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 ${}_{}{}^{37}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{39,40,41}{}_{}{}^{}\mathrm{K}$, and ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$, whose deexciting $\gamma$ 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 assumption that only a fraction of the nuclei feel the full internal magnetic field, while the rest of them do not feel any magnetic interaction at all. Different fractions obtained for ${}_{}{}^{40}{}_{}{}^{}\mathrm{K}$ and ${}_{}{}^{41}{}_{}{}^{}\mathrm{K}$ suggest a migration process on a ns time scale of the implanted ions in the lattice.

NUCLEAR REACTIONS ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}({}_{}{}^{14}{}_{}{}^{}\mathrm{N}, xn, yp){}_{}{}^{37}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{39}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{K}$; ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, xn, yp){}_{}{}^{41}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$; $E=30-35\mathrm{}$ MeV. Measured $I_{\gamma }(\theta , H)$. Deduced $H_{\mathrm{hyp}}$ at Ar(Fe), K(Fe), Ca(Fe).

• Received 19 May 1975

DOI:https://doi.org/10.1103/PhysRevC.12.1873