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 sqrt[s_{NN}]=2.76 TeV
BEOLE', Stefania;BIANCHI, LIVIO;BIOLCATI, EMANUELE;CORRALES MORALES, YASSER;FERRETTI, Alessandro;GAGLIARDI, Martino;GALLIO, Mauro;INNOCENTI, GIAN MICHELE;LUPARELLO, GRAZIA;MASERA, Massimo;MILANO, LEONARDO;ORTONA, GIACOMO;POGHOSYAN, MARTIN;SICILIANO, MELINDA;VERCELLIN, Ermanno;
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.File | Dimensione | Formato | |
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