Measurement of the 2 H( 7 Be, 6 Li) 3 He reaction rate and its contribution to the primordial lithium abundance

In the standard Big Bang nucleosynthesis (SBBN) model, the lithium puzzle has attracted intense interest over the past few decades, but still has not been solved. Conventionally, the approach is to include more reactions flowing into or out of lithium, and study the potential effects of those reactions which were not previously considered. 7 Be(d, 3 He) 6 Li is a reaction that not only produces 6 Li but also destroys 7 Be, which decays to 7 Li, thereby affecting 7 Li indirectly. Therefore, this reaction could alleviate the lithium discrepancy if its reaction rate is sufficiently high. However, there is not much information available about the 7 Be(d, 3 He) 6 Li reaction rate. In this work, the angular distributions of the 7 Be(d, 3 He) 6 Li reaction are measured at the center of mass energies E cm = 4.0 MeV and 6.7 MeV with secondary 7 Be beams for the first time. The excitation function of the 7 Be(d, 3 He) 6 Li reaction is first calculated with the computer code TALYS and then normalized to the experimental data, then its reaction rate is deduced. A SBBN network calculation is performed to investigate its influence on the 6 Li and 7 Li abundances. The results show that the 7 Be(d, 3 He) 6 Li reaction has a minimal effect on 6 Li and 7 Li because of its small reaction rate. Therefore, the 7 Be(d, 3 He) 6 Li reaction is ruled out by this experiment as a means of alleviating the lithium discrepancy.