  A new generation of Ge-based high-resolution gamma-ray spectrometers has
allowed accurate measurements to be made of the profiles, widths and energies
of the gamma-ray lines emitted in the impulsive phases of solar flares. Here we
present measurements in two flares of the energies of the de-excitation lines
of 12C and 16O at 4.4 and 6.1 MeV respectively by the Ge spectrometer SPI on
board INTEGRAL, from which Doppler shifts are derived and compared with those
expected from the recoil of 12C and 16O nuclei which were excited by the
impacts of flare-accelerated ions. An anomalous Doppler measurement (in terms
of recoil theory) has been reported by the Ge spectrometer RHESSI in a flare
near the east limb, and explained by a tilt of the magnetic field lines at the
footpoint of a magnetic loop away from the vertical, and towards the observer.
This might be interpreted to imply a significant difference between the Doppler
shifts on the east and west limbs, if it is a general phenomenon. SPI observed
both east and west limb flares and found no significant difference in Doppler
shifts. We also measured the shapes and fluences of these lines, and their
fluence ratio to the 2.2 MeV line from the capture of flare-generated neutrons.
Analyses of both quantities using thick-target models parametrized by solar
physical and geometric quantities suggest that the two flares studied here also
have magnetic fields tilted towards the observer, though the significance of
the measurements is not high.
