On the use of Sb as the energy estimator

GERMÁN ROS; GUSTAVO A. MEDINA-TANCO; DANIEL SUPANITSKY; LUIS DEL PERAL; MARÍA DOLORES RODRÍGUEZ-FRÍAS

Malargüe

Otro; Reunion de la Colaboración Internacional Pierre Auger; 2012

Colaboración Internacional Pierre Auger

We explore an alternative method for determining the energy of SD events based on the Sb parameter. A calibration curve using golden events is found, showing a good correlation between Sb and the primary energy. Considering golden events with E_FD > 10^18.5 eV and θ < 60^o , their energy is reconstructed without bias and resolution around 30%. No CIC is applied. This technique provides an alternative way to determine the primary energy with results consistent with the standard Auger calibration based on S38. Sb only requires a good geometrical fit, but not a reliable LDF or S 1000 determination. Therefore, we also study the case in which instead of fitting the calibration curve considering the events with E_FD > 10^18.5 eV, all the events with at least 3candidate stations are considered. Thus, we can extend the SD energy range down to 10^17.3 eV (Infill events are not included in this work). In this case, a more complex calibration curve is needed to avoid biases, but it is possible to reduce them below 5% in the most part of the energy range. Finally, the new method has been applied to both, vertical and horizontal events above 10^18.5 eV. The results suggest that it is possible to use a unified treatment for all the events regardless of their zenith angle.