CERN Says Faulty Oscillator, Optical Fiber Connector May Explain Neutrino Timing

The European Organization for Nuclear Research, or CERN, may have found the reason their neutrinos appeared to defy the "cosmic speed limit", as was announced in September 2011.

In an update Thursday, CERN reported finding that an oscillator as well as a optical fiber connector may have malfunctioned, but while "one would increase the size of the measured effect, the other would diminish it", referring to the measurement of the neutrinos' timing.

The results of the CERN Neutrinos to Gran Sasso, or CNGS, experiment indicated that neutrinos fired from CERN appeared to travel to their destination - the detectors at the Gran Sasso National Laboratory, or LNGS, in Italy - faster even than light, whose speed is considered a universal upper limit as per Albert Einstein's theory of general relativity.

In announcing this results the scientists involved had cautiously asked for independent verification of the results, which is now in progress at such labs as Fermi National Accelerator Laboratory, or Fermilab, in the USA.

Of the two components, the defective oscillator could have caused an inaccurate synchronization between the time measured at the CERN facility under the France-Switzerland border and the LNGS. This, according to the scientists, may have led to an "overestimate" of the neutrino timing, which was measured at the LNGS detectors by the Oscillation Project with Emulsion-tRacking Apparatus, or OPERA, team.

The experiment relied heavily on the Global Positioning System, or GPS, to ensure precise recording of the time of neutrinos' arrival in Italy. A fault in the optical fiber connector, which carried the GPS signal to the CERN master clock, could have resulted in an "underestimation" of the time measurement. The exact impact of the two effects is expected to be known only after experiments with short pulsed beams, presently scheduled for May 2012.

The time it took the neutrinos to cover the 732 kilometer-distance to the OPERA detectors was measured to be 60.7 nanoseconds, give or take about 14 nanoseconds, less than the time it would have taken them assuming they traveled at the speed of light. In other words, the neutrinos were traveling faster than light by a margin of 20 parts per million, significant enough to push up the collective eyebrows of the scientific community.

While the discovery of the flaws dilutes the scale of that achievement, a lot still depends on the size of the errors, which is as yet not known. It may also be possible that the two effects nullify each other, thus leaving the original measurement unchanged.

As CERN's Research Director Sergio Bertolucci said when the results were first announced "If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations."

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