Investigating the “kink” plot as a signal of the onset of deconfinement

Abstract

One of the physics goals of the NA61/SHINE collaboration at the CERN Super Proton Synchrotron is to study the phase diagram of hadronic matter. To this end, a series of heavy ion collision measurements are performed. It is believed that above a certain collision energy and system size a phase transition between the hadronic matter and quark–gluon plasma occurs. A number of observables have been developed to determine which of the phases was created at the early stage of the collision. This report discusses the dependence of the ratio of the mean number of produced pions to the mean number of wounded nucleons on the Fermi energy measure. For comparison with other measurements this is often presented in the form of the “kink” plot. This plot is presented enriched with preliminary results for ⁴⁰Ar+⁴⁵Sc central collisions at 13A, 19A, 30A, 40A, 75A and 150A GeV/c beam momenta. The results are finally compared to data from other experiments.