Precise excitation functions for the fusion of 12C, 16O, 28Si, and 35Cl on 92Zr 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 92Zr. 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.
ASJC Scopus subject areas
- Nuclear and High Energy Physics