Fraction of particles initially located in each 2 au radial bin that ultimately collide with Neptune (purple) and Uranus (blue). This provides the probability of collision for a given initial test particle semimajor axis, for any initial surface density. The left plot shows the combined statistics for No Swaps 1&2 while the right plot shows the same for Swaps 1&2. Uranus and Neptune are identified by their locations in their final configuration.