Seminarium Fizyki Jądra Atomowego

Heavy-ion collisions in the few-GeV energy range create strongly interacting matter at extreme baryon densities, comparable to those in neutron star mergers. Precise measurements of the dense-matter Equation-of-State in this regime are therefore essential for the understanding of neutron stars.

We present new results from HADES (High-Acceptance Dielectron Spectrometer) located at the SIS18, GSI Darmstadt, the only current setup capable of measuring rare and penetrating probes at the high baryochemical potential frontier of the QCD phase diagram. High-statistics measurements of collective flow for protons and light nuclei are reported in Au+Au and Ag+Ag collisions at s^1/2_NN= 2.42 and 2.55GeV, along with recent Au+Au data at s^1/2_NN= 1.98, 2.07, 2.16, and 2.24GeV, extending the excitation function to lower beam energies (200 - 800)A MeV. Beyond directed and elliptic flow, flow coefficients v_n up to 6th order are measured for the first time in this energy range, enabling a 3D characterization of angular particle emission in momentum space. Furthermore, the event-by-event flow fluctuations can be explored via correlations between the different flow coefficients, providing even stronger constraints on the Equation-of-State, and will also be presented.