The Battleship in the Soudan Mine: MINOS Part II

The MINOS Far Detector, buried 2,341 feet beneath the earth in the Soudan Mine in northern Minnesota. A mural by Joseph Giannetti about the power of science is painted on the right wall.

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.

Courtesy of Fermilab.

Neutrinos and the Intensity Frontier: Fermilab Part II (& MINOS Part I)

The enormous hole in the MINOS building that leads down to the NuMI neutrino beamline and MINOS

In all the fuss about how amazing the LHC is going to be, we often forget that there are things it won’t be able to do. One of the most glaring holes in the LHC’s research program is how little work it plans to do on neutrino physics, one of the most exciting and promising fields in the quest to go beyond the Standard Model. Neutrinos are elementary particles that are nearly massless and have no charge. They rarely interact with other particles, so you need to make a lot of them to have the faintest hope of detecting just a few in experiments. In other words, you don’t need very high energy protons to produce neutrinos, but you do need a lot of lower energy ones.

It wouldn’t really make sense to devote much of the LHC’s particle yield to experiments that don’t need anything approaching its high energies, especially during the early years of the experiment. So Fermilab, somewhat presciently, is stepping in to fill the gap. As our tour guide and gracious host Kurt Riesselmann told us, “Fermilab is moving from the energy frontier to the intensity frontier” — meaning that instead of producing a small number of the highest possible energy particles, the lab is figuring out how to make as many lower energy particles as possible.