Energy levels of N14 from N15(He3,α)N14

Abstract

The energy level scheme of N14 in the 4-8 MeV range of excitation has been examined by measuring the alpha-particle spectrum from the reaction N15(He3, α)N14*. States are observed at N14 excitations of 3.95, 4.91, 5.113±0.008, 5.691±0.008, 5.832±0.008, 6.048±0.012, 6.224±0.012, 6.436±0.012, 7.032±0.010, 7.97, and 8.06 MeV. Unobserved are the now doubtful states reported near 6.70, 7.40, and 7.60 MeV in N14. The implications of a possible state near 7.60 on the C12/C13 abundance ratio are discussed and it is concluded that observed isotope abundance ratios are consistent with the finding of this experiment; that is, that such a level does not exist. Angular distributions are presented which show the evidence of different reaction mechanisms to different final states. The reaction N14(He3, α)N13* also produced resolvable alpha-particle groups to states in N13 with excitations of 6.38, 6.91, 7.1 6±0.008, and 7.388±0.008 MeV.