The excitation curve for the ${\mathrm{N}}^{15}(p, n){\mathrm{O}}^{15}$ reaction at zero degrees has been measured from threshold at 3.78 Mev to 6.38 Mev bombarding energy. Resonances corresponding to excited states in ${\mathrm{O}}^{16}$ at 16.21, ∼16.3, ∼17.0, 17.13, 17.29, ∼17.5, 17.63, 17.84, 17.97, and 18.05 Mev were observed. The 16.21-Mev state is $J^{\pi }=1^{+}$ and the 16.3-Mev state is $J^{\pi }=0^{-}$. The energy difference between the ${\mathrm{N}}^{15}(p, n){\mathrm{O}}^{15}$ threshold energy and the ${\mathrm{Li}}^7(p, n){\mathrm{Be}}^7$ ${\mathrm{H}}_2^{+}$ beam thick-target threshold was found to be 17.6±0.5 kev. A threshold energy for ${\mathrm{N}}^{15}(p, n){\mathrm{O}}^{15}$ of 3.7808±0.0011 Mev is implied if possible differences in the extrapolated end points of the ${\mathrm{Li}}^7(p, n){\mathrm{Be}}^7$ thresholds with ${\mathrm{H}}^{+}$ and ${\mathrm{H}}_2^{+}$ beams are ignored.

• Received 18 July 1958

DOI:https://doi.org/10.1103/PhysRev.112.1252