Shower spectrum and detection of tau from Earth-skimming neutrinos

A Monte-Carlo simulation code was described for simulation of Earth skimming tau-neutrinos. The Earth density and composition profile, charged/neutral current interaction, energy loss of tau leptons, and tau decay are all included in the code. This paper compares the tau spectrum calculated from two methods, analytical formula and Monte-Carlo simulation. the results consistent with each other, which proves the algorithms are all correct in this simulation code.