Electromagnetic shower absorption in a scintillating crystal NaI

Electromagnetic shower energy (E0 absorption in a crystal is calculated by the Monte Carlo method to detect the reasons of deviations from linearity of the gauge function of the NaI(Tl)-crystal based detector during spectrometry of γ-radiation in the range of 30-900 MeV. It is detected that with E0 growth the energy loss of the crystal increases, but dependence of the energy absorbed on E0 in the range E0 706, 900 MeV remains practically linear. That's why the deviation detected in the experiment from the linear low can be the consequence of detector photomultiplier reloading. Statistical error of calculations doesn't exceed 3%