Low-Lying States ofN16

The gamma rays of low energy resulting from the reaction ${\mathrm{N}}^{15}(d, p){\mathrm{N}}^{16}$ have been studied. Gamma rays of energy 387±5 kev, 268±5 kev, and 118±3 kev are observed by using NaI scintillation techniques, and the presence of another gamma ray of 285±8 kev is inferred. These results indicate states of ${\mathrm{N}}^{16}$ at 118, 285, and 387 kev consistent with earlier studies of heavy particles. The gamma ray of 268 kev results from a cascade from the 387-kev state through the first excited state which is shown to have a lifetime of a few microseconds. By combining these results with the earlier work on heavy particles, it is possible to fix the first excited state of ${\mathrm{N}}^{16}$ as 0- and the third as 1-. The second excited state is with very good probability 2- or 3- with a slight preference for 3-. The ground state is already known to be 2-. These results are in good accord with the theoretical (shell model) predictions of J. P. Elliott.