Charged-particle multiplicity measurement in proton-proton collisions at root s=7 TeV with ALICE at LHC


Aamodt K., Abel N., Abeysekara U., Abrahantes Quintana A., Abramyan A., Adamova D., ...More

EUROPEAN PHYSICAL JOURNAL C, vol.68, no.3-4, pp.345-354, 2010 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 68 Issue: 3-4
  • Publication Date: 2010
  • Doi Number: 10.1140/epjc/s10052-010-1350-2
  • Journal Name: EUROPEAN PHYSICAL JOURNAL C
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.345-354
  • Bursa Uludag University Affiliated: No

Abstract

The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy root s = 7 TeV, were measured in the central pseudorapidity region vertical bar eta vertical bar < 1. Comparisons are made with previous measurements at root s = 0.9 TeV and 2.36 TeV. At root s = 7 TeV, for events with at least one charged particle in |eta vertical bar| < 1, we obtain dN(ch)/d eta = 6.01 +/- 0.01(stat.)(-0.12)(+0.20) (syst.). This corresponds to an increase of 57.6%+/-0.4%(stat.)(-1.8%)(+3.6) (syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.