  We perform a self-consistent calculation of collective neutrino oscillations
including the effect of back scattered neutrinos (Halo effect) in the
`single-angle' approximation, within a spherically symmetric supernova model.
We find that due to the Halo effect the onset of flavor transformations is
pushed to smaller radii, by a few kilometers. The celebrated phenomenon of the
spectral split is found to be robust under the present inclusion of the Halo
effect.
