Dynamical freeze-out criterion in event-by-event hydrodynamics

Abstract

In hydrodynamical modelling of ultrarelativistic heavy-ion collisions the freeze-out is typically assumed to take place on a surface of constant temperature or energy density. In this work we apply a dynamical freeze-out criterion, which compares the hydrodynamical expansion rate with the pion scattering rate, to an event-by-event ideal hydrodynamics at the full RHIC collision energy. We present hadron spectra and elliptic flow calculated using (2+1)-dimensional ideal hydrodynamics, and show the differences between constant temperature and dynamical freeze-out criteria. We find that when the freeze-out ratio is fixed to one, the different freeze-out criteria lead to slightly different spectra and v_2(p_T) in the event-by-event calculations.