Go to the Indico Home Page Oldest event Older event Up to category Newer event Newest event Printable version
  • Event
  • Lecture
    • Switch to the management area of this event
    Login
    CERN Heavy Ion Forum

    J/Psi at the CERN SPS

    by Antonello Polosa (CERN), Luciano Ramello (Universita' del Piemonte Orientale and INFN, Alessandria, Italy)

    → Europe/Zurich
    40-SS-C01 (CERN)

    40-SS-C01

    CERN
    Description
    1. Antonello Polosa (CERN)
    "J/psi Absorbtion in Heavy-Ion Collisions"
    2. Luciano Ramello (Universita' del Piemonte Orientale and INFN, Alessandria, Italy)
    "J/psi and psi' Anomalous Suppression in Pb-Pb Collisions at 158 GeV/nucleon: Latest Results from NA50"
    1. abstract by Antonello Polosa
    To discuss the absorption of J/psi in heavy-ion collisions, we assume the J/psi to be produced inside a thermalized pion gas and introduce the corrections due to absorption by nuclear matter as well. We fit the absorption length of the J/psi to the data obtained at the CERN SPS by the NA50 Collaboration for Pb-Pb collisions. Collisions of lower centrality allow us to determine the temperature and the energy density of the pion gas. A simple extrapolation to more central collisions, which takes into account the increase of the energy deposited due to the increased nucleon flux, fails to reproduce the break in J/psi absorption indicated by NA50.

    2. abstract by Luciano Ramello
    I will present the most recent analysis of data taken by experiment NA50 in years 1998 and 2000 concerning the production of J/psi and psi' at 158 GeV/nucleon as a function of centrality. Using Drell-Yan pair production as the reference process, and both high precision NA50 proton-nucleus data (at 450 and 400 GeV/c) and sulphur-uranium NA38 data (at 200 GeV/nucleon), the amount of normal nuclear absorption is established. For J/psi we obtain an absorption cross-section of 4.3 +- 0.3 mb with no significant difference between p-A and S-U. The anomalous suppression of J/psi is then seen in intermediate and central Pb-Pb collisions, while peripheral collisions are compatible with normal nuclear absorption. For psi' we find an absorption cross-section of 7.4 +- 1.4 mb in proton-nucleus and a much stronger absorption (21.6 +- 2.5 mb) both in S-U and Pb-Pb collisions; in the latter two systems the absorption is the same as a function of centrality.

    Organiser(s): Yiota Foka and Urs Achim Wiedemann
    More information: http://home.cern.ch/a/alicedoc/www/chic/
    more information