Transverse momentum analysis of collective motion in relativistic nuclear collisions

Novel transverse-momentum technique is used to isolate collective motion in the Ar + KCl reaction at 1.8 GeV/nucleon. Previous analysis of this reaction, employing the standard sphericity tensor, revealed no significant effect. In the present analysis, collective effects are observed. They are substantially stronger than in the Cugnon cascade model, and weaker than in the hydrodynamic model. The semiexclusive data of the near-symmetric Ar + KCl (1.8 GeV/nucleon) reaction come from central-trigger measurements in the streamer chamber at the Bevalac. Details of the experiment have been reported previously