Pseudorapidity distributions of the produced charged particles in nucleus-nucleus collisions at low energies on the BNL Relativistic Heavy Ion Collider

The revised Landau hydrodynamic model is used to discuss the pseudorapidity distributions of the produced charged particles in Au+Au and Cu+Cu collisions at energies of sqrt(s_NN)= 19.6 and 22.4 GeV correspondingly on the BNL Relativistic Heavy Ion Collider. It is found that the revised Landau hydrodynamic model alone can give a good description to the experimental measurements. This is different from that in the same collisions but at the maximum energy of sqrt(s_NN)= 200 GeV. Where, in addition to the revised Landau hydrodynamic model, the effects of leading particles have to be taken into account in order to explain the experimental observations. It can be attributed to the different degrees of transparency of participants in different incident energies.