  The ATLAS detector at the LHC obtained the sample of p+Pb data at
$\sqrt{s_{NN}}={}$5.02TeV with integrated luminosity of 25nb${}^{-1}$, which
can be compared to the pp data obtained by interpolating pp measurements at
$\sqrt{s}={}$2.76TeV and 7TeV. Due to the excellent capabilities of the ATLAS
detector, and its stable operation in heavy ion as well as proton-proton
physics runs, the data allow measurements of the nuclear modification factor,
ratio of heavy ion charged particle spectra divided by pp reference, in
different centrality classes over a wide range of rapidity. The charged
particle nuclear modification factor is found to vary significantly as a
function of transverse momentum with a stronger dependence in more peripheral
collisions.
