[time-nuts] Fast than light neutrino
brooke at pacific.net
Mon Sep 26 17:47:14 UTC 2011
I started to read:
(323.2 kB) Pablo Alvarez, 26/09/2011 18:46
but without a glossary to decode all the abbreviations or acronyms it's
very difficult to really understand what's going on.
Is there an introductory document that describes the experiment and
defines the terms used?
pablo alvarez wrote:
> Hi guys,
> Here you have the reports on the CERN's timing chain.
> Questions are welcome!
> On Mon, Sep 26, 2011 at 2:46 PM, Joe Gwinn<joegwinn at comcast.net> wrote:
>> At 6:56 AM +0000 9/26/11, time-nuts-request at febo.com wrote: (really Javier
>>> Date: Mon, 26 Sep 2011 08:56:12 +0200
>>> From: Javier Serrano<javier.serrano.pareja at gmail.**com<javier.serrano.pareja at gmail.com>
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at febo.com>
>>> Subject: Re: [time-nuts] Fast than light neutrino
>>> YY74-G-bkHGEA at mail.gmail.com<60w9_YY74-G-bkHGEA at mail.gmail.com>>
>>> Content-Type: text/plain; charset=ISO-8859-1
>>>> I did not express myself correctly. We know how to do accurate two-way
>>> over a few km of fiber. See e.g.
>>> http://dl.dropbox.com/u/**13409775/wrapper.pdf<http://dl.dropbox.com/u/13409775/wrapper.pdf>(our contribution to the CLIC
>>> Conceptual Design Report).
>> Thanks for the reports.
>> What is new for us is going through more than
>>> 1000 km of fiber (only neutrinos have the luxury of going in a straight
>>> through the crust of the Earth, 732 km). I wonder who one calls for fibers
>>> and also more technical things like optical amplifier technology with
>>> typical ranges, etc. What I gather from the discussion so far is that 100
>>> is within reach of available optical transceivers. I wonder how far one
>>> go with EDFAs.
>> EDFAs can easily achieve 10 dB or running closer to the edge 20 dB of gain,
>> all with no electronics delay, but EDFAs are quite noisy, so there is a
>> tradeoff to be made.
>> EDFAs are inherently bidirectional, although they usually contain an
>> optical circulator to make them unilateral. But it would not be hard to
>> make EDFAs that amplified in one direction for one wavelength, and in the
>> opposite direction at a different (but nearby) wavelength.
>> And one can also have a command wavelength, to allow for commanding of
>> direction reversals and the like, so the fiber companies involvement is
>> limited to hosting and installation of equipment.
>> One thing we could do is establish a fiber link between METAS
>>> in Bern and CERN, and then look for a good metrology place in Rome (the
>>> national one in Italy is in Torino I believe) and have a link between them
>>> and Gran Sasso. Then we could use their UTC data sets to establish a paper
>>> link between CERN and Gran Sasso which would be independent of the current
>> Why do all that, versus just running an amplified fiber between CERN and
>> Gran Sasso? Two links are likely to be twice the trouble and error.
>> Joe Gwinn
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/**
>> and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts