Charged Particle Production in Pb+Pb Collisions at √sNN = 2.76 TeV with the ATLAS Detector at LHC

A broad program of measurements using heavy ion collisions is underway in ATLAS, with the aim of studying the properties of QCD matter at high temperatures and densities. Measurements of inclusive charged particle production, which is dominated by low momentum particles, is a way to study the bulk properties of the matter, as it scales directly with the entropy produced in the early stages of the collision and is thus sensitive to the low x physics of the initial state. This talk describes measurements performed using up to 9 μb−1 of lead-lead collision data provided at a nucleon-nucleon center-of-mass energy of 2.76 GeV by the Large Hadron Collider and collected by the ATLAS detector during November and December 2010. The charged particle multiplicity is measured for particles down to low transverse momentum and large pseudorapidity using a variety of methods and magnetic field configurations. The spectrum of charged particles is also measured, which reflects both the bulk dynamics of the system as well as jet fragmentation.