Milestones for the Tevatron and LHC

This past week saw two big milestones for the two big operating high energy particle colliders in the world. At these machines, we measure the number of collisions with the rather arcane unit of "inverse barns", which is essentially a measure of inverse cross sectional area. It's just like if you are throwing darts at a dart board across the room with your eyes closed: the bigger the dart board, the more likely you are to hit it, and the more darts you throw, the more hits you get.