Speaker
Description
$\bf{A.T. D'yachenko^{1}, I.A. Mitropolsky^{2}}$
$^{1}$ Emperor Alexander I Petersburg State Transport University, St.Petersburg, Russia;
$^{2}$ NRC "Kurchatov Institute", Petersburg Nuclear Physics Institute, Gatchina, Russia
In progress of a hydrodynamic approach with a non-equilibrium state equation for describing heavy ion collisions [1], we consider the emission of pions both at sub-threshold energies and at the SIS (GSI) accelerator energies. The emission of pions at sub-threshold energies is possible due to the collective intra-nuclear movement of nucleons. The influence of this motion is naturally taken into account in the framework of the hydrodynamic approach, which clearly includes the multiparticle nature of colliding heavy ions. In this case, nuclear hydrodynamics must be modified by the non-equilibrium equation of state to account for the transition from the initial non-equilibrium state to the state of local thermodynamic equilibrium. In this approach, highlighting the compression stage, the expansion stage, and the freeze-out stage with the formation of secondary particles, we described experimental inclusive double differential cross sections of pion emission for collisions of different nuclei at sub-threshold energies [2, 3]. Agreement with experimental data is achieved without introducing fitting parameters. We have extended this approach to the SIS energy domain and suggest using it in research at the NICA accelerator complex under construction in Dubna.
$\bf{References}$
1 A.T. D’yachenko, K.A. Gridnev, W. Greiner, J. Phys. $\bf{G 40}$, 085101 (2013).
2.A.T. D’yachenko, I.A. Mitropolsky, Phys. Atom. Nucl. $\bf{82}$ (2019) no. 12.
3.A.T. D’yachenko, I.A. Mitropolsky, Bull. Russ. Acad. Sci. Phys. $\bf{84}$ (2020) no. 4.
