Bochum 2018 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 57: Heavy Ion Collisions and QCD Phases X

HK 57.1: Group Report

Friday, March 2, 2018, 14:00–14:30, HZO 80

Collective flow and correlations measurements with HADES in Au+Au collisions at 1.23 AGeV — •Behruz Kardan — Goethe-Universität, Frankfurt am Main

HADES provides a large acceptance combined with a high mass-resolution and therefore allows to study dielectron and hadron production in heavy-ion collisions with unprecedented precision. With the high statistics of seven billion Au-Au collisions at 1.23 AGeV, the investigation of collective effects and particle correlations is possible with so far unprecedented accuracy. At low energies v1 and v2, related to directed and elliptic flow, have been measured at the BEVALAC and SIS18, but so far high-order harmonics have not been studied. They allow to characterize the properties of the dense hadronic medium produced in these collisions, such as its viscosity, and provide thus an important reference to measurements at higher energies. We will present data on higher-order flow harmonics (v3 and v4) of protons and first results on multi-particle azimuthal correlation analyses. Furthermore, data on directed and elliptic flow of light nuclei will be shown. Information on radial flow can be obtained from the analysis of pion HBT-correlations, deuteron coalescence and transverse momentum spectra of identified particles. We will present new results on these observables extracted from the HADES data and discuss their correlations. From these a consistent picture emerges which provides strong evidence for a substantial radial expansion already at these low beam energies.

Supported by BMBF (05P15RFFCA), HGS-HIRe and H-QM.