Simultaneous determination of the primary energy and Xmax from SD

G. ROS; G. MEDINA-TANCO; A.D. SUPANITSKY; L. DEL PERAL; M.D. RODRÍGUEZ-FRÍAS

Otro; Nota interna de la Colaboración Pierre Auger; 2013

Colaboración Internacional Pierre Auger

The method to reconstruct the primary energy of UHE photon-induced showers with the Auger surface detector (SD) is based on MC parametrizations that relate the surface energy estimator, S(1000), and the maximum of shower development, Xmax [1,2]. In this GAP we adapt this method to hadron primaries by using simulations, we show that the primary energy and Xmax can be inferred without significant bias and resolution around 13% and 7% respectively from pure surface information. In addition, a first application to Auger data is presented. Calibration curves are obtained from Golden events, whose energy and X max are reconstructed with a low bias and resolution around 20% and 7% respectively. This calibration is also applied to surface data but we obtain an energy-dependent underestimation of the primary energy compared to the reconstructed energy with the standard hybrid calibration. Further studies are needed to understand this discrepancy.