Searching for ultrahigh-energy neutrinos with balloon-borne neutrino telescopes

Mary Hall Reno, PhD

Ultrahigh-energy neutrinos carry information about the highest energy astrophysical sources. Neutrinos are not deflected by magnetic fields nor absorbed in transit from the source to Earth. Low fluxes of ultrahigh-energy neutrinos and their weak interactions require very large detection volumes. One technique to detect them is to use the Earth as a tau neutrino converter, in which tau leptons can emerge to produce up-going extensive air showers. In this talk, I will outline how this technique can be used with an optical Cherenkov telescope on a super-pressure balloon (or on a satellite) to set neutrino sensitivity limits, and in the future, potentially indirectly detect neutrinos with energies above 10 PeV. Examples will include EUSO-SPB2 and POEMMA-Balloon with Radio, past and future projects, respectively, of which I am a part. This talk is intended to be an introduction at the level of a colloquium.