Influence of nuclear structure on sub-barrier hindrance in Ni+Ni fusion
  Fusion-evaporation cross sections for $^{64}$Ni+$^{64}$Ni have been measured down to the 10 nb level. For fusion between two open-shell nuclei, this is the first observation of a maximum in the $S$-factor, which signals a strong sub-barrier hindrance. A comparison with the $^{58}$Ni+$^{58}$Ni, $^{58}$Ni+$^{60}$Ni, and $^{58}$Ni+$^{64}$Ni systems indicates a strong dependence of the energy where the hindrance occurs on the stiffness of the interacting nuclei. 
C.L.Jiang, K.E.Rehm, R.V.F.Janssens, H.Esbensen, I.Ahmad, B.B.Back,   P.Collon, C.N.Davids, J.P.Greene, D.J.Henderson, G.Muk...