Energy spectra of solar flare gamma-ray emission in the range 0.03–2 GeV registered by gamma-1 telescope

The gamma-ray telescope GAMMA-1 has registered gamma-emission in the range 30 – 2000 MeV from two solar flares. Spectral analysis with the use of maximum likelihood and maximum entropy methods has revealed the difference of gamma-ray production mechanism. In contrast with impulsive March 26, 1991 event where high energy gamma-rays originate exclusively as a bremstrahlung of primary accelerated electrons, at the extended phase of June 15, 1991 flare mainly the decay of neutral pions is responsible for the observed gamma-emission. An average spectral index for primary nucleons was -3.6. Evolution of the spectra for both flares shows tendency to a decrease of the primary particles mean energies with time.