Energy and Xmax reconstruction of hadron-initiated showers in surface   arrays
  The current methods to determine the primary energy in surface arrays are different when dealing with hadron or photon initiated showers. In this work, we adapt a method previously developed for photon-initiated showers to hadron primaries. We determine the Monte Carlo parametrizations that relate the surface energy estimator and the maximum of shower development for both, proton and Iron primaries. Using for each primary their own set of calibration curves, which is of course impossible in practice, we show that the energy could be inferred with a negligible bias and 12% resolution. However, we show that a mixed calibration could also be performed, including both type of primaries, such that the bias still remains low and the achieved resolution is around 15%. In addition, the method allows the simultaneous determination of Xmax in pure surface arrays with resolution better than 7%. 
G. Ros, G. A. Medina-Tanco, A. D. Supanitsky, L. Del Peral, M. D.   Rodriguez-Frias
astro-ph.HE