What evidence disproves classical preferential scattering of particles in the double slit experiment?

Suppose photons or electrons travel toward a double slit with tiny angles from their direction of travel. Suppose those particles bounce between and off the surfaces of the double slit. What would be the distribution of particles on a screen? What variation of this situation might result in classical preferential scattering of those particles? What evidence directly disproves classical preferential scattering?