Correction of the energy scale nonlinearity in electromagnetic   calorimeters with the pi0 two-photon decays
  The method to calculate the non-linearity correction of the electromagnetic calorimeter response, based on minimisation of the deviation of the measured neutral meson mass on the energies of it decay photons, is described in this paper. This method was developed for the electromagnetic calorimeter LGD2 in the Hyperon-M experiment at U70 accelerator of IHEP. The found correction allowed to reduce significantly variations of the reconstructed $\pi^0$ and $\eta$ masses on the minimal energy of the mesons. 
M.Yu.Bogolyubsky, Yu.V.Kharlov, D.I.Patalakha, B.V.Polishchuk,   S.A.Sadovsky, A.S.Soloviev, M.V.Stolpovskiy
physics.ins-det