Composition of PeV primary cosmic rays from ground based experiments Original Research Article

The composition of primary Cosmic Rays at > 100 TeV has to be determined from indirect experiments. The two parameters, which are most sensitive to the primary composition, are the depth of the shower maximum and the total number of muons in the shower. These parameters can be studied using the Cerenkov and muon components. Because of factors like insufficient detector areas, ambiguous interaction models and intrinsic fluctuations in the processes, the progress in this field has been very slow. However, new experiments and better high-energy interaction models have started giving more consistent results than in the past. These results show that composition at lower energies continues until at least 1 PeV. The options in the knee region are also being narrowed down.