Interaction of ⁸He with ²⁰⁸Pb at near-barrier energies: ⁴He and ⁶He production

Angular distributions for the inclusive ⁴He and ⁶He production cross sections in the ⁸He + ²⁰⁸Pbsystem at incident energies of 16 and 22 MeV measured at the SPIRAL facility of the GANIL laboratory are presented. Using a combination of kinematical arguments and distorted wave Born approximation (DWBA) calculations, neutron transfer reactions were inferred to be the dominant contributors to both inclusive cross sections. Model-dependent values for the ratios of two- to one-neutron stripping, σ2n/σ1n, were derived and compared with previous results for ⁸He and ⁶He projectiles incident on other heavy targets. Three- and four-neutron stripping were inferred to be the main processes leading to ⁴He production, although the exact mechanism remains to be elucidated.