Azimuthal correlations as a test for centrality in heavy-ion collisions

Abstract

Azimuthal correlations of particles emitted in collisions between 197Au target nuclei and projectiles 36Ar (at E A = 35, 50, 80 and 110 MeV) and 129Xe (at E A = 50 MeV) have been measured with the MSU Miniball, a 4π phoswich array with a low detection threshold. Various impact parameter filters, based on the charge-particle multiplicity, transverse energy and midrapidity charge are tested by their ability to suppress collective motion as measured by the azimuthal correlations. The usefulness of a directivity cut in selecting central collisions for these systems is evaluated.