München 2019 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 41: Heavy-Ion Collisions and QCD Phases VIII
HK 41.1: Group Report
Wednesday, March 20, 2019, 16:30–17:00, HS 15
Two-Pion Intensity Interferometry in Collisions of Au+Au @ 1.23AGeV — •Robert Greifenhagen1, 2 and Roland Kotte1 for the HADES collaboration — 1Helmholtz-Zentrum Dresden-Rossendorf — 2Technische Universität Dresden
The HADES apparatus 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 unrivalled accuracy.
We present results on identical pion intensity interferometry (HBT) with substantial charge sign difference. Our data allow access to the dependence of the pion emitting source on both the pair transverse momentum and the collision centrality. Comparing our femtoscopic results at √sNN = 2.4 GeV to similar results achieved for heavy-ion collisions in a wide range of beam energies we see a very smooth evolution of the source parameters, contrary to the preexisting picture.
Furthermore, the high statistics measurements of flow coefficients for protons, deuterons and tritons are presented here. In addition to the directed (v1) and elliptic (v2) flow components also the higher coefficients v3 and v4 are investigated for the first time in this energy regime.
Together with the transverse momentum spectra of identified particles a consistent picture emerges which provides strong evidence for a substantial collective expansion already at these low beam energies.