Measurement of the efficiency of a laser ion source with helium jet transport, laser ablation and RIS

The efficiencies for the various processes in a new laser ion source, which has been proposed for study of radioactive nuclei in previously inaccessible regimes, have been measured off-line with radioactive atoms of ⁶⁷Ga and ¹¹¹In. High efficiencies for evaporation from a filament into helium gas (100%), helium jet transport (40-50%), and laser ablation (often 80-90%) were obtained. The efficiency for resonance ionization was lower than expected, ∼0.1% for ⁶⁷Ga and ∼0.03% for ¹¹¹In in most runs, although much higher RIS efficiency (up to 2%) was obtained in ¹¹¹In with resonant laser ablation. A possible explanation for the disappointing RIS efficiency is discussed