Charged-particle multiplicities in \(pp\) interactions at \(\sqrt{s}\) = 900 GeV measured with the ATLAS detector at the LHC
Aad, Georges; Buanes, Trygve; Burgess, Thomas; Eigen, Gerald; Johansen, Lars Gimmestad; Kastanas, Alex; Lipniacka, Anna; Mohn, Bjarte Alsaker; Øye, Ola Kristoffer; Sandaker, Heidi; Sjursen, Therese; Stugu, Bjarne; Tonoyan, Arshak; Ugland, Maren; Zutshi, V.
Peer reviewed, Journal article
Published version

Åpne
Permanent lenke
https://hdl.handle.net/1956/10618Utgivelsesdato
2010-04Metadata
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Originalversjon
https://doi.org/10.1016/j.physletb.2010.03.064Sammendrag
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 |eta|<2.5 and pT>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 at 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.