Measurement of the centrality dependence of the charged particle pseudorapidity distribution in lead–lead collisions at sNN=2.76 TeV with the ATLAS detector

doi:10.1016/j.physletb.2012.02.045

Physics Letters B

Volume 710, Issue 3, 12 April 2012, Pages 363-382

https://doi.org/10.1016/j.physletb.2012.02.045 Get rights and content

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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 $\sqrt{s_{NN}} = 2.76 TeV$ . 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, $d N_{ch} / d η$ , 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 $\sqrt{s_{NN}}$ results. The shape of the $d N_{ch} / d η$ distribution is found to be independent of centrality within the systematic uncertainties of the measurement.

Cited by (0)

^☆: © CERN for the benefit of the ATLAS Collaboration.

^⋆: E-mail address: [email protected].

^a: Also at Laboratorio de Instrumentacao e Fisica Experimental de Particulas – LIP, Lisboa, Portugal.

^b: Also at Faculdade de Ciencias and CFNUL, Universidade de Lisboa, Lisboa, Portugal.

^c: Also at Particle Physics Department, Rutherford Appleton Laboratory, Didcot, United Kingdom.

^d: Also at CPPM, Aix-Marseille Université and CNRS/IN2P3, Marseille, France.

^e: Also at TRIUMF, Vancouver, BC, Canada.

^f: Also at Department of Physics, California State University, Fresno, CA, United States.

^g: Also at Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Krakow, Poland.

^h: Also at Fermilab, Batavia, IL, United States.

ⁱ: Also at Department of Physics, University of Coimbra, Coimbra, Portugal.

^j: Also at Università di Napoli Parthenope, Napoli, Italy.

^k: Also at Institute of Particle Physics (IPP), Canada.

^l: Also at Department of Physics, Middle East Technical University, Ankara, Turkey.

^m: Also at Louisiana Tech University, Ruston, LA, United States.

ⁿ: Also at Group of Particle Physics, University of Montreal, Montreal, QC, Canada.

^o: Also at Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan.

^p: Also at Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany.

^q: Also at Manhattan College, New York, NY, United States.

^r: Also at School of Physics and Engineering, Sun Yat-sen University, Guanzhou, China.

^s: Also at Academia Sinica Grid Computing, Institute of Physics, Academia Sinica, Taipei, Taiwan.

^t: Also at High Energy Physics Group, Shandong University, Shandong, China.

^u: Also at California Institute of Technology, Pasadena, CA, United States.

^v: Also at Section de Physique, Université de Genève, Geneva, Switzerland.

^w: Also at Departamento de Fisica, Universidade de Minho, Braga, Portugal.

^x: Also at Department of Physics and Astronomy, University of South Carolina, Columbia, SC, United States.

^y: Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary.

^z: Also at Institute of Physics, Jagiellonian University, Krakow, Poland.

^aa: Also at Department of Physics, Oxford University, Oxford, United Kingdom.

^ab: Also at Institute of Physics, Academia Sinica, Taipei, Taiwan.

^ac: Also at Department of Physics, The University of Michigan, Ann Arbor, MI, United States.

^ad: Also at DSM/IRFU (Institut de Recherches sur les Lois Fondamentales de lʼUnivers), CEA Saclay (Commissariat a lʼEnergie Atomique), Gif-sur-Yvette, France.

^ae: Also at Laboratoire de Physique Nucléaire et de Hautes Energies, UPMC and Université Paris-Diderot and CNRS/IN2P3, Paris, France.

^af: Also at Department of Physics, Nanjing University, Jiangsu, China.

^⁎: Deceased.

Physics Letters B

Measurement of the centrality dependence of the charged particle pseudorapidity distribution in lead–lead collisions at sNN=2.76 TeV with the ATLAS detector☆

Abstract

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☆