Experimental barrier distributions for the fusion of 12C, 16O, 28Si, and 35Cl with 92Zr and coupled-channels analyses -: art. no. 064608

Precise excitation functions for the fusion of C-12, O-16, Si-28, and Cl-35 on Zr-92 were measured for bombarding energies spanning the Coulomb barrier regions. Experimental fusion barrier distributions were derived from these data and compared with the results of realistic coupled-channels calculations, which; included couplings to all orders and treated excitation energies correctly. To gain reasonable agreement for the heavier projectiles it was necessary to include double-phonon. excitations of the first 2(+) and 3(-) vibrational states in Zr-92. The diffuseness parameter required to fit the high-energy cross sections increases with increasing charge of the projectile and, as found in earlier work, is higher than that required to fit elastic-scattering data, It is suggested that a potential which falls more rapidly at large distance than the Woods-Saxon form might help explain the anomaly.