https://doi.org/10.1140/epjc/s10052-010-1350-2
Letter
Charged-particle multiplicity measurement in proton–proton collisions at 
TeV with ALICE at LHC
1
Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy
2
Department of Physics Aligarh Muslim University, Aligarh, India
3
National Institute for Nuclear and High Energy Physics (NIKHEF), Amsterdam, Netherlands
4
Physics Department, University of Athens, Athens, Greece
5
Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy
6
Sezione INFN, Bari, Italy
7
China Institute of Atomic Energy, Beijing, China
8
Department of Physics and Technology, University of Bergen, Bergen, Norway
9
Faculty of Engineering, Bergen University College, Bergen, Norway
10
Lawrence Berkeley National Laboratory, Berkeley, CA, USA
11
Institute of Physics, Bhubaneswar, India
12
School of Physics and Astronomy, University of Birmingham, Birmingham, UK
13
Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy
14
Sezione INFN, Bologna, Italy
15
Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
16
Institute of Space Sciences (ISS), Bucharest, Romania
17
National Institute for Physics and Nuclear Engineering, Bucharest, Romania
18
KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary
19
Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy
20
Sezione INFN, Cagliari, Italy
21
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
22
Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa
23
Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy
24
Sezione INFN, Catania, Italy
25
Physics Department, Panjab University, Chandigarh, India
26
Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France
27
Department of Physics, Ohio State University, Columbus, OH, USA
28
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
29
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
30
Universidad Autónoma de Sinaloa, Culiacán, Mexico
31
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
32
Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany
33
Wayne State University, Detroit, MI, USA
34
Joint Institute for Nuclear Research (JINR), Dubna, Russia
35
Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
36
Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany
37
Laboratori Nazionali di Frascati, INFN, Frascati, Italy
38
Gangneung-Wonju National University, Gangneung, South Korea
39
Petersburg Nuclear Physics Institute, Gatchina, Russia
40
European Organization for Nuclear Research (CERN), Geneva, Switzerland
41
Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France
42
Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba
43
Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
44
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
45
Hiroshima University, Hiroshima, Japan
46
University of Houston, Houston, TX, USA
47
Physics Department, University of Rajasthan, Jaipur, India
48
Physics Department, University of Jammu, Jammu, India
49
Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland
50
Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
51
University of Tennessee, Knoxville, TN, USA
52
Saha Institute of Nuclear Physics, Kolkata, India
53
Variable Energy Cyclotron Centre, Kolkata, India
54
Fachhochschule Köln, Köln, Germany
55
Faculty of Science, P.J. Šafárik University, Košice, Slovakia
56
Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia
57
Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy
58
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru
59
Lawrence Livermore National Laboratory, Livermore, CA, USA
60
Division of Experimental High Energy Physics, University of Lund, Lund, Sweden
61
Institut de Physique Nucléaire de Lyon, Université de Lyon 1, CNRS/IN2P3, Lyon, France
62
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
63
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico
64
Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico
65
Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico
66
Institute for Nuclear Research, Academy of Sciences, Moscow, Russia
67
Institute for Theoretical and Experimental Physics, Moscow, Russia
68
Moscow Engineering Physics Institute, Moscow, Russia
69
Russian Research Centre Kurchatov Institute, Moscow, Russia
70
Indian Institute of Technology, Mumbai, India
71
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
72
SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France
73
Yale University, New Haven, CT, USA
74
Budker Institute for Nuclear Physics, Novosibirsk, Russia
75
Oak Ridge National Laboratory, Oak Ridge, TN, USA
76
Physics Department, Creighton University, Omaha, NE, USA
77
Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France
78
Department of Physics, University of Oslo, Oslo, Norway
79
Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy
80
Sezione INFN, Padova, Italy
81
Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic
82
Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
83
Institute for High Energy Physics, Protvino, Russia
84
Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
85
Pusan National University, Pusan, South Korea
86
Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic
87
Dipartimento di Fisica dell’Università ‘La Sapienza’ and Sezione INFN, Rome, Italy
88
Sezione INFN, Rome, Italy
89
Commissariat à l’Energie Atomique, IRFU, Saclay, France
90
Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy
91
California Polytechnic State University, San Luis Obispo, CA, USA
92
Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
93
Universidade de São Paulo (USP), São Paulo, Brazil
94
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
95
Department of Physics, Sejong University, Seoul, South Korea
96
Yonsei University, Seoul, South Korea
97
Technical University of Split FESB, Split, Croatia
98
V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia
99
Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France
100
University of Tokyo, Tokyo, Japan
101
Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy
102
Sezione INFN, Trieste, Italy
103
University of Tsukuba, Tsukuba, Japan
104
Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy
105
Sezione INFN, Turin, Italy
106
Institute for Subatomic Physics, Utrecht University, Utrecht, Netherlands
107
Soltan Institute for Nuclear Studies, Warsaw, Poland
108
Warsaw University of Technology, Warsaw, Poland
109
Purdue University, West Lafayette, IN, USA
110
Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms, Germany
111
Hua-Zhong Normal University, Wuhan, China
112
Yerevan Physics Institute, Yerevan, Armenia
113
Rudjer Bošković Institute, Zagreb, Croatia
* e-mail: jurgen.schukraft@cern.ch
Received:
20
April
2010
Revised:
6
May
2010
Published online:
22
June
2010
The pseudorapidity density and multiplicity distribution of charged particles produced in proton–proton collisions at the LHC, at a centre-of-mass energy TeV, were measured in the central pseudorapidity region |η|<1. Comparisons are made with previous measurements at 
TeV and 2.36 TeV. At TeV, for events with at least one charged particle in |η|<1, we obtain 
. This corresponds to an increase of 
relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.
© Springer-Verlag / Società Italiana di Fisica, 2010
