Tracking ghosts

Neutrinos are one of the most elusive particles around. For a long time, scientists didn’t think they had mass, traveled at the speed of light and really didn’t like interacting with anything else very much. Billions of the things pass through your body every second of every day without causing you to flinch. This has meant that the neutrino has become known as the ghost particle.

Except that know we’re going to get a much better look at them. A clever experiment generates neutrinos at the CERN nuclear physics lab in Geneva and then detects them in an underground cavern hundreds of miles away in Italy has just detected its first neutrinos. It doesn’t detect the neutrinos directly but looks for the tell-tale signs of other particles created when the neutrinos interact in the Italian detector.

Given that the neutrinos take just 2.4 milliseconds to travel the 450 miles between the source and the detector at the Gran Sasso LaboratoryI think they’ve done a stunning job. What they really want to find are so-called tau neutrinos. Neutrinos come in theee “flavours” – electron, muon and tau – and scientists reckon that somehow they oscillate between these flavours by some as yet unexplained mechanism.  All the neutrinos produced at CERN are of the muon type so if they spot anything that looks like a tau neutrino, there’s a good chance that the oscillation theory is correct. It may not sound important but if they are observed, these oscillations will help explain what happens deep in the heart of stars.