Optimizing sea level muon flux modelling: a 2D fit approach and integration into Geant4 generators

Starting from the measurements conducted in 2004 with the ADAMO silicon spectrometer, we have performed a 2D fit procedure to diverse combinations of muon flux datasets documented in the literature. The fit employed three different formulas describing the energy and angular distribution of atmospheric muons at the Earth’s surface. The analysis revealed that some measurements showed discrepancies in their compatibility with the expected results or between them with variations greater than a few sigmas. For example, vertical measurements expand over a wide range of flux values even for similar setup experiments. However, we have identified a formula capable of furnishing comprehensive spectrum coverage utilizing a singular set of parameters. Despite inherent limitations, we have achieved a satisfactory agreement with the Guan parameterization. Subsequently, we have integrated this optimized parameterization into the EcoMug library and a Geant4-based muon generator. The model’s predictive capabilities have been validated by comparing it with experimental flux measurements and against other measurements in the literature. Through this process, we have shown and tested the reliability and accuracy of different muon flux modelling, facilitating advancements in domains reliant on the precise characterization of atmospheric muon phenomena.