Has anyone heard of anyone trying to conduct the double slit experiment with a barrier between the two slits that goes all the way or near the detector? If it could be done maybe it would be interesting to see the result. It may answer the question if the photon (or electron) is interferring with itself (or is it going through both slits at the same time). The barrier may prevent interferrence. If you still see the interferrence pattern, then maybe you could derive that the particle is going through both slit.