"The Low-Frequency Instrument for the Payload for Ultrahigh
Energy Observations (PUEO)"

*Presented by Yuchieh Ku, Graduate Student, Pennsylvania State University

The Payload for Ultrahigh Energy Observations (PUEO) is a long-duration
balloon experiment designed to detect ultra-high-energy (UHE) neutrinos
with energies above 1 EeV. The instrument consists of a Main Instrument
(MI) mounted on the payload and a Low-Frequency (LF) instrument deployed
beneath the payload. The LF instrument comprises eight sinuous
antennas operating in the 50–500 MHz band, complementing the 96
dual-polarized horn antennas of the MI, which cover the 300–1200 MHz
range. The LF system is optimized to detect radio emissions from air
showers induced by cosmic rays and Earth-skimming tau neutrinos. By
extending sensitivity to lower frequencies, the LF instrument enhances
PUEO’s capability to characterize signals and improve event
reconstruction.  In this talk I will review PUEO’s science goals and
instrument performance during its successful flight from December
19, 2025 to January 11, 2026, with particular emphasis on the design,
implementation, and performance of the LF system.