An experimental upper limit for the branching ratio, $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }$, for electromagnetic transitions from the 9.64-MeV state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ has been established through a search for coincidences between inelastically scattered $\alpha$ particles and the associated ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. It is concluded, at a one standard deviation confidence level, that ${\Gamma }_{\mathrm{rad}}$ is less than 14 meV.

NUCLEAR STRUCTURE ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, 9.64-MeV state; measured upper limit on $\frac{{\Gamma }_{\mathrm{rad}}}{\Gamma }$. Helium burning.

• Received 8 April 1974

DOI:https://doi.org/10.1103/PhysRevC.10.909