No abstract

Fusion-evaporationcross sections for "Ni + Ni have been measured with high accuracy in the energy range around the Coulomb barrier. The data yield an "experimental distribution of fusion barriers" around 13 MeV wide, which displays structure characteristic of strong phonon couplings with

Fusion-evaporation cross sections were measured in the two systems 48 Ca + 90,96 Zr in an energy range from well below to well above the Coulomb barrier. The sub-barrier fusion of 48 Ca + 90 Zr is reproduced by coupled-channels calculations including the lowest quadrupole and octupole vibrations of 90 Zr, and using a Woods-Saxon potential with a standard diffuseness parameter a = 0.68 fm. However, the fusion cross sections are overestimated above the barrier. The low-energy slope of the excitation function for 48 Ca + 96 Zr is steeper. This implies a larger diffuseness parameter a = 0.85 fm. Fusion cross sections are well fit in the whole energy range, and the effect of the strong octupole vibration in 96 Zr is predominant. The extracted fusion barrier distributions are reasonably well reproduced by calculations for both systems. A comparison with previous data for 40 Ca + 90,96 Zr is made in an attempt to clarify the role of transfer couplings in sub-barrier fusion.