  Previous experiments on MAST and other tokamaks have indicated that the level
of fast ion redistribution can exceed that expected from classical diffusion
and that this level increases with beam power. In this paper we present a
quantification of this effect in MAST plasmas using a recently commissioned
scanning neutron camera. The observed fast ion diffusivity correlates with the
amplitude of n=1 energetic particle modes, indicating that they are the
probable cause of the non-classical fast ion diffusion in MAST. Finally, it
will be shown that broadening the fast ion pressure profile by the application
of neutral beam injection at an off-axis location can mitigate the growth of
these modes and result in the classical fast ion behaviour
