A scheme to identify collective transverse flow in relativistic heavy ion collisions at CERN SPS

A judicious selection of projectile-target combinations in relativistic heavy ion collisions at CERN SPS may provide us with a number of systems having a similar particle rapidity density per unit transverse area. There may be a formation of quark gluon plasma, followed by hadronization, if the energy density attained is large enough. Electromagnetic radiations from such systems normalized to the initial transverse area would be identical if they do not undergo a transverse expansion. A deviation from this scaling behaviour is shown to provide a novel signature for the transverse flow effects in such experiments. Such a deviation is expected to emerge clearly in a comparison of results for Pb+Pb system, e.g., with those for S+Au.