Abstract
We explore the directed, elliptic, triangular and quadrangular flow of deuterons in Au+Au reactions at a beam energy of 1.23 AGeV within the UrQMD approach. These investigations are of direct relevance for the HADES experiment at GSI that has recently presented first data on the flow of light clusters in Au+Au collisions at 1.23 AGeV. To address the deuteron flow, UrQMD has been extended to include deuteron formation by coalescence. We find that this ansatz provides a very good description of the measured deuteron flow data, if a hard equation of state is used for the simulation. In addition we show that light cluster formation has a sizable impact on the proton flow and has to be taken into account to obtain reliable results in the forward/backward region. Based on the observed scaling of the flow, which is a natural result of coalescence, we conclude that deuteron production at GSI energies is a final state recombination effect. Finally, we also discuss the scaling relations of the higher order flow components up to v4. We show that v3 ∼ v1v2 and as function of transverse momentum and that the integrated over the investigated energy range from Elab = 0.1 AGeV to 40 AGeV.
Highlights
Collisions of heavy ions in today’s largest accelerators allow to explore the characteristics of nuclear matter under extreme temperatures and densities
To address the deuteron flow, ultra relativistic quantum molecular dynamics (UrQMD) has been extended to include deuteron formation by coalescence. We find that this ansatz provides a very good description of the measured deuteron flow data, if a hard equation of state is used for the simulation
Results on the directed flow v1, the elliptic flow v2, the triangular flow v3 and the quandrangular flow v4 of deuterons and free protons in mid-peripheral gold–gold collisions at a fixed-target beam energy of 1.23 AGeV are presented
Summary
Collisions of heavy ions in today’s largest accelerators allow to explore the characteristics of nuclear matter under extreme temperatures and densities. The HADES experiment at the SIS18 accelerator at GSI in Darmstadt has measured Au +Au collisions at a fixed target beam energy of 1.23 AGeV, collecting a significant amount of data, sufficient to determine v1 and v2, and higher flow components with the charged projectile spectators event plane method [38,39,40, 42] which we approximate with the theoretical reaction plane. In particular at the beam energy under investigation in this study, a significant contribution to v3, correlated with the reaction plane, was observed. At this energy one expects a substantial production of clusters allowing to explore their flow. We use the UrQMD transport model with a hard EoS [43, 44]
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More From: Journal of Physics G: Nuclear and Particle Physics
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