Electric-multipole interference effects in the12C(α,γ0)16Oreaction

This paper investigates interference effects involving the $E1\mathrm{}$ and $E2\mathrm{}$ multipole contributions to the ${}^{12}\mathrm{C}(\alpha ,{\gamma }_0{)}^{16}\mathrm{O}$ reaction. The relationships between $\gamma$-ray angular distributions, $E1\mathrm{}$ and $E2\mathrm{}$ capture phases, and ${}^{12}\mathrm{C}+\alpha$ elastic scattering phase shifts are clarified. A detailed study of the energy- and angle-dependent effects near the 2.68-MeV resonance is presented, where a new experimental signature has been identified. In addition, the effects of center-of-mass motion and $\gamma$-ray polarization are discussed.