  The structure of 15C, with an s1/2 neutron weakly bound to a closed-neutron
shell nucleus 14C, makes it a prime candidate for a one-neutron halo nucleus.
We have for the first time studied the cross section for the fusion-fission
reaction 15C + 232Th at energies in the vicinity of the Coulomb barrier and
compared it to the yield of the neighboring 14C + 232Th system measured in the
same experiment. At sub-barrier energies, an enhancement of the fusion yield by
factors of 2-5 was observed for 15C, while the cross sections for 14C match the
trends measured for 12,13C.
