Deuterium Lamb shift via quenching-radiation anisotropy measurements

The Lamb shift of a hydrogenic ion can be deduced from the anisotropy in the angular distribution of the $2s_{\frac{1}{2}}-1\mathrm{}{s}_{\frac{1}{2}}$ electric field quenching radiation. The accuracy of our previous anisotropy measurement for deuterium is improved to about ± 150 ppm. The derived Lamb shift is (1059.36±0.16) MHz. The sources of error are carefully analyzed and the prospects for further improvements in the accuracy are discussed.