Observation of collective flow in relativistic nuclear collisions by transverse momentum analysis

A total of 776 interactions with AgBr in nuclear emulsion has been used to analyze the exclusive data for collective flow from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ at 1.8, 2.1, 1.52, and 0.95A GeV, respectively. The transverse momentum technique has been employed to study this effect which becomes stronger with the increase of incident energy as well as with the decrease of impact parameter.