Transverse decoupling of hyperfine interactions in highly ionized atoms

A new method for measuring hyperfine interaction constants of highly ionized atoms was investigated with the 3.83 MeV (15+/2) state in 41Ca. A large transverse magnetic field of up to 55 kG was applied to the highly stripped calcium atoms travelling in vacuum, and the perturbation due to the atomic hyperfine interaction in the decoupled atom was studied by observing the anisotropy of the nuclear gamma rays as a function of the interaction time, which was varied by the recoil distance method. The nuclear level in the recoil ions was populated by heavy ion reactions. It was found that at different recoil velocities, different atomic states were populated and the following hyperfine fields were measured: H/sub hf/(Ca8+, 3P2) = 21.0(2.5)MG, H/sub hf/-(Ca8+, 3P1) = 15.4(0.6)MG and H/sub hf/(Ca9+, 2S/sub 1/2/) = 20.5(0.8)MG. An exponential decay of the anisotropy was observed for some fraction of the nuclei at all velocities, indicating that a nonstatic atomic environment is present. A simple model can explain the observation