PT Journal
AU ATLAS Collaboration (Aad, Gea
   Amoros, G
   Cabrera Urban, S
   Castillo Gimenez, V
   Costa, MJ
   Escobar, C
   Ferrer, A
   Fuster, J
   Garcia, C
   Gonzalez de la Hoz, S
   Hernandez Jimenez, Y
   Higon-Rodriguez, E
   Irles Quiles, A
   Kaci, M
   Lacasta, C
   Lacuesta, VR
   Marti-Garcia, S
   Miñano, M
   Mitsou, VA
   Moles-Valls, R
   Moreno Llacer, M
   Oliver Garcia, E
   Perez Garcia-Estañ, MT
   Ros, E
   Salt, J
   Sanchis-Lozano, MA
   Solans, CA
   Sanchez, J
   Torro Pastor, E
   Valladolid Gallego, E
   Valls Ferrer, JA
   Villaplana Perez, M
   Vos, M
   Wildauer, A
TI Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC
SO Physics Letters B
JI Phys. Lett. B
PY 2010
BP 21
EP 42
VL 688
IS 1
DI 10.1016/j.physletb.2010.03.064
LA English
DE Charged-particle; Multiplicities; 900 GeV; ATLAS; LHC; Minimum bias
AB The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range vertical bar eta vertical bar < 2.5 and p(T) > 500 MeV. The measurements are compared to Monte Carlo models of proton-proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity eta = 0 is measured to be 1.333 +/- 0.003(stat.) +/- 0.040(syst.), which is 5-15% higher than the Monte Carlo models predict.
ER