Ackermann, M.M.AckermannAjello, M.M.AjelloAllafort, A.A.AllafortTosti, G.G.TostiVitale, V.V.VitaleCiprini, StefanoStefanoCipriniCutini, SaraSaraCutini2020-09-172020-09-172012-02-01https://hdl.handle.net/20.500.13025/2650The Astrophysical Journal, Volume 745, Issue 2, article id. 144, <NUMPAGES>11</NUMPAGES> pp. (2012).The Geostationary Operational Environmental Satellite (GOES) M2-class solar flare, SOL2010-06-12T00 57, was modest in many respects yet exhibited remarkable acceleration of energetic particles. The flare produced an ~50 s impulsive burst of hard X- and gamma-ray emission up to at least 400 MeV observed by the Fermi Gamma-ray Burst Monitor and Large Area Telescope experiments. The remarkably similar hard X-ray and high-energy gamma-ray time profiles suggest that most of the particles were accelerated to energies gsim300 MeV with a delay of ~10 s from mildly relativistic electrons, but some reached these energies in as little as ~3 s. The gamma-ray line fluence from this flare was about 10 times higher than that typically observed from this modest GOES class of X-ray flare. There is no evidence for time-extended >100 MeV emission as has been found for other flares with high-energy gamma-rays.acceleration of particlesSun flaresSun particle emissionSun X-raysgamma rays10.1088/0004-637X/745/2/144http://adsabs.harvard.edu/abs/2012ApJ...745..144A2012ApJ...745..144A