MEASUREMENT OF ATTENUATION LENGTH FOR RADIO WAVE IN NATURAL ROCK SALT SAMPLES CONCERNING ULTRA HIGH ENERGY NEUTRINO DETECTION

Abstract

Ultra high energy (UHE) neutrinos with the energy larger than 1015 eV, surely arrive at the earth with Greisen, Zatsepin, Kuz'min (GZK) effect, though the rate is very few. The rare call requires us to utilize a large mass (>10 Gton) of detection medium. UHE neutrino generates a huge number of unpaired electrons in rock salt. They would emit sensible radio wave by coherent Cherenkov (Askar'yan) effect. The longer attenuation length of radio wave in rock salt reduces the number of antennas required. Several rock salt samples including synthesized one are measured in attenuation length for radio wave transmission at 0.3 and 1.0 GHz. Some show attenuation length larger than 300 m, which indicate a possibility for constructing a salt neutrino detector.