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

Physical Review C (Impact Factor: 3.72). 11/2010; DOI: 10.1103/PhysRevC.82.065803
Source: arXiv

ABSTRACT 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 breakup of 6Li at 150 A  MeV. Even though we cannot separate experimentally the Coulomb contribution from the nuclear one, 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.

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