Gamma Rays from the Proton Bombardment of Sodium

The yield of the (p, $\gamma$) capture process in ${\mathrm{Na}}^{23}$ has been studied for proton energies ranging between 0.85 and 1.70 Mev. Resonances were observed corresponding to excited levels of ${\mathrm{Mg}}^{24}$ at 12.71, 12.72, 12.79, 12.86, 12.90, 12.94, 12.97, 13.01, 13.02, 13.08, 13.10, 13.14, and 13.32 Mev. The energies of the $\gamma$ rays emitted from the most pronounced resonances were measured by photographing the pulse-height spectrum obtained with a single crystal scintillation spectrometer. These experiments indicate two competing modes of decay: the radiative cascade decay leading to the ground state of ${\mathrm{Mg}}^{24}$ and the emission of a low-energy $\gamma$ ray of energy 1.6 Mev which is attributed to the ${\mathrm{Na}}^{23}(\mathrm{p}, \alpha \gamma ){\mathrm{Ne}}^{20}$ reaction. No single-step transitions to the ground state were found in the capture process. Both two - and three-step transitions are observed, but all except one of the $\gamma$-ray cascades lead to the well-known 1.37-Mev state in ${\mathrm{Mg}}^{24}$.