The AMIGA infill detector of the Pierre Auger Observatory: performance and first data

摘要

We present a first analysis of cosmic rays observed with the AMIGA infill array of the Pierre Auger Observatory.The spacing of 750m between the surface detectors, half the distance of the regular array, allows us to extend theenergy range of interest to energies as low as 3×1017 eV. The lateral distribution function is presented and the uncertaintyof the signal at an optimum distance of 450m, used to obtain an energy estimator, is discussed. The first steps towards themeasurement of the energy spectrum are described. The calculation of the array exposure and the strategy for the energycalibration of the infill, obtained from events observed in coincidence with the fluorescence detector, are presented.