Hinting at primary composition using asymmetries in time distributions
  Evidence of azimuthal asymmetries in the time structure and signal size have been found in non-vertical showers at the Pierre Auger Observatory. It has been previously shown that the asymmetry in time distributions offers a new possibility for the determination of the mass composition. New studies have demonstrated that the dependence of the asymmetry parameter in the rise-time and fall-time distributions with sec(theta) shows a clear peak. Both, the position of the peak, X_asymax, and the size of the asymmetry at X_asymax are sensitive to primary mass composition and have a small dependence on energy. In this paper a study of the discriminating power of the new observables to separate primary species is presented. 
M.T.Dova, M.Mancenido (Univ. Nac. de La Plata, Argentina),   A.G.Mariazzi (Univ. of Leeds, UK), F.Arqueros, D.Garcia-Pinto (...