MEASUREMENT OF ATTENUATION LENGTH FOR UHFRADIO WAVE IN NATURAL ROCK SALT SAMPLESCONCERNINGULTRA HIGH ENERGY NEUTRINO DETECTION

摘要

Ultra high energy (UHE ) neutrinos (E>10~(15)eV) exist at any rate due to presence of thecosmic microwave background and UHE cosmic rays implied by Greisen, Zatsepin andKuz'min (GZK). The low rate of GZK neutrinos requires us to utilize a large mass (>50Gton) of detection medium. The UHE neutrino generates a huge number of unpairedelectrons in rock salt. They would emit sensible radio wave by coherent Cherenkoveffect (Askar'yan effect). Attenuation lengths of natural rock salt samples includingsynthesized one at 0.3 and 1.0 GHz were measured to find a suitable site constructing asalt neutrino detector. The result indicates a possibility for constructing the salt neutrinodetector with economical antenna spacing.