Hyperfine interactions of light nuclei recoil-implanted into iron

The perturbed integral angular distribution technique has been used to study hyperfine interactions of light nuclei recoil-implanted into iron. Heavy ion induced fusion-evaporation reactions populated the excited states of 37Ar, 39K, 40K, 41K and 41Ca, whose deexciting γ-rays were observed in a Ge(Li) detector. In all cases the measured shifts of the angular distributions were found much smaller than the ones calculated using the known values of g-factors, lifetimes and strengths of the internal hyperfine fields. This can be explained under the assumptions that only a fraction of the nuclei feels the full internal magnetic field, while the rest of them do not feel any magnetic interaction at all. Different fractions obtained for 40K and 41K suggest a migration process on a ns time scale of the implanted ions in the lattice