  Sandwich gravitational waves are given globally in terms of step functions at
the boundaries. Linearized Einstein-Weyl equations are solved exactly in this
background in Rosen coordinates. Depending on the geometry and composition of
the sandwich wave, the neutrino's energy-momentum redistributes itself. At the
test field level, since the background will not change, the neutrino's energy
density in particular will show variations between positive and negative
extrema when crossing the sandwich wave. This may reveal facts about the weakly
interacting neutrinos in cosmology.
