Total cross sections for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}(p,\alpha ){}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ reaction have been measured by using sealed gas targets and detecting annihilation radiation from the positron decay of ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$. These measurements agree with the recent work of Jacobs et al. above 5.0 MeV and extend the measured cross sections to 3.8 MeV, where the cross section is a factor of 1000 smaller than the higher-energy cross sections. The results determine the low-energy normalization of the inverse ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}(\alpha ,p){}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ reaction, reducing the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ production in big bang model calculations relative to results obtained by using estimated cross sections.

NUCLEAR REACTIONS ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}(p,\alpha )$, $E=3.8\mathrm{}-6.4$ MeV, measured $\sigma \mathrm{}\left(E\right)\mathrm{}$. Inferred $\sigma \mathrm{}\left(E\right)\mathrm{}$ and astrophysical cross section factor for inverse reaction. Sealed gas target.

• Received 20 October 1975

DOI:https://doi.org/10.1103/PhysRevC.13.524