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David Silvermyr

David Silvermyr

Senior lecturer

David Silvermyr

Direct photon production in Pb–Pb collisions at √sNN=2.76 TeV

Author

  • Adam J.
  • P. Christiansen
  • H. Ljunggren
  • A. Oskarsson
  • T. Richert
  • D. Silvermyr
  • C. Søgaard
  • E. Stenlund
  • V. Vislavicius
  • Zyzak M.

Summary, in English

Direct photon production at mid-rapidity in Pb–Pb collisions at sNN=2.76 TeV was studied in the transverse momentum range 0.9<pT<14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e− pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0–20%, 20–40%, and 40–80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT≳5 GeV/c. Direct photon spectra down to pT≈1 GeV/c could be extracted for the 20–40% and 0–20% centrality classes. The significance of the direct photon signal for 0.9<pT<2.1 GeV/c is 2.6σ for the 0–20% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297±12stat±41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2016

Language

English

Pages

235-248

Publication/Series

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

Volume

754

Document type

Journal article

Publisher

Elsevier

Topic

  • Subatomic Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0370-2693