1. Measurement of the centrality dependence of the charged particle pseudorapidity distribution in lead-lead collisions at √(sNN)=2.76 TeV with the ATLAS detector
- Author
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ATLAS Collaboration, Mitsou, Vasiliki, Fuster Verdú, Juan A., Ferrer Soria, Antonio, Castillo Giménez, María Victoria, Cabrera Urbán, Susana, García García, Carmen, Higón Rodríguez, Emilio, Martí García, Salvador, Ros Martínez, Eduardo, González de la Hoz, Santiago, Salt Cairols, José, Valls Ferrer, Juan Antonio, Kaci, Mohammed, Fiorini, Luca, Hernández Jiménez, Yesenia, Lacasta Llácer, Carlos, and Villaplana Pérez, Miguel
- Subjects
Acceleradors de partícules ,High Energy Physics::Experiment ,Nuclear Experiment ,Partícules (Física nuclear) ,Detectors de radiació - Abstract
The ATLAS experiment at the LHC has measured the centrality dependence of charged particle pseudorapidity distributions over vertical bar eta vertical bar < 2 in lead-lead collisions at a nucleon-nucleon centre-of-mass energy of root 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 < vertical bar eta vertical bar< 4.9. Measurements are presented of the per-event charged particle pseudorapidity distribution, dN(ch)/d eta, and the average charged particle multiplicity in the pseudorapidity interval vertical bar eta vertical bar < 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 root s(NN) results. The shape of the dN(ch)/d eta distribution is found to be independent of centrality within the systematic uncertainties of the measurement.
- Published
- 2012