Uncharted Territory

October 14, 2011

Analysis of Fibre Delay Calibration Error in CERN-OPERA Neutrino Speed Experiment

Filed under: Neutrinos, Physics, Relativity — Tim Joslin @ 12:57 am

Following on from my previous two informal posts discussing the apparent measurement of superluminal neutrino velocities in transit between CERN and OPERA, I have drafted a paper on the topic (pdf), which I hope to submit to ArXiv, the open physics online journal.

The paper is a little more precise than the previous blog posts, but makes the same general point. I’d appreciate any comments. Here is the Abstract:

“The OPERA neutrino experiment at the Gran Sasso Laboratory obtained a measurement, v, of the neutrino muon velocity with respect to the speed of light, c, of (v-c)/c = (2.48 ± 0.28 (stat.) ± 0.30 (sys.)) ×10-5, that is, in excess of c by about 1 part in 40,000. Over most of the neutrino flight path from CERN to OPERA, distances and timings were established by GPS signals to within 2cm and (2.3 ± 0.9)ns respectively. These measurements are not problematic. The Gran Sasso Laboratory is underground, however, and a significant part of the measurement of the expected flight time at c was established using two separate fibre delay calibration procedures, both of which are based on the two-way speed of light rather than the reference-frame dependent one-way speed implicit in the GPS and the velocity of neutrinos over the (one-way) flight path from CERN to OPERA. This ignores the moving frame of reference (the Earth system (ES)) in which the experiment was conducted and introduces errors of the same order as the early arrival time of the neutrinos (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns. Similar problems affect all attempts to measure the one-way speed of light. This paper explains these problems, with reference to Einstein’s train thought-experiment and suggests how the expected one-way speed of light in a moving frame of reference such as the ES could be derived using the cosmic microwave background (CMB) as a stationary frame of reference. This problem is additional to the clock synchronisation issues described in Carlo Contaldi’s paper, and can be traced to a flaw in a procedure which may have been used at CERN on other occasions, so may affect other experiments involving the accurate measurement of particle velocities approaching or at c.”

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4 Comments »

  1. […] during their flight time is seriously insignificant). More detail on this point is included in the paper I have subsequently drafted on the erroneous superluminal neutrino result.  (Also made one unrelated wording change in the text, to clarify that the Sagnac Effect is just […]

    Pingback by Frames of Reference and Fast Neutrinos: Misinterpreted Findings? « Uncharted Territory — October 15, 2011 @ 9:29 am

  2. […] during their flight time is seriously insignificant). More detail on this point is included in the paper I have subsequently drafted on the erroneous superluminal neutrino result.  (Also made one unrelated wording change in the text, to clarify that 500 trillion year estimate […]

    Pingback by Einstein’s Train Thought-Experiment, Fast Neutrinos (and One-Way Measurements of the Speed of Light) « Uncharted Territory — October 15, 2011 @ 9:53 am

  3. Hi there Tim Joslin,

    Don’t think your theory will turn out to be correct. The bottom line is that in every previous experiment going back 100 years, the energy of a particle (be it photon, fermion, baryon, meson) has adjusted in such a way that the velocity of a highly relativistic particle exactly equals the speed of light. As far as I know, no-one knows the mechanism of how this self-adjustment takes place. But I agree the OPERA result is probably wrong, but probably due human error, not a Special Relativity effect.

    Regards, Richard

    Comment by Richard G Bowerbank — October 18, 2011 @ 7:43 am

  4. […] post supercedes my previous effort, since it includes an updated version of my paper on the CERN-OPERA neutrino velocity measurement […]

    Pingback by Not so fast neutrinos – how CERN have got it wrong « Uncharted Territory — October 18, 2011 @ 2:07 pm


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