Effects of the in-medium nucleon-nucleon cross section on collective flow and nuclear stopping in heavy-ion collisions in the Fermi-energy domain

Abstract

With the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, a systematic investigation of the effects of in-medium nucleon-nucleon (N N ) elastic cross section on the collective flow and the stopping observables in 197 Au + 197 Au collisions at beam energies from 40 to 150 MeV/nucleon is performed. Simulations with the medium correction factor F = σ in-medium NN /σ free NN = 0.2, 0.3, 0.5, and the one obtained with the FU3FP1 parametrization which depends on both the density and the momentum are compared to the FOPI and INDRA experimental data. It is found that, to best fit the experimental data of the slope of the directed flow and the elliptic flow at mid-rapidity as well as the nuclear stopping, the correction factor F=0.2 and 0.5 are required for reactions at beam energies of 40 and 150 MeV/nucleon, respectively. While calculations with the FU3FP1 parametrization can simultaneously reproduce these experimental data reasonably well. And, the observed increasing nuclear stopping with increasing beam energy in experimental data can also be reproduced by using the FU3FP1 parametrization, while the calculated stopping power in Au+Au collisions with beam energies from 40 to 150 MeV/nucleon almost keeps constant when take F equal to a fixed value.

Effect of internal magnetic field on collective flow in heavy ion collisions at intermediate energies

“…[39]. The experimental data of heavy-ion collisions in intermediate energies can be reproduced reasonably well by this model [39][40][41][42][43][44][45].…”

Quantifying the Effect of Initial Fluctuations on Isospin-Sensitive Observables from Heavy-Ion Collisions at Intermediate Energies

“…In the presently used UrQMD model, the symmetry potential is derived from the Skyrme potential energy density function in the same manner as the improved quantum molecular dynamics (ImQMD) model, see e.g., [48,49]. Together with the introduction of the in-medium nucleon-nucleon cross-sections and the improvement on the cluster recognition criteria, many experimental data in HICs at intermediate energies can be reproduced fairly well [50][51][52]. In the presently used UrQMD version, at the end of the reaction, clusters are recognized with an isospin-dependent minimum spanning tree (iso-MST) method [18,53].…”

Analysis of the dynamical mechanism for elliptic flow production in heavy-ion collisions at intermediate energies

“…对UrQMD模型的平均场、 碰撞项等部分做了相应 的改进 [26][27][28][29][30][31][32][33][34][35][36] . 当前版本进一步引入了Skyrme能量密 度泛函给出的表面能项、表面不对称项以及对称能 项:…”