ИСТИНА

Basing on the AVS-F apparatus data of CORONAS-F/SONG-D detector on definite gamma-ray lines, we study the extreme solar event of 20 January 2005. We calculate the 2.223 MeV gamma-line time profile by the statistical modeling method. We also use the AVS-F data on 4.44 and 6.13 MeV lines. The calculations have been performed in assumption of Bessel type of accelerated particles energy spectrum, different 3He content in the nuclear reactions region and several density models of the solar atmosphere. Comparisons of the results of modeling with observational data reveals the increasing of the ratio of 3He content to 1H content during the flare from 2∙10-5 at the growth phase of the gamma-ray flux up to 2∙10-4 at the decay phase. During the same period the spectrum became harder and the density of solar atmosphere increased too. When averaging over full time of 2.223 MeV gamma-emission, the ratio 3He/1H is equal to (1.4±0.15)∙10-4, the spectral index аT is rather close to 0.1, and the density model with enlarged density up to 2∙10^17 cm-3 in the lower chromosphere and through the whole photosphere is realized.