In the middle of the night of 13 February 2023, the ARCA detector recorded an unprecedented event: during a time window of almost 2 microseconds, more than 28,000 photons were recorded in the almost 12,000 photomultipliers of the detector. The level of illumination was so high that more than 25% of the photomultipliers which detected a signal saturated. From the analysis of the data it was possible to identify a single charged particle, a muon, which had crossed the entire detector. Detailed studies led to an estimate of the muon’s energy at a record value of 120 PeV, 100 trillion times higher than that of visible light photons. This implies that the primary neutrino that generated the muon had an even higher energy, estimated at the level of 220 PeV, significantly higher than any neutrino ever detected before. This result has recently been illustrated in an article published in Nature.
