Ian G. Bearden

Publications (166) View all

• Article: Transverse Momentum Distribution and Nuclear Modification Factor of Charged Particles in p+Pb Collisions at sqrt[s_{NN}]=5.02 TeV.

  B Abelev, J Adam, D Adamová, A M Adare, M M Aggarwal, G Aglieri Rinella, M Agnello, A G Agocs, A Agostinelli, Z Ahammed, [......], D Zhou, X Zhu, J Zhu, H Zhu, A Zichichi, A Zimmermann, G Zinovjev, Y Zoccarato, M Zynovyev, M Zyzak
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  ABSTRACT: The transverse momentum (p_{T}) distribution of primary charged particles is measured in minimum bias (non-single-diffractive) p+Pb collisions at sqrt[s_{NN}]=5.02 TeV with the ALICE detector at the LHC. The p_{T} spectra measured near central rapidity in the range 0.5<p_{T}<20 GeV/c exhibit a weak pseudorapidity dependence. The nuclear modification factor R_{pPb} is consistent with unity for p_{T} above 2 GeV/c. This measurement indicates that the strong suppression of hadron production at high p_{T} observed in Pb+Pb collisions at the LHC is not due to an initial-state effect. The measurement is compared to theoretical calculations.
  Physical Review Letters 02/2013; 110(8):082302. · 7.37 Impact Factor
• Source

  Available from: Varlen Grabski

  Article: Pseudorapidity Density of Charged Particles in p+Pb Collisions at sqrt[s_{NN}]=5.02 TeV.

  B Abelev, J Adam, D Adamová, A M Adare, M M Aggarwal, G Aglieri Rinella, M Agnello, A G Agocs, A Agostinelli, Z Ahammed, [......], Y Zhou, J Zhu, H Zhu, X Zhu, A Zichichi, A Zimmermann, G Zinovjev, Y Zoccarato, M Zynovyev, M Zyzak
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  ABSTRACT: The charged-particle pseudorapidity density measured over four units of pseudorapidity in nonsingle-diffractive p+Pb collisions at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02 TeV is presented. The average value at midrapidity is measured to be 16.81±0.71 (syst), which corresponds to 2.14±0.17 (syst) per participating nucleon, calculated with the Glauber model. This is 16% lower than in nonsingle-diffractive pp collisions interpolated to the same collision energy and 84% higher than in d+Au collisions at sqrt[s_{NN}]=0.2 TeV. The measured pseudorapidity density in p+Pb collisions is compared to model predictions and provides new constraints on the description of particle production in high-energy nuclear collisions.
  Physical Review Letters 01/2013; 110(3):032301. · 7.37 Impact Factor
• Article: Charge separation relative to the reaction plane in Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV.

  B Abelev, J Adam, D Adamová, A M Adare, M M Aggarwal, G Aglieri Rinella, A G Agocs, A Agostinelli, S Aguilar Salazar, Z Ahammed, [......], D Zhou, F Zhou, J Zhu, X Zhu, A Zichichi, A Zimmermann, G Zinovjev, Y Zoccarato, M Zynovyev, M Zyzak
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  ABSTRACT: Measurements of charge-dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudorapidity range |η|<0.8 are presented as a function of the collision centrality, particle separation in pseudorapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge-dependent azimuthal correlations observed at RHIC and LHC energies.
  Physical Review Letters 01/2013; 110(1):012301. · 7.37 Impact Factor
• Article: Measurement of the Cross Section for Electromagnetic Dissociation with Neutron Emission in Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV.

  B Abelev, J Adam, D Adamová, A M Adare, M M Aggarwal, G Aglieri Rinella, A G Agocs, A Agostinelli, S Aguilar Salazar, Z Ahammed, [......], D Zhou, F Zhou, Y Zhou, J Zhu, X Zhu, A Zichichi, A Zimmermann, G Zinovjev, Y Zoccarato, M Zynovyev
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  ABSTRACT: The first measurement of neutron emission in electromagnetic dissociation of ^{208}Pb nuclei at the LHC is presented. The measurement is performed using the neutron zero degree calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at sqrt[s_{NN}]=2.76 TeV with neutron emission are σ_{singleEMD}=187.4±0.2(stat)_{-11.2}^{+13.2}(syst) b and σ_{mutualEMD}=5.7±0.1(stat)±0.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.
  Physical Review Letters 12/2012; 109(25):252302. · 7.37 Impact Factor
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  Available from: C. Oppedisano

  Article: Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV.

  B Abelev, J Adam, D Adamová, A M Adare, M M Aggarwal, G Aglieri Rinella, A G Agocs, A Agostinelli, S Aguilar Salazar, Z Ahammed, [......], Y Zhou, F Zhou, J Zhu, X Zhu, A Zichichi, A Zimmermann, G Zinovjev, Y Zoccarato, M Zynovyev, M Zyzak
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  ABSTRACT: In this Letter we report the first results on π^{±}, K^{±}, p, and p[over ¯] production at midrapidity (|y|<0.5) in central Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV, measured by the ALICE experiment at the LHC. The p_{T} distributions and yields are compared to previous results at sqrt[s_{NN}]=200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with sqrt[s_{NN}], which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/π ratio is in line with predictions from the thermal model, the p/π ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.
  Physical Review Letters 12/2012; 109(25):252301. · 7.37 Impact Factor