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.

THE ATLAS COLL. , G. AAD; MT DOVA ET AL

PHYSICS LETTERS B

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 710 p. 363 - 382

0370-2693

The ATLAS experiment at the LHC has measured the centrality dependence of charged particle pseudorapidity distributions over |eta| < 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 < |eta| < 4.9. Measurements are presented of the per-event charged particle density distribution, dN_ch/deta, and the average charged particle multiplicity in the pseudorapidity interval |eta|