Dynamical nucleus-nucleus potential at short distances

Abstract

The dynamical nucleus-nucleus potentials for fusion reactions 40Ca+40Ca, 48Ca+208Pb and 126Sn+130Te are studied with the improved quantum molecular dynamics (ImQMD) model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for 40Ca+40Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depth of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of fusion barrier is also investigated. For heavy fusion system, the fusion pocket becomes shallow and almost disappears for symmetric systems and the obtained potential at short distances is higher than the adiabatic potential.Comment: 6 figures, accepted for publication in Phys. Rev.

Microscopic dynamics simulations of heavy-ion fusion reactions induced by neutron-rich nuclei

“…To describe the fermionic nature of the N-body system and to improve the stability of an individual nucleus, the modified Fermi constraint [19] in which the total energy of the system at the next time step is simultaneously checked after performing the two-body elastic scattering in the phase-space occupation constraint method [27] is adopted. In addition, considering the fact that the mean-field plays a dominant role in heavy-ion fusion reactions at energies around the Coulomb barrier, the collision term in the traditional QMD model is not involved in the present calculations in order to eliminate the uncertainty of the parameters in the collision term due to the uncertainty of the medium effect in nucleon-nucleon cross sections and the different methods to deal with the Pauli blocking.…”

“…The influence of the microscopic effects on the fusion barrier are empirically described by the barrier distribution function or absorbed in the model parameters. To self-consistently consider the dynamical effects in the fusion reactions, some microscopical dynamics models, such as the time-dependent Hartree-Fock (TDHF) model [15,16], the improved quantum molecular dynamic (ImQMD) model [17][18][19] and the Vlasov simulation plus imaginary times approach [20][21][22] have been developed. The nucleus-nucleus potential and the fusion cross sections at energies above the Coulomb barrier can be successfully described with the TDHF calculations based on the the Skyrme energy-density functional describing the interaction between nucleons.…”

Energy dependence of the nucleus-nucleus potential and the friction parameter in fusion reactions

“…2 and 3(b). The DC-and DD-TDHF have been applied to extract the collective potentials between two nuclei [22,68] which gave similar features as those obtained in the present work and in other QMD simulations [69,70]. With the collective potential and the momentum, we define the collective energy as…”

Finite-size effects on fragmentation in heavy-ion collisions

“…gies, some microscopic dynamics models, such as the time-dependent Hartree-Fock (TDHF) model [10,11], the Boltzmann-Uehling-Uhlenbeck (BUU) model [12][13][14] and the improved quantum molecular dynamics (ImQMD) model [15,16] have been developed. The ImQMD model is a semi-classical microscopic dynamics model and is successfully applied on heavyion fusion reactions and intermediate energy heavy-ion collisions [15,16,18,19].…”

“…The ImQMD model is a semi-classical microscopic dynamics model and is successfully applied on heavyion fusion reactions and intermediate energy heavy-ion collisions [15,16,18,19]. In the ImQMD model, each nucleon is described by a coherent state of a Gaussian wave packet as that in the traditional quantum molecular dynamics (QMD) model.…”