LAUSR

PHOS is one of the two electromagnetic calorimeters of of the ALICE experiment at the LHC. It is a homogeneous calorimeter of fine granularity made of PbWO4 scintillating crystals. PHOS is designed for high precision measurements of direct photon and neutral meson spectra and their correlations in high and low multiplicity environments. These measurements rely on a high purity photon identification. We discuss the existing methods of photon identification in the PHOS and introduce the new method which uses the information from the charged particle veto (CPV) detector. The CPV is a multi-wire proportional chamber with pad readout installed in front of the PHOS detector. The first of three CPV modules was put into operation during LHC Run 2. We discuss the efficiency of the charged-particle track reconstruction and photon identification in the CPV. After presenting its performance in pp collisions at √s=13 TeV and Pb-Pb collisions at √sNN=5.02 TeV we compare methods and discuss the impact on the purity of the photon spectrum.