Description
The ATLAS experiment at the Large Hadron Collider measures charged hadron spectra obtained in 2010 and 2011 lead-lead LHC data taking periods with total integrated statistics of 0.15/nb. The results are compared to the pp spectra of charged hadrons at the same centre-of-mass energy, accumulated by ATLAS in 2013 with the integrated luminosity of 4/pb. This allows for a detailed comparison of the two collision systems in a wide transverse momentum (0.5<pT<150GeV) and pseudorapidity (|η|<2) ranges in different centrality intervals of Pb+Pb collision. The nuclear modification factors RAA and RCP are presented as a function of centrality, pT and η. They show a distinct pT-dependence with a pronounced minimum at about 7 GeV. Above 60 GeV, RAA is consistent with a flat, centrality-dependent, value within the uncertainties. The value is 0.55±0.01(stat.)±0.04(syst.) in the most central collisions. The RAA is observed to be independent of pseudorapidity over the whole transverse momentum range in all centrality classes.
| On behalf of collaboration: | ATLAS |
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