[time-nuts] Neutrino Velocity

Marvin Marshak marshak at umn.edu
Fri Jun 8 10:38:23 UTC 2012


Javier,

What you describe in your email is basically correct. You can see the slides from the three talks
via the website:

http://neu2012.kek.jp/

Choose the Indico link at the very bottom of the page. Then, you need to login with a username and password, but they
are both given to you in the same box that asks for them.

Please let me know if you have problems accessing the slides.

I have learned a lot about timing since the OPERA result was first announced. However, it is quite clear than special
relativity is intact, although I expect that several experiments will now continue to push the systematic errors down to the
~1 ns level.

Best regards,

Marvin

On Jun 8, 2012, at 2:49 AM, Javier Serrano wrote:

> On Fri, Jun 8, 2012 at 1:51 AM, Marvin Marshak <marshak at umn.edu> wrote:
>> Good morning from Japan,
>> 
>> The Neutrino 2012 Conference is being held in Kyoto, Japan, this week. This morning's session is scheduled for 3 talks on neutrino velocity--one from the OPERA Experiment that initially reported the anomalous effect, one discussing other experiments at the Italian Gran Sasso Lab and a third talk from the MINOS Experiment (Fermilab to Soudan MN). The session will begin at 0915 Japan time.
>> 
> 
> Hi Marvin,
> 
> Someone told me the LNGS experiments reported just preliminary results
> (some more fine-tuning of calibrations needed) with central values of
> Dt ranging from 2 to 6 ns with statistical errors around 1 ns and
> systematics ranging from 3 to 6 ns (positive Dt means nu slower than
> light). Apparently MINOS  presented only a reanalysis of the data
> accumulated from 2005 with Dt around -11 ns and a systematic error of
> the order of 15 ns. The analysis of more recent data collected after
> installation of the new timing system will probably be available
> after the Summer. Is this correct?
> 
> BTW, we installed White Rabbit links redundantly to the existing LNGS
> and CERN timing systems for the two weeks of special beam
> (100ns-spaced 2ns-wide bunches). It was quite a rush so it is not
> fully documented. All the data we gathered can be seen at
> https://project-lngstt.web.cern.ch/project-lngstt/ (although it is
> quite useless without explanations of what the data actually mean).
> The important bit is that WR agreed with the legacy systems at least
> at CERN, OPERA and Icarus. Borexino and LVD have not checked yet
> against WR, but should do so in the near future.
> 
> So in terms of redundancy we have:
> - Four different experiments in LNGS basically agreeing on the value
> of the neutrino speed, compatible with c.
> - Two different timing technologies (for internal lab distribution)
> agreeing at CERN and two different timing technologies agreeing in
> LNGS.
> - Two different GPS time transfer systems using two different software
> analysis tools agreeing with each other.
> 
> The only bit of redundancy I see missing is in certain parts of CERN,
> like the length of the cable from the Beam Current Transformer to the
> digitizer, which is common mode to everybody. The MINOS data, when it
> becomes available should provide more reassurance on those last bits.
> 
> Cheers,
> 
> Javier
> 
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Marvin L. Marshak
College of Science and Engineering Professor
Morse-Alumni Professor
University of Minnesota
116 Church Street SE
Minneapolis MN 55455  612-624-1312     612-624-4578 (fax)







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