Composition studies using the surface detector of the Pierre Auger observatory

The Pierre Auger Observarory measures ultrahigh-energy cosmic rays combining two kinds of detectors namely Fluorescence telescopes and water Cherenkov tanks. This characteristic gives the capability to obtain more accurate measurements for estimating the meaningful parameters of the air shower produced by the primary particle. The mass of the primary particle is one of the most relevant characteristics, which gives information about ist nature. The number of muons and the signal risetime of showers detected by the surface detector are explored to reveal the nature of the primary particle.