Last September experiments done as part of the OPERA collaboration recorded faster-than-light travel by neutrinos. But new experiments done to test this finding have shown neutrinos traveling at the speed of light, not faster.
The four experiments used to test this were the Borexino, ICARUS, LVD, and OPERA experiments, all of which measured a neutrino time of flight consistent with the speed of light. All of these experiments measured the time of flight of neutrinos from CERN to the INFN Gran Sasso Laboratory, across a distance of 730 km.
The researchers think that the original OPERA measurement can be attributed to a faulty fibre-optic timing system used in the experiment.
“Although this result isn’t as exciting as some would have liked,” said CERN Research Director Sergio 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 a related development, the OPERA experiment has shown 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.”
Image Credits: INFN, Kamioka Observatory, ICRR, University of Tokyo