A new multiparametric topological method for determining the primary   cosmic ray mass composition in the knee energy region
  The determination of the primary cosmic ray mass composition from the characteristics of extensive air showers (EAS), obtained at an observation level in the lower half of the atmosphere, is still an open problem. In this work we propose a new method of the Multiparametric Topological Analysis and show its applicability for the determination of the mass composition of the primary cosmic rays at the PeV energy region. 
M.Ambrosio, C.Aramo, D.D'Urso, A.D.Erlykin, F.Guarino, A.Insolia