Squeeze-out of nuclear matter in high-energy heavy-ion collisions in the molecular-dynamical model

The squeeze-out effect studied recently in experiment by means of the sphericity and the transverse-momentum methods is considered for the reactions Ca+Ca at E/A=400, 800 MeV, Nb+Nb at E/A=150, 400, 650, 800 MeV and La+La at E/A=800 MeV simulated on the basis of the molecular-dynamical model. The model reproduces qualitatively the main features of the data: (i) the effect has a maximum at intermediate impact parameters (b/R=0.75-1; R is a nuclear radius), (ii) the effect becomes more pronounced for a heavier nuclear system, (iii) the effect increases from the lowest energy of E/A=150 MeV to the maximum value at around 400 MeV with a subsequent smooth decrease with increasing energy, (iv) the effect exists over the whole rapidity region (for the events with b/R<1), (v) the composite particles show a much stronger effect then one-nucleon fragments. The model predicts that the decrease of the effect with increasing energy is due to the composite fragments. It would be of interest to test this fact experimentally. ((orig.))