FUSION AND TRANSFER-REACTIONS IN THE F-19-165 SYSTEM AT ENERGIES NEARTHE COULOMB BARRIER(HO)

Results of the measurements of fusion cross sections and average angul ar momenta in the F-19 + Ho-165 system, for center-of-mass energies ra nging from 7 MeV below to 13 MeV above the Coulomb barrier are present ed. The average angular momenta of the compound system were obtained u sing three independent methods, namely, the gamma-ray multiplicity, th e ratios of the evaporation residues, and the fusion excitation functi on. The transfer probabilities for various one- and two-particle chann els have also been measured at a beam energy of 110 MeV, an energy muc h higher than the Coulomb barrier. The measured e-integrated one and t wo-proton transfer probabilities have been analyzed in terms of an ear lier suggested semiclassical calculation taking into account the nucle ar branch in addition to the usual Coulomb branch of the classical def lection function. It is seen that the ''slope anomaly'' in the measure d one- and two-proton transfer probabilities as a function of the dist ance of closest approach can be explained within this framework. The s trengths of the form factors, required in a coupled channel calculatio n oi fusion, for the important transfer channels were obtained from th e data within such a semiclassical analysis. The observed enhancement of the fusion cross sections and average angular momenta is discussed in terms of the coupled channel model using static deformation for the target, inelastic excitations in the projectile, and couplings to the transfer channels. The data are also compared with the neutron flow m odel suggested by Stelson.