Neutrinos Change Flavor in Mid-Flight

Particles don't oscillate--change from one "flavor" to another--as they travel through the ether. Or do they? The mysterious neutrino, shot from the interior of the Sun through space, through Earth's atmosphere, through you, through your pet cow Bessie, through your schoolhouse walls, starts out as one flavor and becomes one of-or alternately both of-two other possible flavors. The three neutrino flavors are muon, tau, and electron.

CERN has another exciting experiment online next door to the attention grabbing Large Hadron Collider (LHC) experiment, where CERN's accelerator complex (CNGS) generates and then shoots billions and billions of muon-neutrinos in a bombardment toward Italy (a purely friendly gesture) to be caught in the OPERA experiment at Gran Sasso Laboratory in order to document the theory that the number of neutrinos bombarding Earth at any given moment are shy of the predicted number by about a third because neutrinos change their characteristics in mid-flight. There is now reason to believe that the first recorded transformed, or oscillated, muon-neutrino has been caught in OPERA following its transformation to a tau-neutrino.

One reason this is such interesting news is that oscillating particles-particles that start out as one thing and end up as another-alter the known physics prescribed by and active within the Standard Model of physics. This means a glimpse at a universe even more unusual than quantum physics has already shown it to be what with up quarks and down quarks and strange particles and flavors and quantum operations that can't be observed because the observer alters the operation.... . Besides requiring a remodeling of the Standard Model (Who could have predicted particles that alter their characteristics in mid-flight?), oscillating neutrinos may have implications for our understanding of cosmology and astrophysics as well as for particle physics.

The discrepancy between the predicted number of muon-neutrinos and the actual observed number has been noted in several worldwide experiments over about fifteen years. The direct appearance of the altered neutrino was until now yet to be noted. The OPERA experiment was specifically designed to capture oscillations. The logic of the experiment is along this line: If a group of muon-neutrinos is shot at a certain speed and time and at a certain trajectory from a specific location to a specified destination through a predetermined course, then a tau-neutrino that arrives with the muon group and matches all the established identifying criteria of speed, time, trajectory, location of origin, course of travel must be a tau oscillated muon-neutrino. When a few more of these muon-tau oscillations are recorded by OPERA, proof will be firmly established for the neutrino oscillation mechanism, which will represent physics that fall outside the explanations and predictions of the Standard Model.

Since the experiment's beginning in 2006, muon-neutrinos leave CERN at the speed of light and travel the 730 km to Gran Sasso's OPERA in 2.4 milliseconds to bombard the 150,000 highly sensitive photographic cameras (called bricks) that comprise the crux of OPERA and that photographically record the patterns left by the neutrinos. Painstaking analysis was rewarded by the discovery of the first track of a tau-neutrino located in a bombardment of muon-neutrinos. Gran Sasso Laboratory is part of the Italian National Institute of Nuclear Physics (INFN).

Source: INFN Press Release 31 May 2010.