A Monte Carlo exploration of methods to determine the UHECR composition with the Pierre Auger Observatory

PIERRE AUGER COLLABORATION (J. ABRAHAM, ... , A. MARIAZZI, ET AL)

Lodz, Polonia

Conferencia; 31th International Cosmic Ray Conference; 2009

Measuring the mass composition of ultrahigh energy comsic rays is crucial for understandingtheir origin. In this paper, we present three statisticalmethods for determining the mass composition. Themethods compare observables measured with thePierre Auger Observatory with corresponding MonteCarlo predictions for different mass groups obtainedusing different hadronic interaction models. Thetechniques make use of the mean and fluctuations ofXmax, the log-likelihood fit of the Xmax distributionsand the multi-topological analysis of a selectionof parameters describing the shower profile. Weshow their sensitivity to the input composition ofsimulated samples of known mixing and their abilityto reproduce mass sensitive observables, like theaverage shower maximum as a function of the energy,measured at the Pierre Auger Observatory.