Reaction Rates of neutron capture by Li- and Be-isotopes

Abstract

Neutron capture by neutron-rich Li- and Be-isotopes plays a role in big--bang nucleosynthesis, especially in its inhomogeneous version and in the $α$--process occurring in supernovae. New reaction rates for $^{7,8}$Li(n,$γ$)$^{8,9}$Li and $^{9,10,11}$Be(n,$γ$)$^{10,11,12}$Be have been consistently calculated using direct capture for the nonresonant part and the Breit-Wigner formula for the resonant part. The spectroscopic factors, spin/parity assignments and excitation energies of the final bound and initial resonant states have been taken from existing experimental data whenever possible. For unstable nuclei where this information is not experimentally available the shell model was used to determine these quantities.