Multiplicity of charged particles in Pb-Pb collisions at SPS energies

TL;DR

This paper reports measurements of charged particle multiplicity in Pb-Pb collisions at CERN SPS energies, analyzing how it varies with collision centrality and energy, providing insights into particle production mechanisms in heavy-ion collisions.

Contribution

It presents new measurements of charged particle multiplicity at two different beam energies and studies their dependence on collision centrality, expanding understanding of particle production in heavy-ion collisions.

Findings

Multiplicity increases approximately logarithmically with energy.

Charged particle density at mid-rapidity depends on collision centrality.

Data covers about 50% of the inelastic cross section.

Abstract

The multiplicity of charged particles in the central rapidity region has been measured by the NA57 experiment in Pb--Pb collisions at the CERN SPS at two beam momenta: 158 A GeV/{\it c} and 40 A GeV/{\it c}. The value of $dN_{ch}/d\eta$ at the maximum has been determined and its behaviour as a function of centrality has been studied in the centrality range covered by NA57 (about 50% of the inelastic cross section). The multiplicity increases approximately logarithmically with the centre of mass energy.