound electron interact and produce an enormous hyperfine splitting. Therefore, the excitation cannot be performed by radiowaves anymore – as it is the case in hydrogen – but require radiation in the optical regime produced by high power pulsed lasers as shown in Fig. 1. In the experiments, we exploit the strong Doppler boost of the ions revolving in the storage ring at a speed of about 70% of the speed of light.
Completely different experiments are carried out at the storage ring CRYRING (Fig. 2), where we try to polarize singly charged magnesium ions. These can also be used to study in detail the ion and state-population dynamics in the storage ring and the dynamics of synchrotron oscillations in bunched beams