After visiting the point of origin of the MINOS neutrinos on our Fermilab tour at the beginning of the trip, it seemed a fitting conclusion to stop by their destination as my own road neared its end. So with Lizzie in Mexico, I made the Summer’s last science-related stop at the Soudan Mine with my friend Sam on our way back across the country.
As discussed in our previous post, the MINOS experiment uses a beam of neutrinos called NuMI (Neutrinos at the Main Injector) produced by decaying protons from Fermilab’s Main Injector. These neutrinos travel 450 miles through the earth to the 2341-foot deep Soudan Mine in northeast Minnesota (and beyond, of course), where physicists can isolate the Far Detector from just about any interference. Despite the fact that the detector is shaped like an enormous stop sign, only a tiny number of neutrinos obey the symbolic request: of all the trillions of neutrinos produced by NuMI, the Far Detector sees only about one a day.