A parametrized simulation code to simulate the response of ground detector arrays to Extensive Air Showers above 100 TeV

Surface arrays detecting the secondary particles of Extensive Air Showers (EAS) are one of the techniques used to detect gamma-rays from high-energy sources. To evaluate the reconstruction performance, gamma/hadron separation, and sensitivity of such experiments, many simulations of gamma rays and protons are required. The usual approach is divided into two steps. First, the CORSIKA software is used to generate EAS at the observation level. Then, a GEANT4-based full simulation code is used to simulate the array response. For very large fill factors, above 30-100 TeV, the computational resources required become too demanding. In this work, the authors present an alternative way to evaluate the performance-related quantities of a simulated array configuration through the parametrization of the detector response. We will present the implementation of such software, the validation checks we performed, and the application of this tool to a representative future ground-based water-Cherenkov detector array.