Speaker
Description
The autonomous radio-detection of extensive air showers initiated by ultra-high-energy (UHE) particles arriving with very inclined zenith angles has seen significant advancements in recent years, with several large-scale surface arrays planned and prototypes already in operation. Hybrid arrays combining radio antennas and scintillators, could serve as competitive UHE photon detectors. Indeed, for inclined showers, radio emissions can be detected by antennas for both cosmic-ray and photon primaries, while the muon-rich signatures of the former would typically trigger the scintillators. In this talk, I will show that effective separation between the two types of showers could be achieved in a hybrid radio antenna and scintillator setup, using two key observables—the total root mean square of the radio signal and the total energy deposit recorded in the scintillators. As a case study, I will apply this method to the layout of the prototype of the Giant Radio Array for Neutrino Detection (GRAND), GRANDProto300, complemented by Telescope Array-type scintillators. Such a hybrid array could set competitive upper limits on the integral photon flux in the energy range of 0.1 to 3 EeV, opening a yet uncharted territory for photon searches at UHE, by targeting very inclined air showers.