Speaker
Description
The procedure of the energy calibration of the highly granulated electromagnetic calorimeter PHOS of the ALICE experiment is presented. PHOS consists of 12544 PbWO4 crystals with Avalanche PhotoDiodes (APD) as photodetectors. It is accompanied by an LED monitoring system and cooling plant which maintains a stable temperature of the crystals at -25$^\circ$ C.
After this latest and new calibration procedure was applied to the pp-collision data at $\sqrt s$ = 13 TeV, we obtained $\pi^0$ and $\eta$ peak positions close to their PDG mass values over a wide $p_T$ ranges with widths $\sigma^{\pi^0}_m$ = 4.40 $\pm$ 0.03 MeV/$c^2$ and $\sigma^\eta_m$ = 15.3 $\pm$ 1.0 MeV/$c^2$, respectively.
These methods which were used to perform relative gain calibration, to estimate geometrical alignment and corresponding correction of the absolute energy scale, to calculate the time-dependent corrections and to evaluate the non-linearity corrections, will be discussed and illustrated by the PHOS performance in proton-proton collisions at $\sqrt s$ = 13 TeV.
