AVS-F observations of γ-ray emission during January 20, 2005 solar flare up to 140 MeV

The solar flare of January 20, 2005 (X7.1, 06:36-07:26 UT, maximum at 07:01 UT by the GOES soft X-ray data) was the most powerful one in January 2005 series. The AVS-F apparatus onboard CORONAS-F registered γ-emission during soft X-ray rising phase of this flare in two energy ranges of 0.1-20 MeV and 2-140 MeV. The highest γ-ray energy registered during this flare was ∼140 MeV. Six spectral features were registered in energy spectrum of this solar flare: annihilation + αα (0.4-0.6 MeV), 24Mg + 20Ne + 28Si + neutron capture (1.7-2.3 MeV), 21Ne + 22Ne + 16O + 12С (3.2-5.0 MeV), 16O (5.3-6.9 MeV), one from neutral pions decay (25-110 MeV) and one in energy band 15-21 MeV. Four of them contain typical for solar flares lines - annihilation, nuclear de-excitation and neutron capture at 1H. Spectral feature caused by neutral pions decay was registered during several flares too. Some spectral peculiarities in the region of 15-21 MeV were first observed in solar flare energy spectrum.