Fusion of Ca-48+Sm-154 near the Coulomb barrier: enhancement vs. suppression

Fusion-evaporation and fusion-fission cross sections have been measured in the reaction48Ca+154Sm from well below to well above the Coulomb barrier. The comparison of fusion cross sections for this reaction with previous data corresponding to16O+186W, leading to the same compound nucleus202Pb*, puts in evidence an interesting competition between sub-barrier enhancement, due to the strong couplings related to the154Sm deformation, and above barrier suppression for the48Ca induced reaction. The fusion hindrance mechanism has been attributed to the strong quasi-fission component observed in the mass-energy distributions of fission fragments

Shell effects in Fusion-Fission of heavy and superheavy nuclei

The process of fusion-fission of heavy and superheavy nuclei (SHE) with Z=82 12122 formed in the reactions with 48Ca and 58Fe ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) and at the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL) using the time-of-flight spectrometer of fission fragments CORSET and the neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions (MED) of fission fragments, fission, quasi-fission and evaporation residues cross sections, multiplicities of neutrons and \u3b3 quanta and their dependence on the mechanism of formation and decay of compound systems have been studied

Shell effects in fission and quasi-fission of heavy and superheavy nuclei

Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions 12C+204Pb,48Ca+144,154Sm,168Er,208Pb,244Pu,248Cm;58Fe+208Pb,244Pu,248Cm, and64Ni+186W,242Pu are presented in the work. The choice of the above-mentioned reactions was inspired by recent experiments on the production of the isotopes283112,289114 and283116 at Dubna [1],[2] using the same reactions. The58Fe and64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[3] and the neutron multi-detector DEMON[4],[5]. The role of shell effects and the influence of the entrance channel on the mechanism of the compound nucleus fusion-fission and the competitive process of quasi-fission are discussed