THE ISOSPIN DISTRIBUTION OF FRAGMENTS IN REACTIONS ⁹⁶Ru + ⁹⁶Ru, ⁹⁶Ru + ⁹⁶Zr, ⁹⁶Zr + ⁹⁶Ru, and ⁹⁶Zr + ⁹⁶Zr AT BEAM ENERGY 400 AMeV

Abstract

The isospin distribution of particles and fragments in collisions 96Ru + 96Ru, 96Ru + 96Zr, 96Zr + 96Ru and 96Zr + 96Zr at beam energy 400 AMeV is studied with isospin-dependent QMD model. We find that the rapidity distribution of differential neutron–proton counting in neutron rich nucleus–nucleus collisions at intermediate energies is sensitive to the isospin-dependent part of nuclear potential. The study of the N/Z ratio of nucleons, light charged particles (LCP) and intermediate mass fragments (IMF) shows that the isospin-dependent part of nuclear potential drives IMF to be more isospin symmetric and emitted nucleons to be more neutron rich. From the study of the time evolution of the isospin distribution in emitted nucleons, LCP and IMF we find that neutrons diffuse much faster than protons at the beginning and the final isospin distribution is a result of dynamical balance of symmetry potential and Coulomb force under the charge conservation.

Mechanism of ternary breakup in the reactionAu197+Au197atTian1, Wu2, Li3 et al. 2010Phys. Rev. CSelf Cite

“…For fragment recognition, we adopt the conventional coalescence model [20] widely used in the QMD model calculations, in which particles with relative momenta smaller than P 0 and relative distance smaller than R 0 are considered to belong to one cluster. Here, R 0 and P 0 are taken to be 3.5 fm and 300 MeV/c, respectively [21,22]. In this work, we create more than 4000 bombarding events for each small impact parameter (b = 0-6 fm), 7000 bombarding events for b = 7-9 fm, and at least 10 000 events for each large impact parameter (b = 10-12 fm) for the Au + Au reaction at an energy of 15A MeV.…”

On the Lorentz structure of the symmetry energy

“…For densities beyond saturation one needs extrapolations which can only be investigated in dynamical situations of heavy ion collisions at intermediate energies, where hot and dense asymmetric nuclear matter is formed. Indeed, the study of the high density symmetry energy is an object of recently started investigations [24][25][26][27]. Their motivation has been the planning of new experimental heavy ion facilities with neutron-rich radioactive beams with data available in the near future.…”

Connection between the largest Lyapunov exponent, density fluctuation, and multifragmentation in excited nuclear systems

“…In our calculation, the fragment recognition is in terms of the conventional coalescence model [25], in which particles with relative momenta smaller than P 0 and relative distance smaller than R 0 are considered to belong to one cluster. Here R 0 and P 0 are taken to be 3.5 fm and 300 MeV/c, respectively [26,27]. In Fig.…”