Nucleon number dependence of longitudinal radii in ion-ion collisions as a signature of the onset of collective expansion

الأصل · EN

In an attempt to disentangle the effects of nuclear geometry from those of nuclear geometry we study dependence of longitudinal radius on nucleon numbers of colliding nuclei within a simple model of multiple nucleon- nucleon collisions.We discuss two approaches to resulting simple formula.In the former the data up to S-Au can be described by nuclear geometry at the price of two parameters,but Rₗ for Pb-Pb is significantly larger than geometry can accomodate, indicating an onset of a new dynamics. In the latter even collisions induced by lighter ions give evidence of some collective behaviour and the increase of Rₗ for Pb-Pb indicates again the onset of a new dynamics.