Elsevier

Physics Letters B

Volume 688, Issue 1, 26 April 2010, Pages 21-42
Physics Letters B

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

https://doi.org/10.1016/j.physletb.2010.03.064Get rights and content
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open access

Abstract

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 |η|<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 η=0 is measured to be 1.333±0.003(stat.)±0.040(syst.), which is 5–15% higher than the Monte Carlo models predict.

Keywords

Charged-particle
Multiplicities
900 GeV
ATLAS
LHC
Minimum bias

Cited by (0)

© CERN, for the benefit of the ATLAS Collaboration.

☆☆

Date submitted: 2010-03-16T16:00:52Z.

[email protected]

a

Present address FermiLab, United States.

b

Also at CPPM, Marseille, France.

c

Also at TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3, Canada.

d

Also at Faculty of Physics and Applied Computer Science of the AGH-University of Science and Technology (FPACS, AGH-UST), al. Mickiewicza 30, PL-30059 Cracow, Poland.

e

Also at Università di Napoli Parthenope, via A. Acton 38, IT-80133 Napoli, Italy.

f

Also at Institute of Particle Physics (IPP), Canada.

g

Louisiana Tech University, 305 Wisteria Street, P.O. Box 3178, Ruston, LA 71272, United States.

h

At Department of Physics, California State University, Fresno, 2345 E. San Ramon Avenue, Fresno, CA 93740-8031, United States.

i

Currently at Istituto Universitario di Studi Superiori IUSS, V.le Lungo Ticino Sforza 56, 27100 Pavia, Italy.

j

Also at California Institute of Technology, Physics Department, Pasadena, CA 91125, United States.

k

Also at University of Montreal, Canada.

l

Also at Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.

m

Now at Chonnam National University, Chonnam 500-757, South Korea.

n

Also at Petersburg Nuclear Physics Institute, RU-188 300 Gatchina, Russia.

o

Also at School of Physics and Engineering, Sun Yat-sen University, Taiwan.

p

Also at School of Physics, Shandong University, Jinan, China.

q

Also at Rutherford Appleton Laboratory, Science and Technology Facilities Council, Harwell Science and Innovation Campus, Didcot OX11, United Kingdom.

r

Also at School of Physics, Shandong University, Jinan, China.

s

Also at Rutherford Appleton Laboratory, Science and Technology Facilities Council, Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom.

t

University of South Carolina, Dept. of Physics and Astronomy, 700 S. Main St, Columbia, SC 29208, United States.

u

Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary.

v

Also at Institute of Physics, Jagiellonian University, Cracow, Poland.

w

University of Rochester, Rochester, NY 14627, United States.

x

Transfer to LHCb 31.01.2010.

y

Naruto University of Education, Takashima, JP - Tokushima 772, Japan.

z

Also at Dept. of Physics, Nanjing University, China.

Deceased.