Experimental reaction cross sections for ${}^6\mathrm{He}$ and ${}^4\mathrm{He}$ projectiles are reduced and are shown to follow well-defined trajectories that can be characterized by respective Wong-type curves. The strong enhancement observed for the ${}^6\mathrm{He}$ data is interpreted as caused by two separate halo effects: a size effect, which affects the whole energy region, and a dynamic effect, important only near and below the barrier. Evidence for a core-halo decoupling is presented for the ${}^6\mathrm{He}+{}^{64}\mathrm{Zn}$ system, which further supports the hypothesis that the decoupling is a characteristic feature of true halo systems.

• Received 24 December 2010

DOI:https://doi.org/10.1103/PhysRevC.83.021601