Abstract
A
bstract
This paper presents measurements of charged-hadron spectra obtained in
pp
,
p
+Pb, and Pb+Pb collisions at
s
or
s
NN
= 5
.
02 TeV, and in Xe+Xe collisions at
s
NN
= 5
.
44 TeV. The data recorded by the ATLAS detector at the LHC have total integrated luminosities of 25 pb
−
1
, 28 nb
−
1
, 0.50 nb
−
1
, and 3
μ
b
−
1
, respectively. The nuclear modification factors
R
p
Pb
and
R
AA
are obtained by comparing the spectra in heavy-ion and
pp
collisions in a wide range of charged-particle transverse momenta and pseudorapidity. The nuclear modification factor
R
p
Pb
shows a moderate enhancement above unity with a maximum at
p
T
≈ 3 GeV; the enhancement is stronger in the Pb-going direction. The nuclear modification factors in both Pb+Pb and Xe+Xe collisions feature a significant, centrality-dependent suppression. They show a similar distinct
p
T
-dependence with a local maximum at
p
T
≈ 2 GeV and a local minimum at
p
T
≈ 7 GeV. This dependence is more distinguishable in more central collisions. No significant |
η
|-dependence is found. A comprehensive comparison with several theoretical predictions is also provided. They typically describe
R
AA
better in central collisions and in the
p
T
range from about 10 to 100 GeV.