Speaker
Description
Extensive air showers initiated by cosmic particles produce coherent radio frequency (RF) emission, enabling radio detection as a powerful probe at ultrahigh energies above 100 PeV. The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a proposed detector concept comprising mountaintop phased radio arrays in search for 30 – 80 MHz radio emission originating from Earth-skimming tau neutrinos. BEACON is also sensitive to cosmic rays and as part of ongoing efforts to measure the detector’s sensitivity to showers, a prototype instrument in 2023 collected data with a hybrid array of radio and scintillator detectors. With cross-validation from scintillators, a cosmic ray search analysis resulted in a set of 22 events consistent with a particle flux signature coincident with correlated radio signals over an estimated 0.11 event background. Here, we present the analysis methods and results, including additional estimates on the signal polarization. For improving future mountaintop radio arrays, the analysis suggests that sparse arrays could be essential for background rejection and constraining additional properties of CR radio emission.