Detection of ultra high-energy tau-neutrinos with fluorescence detectors

Abstract

We calculate the possible number of Extensive Air Showers originated by tau neutrinos in Fluorescence Detectors like the ones of the Pierre Auger Observatory. We consider models of production of electron and muon neutrinos in extra galactic objects and Topological Defects, as well as the possibility of neutrino flavor change in the propagation of the neutrinos between the source and the Earth. The neutrino cross section was calculated by the extrapolation of the standard model parton distribution functions until energies of the order of 10 21 eV. However, due to uncertainties in the extrapolation for energies higher than 10 12 eV the results are not robust. We conclude that, depending on the relation between flux and cross section, there is a strict range of energy for the tau neutrinos to generate double extensive air showers detectable in Fluorescence Detectors. The tau neutrino energy must be approximately 10 18 eV and the event rate can vary some orders of magnitude around one event per year, depending on the flux-cross section relation and detector characteristics.

A reduction in the UHE neutrino flux due to neutrino spin precession

“…This same mechanism had also been applied in the past to the case of UHE cosmic rays [26,27], mainly motivated by the possibility to detect tau neutrinos appearing from oscillation during the neutrino propagation in cosmological distances [28]. Tau neutrinos could be identified by very unique signatures such as double bang events [29,30] and Earth skimming [31]. At present, thanks to a remarkable experimental effort, there are limits to the neutrino magnetic moment as strong as µ ν ≤ 10 −11 µ B coming from laboratory measurement [32,33] or from a combined analysis [34], and µ ν ≤ 10 −12 µ B from astrophysical observations [35] or from solar data [36].…”