I have a more basic time-nut question. Why is it a problem at all?
How can the time uncertainty between two known and fixed locations be that
large?
If they know they have a 70ns uncertainty in time, that would suggest that
their time measurement is known to be varying at one or both places.
Is this just from a spec or do they see a true variation in time between
something, and if so compared to what?
Is this time difference or variation between several difference timing
devices at each end or is it variation when compared to time of flight of
the supposedly same neutrinos?
I can not say anything about the accuracy of my absolute time, but the
difference and uncertainly comparing the phase difference between different
external Osc Tbolts at the same location is way way under 70ns.
Sure lots of BASIC things to do to make sure the two Tbolts are set the same
so that their oscillator's phase do they agree, such as using the same type
antenna and same cable and length, and getting the antenna's location
correct, etc, etc,
but basic stuff and seems like if using the same basic GPS system at two
different locations, what would the additional problems be except to make
sure both ends are syncing on the same 100ns 10MHz cycle.
I was under the impression that getting down to ns uncertainly differences
(and staying there) at theses distances is old stuff using common view GPS.
So what are the problems that cause their large timing uncertainty?
ws
*****************
Good morning,
Recently physicists using a neutrino beam from Geneva Switzerland to the
Gran Sasso
in Italy have reported a measurement of neutrino velocity that is faster
than the speed of
light. The effect over a 730 km path length is reported as 60 ns, which
means that precise
timing is required at both ends of the beam to have sensitivity to this
effect. The reported
result, if true, has major implications for the fundamental understanding of
physics.
Thus, it is important to carry out independent checks of this measurement.
A similar beam exists between Fermi National Accelerator Lab in Batavia IL
and the University
of Minnesota's Underground Laboratory at Soudan in northeastern Minnesota.
This U.S. beam has
been used to make a similar measurement, but the GPS timing equipment that
was used
(Truetime XL-AK, Model 600-101-015) resulted in an estimated uncertainty of
about 70 ns
in the neutrino time-of-flight, too large to test the recently reported
effect. I am one of a
group of physicists working with the neutrino beam in the U.S.
Although we are also talking with professionals at USNO and NIST, I am
interested in possible
suggestions from the "Time Nut" community with respect to the following:
(a) the possibility of retrospectively improving the existing timing data
recorded since 2005 using
the Truetime XL-AK, and
(b) a quick, low-cost improvement in the timing instrumentation that can be
made right away,
pending arrangements for techniques such as Two-Way Satellite
synchronization.
In addition, if there are any "Time Nuts" in the Minnesota area who would
like to get more involved in this project,
please feel free to contact me at marshak at umn.edu
Thank you very much.
Marvin Marshak
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