Knocking Einstein: Septentrio in CERN Experiment on Faster-than-Light Neutrinos
September 28, 2011Septentrio's precise-timing GPS receiver PolaRx2eTR features prominently in the OPERA experiment being held at CERN, the European laboratory for particle physics in Geneva, Switzerland. The results of this experiment would seem to indicate that neutrinos can travel at a velocity 20 parts per million greater than the speed of light, Septentrio reported.
The experiment used the GNSS receiver to provide precise timing information, since each GNSS satellite is essentially a time beacon containing an ultra precise atomic clock.
Standard GNSS receivers can determine time with an accuracy of some 100 nsec to a few μsec. However, Septentrio’s precise PolaRx2eTR timing receivers run special algorithms that reduce errors even further. Moreover, specialized circuitry in Septentrio receivers allows measurement of the time offset between a local atomic clock and each of the individual GNSS satellite atomic clocks, Septentrio said.
This, together with thorough time calibration procedures, allows the use of common-view time transfer — a standard technique used to synchronize atomic clocks around the world and also used to synchronize the time bases at CERN and Gran Sasso (LNGS) in the OPERA experiment. PolaRx2eTR receivers at both CERN and LNGS compare their local clocks to the clocks of the GNSS satellites commonly visible from both sites simultaneously. This allows researchers to synchronize the time at both laboratories to an accuracy of a couple of nanoseconds, the level needed to measure precisely the neutrino transit times.
“GPS technology would not be possible without the application of Einstein’s theories in various ways," said Peter Grognard, managing director of Septentrio. "It is remarkable to experience that this same technology has now been used to test and challenge these fundamental physical principles.”
A detailed description of the experiment, together with how Septentrio’s receivers were used to measure time, can be found in this PDF. More information and discussion of results can be found on www.cern.org.
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