Weak, low-energy capture radiation has been observed when ${\mathrm{C}}^{12}$ is bombarded by protons of energy 1-3 Mev. From the observed dependence of gamma-ray energy on proton bombarding energy, it is concluded that the radiation arises from a transition to the 2.369-Mev level in ${\mathrm{N}}^{13}$. Since the latter level is unstable to proton emission a second gamma ray is not observed. The excitation curve for this reaction shows an anomaly in the neighborhood of 1.7 Mev, which can be explained as resulting from the interference of a nonresonant $p$-wave radiation with the radiation from the 3.511-Mev, $P_{\frac{3}{2}}$ level in ${\mathrm{N}}^{13}$.

• Received 14 December 1953

DOI:https://doi.org/10.1103/PhysRev.93.1311