The 90° yield of $\gamma$ rays to the ${\mathrm{O}}^{15}$ ground state from the ${\mathrm{N}}^{14}(p, \gamma ){\mathrm{O}}^{15}$ reaction has been measured for proton energies between 12 and 19.5 Mev covering the region of excitation in ${\mathrm{O}}^{15}$ between 18 and 25 Mev. The excitation curve is quite flat (with $\frac{d\sigma }{d\Omega }$ at $90°\approx 16\mu \mathrm{b}/4\mathrm{}\pi$ sr), and shows little evidence of the giant resonance. The results for ${\mathrm{O}}^{15}$ are compared to those for ${\mathrm{N}}^{15}$ obtained by Jacobs and Stephens by means of the ${\mathrm{N}}^{15}(\gamma , p){\mathrm{C}}^{14}$ reaction. The 90° yield of $\gamma$ rays to the ${\mathrm{O}}^{16}$ ground state from the ${\mathrm{N}}^{15}(p, \gamma ){\mathrm{O}}^{16}$ reaction has been measured for proton energies between 10 and 15 Mev, corresponding to ${\mathrm{O}}^{16}$ excitation energies between 21 and 26 Mev. The excitation curve shows two large resonances peaked at 21.8 and 24.7 Mev with integral total cross sections of about 0.27 Mev-mb each if no background is assumed. The ${\mathrm{O}}^{16}$ results are compared to theoretical calculations of Elliott and Flowers and of others.

• Received 28 September 1960

DOI:https://doi.org/10.1103/PhysRev.121.858