Collective Flow and Azimuthally Differential Pion Femtoscopy with the ALICE Experiment at the LHC

Since 2009, the Large Hadron Collider (LHC) at European Organization for Nuclear Research (CERN) has been conducting experiments in $pp$, Pb-Pb, as well as $p$-Pb collisions with the center of mass energy ranging $\sqrt{{s}_{NN}}=0.9-5.05$~TeV. In this thesis, both, estimates of background correlations in anisotropic flow, $v_1-v_5$, measurements in Pb-Pb collisions at $\sqrt{{s}_{NN}}=2.76$~TeV, and azimuthally differential pion femtoscopy of Pb-Pb collisions are reported. Two particle azimuthal correlations are statistically the most precise method of measuring anisotropic flow. The main drawback of this method is its sensitivity to the non-flow correlations, which unlike real flow, do not have geometrical origin. Non-flow contribution can be estimated from two particle azimuthal correlations using $pp$ data. Measurements of the non-flow contribution using the uQ method and Scalar Product (SP) method are reported for $pp$ collisions at $\sqrt{{s}_{NN}}=2.76$~TeV and $\sqrt{{s}_{NN}}=7$~TeV for the first through fifth harmonics. Femtoscopy of non-central heavy-ion collisions provides access to information on the geometry of the effective pion-emitting source. In particular, its shape can be studied by measuring femtoscopic radii as a function of the emission angle relative to the collision plane of symmetry. The first measurements of azimuthally differential femtoscopy in Pb-Pb collisions at $\sqrt{{s}_{NN}}=2.76$~TeV are reported and compared to results from RHIC experiments at lower energies. Oscillations of the extracted radii versus the emission angle are measured, and $R_{side}$ and $R_{out}$ oscillations are found to be out of phase. The relative amplitude of the $R_{side}$ oscillations decreases in more central collisions, however always remains positive. This indicates that the source is out-of-plane extended, similar to that observed at RHIC energies. Results are compared to existing hydrodynamical and transport model calculations.