The FLUKA cosmic ray generator for the high energy region. Results and data comparison for the charge ratio of TeV muons detected underground

In the framework of the underground experiments at the Gran Sasso laboratory, a high energy cosmic ray generator has been developed. This is based on the FLUKA Monte Carlo code and it is primarily dedicated to the analysis of high energy muons detected underground. For this purpose the code simulates both the air shower development and the muon transport in the rock. We analyze the prediction for the charge ratio of underground muons, with the aim of investigating some features of the high energy particle production model. This measurement is particularly sensitive to the pi/K ratio of secondary mesons produced in the proton-Air and Nucleus-Air collisions. We analyze the possible dependence of charge ratio on the event multiplicity and primary composition model. We also compare our predictions with published experimental results.