Understanding 6He induced reactions at energies around the Coulomb barrier

Abstract

Recent developments aimed to understand the observed features arising in the scattering of the Borromean nucleus 6He on heavy targets are discussed and compared with recent data for 6He+208Pb measured at the RIB facility at Louvain-la-Neuve at energies around the Coulomb barrier. The analysis of the elastic scattering data in terms of the optical model, reveals the presence of a long range absorption mechanism, that manifests in the form of a large value of the imaginary diffuseness parameter. The elastic data have been also compared with three–body CDCC calculations, based on a di-neutron model of 6He, and four–body CDCC calculations, based on a more realistic three-body model of this nucleus. Finally, the angular and energy distribution of a particles emitted at backward angles are discussed and compared with different theoretical approaches.We find that these a particles are produced mainly by a two-neutron transfer mechanism to very excited states in the residual nucleus.