Measurement of the total proton-proton cross section at sqrt(s)=7TeV with the ATLAS detector at the LHC

Presentation prepared for young researches session during Epiphany Conference 2015 is relied on the document titled "Measurement of the total cross section from elastic scattering in pp collisions at sqrt(s)=7TeV with the ATLAS detector" written by ATLAS Collaboration. The purpose of the talk is to present how total pp cross section was measured at LHC. To measurement ALFA sub detector of ATLAS was performed. As a first theoretical input is introduced: how to find total pp cross section value based on differential elastic cross section and four-momentum transfer |t| measurement. Measurement results are shown without and with a fitting function. In conclusion results from ALFA are compared with results from TOTEM and theoretical prediction.