A measurement of the cascade $\gamma$ radiation from the 7.65-MeV $J^{\pi }=0^{+}$ state in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ is reported. The cascade $\gamma$ radiation through the 4.44-MeV $J^{\pi }=2^{+}$ state in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ is responsible for 98% of stellar ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ production, the remaining 2% proceeding by $E0\mathrm{}$ pair decay. The two $E2\mathrm{}$ $\gamma$ rays were measured in coincidence with inelastically scattered protons which resonantly populated the 7.65-MeV state at $E_p=10.48\mathrm{}$ MeV. A high efficiency detection system was used, consisting of four 12.5-cm × 12.5-cm NaI $\gamma$ detectors and four silicon surface barrier particle counters. A value of (4.09 ± 0.29) × ${10}^{-4\mathrm{}}$ was obtained for the radiative branching ratio, in agreement with the larger of the two sets of values previously reported.

NUCLEAR STRUCTURE ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, 7.65 MeV state; measured $\frac{{\Gamma }_{\gamma }}{\Gamma }$. Stellar helium burning.

• Received 2 September 1975

DOI:https://doi.org/10.1103/PhysRevC.13.2033