Last fall was a busy time for CERN. Two really important results were announced - indication of the presence of Higgs boson and the detection of Faster Than Light Neutrinos. Though the news about Higgs boson was exciting, it was the latter that took the world by storm. FTL neutrinos polarized the Physics community with the detractors of the results outnumbering the supporters. This made it all the more important for the experimenters at CERN to make sure that there were no experimental errors.
Rumors began surfacing last Tuesday (22nd February) that the experimenters had identified the source of the discrepant result to be a bad connection between the timing apparatus and the experiment. Though many physicists were confident that neutrinos could not travel faster than light, the nature of the error came as a surprise. If the experimenters had really missed the bad connection, then they must have somehow ignored optical fibers as long as 20 meters. That doesn't sound like a minor experimental error. Hence not all the physicists were ready to believe the rumor.
Later in the day, CERN released an official statement, which read
"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."
This statement confirmed that there was a connection problem and at the same time talked about another problem linked to the oscillator. The key sentence here is - "These two issues can modify the neutrino time of flight in opposite directions". This means that even if the bad connection problem didn't have any effect on the previous result, correcting the oscillator problem could actually strengthen the claim that neutrinos do travel faster than the speed of light. This was quite unexpected.
Like mentioned in the statement, the experimenters will rectify the problems and then perform more experiments this summer before coming to any conclusion. Thus the debate about FTL neutrinos will be open at least till the end of this year.
For more information on this news, here are articles from sciencemag and Nature news blog.
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