Prompt Emission of Relativistic Protons up to GeV Energies from M6.4-Class Solar Flare on July 17, 2023

We show evidence of particle acceleration at GeV energies associated directly with protons from the prompt emission of a long-duration M6-class solar flare on July 17, 2023, rather than from protons acceleration by shocks from its associated coronal mass ejection (CME), which erupted with a speed of 1342 km/s. Solar energetic particles (SEP) accelerated by the blast have reached Earth, up to an almost S3 (strong) category of a radiation storm on the NOAA scale. Also, we show a temporal correlation between the fast increase in the GOES-16 proton flux and the ground-level count rate excess of the New-Tupi muon detector, located in the central region of the South Atlantic Anomaly (SAA) an area where the Earth’s magnetic field is anomalously weak. A Monte Carlo spectral analysis based on muon excess at New-Tupi is consistent with the acceleration of electrons and protons (ions) up to relativistic energies (GeV energy range) in the impulsive phase of the flare. In addition, we present another two marginal particle excesses (with low confidence) at ground-level detectors in correlation with the solar flare prompt emission.