  We present the first experimental evidence supporting the postulation that an
optical-dipole potential in a condensate undergoing superradiant scattering
modifies the structure factor of the system and significantly impacts the
scattering. Several consequences of this new detuning-dependent mechanism are
discussed and verified experimentally. Our experiments indicate that whenever
the generation and propagation growth of a new field are significant, the
dynamic response of the condensate can have a profound impact on the scattering
process.
