Permafrost - An Alternative Target Material for Ultra High Energy Neutrino Detection?

The detection of cosmic neutrinos with energies above 1017 eV got growing interest during recent years. Possible target materials for in-matter arrays of ~100 km3 size under discussion are water, ice and rock salt. Here we propose to investigate permafrost as an additional alternative, covering ~20% of Earth land surface and reaching down to more than 1000 m depth at certain locations. If sufficiently large attenuation lengths for radio and acoustic signals can be demonstrated by in-situ measurements, the construction of a large hybrid array within this material may be possible in the Northern hemisphere. Properties and problems of a possible location in Siberia are discussed below. Some acoustic data are compared to laboratory measurements using "artificial" permafrost.