Laser spectroscopy of the 1s HFS of H-like ions at a bunched beam in the storage ring ESR

The investigation of the 1s HFS provides a good possibility for testing QED effects in a combination of a strong electric and magnetic field. Here, we report about the laserspectroscopic measurements of the ground state hyper fine splitting in Pb-207(81+). TO handle this Mi-transition in the infrared optical regime with its long lifetime, we developed a new detection techni que using a bunched ion beam. For the observation of fluorescence light, a new mirror system is adapted to the emission characteristics from an ion be am at relativistic velocities.