The 8Li(d,p)9Li Reaction and the Astrophysical 8Li(n,g)9Li Reaction Rate

Abstract

The ${}^8$Li($n,\gamma$)${}^9$Li reaction plays an important role in both the r-process nucleosynthesis and the inhomogeneous big bang models, its direct capture rates can be extracted from the ${}^8$Li($d,p$)${}^9$Li reaction, indirectly. We have measured the angular distribution of the ${}^8$Li($d,p$)${}^9$Li${}_{\text{g.s.}}$ reaction at $E_{\text{c.m.}}$ = 7.8 MeV in inverse kinematics using coincidence detection of ${}^9\text{Li}$ and recoil proton, for the first time. Based on Distorted Wave Born Approximation (DWBA) analysis, the ${}^8\text{Li}(d,p{)}^9{\text{Li}}_{\text{g.s.}}$ cross section was determined to be 7.9 $\pm$ 2.0 mb. The single particle spectroscopic factor, $S_{1,3/2}$, for the ground state of ${}^9\text{Li}$ = ${}^8\text{Li}\otimes n$ was derived to be $0.68\pm 0.14$, and then used to calculate the direct capture cross sections for the ${}^8\text{Li}(n,\gamma {)}^9{\text{Li}}_{\text{g.s.}}$ reaction at energies of astrophysical interest. The astrophysical ${}^8\text{Li}(n,\gamma {)}^9{\text{Li}}_{\text{g.s.}}$ reaction rate for the direct capture was found to be 3970 $\pm$ 950 ${\text{cm}}^3{\text{mole}}^{-1}{s}^{-1}$ at $T_9$ = 1. This presents the first experimental constraint for the ${}^8\text{Li}(n,\gamma {)}^9\text{Li}$ reaction rates of astrophysical relevance.

10 pages and 6 figures

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