Study of neutral pions in Pb-Pb collisions at $\sqrt{^{s}}NN$= 2.76 TeV with the PHOS detector at ALICE

A state of decon ned quarks and gluons, called quark-gluon plasma (QGP), is created in high-energy heavy-ion collisions. The ALICE experiment is one of the heavy-ion collider experiments at the LHC to investigate such the new state of mat- ter. Neutral mesons such as 0 that decays into two photons are suitable to study parton energy-loss in the QGP, since they can be identi ed by a ne-segmented elec- tromagnetic calorimeter in a wide p T range. It is quite competitive with respect to other particle identi cation methods. The energy-loss results in a suppression of hadrons yields quanti ed with a nuclear modi cation factor R AA de ned as hadron yields in A-A collisions with respect to those in p-p collisions. Partons created by a hard scattering interacts with the medium and lose energy. This phenomenon modi es hadron yields at a high p T and can be powerful probe to disentangle mechanism of the energy-loss in the QGP.