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International audience; Measurements of fusion excitation functions of Ni-58 + Sn-124 and Ni-64 + Sn-124 are extended towards lower energy to cross sections of 1 mu b and are compared to detailed coupled-channels calculations. The calculations clearly show the importance of including transfer reactions in a coupled-channels treatment for such heavy systems. This result is different from the conclusion made in a previous article which claimed that the influence of transfer on fusion is not important for fusion reactions of Ni + Sn. In the energy region studied in this experiment no indication of fusion hindrance has been observed, which is consistent with a systematic study of this behavior.

Quasielastic (QE) excitation function measurements have been carried out for the ${}^{12}\mathrm{C}{+}^{232}\mathrm{Th}$ fissile system at ${\ensuremath{\theta}}_{\mathrm{lab}}=170\ifmmode^\circ\else\textdegree\fi{}$ in the energy range of ${E}_{\mathrm{lab}}$ = 51\char21{}79 MeV. The data has been analyzed to obtain a representation of the fusion barrier distribution, which has been compared with that obtained from fusion-fission excitation function measurements available from literature. The QE data have also been analyzed in the framework of generalized elastic scattering model to obtain the mean-square average compound nuclear spin $(〈{l}^{2}〉)$ values, which has been compared with the prediction of standard fusion model (CCDEF) calculations and also with that obtained from fission fragment angular anisotropy measurements. The results show that the barrier distributions obtained from QE and fission excitation function measurement are consistent with each other. The $〈{l}^{2}〉$ values are also consistent with prediction of CCDEF calculations, but are in disagreement with the experimental $〈{l}^{2}〉$ values obtained from fission fragment anisotropy measurements.

A representation of the fusion barrier distributions has been deduced from the back angle quasielastic scattering cross section data in O-1618+ Sn-12,Sn-124 reactions, measured over a wide range of bombarding energies around the Coulomb barrier. The results have been compared with coupled channel calculations using the CCDEF code to study the effects of projectile and target inelastic excitations and nucleon transfer couplings on the representation of fusion barrier distributions in these systems. The present studies bring out the importance of coupling of 2n pickup in the O-16+ Sn-120,Sn-124 reactions and 2n stripping in the O-18+ Sn-120,Sn-124 reactions in explaining the observed barrier distributions.

A systematic study of the decay properties of Yb-164 compound nuclei with excitation energies of 100-300 MeV was performed. The emission patterns of light charged particles detected in coincidence with evaporation residues produced in Ni-64 + Mo-100 and O-16 + Sm-148 reactions have been measured and compared to statistical model predictions. There is found to be significant disagreement between the experiment and the model calculations in the magnitude of the multiplicities and the peak position in the energy spectra. For deuterons and tritons, significant nonstatistical components were present at all excitation energies. The proton energy spectrum did not exhibit any entrance-channel dependence at an excitation energy of similar to 170 MeV. However for alpha particles, there is an enhancement in the spectrum at the lowest kinetic energies for the more symmetric reaction. It is suggested that the emission and subsequent decay of He-5 fragments, can account for a large fraction of the apparent, and often reported, decrease in the Coulomb barrier for alpha particle emission.