High-energy break-up of 6Li as a tool to study the Big-Bang nucleosynthesis reaction ~2H (α,γ)~6Li

摘要

The recently claimed observations of non-negligible amounts of ~6Li in old halo stars have renewed interest in the big bang nucleosynthesis (BBN) of ~6Li. One important ingredient in the predicted BBN abundance of ~6Li is the low-energy ~2H(~(α,γ))~6Li cross section. Up to now, the only available experimental result for this cross section showed an almost constant astrophysical S-factor below 400 keV, contrary to theoretical expectations. We report on a new measurement of the ~2H(~((α,γ)))~6Li reaction using the break-up of ~6Li at 150 A MeV. We find clear evidence for Coulomb-nuclear interference by analyzing the scattering-angular distributions. This is in-line with our theoretical description which indicates a drop of the ~(S24)-factor at low energies as predicted also by most other models. Consequently, we find even lower upper limits for the calculated primordial 6Li abundance than before.