Abstract

The ATLAS experiment at the LHC has measured the centrality dependence of charged particle pseudorapidity distributions over |η|<2 in lead–lead collisions at a nucleon–nucleon centre-of-mass energy of sNN=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<|η|<4.9. Measurements are presented of the per-event charged particle pseudorapidity distribution, dNch/dη, and the average charged particle multiplicity in the pseudorapidity interval |η|<0.5 in several intervals of collision centrality. The results are compared to previous mid-rapidity measurements at the LHC and RHIC. The variation of the mid-rapidity charged particle yield per colliding nucleon pair with the number of participants is consistent with lower sNN results. The shape of the dNch/dη distribution is found to be independent of centrality within the systematic uncertainties of the measurement.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call