Evidence for core-halo decoupling in halo systems

Evidence is presented showing that for the He-6 + Bi-209 system, the reaction cross sections can be entirely accounted for by interactions of the halo state of 6He plus reactions that occur with the He-4 core. These and similar conclusions about core-halo decoupling reported earlier for B-8 + Ni-58 are further supported by proving that no such decoupling occurs for reactions with O-17, whose valence neutron is rather weakly bound but does not form a halo. The preceding conclusions are based on comparisons with purely experimental data, using a quite reasonable scaling. Thus such a decoupling seems to stand out as a characteristic feature of true halo systems.