Multi-neutron transfer in $^{8}$He induced reactions near the Coulomb barrier

TL;DR

This paper reevaluates neutron transfer mechanisms in $^{8}$He induced reactions near the Coulomb barrier, concluding that 1n stripping dominates $^6$He production and proposing 4n stripping as the main process for $^4$He formation.

Contribution

It provides a revised analysis of neutron transfer processes, emphasizing the dominance of 1n stripping for $^6$He and proposing 4n stripping as the primary mechanism for $^4$He production.

Findings

1n stripping is the main contributor to $^6$He production.

2n stripping contribution is limited by kinematic constraints.

Direct 4n stripping is proposed as the main mechanism for $^4$He production.

Abstract

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