ENERGY THRESHOLD DETERMINATION FOR AMIGA MUON COUNTERS VIA GEANT4 SIMULATION

Muons from extensive air shower with energy greater than or equivalent to 1 GeV propagating in the soil are able to reach the AMIGA (Auger Muons and Infill for the Ground Array) detector. Although the air shower muonic component is attenuated much less than the electromagnetic component, the shielding of approximately 2.25 m of soil adds 540 g/cm2 of vertical mass. Thus, in order to better understand attenuation mechanisms (shielding effects) of muons, a Monte Carlo simulation with Geant4 was made to determine the muon energy threshold. This threshold can be used to test the Geant4 simulation program, since the muon energy threshold is well calculated via the Bethe-Bloch formula. From the energy thresholds and the energy distribution at ground level for different particles from extensive air showers, the contribution of those particles to the data recorded by the detectors can be calculated. This contribution is crucial to correctly determine the number of muons in an extensive air shower, which is one of the main aims of the AMIGA enhancement.