Alternative path for bridging the A = 5, 8 gap in neutron-rich nucleosynthesis scenarios

Abstract

In neutron-rich nucleosynthesis scenarios the mass gaps A = 5, 8 are assumed to be bridged by the three-body electromagnetic recombination reaction 4He(αn, γ)9Be. However, an alternative path, the nuclear four-body neutron-recoil recombination reaction 4He(αnn, n)9Be, is also conceivable in neutron-rich environments. We estimate the rate of the alternative reaction and show that for temperatures of about 109 K it is comparable with the electromagnetic rate if the neutron density is of about 1030 neutrons per cm3. At higher neutron densities the nuclear process dominates.