Measurement of the centrality dependence of the charged particle pseudorapidity distribution in lead-lead collisions at sqrt(s_NN) = 2.76 TeV with the ATLAS detector

G. Aad, Mogens Dam, Jørgen Beck Hansen, Peter Henrik Hansen, John Renner Hansen, Jørn Dines Hansen, Simon Johann Franz Heisterkamp, Morten Dam Jørgensen, Nele Maria Philomena Boelaert, Esben Bryndt Klinkby, Sascha Mehlhase, Björn Stefan Nilsson, Troels Christian Petersen, Ask Emil Løvschall-Jensen, Stefania Xella

106 Citationer (Scopus)

Abstract

The ATLAS experiment at the LHC has measured the centrality dependence of charged particle pseudorapidity distributions over |η|<2 in lead-lead collisions at a nucleon-nucleon centre-of-mass energy of √s NN=2.76 TeV. In order to include particles with transverse momentum as low as 30 MeV, the data were recorded with the central solenoid magnet off. Charged particles were reconstructed with two algorithms (2-point "tracklets" and full tracks) using information from the pixel detector only. The lead-lead collision centrality was characterized by the total transverse energy in the forward calorimeter in the range 3.2<|η|<4.9. Measurements are presented of the per-event charged particle pseudorapidity distribution, dN ch/dη, and the average charged particle multiplicity in the pseudorapidity interval |η|<0.5 in several intervals of collision centrality. The results are compared to previous mid-rapidity measurements at the LHC and RHIC. The variation of the mid-rapidity charged particle yield per colliding nucleon pair with the number of participants is consistent with lower sNN results. The shape of the dN ch/dη distribution is found to be independent of centrality within the systematic uncertainties of the measurement.

OriginalsprogEngelsk
TidsskriftPhysics Letters B
Vol/bind710
Udgave nummer3
Sider (fra-til)363-382
Antal sider19
ISSN0370-2693
DOI
StatusUdgivet - 12 apr. 2012

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