Chemical equilibration and freeze-out in nucleus-nucleus collisions at incident beam energies from 1A to 2A GeV

Chemical equilibrium in relativistic nucleus-nucleus collisions at incident beam energies from 1A to 2A GeV is tested. The yields of nonstrange particles are consistent with the chemical equilibrium scenario. However, strange hadrons are not in chemical equilibrium with nonstrange particles, while the relative yields of strange hadrons among themselves are in agreement with the model calculation, taking into account the current experimental errors. The freeze-out points at these beam energies are far below the estimated deconfinement phase boundary, in contrast to the results at the Alternating Gradient Synchrotron and the Super Proton Synchrotron.