Charged-particle multiplicity density at mid-rapidity in central Pb-Pb collisions at √sNN=2.76 TeV

David Evans, Orlando Villalobos Baillie, Lee Stuart Barnby, Peter Jones, Roman Lietava, Anton Jusko, Arvinder Palaha, Plamen Petrov, Marian Krivda, Cristina Lazzeroni, Zoe Matthews, Ravjeet Kour, Sparsh Navin

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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.
Original languageEnglish
Article number252301
Number of pages10
JournalPhysical Review Letters
Issue number25
Publication statusPublished - 13 Dec 2010


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