The absolute cross sections of the reactions (1) ${\mathrm{N}}^{15}(p,\alpha ){\mathrm{C}}^{12}$, (2) ${\mathrm{N}}^{15}(p,\alpha \gamma ){\mathrm{C}}^{12}$, and (3) ${\mathrm{N}}^{15}(p,\gamma ){\mathrm{O}}^{16}$ have been measured from 0.2 to 1.6 Mev. The thick target yield of reaction (1) was also measured at 0.100 Mev. Resonances were found at 0.338, 1.05, and 1.210 Mev for reaction (1); at 0.429, 0.898, 1.210, and possibly 1.05 Mev for reaction (2); and at 1.05 Mev for reaction (3). Most of the resonances follow closely the shape of the single level dispersion formula. The 1.05-Mev resonance is asymmetric and cannot be explained as easily. The cross section of reaction (1) has been extrapolated to stellar energies and is given by $\sigma =\left(\frac{110}{E}\right)\times \exp (-6.95\mathrm{}{E}^{-\frac{1}{2}})$ barns for $E$ in Mev in the energy region near 0.030 Mev.

• Received 8 February 1951

DOI:https://doi.org/10.1103/PhysRev.86.527