Fusion cross section measurements for the ${}^{16,18}\mathrm{O}{+}^{58,60,64}\mathrm{Ni}$ systems, in the energy range $38<~E_{\mathrm{lab}}<~64$ MeV are presented. The standard radius deviations obtained from the data analysis, considering the zero-point motion of the nuclear surface, are compared to those associated to quadrupole and pairing vibration modes. Using the optical model analysis of the elastic data, the connection between the threshold anomaly and the subbarrier fusion enhancement is investigated.

• Received 7 February 1996

DOI:https://doi.org/10.1103/PhysRevC.55.3155