With LIST and dedicated Lasers - On-line Laser Ion Source Developments and Applications at ISOLDE

The resonance ionization laser ion source RILIS has today conclusively demonstrated its outstanding properties for production of exotic ions and has thus developed into the prominent tool for efficient formation of pure radioactive ion beams at all on-line facilities world-wide. Laser development towards maintenance-free, long-term operational availability in combination with dedicated ion source materials and geometries increased the number of elements produced and extended the accessible yield of radioisotopes towards the most challenging candidates of shortest lifetimes. The laser ion source and trap device (LIST) enhances the ion beam specifications in respect to isobaric purity, i.e. the limiting factor for the study of numerous isotopes of fundamental interest, due to the unavoidable presence of contaminations from easily ionizable alkaline elements. In addition, the RILIS technology is increasingly applied for in-source laser spectroscopic investigations on its own. Nuclear charge radii, deformations and moments, encoded in the atomic hyperfine splitting or isotope shift, can be determined by scanning one of the RILIS laser wavelengths in a multi-step resonant ionization scheme across the corresponding spectral range. Atomic physics parameters like the ionization potential, fine structure splittings or general energetic level positions, are derived for rare exotic species by long range laser scans through so far unknown atomic spectra. This has been demonstrated very successfully for the heaviest halogen element astatine. Since the technique is applied at the ion source itself, its sensitivity is optimum and any decay losses for short lived isotopes are minimized. In combination with dedicated detection techniques specific decay properties of individual radionuclides are exploited and may increase the inherent selectivity of the RILIS/LIST technique further. An overview on the state of the art with focus on experimental activities at ISOLDE/CERN will be given in the presentation.