Resonant laser ionization of radioactive atoms

Intense radioactive ion beams are produced by the isotope separation on-line method. The resonance ionization laser ion source (RILIS) can provide the chemical selectivity to separate beams with reduced isobaric contamination. The hot cavity RILIS at ISOLDE (CERN) uses copper vapor laser pumped dye lasers for the resonant transitions. Up to now 22 elements have been ionized with efficiencies of the order of 10%. Additional elements have been ionized with similar RILIS set-ups at the Institute of Spectroscopy (Troitsk), IRIS (Gatchina), Mainz University and TIARA (Takasaki). Ideas are discussed for future developments of this type of RILIS, which could further improve the efficiency, selectivity, rapidity of release and stability of the operation. The RILIS can also be applied for atomic spectroscopy studies of exotic radioactive isotopes, which are produced at rates of few atoms per second only. An interesting parallel is shown to the atomic vapor laser isotope separation (AVLIS), a large-scale application of resonance ionization, which could be used for the isotope enrichment of macroscopic amounts: tens of kg per h.