Atmospheric MUons from PArametric formulas: a fast GEnerator for neutrino telescopes (MUPAGE) Original Research Article

Neutrino telescopes will open, in the next years, new opportunities in observational high energy astrophysics. In these detectors, atmospheric muons from primary cosmic ray interactions in the atmosphere play an important role, because they provide the most abundant source of events for calibration and test. On the other side, they represent the major background source. In this paper a fast Monte Carlo generator (called MUPAGE) of bundles of atmospheric muons for underwater/ice neutrino telescopes is presented. MUPAGE is based on parametric formulas [Y. Becherini, A. Margiotta, M. Sioli, M. Spurio, Astrop. Phys. 25 (2006) 1] obtained from a full Monte Carlo simulation of cosmic ray showers generating muons in bundle, which are propagated down to 5 km w.e. It produces the event kinematics on the surface of a user-defined cylinder, surrounding the virtual detector. The multiplicity of the muons in the bundle, the muon lateral distribution and energy spectrum are simulated according to a specific model of primary cosmic ray flux, with constraints from measurements of the muon flux with underground experiments. As an example of application, the result of the generation of events on a cylindrical surface of ∼1.4 km2 at a depth of 2450 m of water is presented.