Observation of an Anomalous Angular Distribution in the Single-Nucleon-Transfer ReactionC12(N14,N13)C13at 100 MeV

The reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ has been studied at a bombarding energy of 100 MeV. The measured differential cross sections have been compared with exact finite-range distorted-wave Born approximation calculations including recoil. The angular distribution of the reaction populating the $2s_{\frac{1}{2}}$ state in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ at 3.09 MeV shows pronounced oscillations which are out of phase with those of the predicted angular distribution.