[time-nuts] Neutrinos not so fast? (defectove connector)
azelio.boriani at screen.it
Thu Feb 23 01:14:48 UTC 2012
On Thu, Feb 23, 2012 at 2:10 AM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:
> On 02/22/2012 11:26 PM, Poul-Henning Kamp wrote:
>> In message<9A458DBA-3875-43B2-8383-5CA2F86BE8E2 at leapsecond.com>, "Tom
>> Van Baak
>> (lab)" writes:
>> Could be on the electrical side of the adapter, not the optical
>>> side. It's not impossible to get 60 ns of phase or trigger error
>>> with RF connectors.
>> I don't buy that explanation.
>> It's very hard to get 60 ns *consistent* phase or trigger error,
>> with any kind of connector, almost no matter how you go about it.
> OTDR works just as normal TDR. If the fibre is not connected you get a
> reflection and not enough transmission. This is what you use OTDRs for.
> I agree it needs more details to be believable.
> 20m of extra fiber sounds *much* more plausible.
> 60 ns is more like 12 m of fibre. SMF-28 has a refraction index of about
> 1.45 depending on the wavelength of the laser. I use the rule of thumb that
> 1 ns is 3 dm in free air and 2 dm in coax and fibre, it's usually good
> enough for reality check calculations. Oh, and it's about 40 feet.
> Anyway, I would like to see much more detailed description to see that it
> indeed was due to this error. Also I'd love to see it repeated such that
> one can see the time error go "on" and "off".
> Inventing an excuse about a loose connector to cover up the mistake
>> sounds even more plausible.
>> You really don't want to defend your phd dissertation, being known
>> as the idiot who made a fool of both CERN and SanGrasso in one go.
> This is science, making a spectacular error and then explain it in
> painstakingly detail can teach a lot more than a otherwise uneventful day
> at the lab, doing about the same measurement.
> Learning something means better prepared to avoid it next time. Experience
> is being built.
> Still don't know what really happened here, rumours at the best.
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