Monday, June 11, 2012

Latest on the OPERA Neutrino Experiments

From the New Scientist (h/t Instapundit):
OPERA shocked the world in September 2011 when it announced that neutrinos zipping from CERN in Switzerland to detectors beneath the Gran Sasso mountains in Italy were outpacing the speed of light, a feat that violated Einstein's rules of relativity and opened the door to exotic physics. But over the next few months, two errors – a leaky fibre-optic cable and a malfunctioning clock – emerged, which slowed the neutrinos back down, dashing post-Einsteinian dreams and causing chaos within the OPERA collaboration.

The measurement wasn't a waste of time, says OPERA team member Dario Autiero. The new, preliminary result shows neutrinos' speed is within 0.5 nanoseconds of light speed, with an error of 8 nanoseconds. That error should shrink with further analysis, says OPERA co-spokesperson Giovanni De Lellis of the Italian National Nuclear Physics Institute (INFN).

"This is the first time that velocity was measured with that level of accuracy," Autiero says.

But all of that was a sidebar to the experiment's real goal: catching shape-shifting neutrinos in the act. Neutrinos come in three flavours: electron, muon and tau. Several experiments had seen evidence for neutrinos spontaneously switching, or oscillating, from one type to another. Those oscillations proved, to many physicists' surprise, that the supposed massless particles must have some infinitesimal mass, and offered a route to explaining why there is more matter than anti-matter in the universe.
I'm not sure how results of a .5 nanoseconds less than the speed of light, +/- 8 nanoseconds, actually confirms that the neutrinos traveled less than the speed of light. Perhaps someone less arithmetically impaired can explain.

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