[time-nuts] Opera coordinator has resigned

paul swed paulswedb at gmail.com
Fri Mar 30 17:15:10 UTC 2012


I have to say that in general I have been staying clear of this thread.
But its really a surprise that they are that sloppy and basing the results
on a Vectron OCXO. Not that I have ever had a complaint about those.
It just seems like the stunt I would do in the basement on my surplus
accelerator.
Regards
Paul.

On Fri, Mar 30, 2012 at 12:57 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> Hi Javier,
>
> Thanks very much for posting the link to the presentations.
>
> For those of you who just want a summary of the resolution of
> the "neutrino faster than light" problem, here's what happened:
>
> 1) For several years an optical cable connector was loose. I have
> attached photos from pages 7 and 8 of the G._Sirri.pptx where
> you can see the actual connector and waveforms, before/after.
>
> 2) They used a Vectron OCXO to generate timestamps within each
> 0.6 second measurement cycle. This oscillator was found to be high
> in frequency by 0.124 ppm. Thus, depending on where within this
> 0.6 s interval the timestamp was made a timing bias of 0 to 74 ns
> would occur.
>
> Javier -- if you have contacts there, it looks to me like they forgot
> to include OCXO frequency drift effects into their analysis. What
> they did was compensate for linear time drift (which assumes a
> fixed frequency offset). They call the 124.1 ns/s time drift "stable"
> since 2008. What evidence do they have for this? We know that
> OCXO will drift in *frequency* over time; the time drift is quadratic.
> The time drift rate may be 124e-9 today, but it probably wasn't last
> month or last year, etc.
>
> /tvb
>
>  There was a meeting in Gran Sasso on Wednesday. You can see some of
>> the slides at http://agenda.infn.it/**materialDisplay.py?materialId=**
>> slides&confId=4896<http://agenda.infn.it/materialDisplay.py?materialId=slides&confId=4896>
>>
>> I found particularly interesting the ones by Maximiliano Sioli, where
>> he explained the two mistakes found in the OPERA data acquisition
>> chain and how, after correcting for their best estimate of their
>> effects, the time of flight is compatible with a speed of c.
>>
>> I saw the webcast of the event. Some people did give the OPERA
>> spokesman a hard time, and he admitted to not having fully checked
>> everything they could have. Ah well, everyone makes mistakes. There
>> will be another run with neutrinos spaced by 100 ns in May. If all
>> four experiments in LNGS give the same result this time, I suppose the
>> case will be closed. It will also be very interesting to see the MINOS
>> results.
>>
>> In any event, from a time-nut point of view this is quite exciting. It
>> is the first time neutrino speed is measured with this precision. I
>> think this will pave the way for future experiments using precision
>> geodesy and time transfer.
>>
>> Cheers,
>>
>> Javier
>>
>
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