Radar Chamber for Detection of UHE Neutrinos

We have found a radio-wave-reflection effect in rock salt that could be used for the detection of ultra-high energy neutrinos (UHEν's).They were predicted by Berezinsky and Zatsepin to be generated in Greisen, Zatsepin, and Kuzmin (GZK) processes in the universe.When an UHEν interacts with rock salt or ice as a detection medium, a shower is generated.The shower is composed by hadronic and electromagnetic avalanche processes.The energy of the UHEν shower converts to thermal energy through ionization processes.Consequently, the temperature rises along the shower.The refractive index of the medium rises with temperature.The irregularity of the refractive index in the medium leads to a reflection of radio waves.This reflection effect combined with the long attenuation length of radio waves in rock salt and ice would give rise to a new method to detect UHEν's.We measured the power reflection fraction and the phase of the reflected radio wave under irradiation with an electron beam on ice and rock salt powder.A series of simulations of Geant4 (CERN) and Multiphysics (COMSOL AB Co. Ltd. ,Sweden) had been done to know how they could reproduce the experimental results.They did not coincided in absolute values but their curves of the reflection fraction and phase shift of the reflected radio wave with irradiation time were similar in shapes.Due to the similar shapes, we regard that the reflection mechanism was verified by the simulations.