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Browsing by Author "Rybicki, Andrzej"

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    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.
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    Spectator-induced electromagnetic effects in 40Ar+45Sc collisions at 40A GeV/c beam momentum
    (The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, 2023) Bhosale, Sneha; Rybicki, Andrzej; Grabowska-Bołd, Iwona; Siemiarczuk, Teodor; Szumlak, Tomasz
    Eksperyment NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) w CERN to przedsięwzięcie naukowe, mające na celu zbadanie własności zjawisk produkcji hadronów w zderzeniach hadron-hadron, hadron-jądro i jądro-jądro. Niniejsza rozprawa doktorska przedstawia studium doświadczalne efektów elektromagnetycznych wywołanych przez "układy spektatorów" w zderzeniach Ar+Sc przy pędzie wiązki równym 40A GeV/c (√sNN = 8.76 GeV). Studium to polega na zbadaniu modyfikacji stosunków emisji naładowanych pionów (π+/π−) w funkcji zmiennej Feynmana xF, pędu poprzecznego pT i centralności zderzenia. Przedstawiona analiza eksperymentalna udowadnia obecność spowodowanych przez układy spektatorów efektów elektromagnetycznych w systemach zderzających się niewielkich jąder przy energiach akceleratora SPS. Z rosnącą peryferyjnością zderzenia, elektromagnetyczna dystorsja stosunków π+/π− zwiększa się wraz z rosnącym całkowitym ładunkiem układu spektatorów. Zaprezentowana w rozprawie analiza powiększa naszą wiedzę o nakładaniu się efektów elektromagnetycznych i izospinowych w zderzeniu. Zawiera ona także studium porównawcze pomiędzy zderzeniami Ar+Sc oraz danymi z peryferyjnych zderzeń Pb+Pb przy pędzie wiązki równym 158A GeV/c (√sNN = 17.3 GeV), uzyskanymi przez eksperyment NA49 na akceleratorze SPS. Studium to uzupełnia dyskusja jakościowych podobieństw oraz ilościowych różnic w efektach elektromagnetycznych w zderzeniach Ar+Sc i Pb+Pb. Wreszcie, uwzględniając fakt że wspomniane efekty mogą rzucić nowe światło na czasoprzestrzenną ewolucję procesu produkcji cząstek, rozprawa zawiera również obliczenia modelowe wykonane za pomocą symulacji Monte Carlo i mające na celu analizę tej ewolucji. The SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) at CERN is a scientific endeavour aimed at scrutinizing the characteristics of hadron pro- duction in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. In this doctoral dissertation, a comprehensive experimental study of spectator-induced electromagnetic (EM) effects in Ar+Sc collisions at 40A GeV/c (√sNN = 8.76 GeV) is presented. The study is carried out by analyzing the modification of charged pion (π+/π−) ratios as a function of the Feynman variable xF, transverse momentum pT, and collision centrality. The exper- imental analysis presented herein demonstrates the presence of spectatorinduced EM effects in small-scale nuclear collision systems at SPS energies. With increasing peripherality of the collision, the EM distortion of π+/π− ratios increases as a function of increasing spectator charge. The study presented in this dissertation enhances our understanding of the interplay between EM and isospin effects in the collision. Also, it in- cludes a comparative analysis between current Ar+Sc results and earlier results from the NA49 experiment’s Pb+Pb data for peripheral collisions at 158A GeV/c (√sNN = 17.3 GeV) obtained at the SPS. This analysis is sup- plemented by a discussion of the qualitative similarities and quantitative differences in EM effects in Ar+Sc and Pb+Pb collisions. Finally, acknowl- edging that these effects can shed new light on the space-time evolution of particle production, the study incorporates a dedicated Monte Carlo model simulation to explore this evolution.
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    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.