Master thesis defense by Anne Mette Frejsel – University of Copenhagen

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Master thesis defense by Anne Mette Frejsel

Title: Morphological Study of Heavy Ion Collisions Using CMB Methods

This thesis implements methods developed for Cosmic Microwave Background (CMB) analysis into the framework of heavy ion physics. This is done in order to investigate simulations of high-multiplicity heavy ion collisions (events) on an event-by-event basis. A qualitative method for determining the elliptic flow amplitude and the event plane angle on an event-by-event basis is developed. The CMB methods are based on the decomposition of a signal into spherical harmonics. Using the coefficients of the decomposition, called a_lm, an analytical formula for extracting information on both odd and even collective flow moments in a heavy ion event is derived. It is shown that elliptic flow is tightly connected to the a_22 coefficient. The data analysis is done on both simple toy model simulations and on HIJING (Heavy-Ion Jet INteraction Generator) simulations. A linear relationship is seen for both toy model and HIJING simulations (as predicted from the analytical formula). The methods developed here should be applicable for higher order flow as well.