Charged particle multiplicity in proton-lead collisions at $\sqrt{s_{_{NN}}} = 5.02$ TeV in the ATLAS experiment

This note describes ATLAS results on multiplicity of produced charged particles in p+Pb collisions at the centre-of-mass energy of 5.02 TeV. The particle density was measured in a wide $- 2.7<\eta<2.7$ range in eight centrality classes using 2.1 million events which were collected during a "pilot run" in September 2012. Analysis methods, centrality determination and the particle production dependence on the number of nucleons participating in the collisions are presented.