The new generation of isotope separator on-line (ISOL) facilities like the Selective Production of Exotic Nuclei (SPES), which is in advanced construction phase at Legnaro INFN Laboratory, will be able to deliver powerful and pure ion beams. The intensity and physical composition of the radioactive ion beams produced, are strongly dependent on the type of source used to ionize the isotopes of interest.
The resonant ionization laser ion source (RILIS) technique, due to its high theoretical and practical selectivity, is the adopted paramount ions source in many different ISOL facilities. Also the SPES project, since its first preliminary layout, was designed to heavily involve selective laser resonant ionization method based on resonant excitation of atomic transitions by tunable lasers.
Ions of a selected element are ionized via stepwise atomic resonant excitations using, mainly, two or three laser beams tuned to the transition energies of the element of interest. Because each element has its own specific atomic energy levels, the resonant photo-ionization process can provide a theoretical and practical selectivity of nearly 100%.
To familiarize with this paramount ionization method and to be ready with the proper know how once the facility will be operative, a new offline laser laboratory started in 2013 and an international tender for purchasing a new state of the art solid-state laser system was realized at the end of 2014 for the future online laboratory.
Nowadays, with its three tunable dye laser systems, the offline laboratory is capable of spectroscopy and ionization efficiency studies on several elements using both Hollow Cathode Lamps and an home made Time of Flight Mass Spectrometer.
Works in the offline laboratory are finalized to investigate and verify possible ionization schemes for the future online laboratory, according elements of interest by the letters of intents received by SPES project.
Furthermore several developments in the instrumentations are foreseen in order to increase mass separation capability and ionization efficiency estimation for the time of flight and lasers wavelength identification.