The ASY-EOS experiment at GSI: investigating symmetry energy at supra-saturation densities, P. Russotto, INFN-LNS & Università di Catania, Italy − The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of neutron rich heavy-ions at intermediate energies is proposed as an observable sensitive to the strength of the symmetry term in the nuclear equation of state at supra-saturation densities. The results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model favours a moderately soft symmetry term but suffer from a considerable statistical uncertainty [1].  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.  The flows of neutrons, protons and light complex particles were measured for 197Au+197Au, 96Ru+96Ru, and 96Zr+96Zr collisions at 400 MeV/nucleon using the LAND neutron detector, the forward part of CHIMERA device, the Aladin ToF-Wall, the Si-CsI Krakow Array and the Microball detector.  First results will be reported.


[1] P. Russotto et al., Phys. Lett. B 697 (2011) 471.