11 research outputs found
Measurement of a Phase of a Radio Wave Reflected from Rock Salt and Ice Irradiated by an Electron Beam for Detection of Ultra-High-Energy Neutrinos
We have found a radio-wave-reflection effect in rock salt for the detection
of ultra-high energy neutrinos which are expected to be generated in Greisen,
Zatsepin, and Kuzmin (GZK) processes in the universe. When an UHE neutrino
interacts with rock salt or ice as a detection medium, a shower is generated.
That shower is formed by hadronic and electromagnetic avalanche processes. The
energy of the UHE neutrino shower converts to thermal energy through ionization
processes. Consequently, the temperature rises along the shower produced by the
UHE neutrino. 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 yield a new method to detect UHE
neutrinos. We measured the phase of the reflected radio wave under irradiation
with an electron beam on ice and rock salt powder. The measured phase showed
excellent consistence with the power reflection fraction which was measured
directly. A model taking into account the temperature change explained the
phase and the amplitude of the reflected wave. Therefore the reflection
mechanism was confirmed. The power reflection fraction was compared with that
calculated with the Fresnel equations, the ratio between the measured result
and that obtained with the Fresnel equations in ice was larger than that of
rock salt.Comment: 6 Pages, 5th International Workshop on Acoustic and Radio EeV
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