Determination of the proton-to-helium ratio in cosmic rays at ultra-high energies from the tail of the $X_{\max }$ distribution

Alexey Yushkov, Markus Risse, Marek Werner +1

We present a method to determine the proton-to-helium ratio in cosmic rays at ultra-high energies. It makes use of the exponential slope, $\Lambda$, of the tail of the $X_{\max }$ dist…