Cross Sections for Elastic Scattering and Reactions Due to Protons onN15

Absolute differential cross sections were measured for the reactions ${\mathrm{N}}^{15}(p, p){\mathrm{N}}^{15}$, ${\mathrm{N}}^{15}(p, {\alpha }_0){\mathrm{C}}^{12}$ (ground state), and ${\mathrm{N}}^{15}(p, {\alpha }_1){\mathrm{C}}^{12*}$ (first excited state). Thin gas targets, enriched up to 98% in ${\mathrm{N}}^{15}$, and a 6-mil CsI(Tl) crystal detector were used. Numerous angles were studied for bombarding energies between 1 Mev and 3.6 Mev. Spins and parities are discussed where resonances suggest the existence of excited states in ${\mathrm{O}}^{16}$. Results are as follows: At the 1210-kev resonance, the incident energy for which the ${\alpha }_0$ yield is maximum depends on the angle of observation. This is probably the result of interference and has bearing on the spin and parity assignment of this level. The anomaly at 1890 kev cannot be positively identified as due to resonance.