Characterisation of the electromagnetic component in ultra-high energy inclined air showers

Inclined air showers – those arriving at ground with zenith angle with respect to the vertical θ > 60 ° – are characterised by the dominance of the muonic component at ground which is accompanied by an electromagnetic “halo” produced mainly by muon decay and muon interactions. By means of Monte Carlo simulations we give a full characterisation of the particle densities at ground in ultra-high energy inclined showers as a function of primary energy and mass composition, as well as for different hadronic models assumed in the simulations. We also investigate the effect of intrinsic shower-to-shower fluctuations in the particle densities.