The first measurement of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at a centre-of- mass energy per nucleon pair sqrt(sNN) = 2.76 TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section the pseudo-rapidity density of primary charged particles at mid-rapidity is 1584 +- 4 (stat) +- 76 (sys.), which corresponds to 8.3 +- 0.4 (sys.) 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 sqrt(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 √sNN=2.76 TeV

DE CARO, ANNALISA;DE GRUTTOLA, DANIELE;DE PASQUALE, Salvatore;FUSCO GIRARD, Mario;PAGANO, PAOLA;VIRGILI, Tiziano;
2010-01-01

Abstract

The first measurement of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at a centre-of- mass energy per nucleon pair sqrt(sNN) = 2.76 TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section the pseudo-rapidity density of primary charged particles at mid-rapidity is 1584 +- 4 (stat) +- 76 (sys.), which corresponds to 8.3 +- 0.4 (sys.) 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 sqrt(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/11386/3016221
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