Determination of theY40Components in the Equilibrium Nuclear Shapes ofTh232andU238

Differential cross sections have been measured for the excitation, by 22.95-MeV protons, of states (up to and including the $6^{+}$ at some angles) in the ground-state rotational bands of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. Coupled-channel analyses of the angular distributions allow determination of the equilibrium deformation parameters ${\beta }_4$. The values ${\beta }_4={0.017}_{-0.030\mathrm{}}^{+0.015\mathrm{}}$ for ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ and ${\beta }_4=0.050\mathrm{}\pm 0.015$ for ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ do not agree well with theoretical predictions by Möller et al.