Inelastic excitation ofC12andN14by 122 MeV protons and implications for the effective nucleon-nucleon interaction

Cross sections for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($p$,$p^{\prime }$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$($p$,$p^{\prime }$)${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ reactions have been measured at $E_p=122\mathrm{}$ MeV. Scattered protons were momentum analyzed in a dispersion-matched magnetic spectrograph and detected in a helical-cathode position-sensitive proportional counter. Transitions to states in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at 4.44 MeV ($2^{+}$,$T=0\mathrm{}$), 12.71 MeV ($1^{+}$,0), 15.11 MeV ($1^{+}$,1), 16.11 MeV ($2^{+}$,1), and in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ at 2.31 MeV ($0^{+}$,1) and 3.95 MeV ($1^{+}$,0), are very useful for studying the spin-isospin dependence of the effective two-nucleon interaction. Cross sections for these states from the present experiment and from earlier measurements at 185 MeV have been analyzed in the distorted-wave impulse approximation. Simultaneous consideration of ($e$,$e^{\prime }$) data for the same transitions helped to disentangle some nuclear-structure and reaction-mechanism effects. The distorted-wave impulse approximation provides a good description of those transitions in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ mediated predominantly by the $S=T=1\mathrm{}$ part of the effective interaction and also gives a reasonable description of the $S=T=0\mathrm{}$ transitions in both nuclei. The mechanisms for excitation of the 12.71-MeV state in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ($S=1\mathrm{}$, $T=0\mathrm{}$) and the 2.31-MeV state in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ($S=1\mathrm{}$, $T=1\mathrm{}$) remain a puzzle.