Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC

Charged-particle multiplicities in pp interactions at root s=900 GeV measured with the ATLAS detector at the LHC

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 m...

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Bibliographic Details
Main Authors: Aad, G, Abat, E, Abbott, B, Abdallah, J, Abdelalim, A, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, B, Ackers, M, Adams, D, Addy, T, Adelman, J, Aderholz, M, Adorisio, C, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, J, Aharrouche, M, Ahlen, S
Format: Journal article
Language:English
Published: ELSEVIER SCIENCE BV 2010
Description
Summary: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. (C) 2010 Published by Elsevier B.V.

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