Angular distributions have been measured for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}(\mathrm{n},\mathrm{n})\mathrm{}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(\mathrm{n},\mathrm{n})\mathrm{}$ at $E_{\mathrm{n}}=30.3\mathrm{} \mathrm{and} 40.3$ MeV. Coupled channels analyses of these and lower energy data have been performed and the resulting potentials compared with those from similar analyses of proton scattering. Data for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are also reanalyzed in the same manner. After correcting for purely Coulomb effects, twice the differences between the neutron and proton volume integrals per nucleon of the real potential, $2(J_{\mathrm{n}}-J_{\mathrm{p}}^{\prime })$, are as follows: 0±24 (${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$), -30±11 (${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$), -29±16 (${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$), and 8±14 (${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$) MeV ${\mathrm{fm}}^3$. These results are used to put limits on charge symmetry breaking in the nuclear mean field.

• Received 14 June 1985

DOI:https://doi.org/10.1103/PhysRevC.33.1