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Charged-particle multiplicity measurement in proton-proton collisions at √s 0.9 and 2.36 TeV with ALICE at LHC

  • Author(s): Aamodt, K
  • Abel, N
  • Abeysekara, U
  • Abrahantes Quintana, A
  • Abramyan, A
  • Adamová, D
  • Aggarwal, MM
  • Aglieri Rinella, G
  • Agocs, AG
  • Aguilar Salazar, S
  • Ahammed, Z
  • Ahmad, A
  • Ahmad, N
  • Ahn, SU
  • Akimoto, R
  • Akindinov, A
  • Aleksandrov, D
  • Alessandro, B
  • Alfaro Molina, R
  • Alici, A
  • Almaráz Aviña, E
  • Alme, J
  • Alt, T
  • Altini, V
  • Altinpinar, S
  • Andrei, C
  • Andronic, A
  • Anelli, G
  • Angelov, V
  • Anson, C
  • Antičić, T
  • Antinori, F
  • Antinori, S
  • Antipin, K
  • Antończyk, D
  • Antonioli, P
  • Anzo, A
  • Aphecetche, L
  • Appelshäuser, H
  • Arcelli, S
  • Arceo, R
  • Arend, A
  • Armesto, N
  • Arnaldi, R
  • Aronsson, T
  • Arsene, IC
  • Asryan, A
  • Augustinus, A
  • Averbeck, R
  • Awes, TC
  • Äystö, J
  • Azmi, MD
  • Bablok, S
  • Bach, M
  • Badalà, A
  • Baek, YW
  • Bagnasco, S
  • Bailhache, R
  • Bala, R
  • Baldisseri, A
  • Baldit, A
  • Bán, J
  • Barbera, R
  • Barnaföldi, GG
  • Barnby, L
  • Barret, V
  • Bartke, J
  • Barile, F
  • Basile, M
  • Basmanov, V
  • Bastid, N
  • Bathen, B
  • Batigne, G
  • Batyunya, B
  • Baumann, C
  • Bearden, IG
  • Becker, B
  • Belikov, I
  • Bellwied, R
  • Belmont-Moreno, E
  • Belogianni, A
  • Benhabib, L
  • Beole, S
  • Berceanu, I
  • Bercuci, A
  • Berdermann, E
  • Berdnikov, Y
  • Betev, L
  • Bhasin, A
  • Bhati, AK
  • Bianchi, L
  • Bianchi, N
  • Bianchin, C
  • Bielčík, J
  • Bielčíková, J
  • Bilandzic, A
  • Bimbot, L
  • Biolcati, E
  • Blanc, A
  • Blanco, F
  • et al.
Abstract

Charged-particle production was studied in proton-proton collisions collected at the LHC with the ALICE detector at centre-of-mass energies 0.9 TeV and 2.36 TeV in the pseudorapidity range {pipe}η{pipe}<1.4. In the central region ({pipe}η{pipe}<0.5), at 0.9 TeV, we measure charged-particle pseudorapidity density dN /dη= 3.02 ± 0.01 (stat.) (syst.) for inelastic interactions, and dN /dη = 3.58 ± 0.01 (stat.) (syst.) for non-single-diffractive interactions. At 2.36 TeV, we find dN /dη = 3.77 ± 0.01 (stat.) (syst.) for inelastic, and dN /dη = 4.43 ± 0.01(stat.) (syst.) for non-single-diffractive collisions. The relative increase in charged-particle multiplicity from the lower to higher energy is 24.7% ± 0.5%(stat.) (syst.) for inelastic and 23.7% ± 0.5%(stat.) % 1.1%(syst.) for non-single-diffractive interactions. This increase is consistent with that reported by the CMS collaboration for non-single-diffractive events and larger than that found by a number of commonly used models. The multiplicity distribution was measured in different pseudorapidity intervals and studied in terms of KNO variables at both energies. The results are compared to proton-antiproton data and to model predictions. © 2010 CERN for the benefit of the ALICE collaboration. ch -0.05 ch -0.12 ch -0.12 ch -0.12 -2.8 -1.1 +0.08 +0.12 +0.25 +0.17 +5.7 +4.6

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