Isospin violation in theC12(Li6,α)N14(2.31 MeV)reaction

The isospin violating reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^6{}_{}{}^{}\mathrm{Li},\alpha ){}_{}{}^{14}{}_{}{}^{}\mathrm{N}\left(2.31\mathrm{} \mathrm{MeV}\right)$ was investigated in the range of beam energies from 9.0 to 14.0 MeV. Excitation functions were measured for the ground state, 2.31-MeV state and 3.95-MeV state of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ at 15°, 20°, 60°, and 160°. Excitation functions were taken at 40° for the ground state and 3.95-MeV states. Angular distributions were obtained at 10.5-, 11.25-, 12.5-, 13.75-, and 20.0-MeV beam energies. The cross section for the isospin forbidden reaction to the 2.31-MeV state is 0.4 to 1.8% of that to the allowed ground state and 3.95-MeV state in the beam energy range 9 to 14 MeV. At 20.0 MeV the yield to the forbidden state is only 0.02% of the allowed yield. Isospin mixing by the Coulomb force is believed responsible for the forbidden yield observed between 9-14 MeV.