Measurement of the transverse momentum dependence of the elliptic flow of charged particles in lead-lead collision at √(s_NN )=2.76 TeV

University essay from Lunds universitet/Fysiska institutionen

Author: Pouria Jaberi; [2013]

Keywords: Physics and Astronomy;

Abstract: One of the biggest question in physics is to investigate the early universe or big bang. 10 µs after big bang, there existed a phase of transition called QGP (Quark Gluon Plasma). In this phase of transition quarks and gluon were free from each other. In normal life neutron and proton consist of three quarks with exchanging gluons. To simulate QGP scientists has built the large accelerator at CERN called LHC. They set the ALICE detector with colliding two heavy nuclide specially lead-lead to probe this phase of transition. This phase of transition behaves like a near-ideal Fermi liquid. So a lot of flow research is going on at ALICE group at CERN. In this thesis I investigate elliptic flow (second order of flow) using Fourier expansion of azimuthal distribution. The elliptic flow is in almond shape. All the analyses in this thesis have been obtained by a C++ analysis program which utilizes the ROOT framework. First part has been measured elliptic flow with the method "event plane". The second part has been measured elliptic flow with the method "cumulant". The second part consist of 2-particle cumulant and 4-particle cumulant. The number of events used in this analysis, are 11,154,977 from the TPC (the main part of ALICE detector). The analyses is divided to different centrality collision. The main part of this thesis has been measured elliptic flow as a function of transverse momentum especially at low transverse momentum.

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