The first measurement of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair ffiffiffiffiffiffiffiffi sNN p ¼ 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 4ðstatÞ 76ðsystÞ, which corresponds to 8:3 0:4ðsystÞ 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 ffiffiffiffiffiffiffiffi sNN p ¼ 0:2 TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.
Charged-particle multiplicity measurement in proton-proton collisions at root s=0.9 and 2.36 TeV with ALICE at LHC
Aamodt K;BRUNO, GIUSEPPE EUGENIO;
2010-01-01
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 ffiffiffiffiffiffiffiffi sNN p ¼ 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 4ðstatÞ 76ðsystÞ, which corresponds to 8:3 0:4ðsystÞ 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 ffiffiffiffiffiffiffiffi sNN p ¼ 0:2 TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
