The Main Injector Neutrino Oscillation Search experiment, half a mile underground in the historic Soudan iron mine in northern Minnesota, uses a neutrino beam from the Main Injector accelerator at Fermilab to probe the secrets of neutrinos: where do they come from, what are their masses, and how do they transform from one flavor of neutrino into another?

In the MINOS experiment, a “near’ detector on the Fermilab site, outside Chicago, measures the beam of muon neutrinos as it leaves the accelerator. The neutrinos travel 450 miles straight through the earth from Fermilab to Soudan—no tunnel needed. In Minnesota, the 6,000-ton “far” detector searches the beam for muon neutrinos that may have changed into electron neutrinos or tau neutrinos during the split-second trip. More than a trillion man-made neutrinos will pass through the MINOS detector each year. Because neutrinos interact so rarely, only about 1,500 of them will collide with atomic nuclei inside the detector. The rest traverse the detector without a trace. The 200-plus MINOS experimenters use the change, or oscillation, from one type of neutrino to another as the key to investigating neutrino mass.

University scientists from Brazil, France, Greece, Russia, United Kingdom and the United States collaborate on the MINOS experiment using intense neutrino beams from a particle accelerator to discover the secrets of this most elusive of particles.

Photo Credit: Fermilab