GPS and Neutrinos

http://www.septentrio.com/sites/default/files/NR_OPERA_final.pdf

=93GPS technology would not be possible without the application of
Einstein=92s theories in various ways. It is remarkable to experience
that this same technology has now been used to test and challenge
these fundamental physical principles.=94

The OPERA paper:

http://arxiv.org/ftp/arxiv/papers/1109/1109.4897.pdf

The paper mentions 3 GPS timing receivers -- Septentrio PolaRx2e,
Symmetricom Xli, and ESAT GPS2000.

http://www.septentrio.com/products/receivers/polarx2eat

http://www.symmetricom.com/products/gps-solutions/gps-time-frequency-receiv=
ers/XLi/

http://www.esat.it/EN/orologio_gps2000.htm

Ref [16] in the OPERA paper, on use of the PolaRx2e for time transfer:

http://tycho.usno.navy.mil/ptti/ptti2003/paper7.pdf

A few user group discussions of OPERA:

http://six.pairlist.net/pipermail/leapsecs/2011-September/003271.html

with a nice list of applications of precise time:

http://www.febo.com/pipermail/time-nuts/2011-September/059317.html

OPERA web site:

http://operaweb.lngs.infn.it/

http://arxiv.org/abs/1109.6562

Nobel laureate Sheldon Glashow and Andrew Cohen make the rather simple
and eyebrow-raisingly obvious observation that superluminal neutrinos
would radiate like crazy (via bremsstrahlung to electron-positron
pairs). This is essentially the same effect as Cerenkov radiation when
particles exceed c/n in a material of index of refraction n.

The threshold neutrino energy for bremsstrahlung would be about 140 MeV,
if the value of the fractional speed excess is about 5 x 10^-5 as OPERA
and MINOS claim, and most (about 3/4) of the neutrino energy would be
lost in each emission. The result would be an asymptotic value of
neutrino energy of about 12.5 GeV, in contrast with the 17.5 GeV claimed
detected by OPERA.

This result is completely independent of the questions of how the
surveying was done, how the timing was done, or whether
Lorentz-violating neutrinos are jumping branes to do so. Basically it
means that neutrinos can't behave this way, even if you believe that c
is not a hard speed limit.

Furthermore, they point out that you can use the same argument looking
at cosmic ray showers in the Ice Cube detector, where the energies are a
factor of thousand higher, and deduce a fractional speed excess of about
4 x 10^-10, which is even more stringent than the low energy (~10 MeV)
neutrino limit from SN1987A.

Bottom line: It now appears pretty clear that the OPERA experiment
messed up *somewhere*, even if it's not obvious where.

As far as I understood they run GPS base stations,
at both ends of the tunnel.
This should give their location at cm accuracy,
and the time to a tenth of a nanosecond.

This leaves only the transport of time and location
through 5 km of tunnel and some turns.
It seems hard to make a 20 m or 60ns error in that,

Jan

J. J. Lodder wrote:

According to a New Scientist article I have just read, the sensor position
is known to 20cm. There are similar uncertainties about where and when the
neutrinos are generated because it is an indirect process. But these errors
cannot account for the measurement discrepancy.

Mike.
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nospam@de-ster.demon.nl (J. J. Lodder) writes:

I'm not sure it is *that* hard to make a 60ns error in 5km of cable.
The speed of light in a cable is far from c. I recall reading that a
certain popular ethernet transport was approximately c/2. (rg-58/u
maybe???)

-wolfgang
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