Study of the $^7$Be($d$,$^3$He)$^6$Li* reaction at 5 MeV/u

TL;DR

This study measures the $^7$Be($d$,$^3$He)$^6$Li* reaction at 5 MeV/u, observing the excited state of $^6$Li for the first time, analyzing angular distributions, and assessing its impact on lithium abundances in big-bang nucleosynthesis.

Contribution

It provides the first measurement of the $^7$Be($d$,$^3$He)$^6$Li* reaction cross section at 5 MeV/u and analyzes its implications for primordial lithium abundances.

Findings

First observation of the 2.186 MeV excited state of $^6$Li in this reaction.

The $S$ factor is about 50% lower than previous data at similar energies.

The reaction rate has a negligible effect (<0.1%) on $^{6,7}$Li abundances in big-bang nucleosynthesis.

Abstract

The measurement of the $^7$Be($d$,$^3$He)$^6$Li* transfer cross section at 5 MeV/u is carried out. The population of the 2.186 MeV excited state of $^6$Li in this reaction channel is observed for the first time. The experimental angular distributions have been analyzed in the finite range DWBA and coupled-channel frameworks. The effect of the $^7$Be($d$,$^3$He)$^6$Li reaction on both the $^6$Li and $^7$Li abundances are investigated at the relevant big-bang nucleosynthesis energies. The excitation function is calculated by TALYS and normalized to the experimental data. The $S$ factor of the ($d$,$^3$He) channel from the present work is about 50$\%$ lower than existing data at nearby energies. At big-bang energies, the $S$ factor is about three orders of magnitude smaller than that of the ($d,p$) channel. The ($d$,$^3$He) reaction rate is found to have a less than 0.1$\%$ effect on the $^{6,7}$Li abundances.