  Novel transverse-momentum technique is used to analyse charged-particle
exclusive data for collective motion in the Ar+KCl reaction at 1.8 GeV/nucl.
Previous analysis of this reaction, employing the standard sphericity tensor,
revealed no significant effect. In the present analysis, collective effects are
observed, and they are substantially stronger than in the Cugnon cascade model,
but weaker than in the hydrodynamical model.
