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.
The term “barn” came from the early days of nuclear physics when Fermi quipped that a nucleus is “as big as a barn.” And so a new physics unit was born: one barn is 10-28 m2, about the size of a big nucleus. At the Tevatron at Fermilab, we’ve just crossed over 10.0 inverse femtobarns of integrated luminosity, after over ten ...
