Testing Heavy Neutral Leptons in Cosmic Ray Beam Dump experiments

A bstract In this work, we discuss the possibility to test Heavy Neutral Leptons (HNLs) using “Cosmic Ray Beam Dump” experiments. analogy with terrestrial beam dump experiments, where a first hits target and is then absorbed by shield, consider high-energy incident cosmic rays impinging on Earth’s atmosphere surface. We focus here HNL production from atmospherically produced kaon, pion D -meson decays, possible explanation of appearing Cherenkov showers observed SHALON telescope ultra-high energy events detected neutrino experiment ANITA. show that these observations can not be explained long-lived HNL, as relevant parameter space excluded existing constraints. Then propose two new experimental setups are inspired namely pointing at sub-horizontal angle shielded mountain cliff Mount Thor, geostationary satellite observes part Sahara desert. Thor probe currently untested for masses below kaon mass. also significantly increase coverage in whole mass range 10 MeV up 2 GeV mixing | U α 4 down − 11 around 300 MeV.