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Pion decay and neutrino oscillation in OPERA

  1. Jan 3, 2012 #1
    I hope you don’t mind me asking this OPERA question here but I think it’s more of a QM question. I just watched NOVA Ghost Particle and it got me thinking. The only problem is that my brain isn’t strong enough to hold all that I’m reading about this experiment.

    From what I gather, the CERN end of the experiment generates pions which decay into muons and electron neutrinos. According to that NOVA episode, electron neutrinos eventually oscillate into other neutrino flavors. If they’re travelling at the speed of light, they wouldn’t have time to oscillate. This discovery required a change to the standard model so that neutrinos have mass and do not travel at the speed of light. I don’t know if the Gran Sasso detector can distinguish between neutrino flavors. But working logically backwards, I assume that would help in determining the speed of the neutrinos. Does that make sense?

    Here’s another thing. If the neutrinos travel at or above the speed of light, I assume they must have been going that fast back when they were created from the pions. So either the pions were going that fast or the decay must have given the neutrinos a little speed boost. And that boost must have been in the direction of travel. I would expect a lot of the neutrinos to get boosted in different directions. That would cause a lot of them to miss the target. And in that case, I would expect the detector to pick up far fewer neutrinos than predicted. Does any of this make sense?
  2. jcsd
  3. Jan 3, 2012 #2


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    Just to clear things up, the beam generated by the SPS at CERN consists of muon neutrinos. The OPERA detector is built specifically to observe oscillations to tau neutrinos.
  4. Jan 3, 2012 #3
    Oh cool. So then you know they must be oscillating. I wonder if they know how much.
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