The first measurement of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair √sNN=2.76  TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section, the pseudorapidity density of primary charged particles at midrapidity is 1584±4(stat)±76(syst), which corresponds to 8.3±0.4(syst) per participating nucleon pair. This represents an increase of about a factor 1.9 relative to pp collisions at similar collision energies, and about a factor 2.2 to central Au-Au collisions at √sNN=0.2  TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.

Charged-Particle Multiplicity Density at Midrapidity in Central Pb-Pb Collisions at root s(NN)=2.76 TeV

SORAMEL, FRANCESCA;CAFFARRI, DAVIDE;LUNARDON, MARCELLO;MORANDO, MAURIZIO;MORETTO, SANDRA;SCARLASSARA, FERNANDO;SEGATO, GIANFRANCO;TERREVOLI C;VIESTI, GIUSEPPE;
2010

Abstract

The first measurement of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair √sNN=2.76  TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section, the pseudorapidity density of primary charged particles at midrapidity is 1584±4(stat)±76(syst), which corresponds to 8.3±0.4(syst) per participating nucleon pair. This represents an increase of about a factor 1.9 relative to pp collisions at similar collision energies, and about a factor 2.2 to central Au-Au collisions at √sNN=0.2  TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2425160
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