Gamow shell model description of the radiative capture reaction ${}^8$Li$(n,\gamma )$${}^9$Li

Abstract

The ${}^8$Li$(n,\gamma )$${}^9$Li reaction plays a critical role in several reaction chains leading to the nucleosynthesis of $A>12$ nuclei. Due to unstable nature of ${}^8$Li and the unavailability of neutron targets, direct measurements of this reaction are exceedingly difficult. Only upper limits of this cross section, provided by the indirect experiments, have been obtained so far. In this work, we use the Gamow shell model (GSM) in the coupled-channel representation (GSM-CC) to study the properties of ${}^9$Li and the radiative capture reaction ${}^8$Li$(n,\gamma )$${}^9$Li. In GSM-CC calculations, a translationally invariant Hamiltonian is used with a finite-range two-body interaction tuned to reproduce the low-energy spectra of ${}^{8-9}$Li. In the calculation of ${}^8$Li$(n,\gamma )$${}^9$Li cross section, all relevant E1, M1, and E2 transitions from the initial continuum states to the final bound states ${3/2}_1^{-}$, ${1/2}_1^{-}$ and the resonance ${5/2}_1^{-}$ of ${}^9$Li are included. The GSM-CC approach reproduces the experimental low-energy spectrum, neutron emission threshold, and spectroscopic factors in ${}^9$Li. The calculated reaction rate is consistent with the experimental upper limit of the reaction rate obtained in the indirect measurements at stellar energies. The GSM-CC calculations suggest that the ${}^8$Li$(n,\gamma )$${}^9$Li reaction can reduce heavy-element production via the main chain ${}^7$Li($n,\gamma$)${}^8$Li($\alpha ,n$)${}^{11}$B($n,\gamma$)${}^{12}$B(${\beta }^{+}$)${}^{12}$C. Major contribution to the calculated cross section is given by the direct E1 transition to the ground state of ${}^8$Li. The contribution of excited states to the reaction rate does not exceed $\sim$18% of the total reaction rate.

References in corpus (10)

• Shell Model in the Complex Energy Plane
• Threshold Effects in Multi-channel Coupling and Spectroscopic Factors in Exotic Nuclei
• Fermion Pair Dynamics in Open Quantum Systems
• The 8Li(d,p)9Li Reaction and the Astrophysical 8Li(n,g)9Li Reaction Rate
• Continuum Coupling and Single-Nucleon Overlap Integrals
• Neutron Transfer reactions induced by 8Li on 9Be
• Gamow shell model description of ${}^4$He($d$,$d$) elastic scattering reactions
• Coulomb dissociation of 9Li and the rate of the 8Li(n,g)9Li reaction
• Microscopic investigation of the ${}^8$Li($n,\gamma$)${}^9$Li reaction
• Precision measurement of the electric quadrupole moment of 31Al and determination of the effective proton charge in the sd-shell

Cited by in corpus (3)

• Puzzling $B(E2;0^{+}\to 2^{+})$ strength in the proton dripline nucleus ${}^{36}$Ca
• ${}^{19}$F$(p,\gamma )$${}^{20}$Ne reaction rate and the puzzling calcium abundance in metal poor stars
• Green's Function Formalism for Impurity-Induced Resonances in Sub-barrier Proton-Nucleus Scattering