Radar for detection of ultra-high-energy neutrinos reacting in a rock salt dome

Detection of GZK (Greisen, Zatsepin and Kuzmin) neutrinos that have an energy larger than 1×1016 eV are expected to explore ultra-high-energy (UHE) interactions between UHE protons (>4×1019 eV) and cosmic-microwave background in the cosmological distances. A study of the radar method was carried out using a 2 MeV electron beam to irradiate rock salt powder filled in a 435 MHz waveguide. Reflection of radio wave from the irradiated rock-salt powder was observed inside the waveguide. The reflection mechanism was elucidated and the reflection power ratio was compared with a Fresnel equation.