Charge-state Distribution of Li Ions from the Β Decay of Laser-Trapped He6 Atoms

The accurate determination of atomic final states following nuclear beta decay plays an important role in several experiments. In particular, the charge state distributions of ions following nuclear beta decay are important for determinations of the beta-nu angular correlation with improved precision. Beyond the hydrogenic cases, the decay of neutral He-6 presents the simplest case. Our measurement aims at providing benchmarks to test theoretical calculations. The kinematics of Lin+ ions produced following the beta decay of He-6 within an electric field were measured using He-6 atoms in the metastable (ls2s,S-3(1)) and (ls2p,P-3(2)) states confined by a magneto-optical trap. The electron shakeoff probabilities were deduced, including their dependence on ion energy. We find significant discrepancies on the fractions of Li ions in the different charge states with respect to a recent calculation.