Constraints on the 7Be(p,γ)8B radiative capture rate from charge symmetry -: art. no. 047603

Cross sections for the dipole radiative capture reactions Li-7(n,gamma)Li-8 and Be-7(p,gamma)B-8 are calculated in a two-body model, which is based on a Woods-Saxon parametrization of the nuclear interaction. The well depth is adjusted for each reaction channel so that the measured separation energies and s-wave scattering lengths are reproduced. The calculations are repeated for a wide range of the radius and the diffuseness of the interaction. The predicted S factor for the radiative proton capture on Be-7 falls within a surprisingly narrow range of values when the model is calibrated to reproduce measurements of the mirror reaction Li-7(n,gamma)Li-8. The simplified model used here is consistent with the shell model approach for proton capture on Be-7 but it gives a significantly smaller cross section for neutron capture on Li-7.