Low-energy ³He(α,α)³He elastic scattering and the ³He(α,γ)⁷Be reaction

The cross sections of the $^3$He($\alpha$,$\alpha$)$^3$He and $^3$He($\alpha$,$\gamma$)$^7$Be reactions are studied at low energies using a simple two-body model in combination with a double-folding potential. At very low energies the capture cross section is dominated by direct s-wave capture. However, at energies of several MeV the d-wave contribution increases, and the theoretical capture cross section depends sensitively on the strength of the L=2 potential. Whereas the description of the L=2 elastic phase shift requires a relatively weak potential strength, recently measured capture data can only be described with a significantly enhanced L=2 potential. A simultaneous description of the new experimental capture data and the elastic phase shifts is not possible within this model. Because of the dominating extranuclear capture, this conclusion holds in general for most theoretical models.