Mass composition of ultra-high energy cosmic rays: analysis of muon arrival time distribution from extensive air showers with Pierre Auger Observatory.
Mallamaci M. per la Collaborazione Pierre Auger
The surface detector array of the Pierre Auger Observatory provides information about the longitudinal development of the muonic component of extensive air showers. The depth along the shower axis where the muon production reaches a maximum is called Xmumax. This is a useful observable to infer the mass composition of ultrahigh-energy cosmic rays, which is one of the most intriguing open issue of modern astrophysics. Xmumax is also a tool to test hadronic interactions at ultrahigh energies, since the longitudinal development is dependent on the hadronic interaction properties. The methods for the reconstruction of the muon production depth distributions will be presented and published results will be shown.