Accuracy of the event geometry reconstruction with the SD-433

D. RAVIGNANI; G. SILLI; D. MELO; N. GONZÁLEZ; M. RONCORONI

PUBLICACION INTERNA DE LA COLABORACION INTERNACIONAL AUGER

Pierre Auger Observatory

Año: 2020

2250-835X

The SD-433 is the low-energy extension of the surface detector. It is composed by 19 waterCherenkov detectors separated by 433 m deployed around the station Tina Turner (id 1764). The arrayhas been operational since January 2013. In view of the current efforts to expand the AugerPrimephoton search programme down to around 10**16 eV, we report an in-depth analysis of the air-shower coreposition and angular resolutions of the SD-433 with real data. The dependence of these magnitudeson the event multiplicity, impact point, primary energy and zenith angle are discussed. After applying Monte-Carlo-based trigger efficiency quality cuts in the primary energy-zenith phase space andassuming a pure-proton composition, the core position and angular resolutions reach 30 m and 2.3 degat the full-efficiency energy threshold of 1.3 x 10**16 eV. The resolutions improve significantly with theprimary energy, for instance being 23 m and 1.4◦ when restricting the event selection to E > 3 x 10**16 eVand θ < 45 deg.