INTEGRAL/SPI observation of the 2003 Oct 28 solar flare

The very powerful X-class solar flare in 2003 Oct. 28 was detected by several instruments on board INTEGRAL as an intense flash of about 15 minutes in the hard-X and gamma-ray bands. Despite the non-standard incidence of the solar gamma-rays, time-resolved spectra including several nuclear gamma-ray lines and a continuum at high energy were obtained with SPI. For the first time, in addition to the 2.2 MeV H-1 neutron capture line, the 4.4 MeV C-12* and 6.1 MeV O-16* nuclear interaction lines, the 6.9 and 7.1 MeV lines from O-16* are clearly resolved. Flux evolutions on a fraction of minute scale show significant differences between lines and continuum. Several spectra have been extracted during the flash. A preliminary analysis and interpretation of the time profiles and the spectra, including the 6.9 and 7.1 MeV O-16* lines will be given.