Beams of short lived nuclei produced by selective laser ionization in a gas cell

An on-line laser ion source has been developed for the production of elemental and isobaric pure beams of radioactive ions. It is based on selective resonant laser ionization of nuclear reaction products thermalized and neutralized in a noble gas at high pressure. The ion source has been tested in a wide range of recoil energies going from 1.3 MeV to similar to 90 MeV, Efficient schemes of two step laser ionization through autoionizing states have been found for nickel, cobalt and rhodium. Residence times of the reaction products in a gas cell have been measured for helium and argon as buffer gas, Elementally pure beams of Ni-54,Ni-55 and Co-54, produced in a light-ion induced fusion-evaporation reaction, and of Rh-113, produced in proton-induced fission of U-238, were obtained. An efficiency of the ion source of 6.6% for fusion reactions and of 0.22% for fission reactions has been obtained. A selectivity of the ion source of 300 for fusion and 50 for fission reactions has been achieved.