PUEO and the Search for Ultrahigh Energy Neutrino

The Payload for Ultrahigh Energy Observations, or PUEO, is a long duration balloon-bone experiment designed to measure the flux of ultrahigh energy (UHE) neutrinos (>1 EeV), which are predicted to be produced by the interaction of UHE cosmic rays with the cosmic microwave background through the GZK effect, or even produced directly within the environments of UHE accelerators.

PUEO is scheduled to fly from McMurdo Station, Antarctica during the 2025-2026 austral summer, and is currently under construction. The broadband interferometric array of radio frequency antennas on PUEO has been designed to detect Askaryan emission produced by UHE neutrinos in the ice sheet. Additionally, it has a low frequency drop-down instrument optimized for detecting atmospheric air showers, which may be produced by cosmic rays or by the decay of tau leptons from below the horizon which are created by tau neutrinos within the Earth's crust. PUEO is based on the success of the ANITA experiments, which flew four times over Antarctica between 2007 and 2016. Several design improvements, such as a larger collection area and a phased array trigger, will give PUEO an order-of-magnitude increase in sensitivity over ANITA; these will allow PUEO to set the best limits to-date on the UHE neutrino flux, or hopefully to make their first ever detection.