Elliptical flow and isospin effects in heavy-ion collisions at intermediate energies

TL;DR

This paper investigates elliptical flow in heavy-ion collisions across energies 50-1000 MeV/nucleon using the IQMD model, revealing a transition from in-plane to out-of-plane flow and its dependence on system parameters.

Contribution

It introduces a detailed analysis of the transition energy in elliptical flow and its dependence on system size, impact parameter, and model ingredients, supported by experimental data comparison.

Findings

Transition energy depends on system size and impact parameter.

Elliptical flow exhibits a power-law mass dependence.

Model calculations agree with experimental excitation functions.

Abstract

The elliptical flow of fragments is studied for different systems at incident energies between 50 and 1000 MeV/nucleon using the isospin-dependent quantum molecular dynamics (IQMD) model. Our findings reveal that elliptical flow shows a transition from positive (in-plane) to negative (out-of-plane) values in the midrapidity region at a certain incident energy known as the transition energy. This transition energy is found to depend on the model ingredients, size of the fragments, and composite mass of the reacting system as well as on the impact parameter of the reaction. A reasonable agreement is observed for the excitation function of elliptical flow between the data and our calculations. Interestingly, the transition energy is found to exhibit a power-law mass dependence.