Hindrance of Heavy-ion Fusion at Extreme Sub-Barrier Energies in   Open-shell Colliding Systems
  The excitation function for the fusion-evaporation reaction 64Ni+100Mo has been measured down to a cross-section of ~5 nb. Extensive coupled-channels calculations have been performed, which cannot reproduce the steep fall-off of the excitation function at extreme sub-barrier energies. Thus, this system exhibits a hindrance for fusion, a phenomenon that has been discovered only recently. In the S-factor representation introduced to quantify the hindrance, a maximum is observed at E_s=120.6 MeV, which corresponds to 90% of the reference energy E_s^ref, a value expected from systematics of closed-shell systems. A systematic analysis of Ni-induced fusion reactions leading to compound nuclei with mass A=100-200 is presented in order to explore a possible dependence of the fusion hindrance on nuclear structure. 
C. L. Jiang, K. E. Rehm, H. Esbensen, R. V. F. Janssens, B. B. Back,   P. Collon, C. N. Davids, J. P. Greene, D. J. Henderso...