C. P. Silva

Toward a global description of the nucleus-nucleus interaction

Extensive systematizations of theoretical and experimental nuclear densities and of optical potential strengths extracted from heavy-ion elastic scattering data analyses at low and intermediate energies are presented. The energy dependence of the nuclear potential is accounted for within a model based on the nonlocal nature of the interaction. The systematics indicates that the heavy-ion nuclear potential can be described in a simple global way through a double-folding shape, which basically depends only on the density of nucleons of the partners in the collision. The possibility of extracting information about the nucleon-nucleon interaction from the heavy-ion potential is investigated.

A parameter-free optical potential for the heavy-ion elastic scattering process☆

Abstract Thirty elastic scattering angular distributions for seven heavy-ion systems, in wide energy ranges, have been studied with the aim of systematizing the optical potential, real and imaginary parts, in a global way. The framework is: (i) an extensive systematization of nuclear densities, (ii) the energy dependence of the bare potential accounted by a model based on the nonlocal nature of the interaction, and (iii) the real and imaginary parts of the optical potential assumed to have the same radial shape.

Isotopic dependence of the ion-ion potential in the systems 16O+58,60,62,64Ni☆

Abstract Precise measurements of the elastic and inelastic scattering cross sections for the systems 16 O+ 58,60,62,64 Ni at the sub-barrier energies were made. Coupled-channel analysis were performed. The isotopic dependence of the resulting ion-ion potentials is compared with theoretical calculations using the double-folding method with the M3Y as the nucleon-nucleon interaction and shell-model densities.

Experimental investigation of the ion-ion potential for the 16O + 60 Ni system at large interaction distances

Abstract Precise measurements of the elastic and inelastic scattering cross sections for the 16 O + 60 Ni system at the sub-barrier energies were made. Coupled channel analysis of the only two open channels were performed. The behaviour of the ion-ion potential at large distances is discussed.

Elastic, inelastic scatterings and transfer reactions for 16,18O on 58Ni described by the São Paulo potential

We have used a parameter - free potential, obtained from data analysis at sub-barrier energies, to explain our measurements of elastic and several inelastic scattering cross sections for the 16,18O + 58Ni systems at an energy above the barrier. The data were analyzed through extensive coupled-channel calculations. Transfer cross sections could also be explained by the same interaction, which is consistent with the more fundamental Sao Paulo potential.

Coulomb and Nuclear Potentials Between Deformed Nuclei Applied to the Fusion Process

We obtained theoretical fusion cross sections based on a new and accurate procedure to calculate the Coulomb and nuclear interactions between deformed nuclei. The calculations were performed within the context of the barrier penetration model with zero point motion for the 64Ni + 64Ni system.

Nonlocal description of the nuclear interaction

Extensive systematizations of theoretical and experimental nuclear densities and of optical potential strengths extracted from heavy-ion elastic scattering data analyses at low and intermediate energies are presented. The energy-dependence of the nuclear potential is accounted for within a model based on the nonlocal nature of the interaction. The systematics indicates that the heavy-ion nuclear potential can be described in a simple global way through a double-folding shape, which basically depends only on the density of nucleons of the partners in the collision. The possibility of extracting information about the nucleon-nucleon interaction from the heavy-ion potential is investigated.

The ion - ion potential and neutron transfer processes in the systems at sub-barrier energies

Recently we have presented a realiable determination of the ion - ion potentials for the systems, at the large interacting radius , by measuring the elastic (1% precision) and inelastic cross sections at sub-barrier energies. In the present work, we have extended those studies to the systems, and we have investigated: (i) the influence of the neutron-transfer processes in the determination of the ion - ion potentials using the coupled-channel (CC) analysis of the data, (ii) the comparison between the resulting CC ion - ion potentials and the theoretical calculations using the double-folded method and shell-model densities, (iii) possible influence of the two-neutron transfer process in the measured fusion cross sections for the .

Nuclear reaction studies with particle-gamma coincidences using the Saci-Perere spectrometer

The Saci-Perere spectrometer of the University of Sao Paulo has been configured to perform particle-gamma coincidence measurements in order to study nuclear reaction mechanisms. The motivation of this type of measurement comes from the recent development of nuclear reaction models based on the Sao Paulo potential with the inclusion of an imaginary part with no adjustable parameters. New preliminary data on the 18O+110Pd transitional system are presented, and apparent similarities to weakly bound cases (e.g. 7Li + 120Sn) are briefly discussed.

Experimental Determination of the 6,7Li Nucleon Densities

In this work we present optical model analysis of new near barrier‐quasi‐elastic experimental data, for the systems 6,7Li+120Sn. From the analysis it was possible to extract the ground state nucleon densities of the weakly bound 6,7Li isotopes. The apparent discrepancies between the experimental densities, as compared with those based on Dirac‐Hartree‐Fock‐Bouguliubov (DHB) calculations were removed, considering in the reaction mechanism, the projectile break‐up and a positive polarization from couplings of 6,7Li states of the continuum.