Angular Distribution Anisotropy of the $E_{c.m.}$=2.68-MeV Resonance in the $^{12}$C($\alpha$,$\gamma$)$^{16}$O Reaction

The ${}^{12}{\rm C}(\alpha,\gamma){}^{16}{\rm O}$ reaction, in combination with the triple-alpha process, determines the $^{12}{\rm C}/{}^{16}{\rm O}$ fraction at the end of stellar helium-burning. This fraction has been shown to strongly influence any subsequent stellar evolution and, due to imprecise knowledge of ${}^{12}{\rm C}(\alpha,\gamma){}^{16}{\rm O}$ reaction rate, severely complicate precision tests of stellar models. A large uncertainty in the reaction belongs to the cross section for electric-quadrupole ($E2$) capture into the ground state of ${}^{16}{\rm O}$. A prominent feature in the measured $E2$ cross section is the narrow resonance at $E$=2.68~MeV. The resonance affects the $E2$ cross section over a region of experimental significance. How the resonance affects the cross section depends on the relative sign of its amplitude to other $E2$ amplitudes. The sign is not well determined by existing capture data and has a non-negligible effect on extrapolating the $E2$ cross section to helium-burning energies ($E_0$). Details about the recent measurement of the sign at the Ohio University Accelerator Laboratory and its importance for a new $E2$ cross section at $E_0$ will be discussed.