Constraining the 6.05 MeV 0+ and 6.13 MeV 3- Cascade Transitions in the 12C(α,γ)16O Reaction Using the Asymptotic Normalization Coefficients.

The 12C(α,γ)16O reaction plays a fundamental role in astrophysics and needs to be known with accuracy better than 10%. Cascade y transitions through the excited states of 160 are contributing to the uncertainty. We constrained the contribution of the 0+ (6.05 MeV) and 3-(6.13 MeV) cascade transitions by measuring the asymptotic normalization coefficients for these states using the a-transfer reaction 6Li(12C, d)160 at sub-Coulomb energy. The contribution of the 0+ and 3- cascade transitions at 300 keV is found to be 1.96 ± 0.3 and 0.12 ± 0.04 keVb for destructive interference of the direct and resonance capture and 4.36 ± 0.45 and 1.44 ± 0.12 keVb for constructive interference, respectively. The combined contribution of the 0+ and 3- cascade transitions to the 12C(α,γ)16O reaction cross section at 300 keV does not exceed 4%. Significant uncertainties have been dramatically reduced. [ABSTRACT FROM AUTHOR]