A new parameter for composition discrimination of Ultra-High Energy Cosmic Rays

G. ROS; A.D. SUPANITSKY; G MEDINA-TANCO; L. DEL PERAL; J. C. DOLIVO; M. D. RODR ́ıGUEZ-FR ́ıAS

Malargüe

Otro; Reunion de la Colaboración Internacional Pierre Auger; 2009

Colaboración Internacional Pierre Auger

A new family of parameters intended for composition studies is presented. It makes exclusive use of surface data combining the information from the total signal at each triggered detector and the array geometry. The parameters are sensitive to the combined effects of the different muon and electromagnetic components on the lateral distribution function of proton and iron showers at any given energy. We perform analytical and numerical studies of these composition estimators in order to assess their reliability, stability and optimization. The effects of experi-mental uncertainties, intrinsic fluctuations and reconstruction errors are discussed in a quantitative way. The stability of the parameter in face of a possible underestimation of the size of the muon component by the shower simulation codes, as it is suggested by experimental evidence, is also analyzed. The potential discrimination power of an optimized realization of these parameters is compared on a simplified, albeit quantitative way, with that expected from other surface and fluorescenceestimators in analogous experimental conditions.