(Left) Correlation between the reconstructed ($N_{\rm p}^{\rm rec}$) and the generated ($N_{\rm p}^{\rm gen}$) number of protons for the most central Pb--Pb collisions simulated using the HIJING model . (Right) Distribution of reconstructed proton number for a fixed value of $N_{\rm p}^{\rm gen}=36$, where the fit demonstrates the deviation from a binomial efficiency loss.