On 12/24/2011 1:11 PM, unruh wrote: > On 2011-12-24, John Hasler <[email protected]> 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.
You need a very good atomic clock at both ends that are synchronized to each other. Chances are very good that they have a number of them at each end. Nothing less than an atomic clock will do. Now what has this to do with the original question? Danny _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
