64^{64}Ni+64^{64}Ni fusion reaction calculated with the density-constrained time-dependent Hartree-Fock formalism

We study fusion reactions of the $^{64}$Ni+$^{64}$Ni system using the density-constrained time-dependent Hartree-Fock (TDHF) formalism. In this formalism the fusion barriers are directly obtained from TDHF dynamics. In addition, we incorporate the entrance channel alignments of the slightly deformed (oblate) $^{64}$Ni nuclei due to dynamical Coulomb excitation. We show that alignment leads to a fusion barrier distribution and alters the naive picture for defining which energies are actually sub-barrier. We also show that core polarization effects could play a significant role in fusion cross section calculations.Comment: 7 pages, 6 figure

Probing surface diffuseness of nucleus-nucleus potential with quasielastic scattering at deep sub-barrier energies

We perform a systematic study on the surface property of nucleus-nucleus potential in heavy-ion reactions using large-angle quasielastic scattering at energies well below the Coulomb barrier. At these energies, the quasielastic scattering can be well described by a single-channel potential model. Exploiting this fact, we point out that systems which involve spherical nuclei require the diffuseness parameter of around 0.60 fm in order to fit the experimental data, while systems with a deformed target between 0.8 fm and 1.1 fm.Comment: 6 pages, 6 figure

Study of refractive structure in the inelastic 16O+16O scattering at the incident energies of 250 to 1120 MeV

The data of inelastic 16O+16O scattering to the lowest 2+ and 3- excited states of 16O have been measured at Elab = 250, 350, 480, 704 and 1120 MeV and analyzed consistently in the distorted wave Born approximation (DWBA), using the semi- microscopic optical potentials and inelastic form factors given by the folding model, to reveal possible refractive structure of the nuclear rainbow that was identified earlier in the elastic 16O+16O scattering channel at the same energies. Given the known transition strengths of the 2+ and 3- states of 16O well determined from the (e,e') data, the DWBA description of the inelastic data over the whole angular range was possible only if the absorption in the exit channels is significantly increased (especially, for the 16O+16O(2+) exit channel). Although the refractive pattern of the inelastic 16O+16O scattering was found to be less pronounced compared to that observed in the elastic scattering channel, a clear remnant of the main rainbow maximum could still be seen in the inelastic cross section at Elab = 350 - 704 MeV.Comment: 26 pages, 10 figures, Accepted for publication in Nucl. Phys.

TRABZO: a novel combined model for heavy-ion fusion/capture accounting for zero-point shape oscillations and dissipative effects

The fusion/capture cross sections (CSs) of complex nuclei (heavy ions) are often described in the literature within two approaches: i) the coupled channels model accounting for structure of the colliding nuclei and ii) trajectory models with friction and thermal fluctuations (dissipative effects). The first approach does not account for friction whereas the second one is not able to deal with sub-barrier CSs. In the present work, we have developed an algorithm for calculating the capture CSs of collision of spherical nuclei accounting for both zero-point oscillations (ZPO) of the nuclear shapes (structure effects) and for dissipative effects; i.e., in a sense we have combined the above two approaches. The bare nucleus-nucleus potential is evaluated using the semi-microscopic double-folding model with M3Y-Paris nucleon-nucleon forces. The nucleon densities are taken from the IAEA data base. For each collision partner several deformations of quadrupole and octupole type are accounted for with the probabilities corresponding to the harmonic oscillator at the ground state. The dissipative effects enter into our combined approach within the surface friction model well known in the literature. The final fate of a trajectory is decided by means of quantum transmission coefficients. There are two fitting parameters in the model, tau and K_R. Parameter tau reflects to what extent ZPO survives when the reagents approach each other. Parameter K_R is the friction strength for the radial motion. All calculations have been performed for 16O+92Zr reaction. The calculated CSs and barrier distribution are found in good agreement with the precision experimental data at reasonable values of tau and K_R. Calculations show that the CSs are mostly sensitive to tau at low (sub-barrier) collision energies whereas the value of K_R is important at the above barrier energies.Comment: 14 pages, 10 figures (submitted to NPA