[ntp:questions] Accuracy of NTP - Advice Needed

unruh unruh at invalid.ca
Sat Dec 24 18:11:19 UTC 2011

On 2011-12-24, John Hasler <jhasler at newsguy.com> wrote:
> I wrote:
>> An upcoming experiment at Fermilab will observe neutrinos at both ends
>> (the far end will be in Minnesota).
> unruh writes:
>> Well, no. At best the electrons or muons at one end.
> At best the electrical pulse produced by a photomultiplier when struck
> by a photon generated when a muon or electron emitted as a result of a
> neutrino collision interacts with the detector medium (there are a
> variety of detector designs but photomultipliers are almost always
> involved).
> However, the use of similar or identical neutrino detectors at both ends
> means that systemic errors in delay estimation will tend to cancel.  I
> assume that they will try to match up the timing equipment at both ends
> as well.

Just saying, it is not the same neutrino that is being detected at both
ends. The detection probability is just too small. Thus again there is
the same inference that the timing at one end measures the same class of
things as teh timing at the other. 

Yes, the timing equipment is a worry. They require ns accuracy in the
timing and m accuracy in the distance. And the timing is not simply gps
( although they could have gotten that wrong) but then that timing has
to be brought down into the mine a km or so below ground and
horizontally and that also has to be surveyed for the distance.



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