Neutrino Oscillations

In one of the more interesting experiments I can think of, the Main Injector Muon Oscillation Search (MINOS) has yielded preliminary results that, indeed, neutrinos do oscillate and that the rates are consistent with muon oscillation theoretical predictions. This experiment begins at Fermilab, where protons from the Main Injector beam are slammed into a carbon target. Nuclear reactions take place that produce some number of muon neutrinos. This beam of muon neutrinos then begins a journey through 725 miles of the Earth to a detector in a mineshaft in Soudan, Minnesota. There, the muon neutrinos are counted. There are half as many muon neutrinos left, which is a statistically significant result that neutrinos oscillate. Oscillations are expected if there is a mass difference between the various neutrino (electron, muon, tau) flavors, and results are being extracted from the data on the value of the mass difference.