Nature of ultra high energy cosmic rays on the basis of the recent results from experiment AUGER

Sources and chemical (mass) composition of the ultra high energy cosmic rays (UHECRs) are still unknown. Once more, recent results of the experimental measurements of the energy spectrum and chemical composition of UHECRs presented by AUGER, HIRES and TA are contradictory: HIRES and TA data are consistent with a proton-dominated flux of UHECRs for the all energy diapason, while AUGER data suggest increasing contribution of heavy nuclei at highest energy. In this paper the energy dependence of the depth of the shower maximum development Xmax for UHECR flux composed of mixture of protons and irons is investigated. It is shown, that AUGER 2011 data about the spectrum and chemical composition can be explained as a sum of fluxes of light (proton) and heavy (iron) components with domination of proton component (maximum contribution of iron component about 30%).