DEUTERIUM SYNTHESIS DURING THE SOLAR-FLARE OF MARCH 22, 1991 (GRANAT DATA)

The solar flare of March 22, 1991 was observed on the Granat satellite at 22(h)42(m)51(s) (UT) at energies up to 120 MeV. During this flare, strong emission in the 2.2-MeV gamma-ray line, which accompanies the deuterium synthesis H-1(n, gamma)H-2, was detected. The peak of the li ght curve in this line is delayed relative to the emission peak in the range 65-124 MeV by similar to 30 s. The declining flux in the line o f deuterium synthesis was recorded for more than 300 s after the termi nation of an intense high-energy phase of the flare. The total luminos ity in the 2.2-MeV line during the flare was 130 +/- 15 photons cm(-2) , and the e-folding decay time was 56 +/- 6 s immediately after reachi ng the peak luminosity in this line. As the flare decayed, the e-foldi ng time increased, reaching 105 +/- 25 s within 150 s after the lumino sity peak in the line. The detection of free neutrons near the Earth's orbit already similar to 75 s after the onset of the main phase of ac celeration in this flare implies that the peak neutron energy was simi lar to 1 GeV, while protons during the impulsive phase were accelerate d to relativistic energies.