Tau lepton fluxes in underground salt dome

Ultrahigh-energy neutrino originated from the GZK effect is the most plausible source for high energy neutrinos. However, their small flux and low interaction probability make their detection very challenging. To have a proper event rate, the interaction volume must be much larger than the km ³-size detector currently under construction. One of the alternative techniques resorts to the detection of coherent radio waves produced inside an underground salt dome. We have developed a Monte-Carlo simulation code for the interactions and propagations of leptons inside the Earth. In this code, the Earth is treated as a three-layer sphere consisting of iron in the core, standard rock in the mantle and water on the surface. We have also added salt as the fourth material surrounding the detector. The energy loss of muons and tau leptons in salt are calculated. To simulate a 100-km³ water-equivalent target volume, we employ a spherical sphere salt dome of 5 km in radius. The tau lepton fluxes .