Repository logo

Browsing by Author "Rybicki, Andrzej"

  • Thumbnail Image
    Item
    Centrality in hadron-carbon, hadron-lead, and lead-lead Reactions at 158 GeV/c
    (Institute of Nuclear Physics Polish Academy of Sciences, 2006) Rybicki, Andrzej
    A study of centrality in p+C, π+C, p+Pb, π+Pb, and Pb+Pb reactions is made. The analysis is performed by means of a simple geometrical model. The mean number of elementary collisions, < υ>, is estimated in minimum bias p+C reactions. For the specific case of the carbon nucleus, estimates on < υ> appear to depend strongly on assumed nuclear densities. Most realistic of the presented assumptions result in a value of < υ>= 1.71 ± 0.05. Additional quantities, like predictions for the total inelastic cross-section in p+C reactions, or the number of participants in minimum bias C+C collisions, are given. The analysis is subsequently extended to minimum bias π +C, π +Pb, and p+Pb reactions. Estimates are given for the mean number of elementary collisions as well as for the contribution of single collisions P(1). A comparison with experimental data is made. Finally, the impact parameter dependence of p+Pb and Pb+Pb collisions is discussed. In view of future studies, various aspects of the analysis are discussed in detail; a bibliography of used references is included.
  • Thumbnail Image
    Item
    Strong and electromagnetic effects in peripheral nucleus-nucleus collisions at SPS energies
    (Institute of Nuclear Physics Polish Academy of Sciences, 2010) Rybicki, Andrzej
    This paper deals with low momentum transfer (“soft”) hadronic interactions which build up most of the total cross section in high energy collisions of hadrons or atomic nuclei. The quantitative features of these interactions cannot be predicted on the basis of the present theory of strong interactions, Quantum Chromodynamics. The understanding of these processes relies therefore mostly on experimental knowledge. The main emphasis in this work is put on an attempt to extract new, quantitative information on the process of particle production in the reaction center-of-mass energy regime of several GeV per incoming hadron. This specifically concerns two issues: 1) the change induced in this process by transition from the elementary nucleon-nucleon collision to the nuclear heavy ion reaction, and 2) the possibility of obtaining novel information on the strong interaction on the basis of specific electromagnetic processes. Both issues are studied by means of a new, high quality experimental dataset on π meson production in peripheral lead-lead collisions. This dataset is compared with equally precise reference data on elementary interactions, allowing for the disentanglement of several effects present in the nuclear collision. One of these effects, the electromagnetic interaction between produced particles and the highly charged nuclear remnant (“spectator system”) is subsequently subject to a phenomenological analysis. The results of this analysis suggest that the latter electromagnetic effect can provide new information on the space-time evolution of the reaction.