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Antimatter and matter production in heavy ion collisions at CERN (The NEWMASS experiment NA52)

  • K. Pretzl
  • G. Ambrosini
  • R. Arsenescu
  • C. Baglin
  • H. P. Beck
  • K. Borer
  • A. Bussière
  • K. Elsener
  • Ph. Gorodetzky
  • J. P. Guillaud
  • P. Hess
  • S. Kabana
  • R. Klingenberg
  • G. Lehmann
  • T. Lindén
  • K. D. Lohmann
  • R. Mommsen
  • U. Moser
  • K. Pretzl
  • J. Schacher
  • R. Spiwoks
  • F. Stoffel
  • J. Tuominiemi
  • M. Weber
Article

Abstract

Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. Together with previous data taking at a rigidity of −20 GeV/c we obtained \(10^6 \bar p, 10^3 \bar d\) and two \(\overline {^3 He} \) without centrality requirements. We measured nuclei and antinuclei (p, d, \(\bar p,\bar d\)) near midrapidity covering an impact parameter range of b ∼ 2–12 fm. Our results strongly indicate that nuclei and antinuclei are mainly produced via the coalescence mechanism. However, the centrality dependence of the antibaryon to baryon ratios shows that antibaryons are diminished due to annihilation and breakup reactions in the hadron dense environment. The volume of the particle source extracted from coalescence models agrees with results from pion interferometry for an expanding source. The chemical and thermal freeze-out of nuclei and antinuclei appear to coincide with each other and with the thermal freeze-out of hadrons.

Keywords

heavy ion antiparticles 

PACS

25.75.Dw 

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Copyright information

© Akadémiai Kiadó 2001

Authors and Affiliations

  • K. Pretzl
    • 1
  • G. Ambrosini
    • 1
  • R. Arsenescu
    • 1
  • C. Baglin
    • 2
  • H. P. Beck
    • 1
  • K. Borer
    • 1
  • A. Bussière
    • 2
  • K. Elsener
    • 3
  • Ph. Gorodetzky
    • 5
  • J. P. Guillaud
    • 2
  • P. Hess
    • 1
  • S. Kabana
    • 1
  • R. Klingenberg
    • 1
  • G. Lehmann
    • 1
  • T. Lindén
    • 4
  • K. D. Lohmann
    • 3
  • R. Mommsen
    • 1
  • U. Moser
    • 1
  • K. Pretzl
    • 1
  • J. Schacher
    • 1
  • R. Spiwoks
    • 1
  • F. Stoffel
    • 1
  • J. Tuominiemi
    • 4
  • M. Weber
    • 1
  1. 1.Laboratory for High Energy PhysicsUniversity of BernBernSwitzerland
  2. 2.CNRS-IN2P3LAPP AnnecyAnnecy-le-VieuxFrance
  3. 3.SL DivisionCERNGeneva 23Switzerland
  4. 4.Department of PhysicsUniversity of HelsinkiHelsinkiFinland
  5. 5.PCC-Collège de FranceParisFrance

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