The composition of ultra-high energy cosmic rays is still poorly known and constitutes a very important topic in the field of high-energy astrophysics.

Figure: geometric distance D to the observer as a function of the atmospheric depth X using ρ (US) (plain red curve) and ρ (GDAS) (plain blue curve). The two red points correspond to the reconstructions obtained with (ρ (US),N (US)), (ρ (US),N (GDAS)); the blue GD HF point corresponds to (ρ (GDAS),N (GDAS)). The green star corresponds to the true value of HF the reference shower. Figure: geometric distance D to the observer as a function of the atmospheric depth X using ρ (US) (plain red curve) and ρ (GDAS) (plain blue curve). The two red points correspond to the reconstructions obtained with (ρ (US),N (US)), (ρ (US),N (GDAS)); the blue GD HF point corresponds to (ρ (GDAS),N (GDAS)). The green star corresponds to the true value of HF the reference shower.
Detection of ultra-high energy cosmic rays is carried out via the extensive air showers they create after interacting with the atmosphere constituents. The secondary electrons and positrons within the showers emit a detectable electric field in the kHz-GHz range. It is possible to use this radio signal for the estimation of the atmospheric depth of maximal development of the showers Xmax, with a good accuracy and a duty cycle close to 100

Published by F. Gaté, B. Revenu, D. García-Fernández, V. Marin, R. Dallier, A. Escudié, L. Martin, in Astroparticle Physics 98, January 2018, P. 38–51 https://doi.org/10.1016/j.astropartphys.2018.01.007