4 ms·

Similar results seem to have already been obtained in the past http://en.wikipedia.org/wiki/Neutrino#Speed http://en.wikipedia.org/wiki/Neutrino#Speed QUOTE

Similar results seem to have already been obtained in the past http://en.wikipedia.org/wiki/Neutrino#Speed http://en.wikipedia.org/wiki/Neutrino#Speed QUOTE In the early 1980s, first measurements of neutrino speed were done using pulsed pion beams (produced by pulsed proton beams hitting a target). The pions decayed producing neutrinos, and the neutrino interactions observed within a time window in a detector at a distance were consistent with the speed of light. This measurement has been repeated using the MINOS detectors, which found the speed of 3 GeV neutrinos to be 1.000051(29) c. While the central value is higher than the speed of light, the uncertainty is great enough that it is very likely that the true velocity is not greater than the speed of light. This measurement set an upper bound on the mass of the muon neutrino of 50 MeV at 99% confidence. /QUOTE The value looks awfully like what we have in front of us today, but the uncertainty was too big to investigate further EDIT : actual paper :http://arxiv.org/abs/0706.0437 http://arxiv.org/abs/0706.0437

joeyespo 15y ago
On a side note, it's pretty wild seeing history being written in Wikipedia. The BBC site has just been referenced on that part of the Neutrino article.
Panoramix 15y ago
Experimental error seems likely to me once again. 10ns at c is 3 meters, over 730km + uncertainty in time of particle generation and decay + detector uncertainty...I don't buy it. From the project site: http://operaweb.lngs.infn.it/spip.php?rubrique41 http://operaweb.lngs.infn.it/spip.php?rubrique41 OPERA needs an intense and energetic beam of muon neutrinos traveling a distance of hundreds of kilometers to seek for the appearance of oscillated tau neutrinos. A beam of this type is generated from collisions of accelerated protons with a graphite target after focussing the particles produced (pions and kaons in particular) in the desired direction. The products of their decays, muons and neutrinos, continue to travel in generally the same direction as the parent particle. Muon neutrinos produced in this way at CERN cross the earth crust reaching OPERA after a 732 km journey.
- nickolai 15y ago
  >I don't buy it I didn't mean to try to 'sell' anything, though I agree that my comment was needlessly biased here. Revised it accordingly.
cpeterso 15y ago
> ... found the speed of 3 GeV neutrinos to be 1.000051(29) c. What does the "(29)" in "1.000051(29) c" mean?
- jarek 15y ago
  Repeating. It's 1.000051292929292929... edit: sorry if that's incorrect in this case. "1.000051(29)" is one of the formats of indicating repeating decimals, per http://en.wikipedia.org/wiki/Repeating_decimal#Notation http://en.wikipedia.org/wiki/Repeating_decimal#Notation
- BoppreH 15y ago
  I'm not sure, but I think it represents uncertainty over the last digits. So 1.000051(29) would be equivalent to 1.000051 +- 0.000029.
  - kaybe 15y ago
    Yes, that is what it means. :)
    - jlarocco 15y ago
      That can't be it because the error wouldn't straddle the speed of light. It would put the range at 1.000022c to 1.000080c, both of which exceed c, so they wouldn't have written it off as error.
      - Ralith 15y ago
        But that doesn't indicate a hard error bound; this is a statistical matter, after all. Most likely it's just an expected standard deviation.
        Bootvis 15y ago
        It indeed is the standard deviation.
      - 15y ago
smallblacksun 15y ago
This article (http://www.google.com/hostednews/ap/article/ALeqM5in1T5nvGNckqh0WyG9Y3B_YI4VQg?docId=94691396d0b44f3aa8105740b51e9e9f http://www.google.com/hostednews/ap/article/ALeqM5in1T5nvGNc...) mentions previous results and that they were thought to be due to measurement error, but claims that these readings had a speed of c + 60 nS, with a measurement margin of error of +-10 nS.

joeyespo 15y ago

On a side note, it's pretty wild seeing history being written in Wikipedia. The BBC site has just been referenced on that part of the Neutrino article.

Panoramix 15y ago

Experimental error seems likely to me once again. 10ns at c is 3 meters, over 730km + uncertainty in time of particle generation and decay + detector uncertainty...I don't buy it. From the project site: http://operaweb.lngs.infn.it/spip.php?rubrique41 http://operaweb.lngs.infn.it/spip.php?rubrique41 OPERA needs an intense and energetic beam of muon neutrinos traveling a distance of hundreds of kilometers to seek for the appearance of oscillated tau neutrinos. A beam of this type is generated from collisions of accelerated protons with a graphite target after focussing the particles produced (pions and kaons in particular) in the desired direction. The products of their decays, muons and neutrinos, continue to travel in generally the same direction as the parent particle. Muon neutrinos produced in this way at CERN cross the earth crust reaching OPERA after a 732 km journey.

nickolai 15y ago
>I don't buy it I didn't mean to try to 'sell' anything, though I agree that my comment was needlessly biased here. Revised it accordingly.

cpeterso 15y ago

> ... found the speed of 3 GeV neutrinos to be 1.000051(29) c. What does the "(29)" in "1.000051(29) c" mean?

jarek 15y ago
Repeating. It's 1.000051292929292929... edit: sorry if that's incorrect in this case. "1.000051(29)" is one of the formats of indicating repeating decimals, per http://en.wikipedia.org/wiki/Repeating_decimal#Notation http://en.wikipedia.org/wiki/Repeating_decimal#Notation
BoppreH 15y ago
I'm not sure, but I think it represents uncertainty over the last digits. So 1.000051(29) would be equivalent to 1.000051 +- 0.000029.
- kaybe 15y ago
  Yes, that is what it means. :)
  - jlarocco 15y ago
    That can't be it because the error wouldn't straddle the speed of light. It would put the range at 1.000022c to 1.000080c, both of which exceed c, so they wouldn't have written it off as error.
    - Ralith 15y ago
      But that doesn't indicate a hard error bound; this is a statistical matter, after all. Most likely it's just an expected standard deviation.
      - Bootvis 15y ago
        It indeed is the standard deviation.
    - 15y ago

smallblacksun 15y ago

This article (http://www.google.com/hostednews/ap/article/ALeqM5in1T5nvGNckqh0WyG9Y3B_YI4VQg?docId=94691396d0b44f3aa8105740b51e9e9f http://www.google.com/hostednews/ap/article/ALeqM5in1T5nvGNc...) mentions previous results and that they were thought to be due to measurement error, but claims that these readings had a speed of c + 60 nS, with a measurement margin of error of +-10 nS.