February 22, 2012 | 7
Although still awaiting full confirmation, a breaking news report in Science (and Nature, see below) indicates that the measurement of an apparently faster-than-light travel time for muon-neutrinos generated at CERN and detected at the Gran Sasso laboratory – which hit the world headlines back in September 2011 – may have been due to a problematic physical connection between a fiber-optic cable and an electronics card in a computer.
The rumor is that when this connection was tightened and the signal timing through the cable re-evaluated it matched precisely the 60 nano-second discrepancy that had been attributed to possible superluminal neutrino speeds. Since the cable fed data from a GPS unit used in timing the neutrino passage, this would be a critical problem. It is also possible that the GPS was providing incorrect timestamp information.
A more detailed report of the issues and the intentions of the OPERA collaboration are available at this Nature web site. And I quote here:
“The OPERA Collaboration, by continuing its campaign of verifications on the neutrino velocity measurement, has identified two issues that could significantly affect the reported result. The first one is linked to the oscillator used to produce the events time-stamps in between the GPS synchronizations. The second point is related to the connection of the optical fiber bringing the external GPS signal to the OPERA master clock.
These two issues can modify the neutrino time of flight in opposite directions. While continuing our investigations, in order to unambiguously quantify the effect on the observed result, the Collaboration is looking forward to performing a new measurement of the neutrino velocity as soon as a new bunched beam will be available in 2012. An extensive report on the above mentioned verifications and results will be shortly made available to the scientific committees and agencies.”
We will have to wait and see if this is corroborated, but it suggests that any hopes of having spotted neutrinos skipping the light fantastic may have indeed been wishful thinking. Such is the nature of complex and extremely tricky physics experiments, a dodgy bit of wiring, or a piece of electronics slightly outside its design tolerance can make all the difference.