Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at sqrt(sNN)=2.76 TeV

A measurement is presented of the charged hadron multiplicity in hadronic PbPb collisions, as a function of pseudorapidity and centrality, at a collision energy of 2.76TeV per nucleon pair. The data sample is collected using the CMS detector and a minimum-bias trigger, with the CMS solenoid o. The number of charged hadrons is measured both by counting the number of reconstructed particle hits and by forming hit doublets of pairs of layers in the pixel detector. The two methods give consistent results. The charged hadron multiplicity density, dNch/deta|eta=0, for head-on collisions is found to be 161255, where the uncertainty is dominated by systematic eects. Comparisons of these results to previous measurements and to various models are also presented