MUons from PArametric formulas: A fast GEnerator of atmospheric -bundles for neutrino telescopes (MUPAGE)

Atmospheric muons play an important role for neutrino telescopes, because they provide the most abundant source of events for real time monitoring, calibration and tests. On the other side, they also represent the major background source. Monte Carlo generator (called MUPAGE) of atmospheric muon bundles for underwater/ice neutrino telescopes is presented here. MUPAGE is based on parametric formulas [Y. Becherini, A. Margiotta, M. Sioli, M. Spurio, Astrop. Phys. 25 (2006) 1–13; M. Spurio, Nucl. Instr. and Meth. A 567 (2006) 492] obtained from a full Monte Carlo simulation of cosmic ray showers generating muons in bundles, which are propagated down to 5 km w.e. It produces the event kinematics on the surface of a user-defined virtual cylinder, surrounding the detector. The multiplicity of the muons in the bundle, the muon lateral distribution and energy spectrum are simulated according to a specific model of the primary cosmic ray flux, with constraints from measurements of the muon flux obtained in underground experiments. Some examples of application are presented.