HE+ 2P STATE LIFETIME BY A QUENCHING-ASYMMETRY MEASUREMENT

An interference asymmetry in the angular distribution of the Ly-a quenching radiation emitted by He+ ions in the metastable 2s1/2 state is measured to high precision to obtain the lifetime of the 2p1/2 state. The derived lifetime of (0.997 17 +/- 0.000 75) x 10(-10) s is the most accurate available for a fundamental atomic system. A detailed discussion of systematic corrections is included. The result is in good agreement with theory, thereby confirming the theory of radiative transition probabilities to +/- 0.075%, and indicating that differences between theory and experiment for the alkali metals must be due to either inadequate wave functions or experimental errors.