The controversy 3/2+ state in 7Be and its effect on the 3He(α,γ)7Be reaction

Abstract

The 3He(α,γ)7Be reaction is important for the solar hydrogen burning and the Big Bang Nucleosynthesis. The cross sections at astrophysical energies have not yet been precisely determined, the extrapolation has to rely on the full excitation spectrum of 7Be. A controversy 3/2+ resonance state firstly reported in the study of the 6Li(p,γ)7Be reaction has attracted many attentions in the recent years. In this work, both reactions of 3He(α,γ)7Be and 6Li(p,γ)7Be are reanalyzed together in the formalism of R-matrix with and without the 3/2+ state in 7Be. The results show that this nonnormal state cannot be ruled out based on existing data. According to the present analysis, the 3/2+ resonance does not have a significant impact on the 3He(α,γ)7Be reaction at astrophysical energies, but the accurate measurement of the cross sections of 3He(α,γ)7Be at Ecm > 4 MeV can be used as a verification for the existence of the state.