CERN
The CERN Neutrinos to Gran Sasso experiment sends muon neutrinos through a tunnel at the French-Swiss border in the direction of a detector in Italy, more than 450 miles away.
By Alan Boyle
Months after researchers reported that they measured neutrinos traveling faster than light, they're finding that the incredible result may have been due to a bad connection rather than a violation of Albert Einstein's special theory of relativity.
The potential instrumental glitches, first reported today by ScienceInsider's Edwin Cartlidge, is due to be addressed on Thursday in a statement from the OPERA Collaboration, the group behind the controversial neutrino-beam experiments.
Last year, the OPERA team made ultra-precise measurements of how long it took for neutrinos to make the 450-mile (732-kilometer) trip between the CERN particle physics lab on the French-Swiss border and Italy's Gran Sasso National Laboratory. When they took the speed of light and a wide variety of other experimental factors into consideration, they determined that the neutrinos arrived 60 nanoseconds before they should have.
If the results were to stand up, they'd mark the first failed test for Einstein's century-old theory. That's one reason why researchers found them so hard to believe, even though a repetition of the experiment yielded the same results. The OPERA team has been reviewing the entire experiment, and several other research groups have been trying to replicate it. A key concern has been the Global Positioning Satellite system used to clock the neutrinos' transit time. The measurements are required to be so precise that the relativistic effects of Earth's gravitational field on the GPS system had to be taken into account.
Now sources familiar with the OPERA review say scientists have identified two potential problems with the experimental apparatus. One has to do with a fiber-optic connector that sends a GPS time stamp to the experiment's master clock. That connector may not have been functioning correctly when the neutrino-timing measurements were made, and as a result, the recorded flight time would be shorter than the actual time. That alone could explain the seemingly faster-than-light results.
Another potential problem has to do with the oscillator that was used to generate the time stamps for GPS synchronization. This problem could have made the flight time look longer than it really was.
The sources I contacted via email declined to be identified because they weren't authorized to speak in advance of Thursday's scheduled statement. One of the scientists said the glitches should not be characterized as "errors," but instead as "nasty instrumental effects."
CERN spokesman James Gillies confirmed that the GPS connector problem was being investigated, but he emphasized that the effects still had to be confirmed. "More beam will be needed before we know for sure," he told me in an email. Tests with short pulsed beams have been scheduled for May.
More about those pesky neutrinos:
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Source: http://cosmiclog.msnbc.msn.com/_news/2012/02/22/10479879-glitch-found-in-faster-than-light-setup
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