The ATLAS detector at the LHC recorded 0.49nb$^{ -1}$ of Pb+Pb collisions and 25pb$^{ -1}$ of $pp$ collisions, both at the center-of-mass energy 5.02TeV per nucleon pair. Recently, ATLAS also recorded 3$\mu$b$^{ -1}$ of Xe+Xe collisions at the center-of-mass energy 5.44TeV, which provides a new opportunity to study the system-size dependence of the charged-hadron production in heavy-ion collisions. The large acceptance of the ATLAS detector allows to measure the spectra of charged hadrons in a wide range of pseudorapidity and transverse momentum. The nuclear modification factors $R_\mathrm{ AA}$ are constructed as a ratio of the spectra measured in Pb+Pb or Xe+Xe collisions to that measured in $pp$ collisions. The $R_\mathrm{ AA}$ obtained in the two systems are presented for different centrality intervals and the results are discussed.
Categories: hep-ex nucl-ex