A variety of approximations are investigated which allow us to estimate rather simply the dominant dipole part of the Coulomb-excited nuclear polarization corrections to the $\mu -{}_{}{}^4{}_{}{}^{}\mathrm{He}$ atom in $S$ states. In particular, the unretarded dipole approximation provides an effective upper limit to this correction and lowest-order Coulomb corrections have been calculated in this approximation. We find that -3.1 meV ± 20% is a reasonable estimate for the complete result.

NUCLEAR STRUCTURE Polarization corrections; muonic atoms; ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.

• Received 15 March 1977

DOI:https://doi.org/10.1103/PhysRevC.16.1540