First Measurement of Pure Electron Shakeoff in the β Decay of Trapped 6He+ Ions

The electron shakeoff probability of Li-6(2+) ions resulting from the beta(-) decay of He-6(+) ions has been measured with high precision using a specially designed recoil ion spectrometer. This is the first measurement of a pure electron shakeoff following nuclear beta decay, not affected by multielectron processes such as Auger cascades. In this ideal textbook case for the application of the sudden approximation, the experimental ionization probability was found to be P-so(exp) 0: 023 39(36) in perfect agreement with simple quantum mechanical calculations.