Jet Study in Ultra-Relativistic Heavy-Ion Collisions with the ALICE Detectors at the LHC

In ultra-relativistic heavy-ion collisions at $\sqrt{s_{NN}}$ = 5.5 TeV at the ALICE experiment at the LHC, interactions between the high-$p_{T}$ partons and the hot, dense medium produced in the collisions, are expected to lead to jet energy loss (jet-quenching) resulting in changes in the jet fragmentation functions as compared to the unquenched case. In order to reconstruct jet fragmentation functions, accurate information on the jet energy, direction and momentum distribution of the jet particles is needed. This thesis presents first results on jet reconstruction in simulated Pb+Pb collisions using the ALICE detectors and a UA1-based cone jet finding algorithm which has been modified and optimised to reconstruct high-$p_{T}$ jets on an event-by-event basis. Optimisation of the algorithm parameters and methods used to suppress the large background energy contribution while maximising the algorithm efficiency, are discussed and the resulting jet energy and direction resolutions are presented. Accurate jet reconstruction will allow measurement of the jet fragmentation functions and consequently the degree of quenching and therefore provide insight on the properties of the hot and dense medium (for example the initial gluon density) created in the collisions.