Multi-neutron transfer in 8He induced reactions near the Coulomb barrier

Abstract

The measured inclusive 6He and 4He production cross sections of Marquínez-Durán et al., [Phys. Rev. C 98, 034615 (2018)] are reexamined and the conclusions concerning the relative importance of 1n and 2n transfer to the production of 6He arising from the interaction of a 22 MeV 8He beam with a 208Pb target revised. A consideration of the kinematics of the 2n-stripping reaction when compared with the measured 6He total energy versus angle spectrum places strict limits on the allowed excitation energy of the 210Pb residual, constraining distorted wave Born approximation calculations such that the contribution of the 2n stripping process to the inclusive 6He production can only be relatively small. It is therefore concluded that the dominant 6He production mechanism must be 1n stripping followed by decay of the 7He ejectile. Based on this result we present strong arguments in favor of direct, one-step four-neutron (4n) stripping as the main mechanism for 4He production.