(p,n) reactions onC14andN14and the effective nucleon-nucleon interaction

Differential cross sections for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(p,n)${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$(g.s.) reaction have been measured at $E_p=35.2\mathrm{}$ MeV with a gas-cell target. Differential cross sections for (p,n) reactions on ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ leading to the first three levels in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ have been obtained with an isotopically-enriched graphite target for bombarding energies of 25.7, 35, and 45 MeV. The ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(p,n)${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(2.31 MeV) cross sections have been analyzed with Lane-model distorted-wave Born approximation calculations to extract energy-dependent well depths for the isovector part of the optical potential. These isovector well depths have been combined with a set of isoscalar optical-potential parameters derived from elastic proton scattering on ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$. The resulting optical potential has been used in microscopic distorted-wave Born approximation analyses of the (p,n) differential cross sections. Strengths for the isovector central $V_{\tau }$ and $V_{\sigma \tau }$ and isovector tensor $V_{T\tau }$ components of the effective interaction have been extracted. A comparison of the isospin-symmetric ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(p,n)${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(g.s.), ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(p,n)${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$(g.s.), and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(p,p′)${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(2.31 MeV) reactions has been made, and unexpected differences among the angular distributions are found.