Charged-particle production in Pb+Pb and Xe+Xe collisions measured with the ATLAS detector

The measurement of charge-particle production in heavy-ion collision systems and its comparison to $pp$ data provide an insight into the properties of the quark-gluon plasma produced in collisions of heavy ions. In 2015, the ATLAS detector at the LHC recorded 0.49 nb$^{-1}$ of Pb+Pb collisions and 25 pb$^{-1}$ of $pp$ collisions at the center-of-mass energy $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. In addition, around 3 $\mu$b$^{-1}$ of Xe+Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV were recorder in 2017. These samples provide an opportunity to study the system size dependence of the parton energy loss. The large acceptance of the ATLAS detector allows measurements of charged-particle spectra in a wide range of both pseudorapidity and transverse momentum, differentially in collision centrality. The charged-particle spectra measured in Pb+Pb and Xe+Xe collisions are compared to the analogous spectra measured in $pp$ collisions, and the resulting nuclear modification factors are scrutinized.