Neutrinos respect the cosmic speed limit

At the 25th International Conference on Neutrino Physics and Astrophysics in Kyoto today (June 8, 2012), CERN Research Director Sergio Bertolucci presented results on the time of flight of neutrinos from CERN to the INFN Gran Sasso Laboratory on behalf of four experiments situated at Gran Sasso. The four, Borexino, ICARUS, LVD and OPERA all measure a neutrino time of flight consistent with the speed of light. 

The Gran Sasso National Laboratory of the Italian Institute of Nuclear Physics, located nearly a mile below the surface of the Gran Sasso mountain about 60 miles outside of Rome, detects tiny particles called neutrinos [Credit: Paolo Lombardi INFN-MI]

This is at odds with a measurement that the OPERA collaboration put up for scrutiny last September, indicating that the original OPERA measurement can be attributed to a faulty element of the experiment’s fibre optic timing system. 

“Although this result isn’t as exciting as some would have liked,” said Bertolucci, “it is what we all expected deep down. The story captured the public imagination, and has given people the opportunity to see the scientific method in action – an unexpected result was put up for scrutiny, thoroughly investigated and resolved in part thanks to collaboration between normally competing experiments. That’s how science moves forward.” 

In another development reported in Kyoto, the OPERA experiment showed evidence for the appearance of a second tau-neutrino in the CERN muon-neutrino beam, this is an important step towards understanding the science of neutrino oscillations. 

Source: CERN, the European Organization for Nuclear Research [June 08, 2012]