Analysis of the First Cosmic Ray Data Collected with the Complete ALICE TPC

The Large Hadron Collider (LHC), which will soon be operational at CERN, will provide a powerful tool to study particle physics. With 14TeV proton- proton collision at a luminosity of 10$^{34}$s$^{−1}$ cm$^{−2}$, it will be by far the most powerful accelerator ever built. It will allow experiments such as ATLAS, CMS and LHCb to test the limit of the Standard Model and to find evidence of new physics such as SUperSymmetrY (SUSY). It will also be possible to recreate one of the first phases of the early Universe, to study the hadronic matter under extreme conditions of temperature and density. This is the purpose of ALICE (A Large Ion Collider Experiment), which will study the Quark Gluon Plasma (QGP) created in collisions of heavy ions at LHC. The study of this very interesting but very ephemeral medium requires a complex detection apparatus. One of the main detectors, the Time Projection Chamber (TPC) will track all the charged particles emitted in a region around mid-rapidity. The very high track density expected makes this an ambitious project. The TPC construction has recently been completed and the TPC is currently down in the ALICE pit ready to be installed. The first tests of the complete TPC have been done with cosmic rays and laser tracks, and are now studied to understand and optimise the operating configuration and the data processing software. In this thesis I present results of studies I carried out of the first cosmic data. I focused on selected runs to identify the flaws in the data. Some of the results shown here were presented at the first ALICE Nordic collaboration meeting in Copenhagen and the ALICE TPC meeting at GSI, Darmstadt.