The energy level scheme of ${\mathrm{N}}^{14}$ in the 4-8 MeV range of excitation has been examined by measuring the alpha-particle spectrum from the reaction ${\mathrm{N}}^{15}({\mathrm{He}}^3, \alpha ){\mathrm{N}}^{14*}$. States are observed at ${\mathrm{N}}^{14}$ 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 ${\mathrm{N}}^{14}$. The implications of a possible state near 7.60 on the ${\mathrm{C}}^{12}$/${\mathrm{C}}^{13}$ 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 ${\mathrm{N}}^{14}({\mathrm{He}}^3, \alpha ){\mathrm{N}}^{13*}$ also produced resolvable alpha-particle groups to states in ${\mathrm{N}}^{13}$ with excitations of 6.38, 6.91, 7.1 6±0.008, and 7.388±0.008 MeV.

• Received 16 July 1962

DOI:https://doi.org/10.1103/PhysRev.128.2254