The 18F(p, α) 15O low-energy S-factor: A microscopic approach

The 18F(p, α) 15O S-factor is determined in a microscopic cluster model. The wave functions are defined in the Generator Coordinate Method, involving various 18F + p, 15O+α, and 18Ne + n configurations. We analyze the 19Ne level scheme, and test the model with the 19F spectrum, better known experimentally. We focus on 1/2+ and 3/2+ states, corresponding to s waves, and expected to represent the main contribution in the 18F(p, α) 15O cross section at stellar energies. The 1/2+ partial wave is shown to play an important role in a wide energy range. This property reduces the uncertainties associated with interference patterns in the 3/2+ contribution. The relevant 1/2+ states have been observed in 19F, but have not been searched for in 19Ne. An elastic-scattering experiment above 1 MeV is suggested.