Acceptance and Angular Resolution of an Infill Array for the Pierre Auger Surface Detector

C. MEDINA; M. GÓMEZ BERISSO; I. ALLEKOTTE; A. ETCHEGOYEN; G. MEDINA-TANCO; D. SUPANITSKY

Iguazu, Argentina

Simposio; VI Latin American Symposium on Nuclear Physics and Applications; 2005

The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E > 10^19 eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km. In this paper we show how adding a "small" area of surface detectors at half the above mentioned spacing would make it possible to lower the detection threshold by one order of magnitude, thus allowing the Observatoly to reach lower energies where the cross-over from galactic to extragalactic sources is expected. We also analyze the angular resolution that can be attained with such an infill array.