Speaker
Description
In this contribution, we present the status and first data from the Radio Detector (RD) at the Pierre Auger Observatory, consisting of 1660 radio antennas deployed across the 3000 km² surface detector array. These antennas measure the radio emission from extensive air showers in the 30–80 MHz band, enabling electromagnetic energy measurements for air showers with zenith angles above 60°. Combined with the muonic measurements from the water-Cherenkov detectors (WCDs), this allows mass composition studies at the highest energies. The large-scale deployment of the RD began in June 2023 and was completed in November 2024. A full end-to-end calibration shows consistency between Galactic and in-lab calibration to better than 5% and includes continuous monitoring for hardware failures, ensuring, for example, antenna alignment within 5°. In addition, a new electric field mill network is in place to monitor thunderstorm conditions. The calibrated event reconstruction of the RD delivers an expected electromagnetic energy resolution of 6%. We present the first data, demonstrating a strong correlation between the electromagnetic energy measured by the RD and the total shower energy measured by the WCD, confirming that the full detector chain—including triggering, data readout, absolute calibration, and reconstruction—is understood at the 5% level. We highlight a particularly impressive 36 EeV shower at a zenith angle of 85°, producing a 50 km-long radio footprint, showcasing the unique capabilities of this detector.
| Collaboration(s) | Pierre Auger Collaboration |
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