Study Of V~0 Signal Extraction Optimization In Pb-Pb Collisions With ALICE At The LHC

The high-energy heavy-ion collision experiment aims to study the properties of a new state of matter-the quark-gluon plasma(QGP)-under the extreme conditions of high temperature and energy density.The QGP is believed to exist in the early Universe after a few microseconds of the Big Bang and inside dense asters(such as neutron stars)in the current Universe.Such studies will not only help to understand the early history of the universe but will also help to reveal the deep-level structure of the current material world.It is one of the major research fields in the frontier of fundamental physics.The CERN Large Hadron Collider(LHC)is the world's largest proton and heavy-ion accelerator.It is the only experimental platform that can provide the collisions with energy reaching TeV magnitude.The QGP generated at LHC energies has almost zero net-baryon density,closer to the conditions in the early Universe.ALICE(A Large Ion Collider Experiment)is one of the four main experiments at the LHC,and it is the only heavy-ion orientated experiment at TeV energies.The R&D of the ALICE detector is based on the ultra-high occupancy created in the most central heavy-ion collisions.It provides the unique capability for investigating the QGP matter under the TeV energy frontier.Studying the production properties of hadrons containing at least one valence strange quark(strange hadrons)in heavy-ion collisions will bridge the non-perturbative(hydrodynamics)and perturbative(hard-parton energy redistribution)properties of the QGP matter,as well as provide the important constraint on characterizing the quantum chromodynamics(QCD)behaviors in the high-density multi-body system.Besides the informative QGP property probes,the two-body hadronic decay products of KS0 mesons and ? baryons(V0 particles)are also important tools for particle identification detection calibration.The studies of this thesis are based on the ALICE detector.The traditional strategy for the V0 particle reconstruction and its defects are discussed.A new reconstruction algorithm,which relies on a 2-dimension topologic pre-selection,is explored to correct the traditional strategy-generated bias.The optimization on the V0 particle decay kinematics selections is discussed in this thesis as well.This thesis is organized as the following.Chapter 1 is a brief introduction of the physics motivation.The ALICE detectors are introduced in Chapter 2.Chapter 3 explores the pre-selection algorithm used to correct the bias on the traditional reconstruction strategy.Chapter 4 shows the performance studies in data.The results and discussions are given in Chapter 5.At final,the summary and the outlook are presented in Chapter 6.