The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities

TL;DR

The ASY-EOS experiment at GSI investigates the symmetry energy at densities above nuclear saturation by analyzing neutron-proton elliptic flow ratios in heavy-ion collisions, aiming to refine the nuclear Equation of State.

Contribution

This study presents new experimental data from the GSI ASY-EOS collaboration to better constrain the symmetry energy at supra-saturation densities, improving upon previous statistical uncertainties.

Findings

Initial estimates of the symmetry term from earlier data.

Extended dataset from GSI enhances understanding of symmetry energy.

Potential implications for nuclear physics and astrophysics.

Abstract

The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich heavy-ions systems at intermediate energies has been proposed as an observable sensitive to the strength of the symmetry term in the nuclear Equation Of State (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for $^{197}$Au+$^{197}$Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.