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back to article CERN boffins re-running neutrino speed test

In the wake of September’s surprising experimental results that suggested the observation of faster-than-light neutrinos, CERN has announced that it has been re-running the experiment over recent days. Since the pre-publication release of its original dataset, CERN’s data has been raked over by physicists, scientists, computer …

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  1. Dan 10

    Take note...

    .. all those involved in hysteria-backed (as opposed to purely evidence-based) debates such as the dreaded global warming:

    THIS IS HOW YOU 'DO' SCIENCE. IT IS NOT HERETIC TO CHALLENGE SOMEONE'S FINDINGS.

    Or maybe it's just the lack of government tax £££/$$$ etc that leave the neutrino debate to people that know what they are talking about, rather than politicians.

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    1. Sorry that handle is already taken. Silver badge
      Reply Icon
      Facepalm

      No, it's not heretical to challenge someone's findings

      But it is considered poor form if you fail to propose an alternative explanation for the evidence and simply accuse the "other side" of political bias.

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  2. John Smith 19 Gold badge
    Thumb Up

    Whatever happens will be interesting.

    Either CERN learns more about the sort of subtle errors that can mess up this sort of experiment (no difference) or it learns something new about the physics.

    Good result either way.

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    1. Andy Fletcher
      Reply Icon

      Or perhaps....

      ...quantum tunneling wasn't taken into account, so we just get confirmation of something we knew already (in the 1920's). If it's not a measurement error, that's where my money goes given that neutrino's travelling through the vaccuum go slower than light, but neutrinos going through rock (perhaps) go a tiny bit faster.

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  4. Loyal Commenter Silver badge
    Boffin

    Question:

    How can the scientists involved be certain that the neutrinos they measured were the ones sent from CERN?

    Given that huge numbers of these things come streaming through space from all directions and zip happily through the Earth all the time, could the measurement not been of neutrinos from another source, such as solar neutrinos?

    Is it a case of the neutrinos being generated at CERN being somehow focussed into a tight beam, and multiple detections being made at Gran Sasso at the same time? I find this unlikely, especially the focussing of neutrinos, which AFAIK are only susceptible to the weak nuclear force.

    Of course, I stand to be corrected...

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    1. Ian Michael Gumby
      Reply Icon
      Devil

      Answer...

      You're right.

      The Neutrinos could be from outside the chamber. But then again, they could probably discount them through statistical analysis or tracking of the path and direction.

      I think that they may have gotten it right by changing some of the parameters of the experiment.

      Personally I would love for the changes not to work and explain the neutrinos. Sorry, I'm a sci-fi geek at heart and the unanswered question makes for some good sci-fi type speculation.

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    2. Anonymous Coward
      Reply Icon
      Anonymous Coward

      correctional measures applied

      the neutrinos are generated from a tight beam of 2GeV protons, whose momentum constrains the neutrino beam, the neutrinos having very little transverse velocity. Its more complicated, of course, there are intermediate pions and a magnetic funnelling, if the link below describes what is actually done. (paywalled, abstract only) http://www.sciencedirect.com/science/article/pii/S0168900203007113

      So, the focus is achieved by tuning the protons to have just enough energy to generate the neutrinos "at rest" in the moving frame of the protons (- i.e. near "c") - this eliminates transverse velocity and therefore produces a non-diverging beam.

      Therefore there is a reasonable signal-to-noise in the detector - still only a few detections per bunch of 10^14 neutrinos, but enough for a picture to emerge. - that we can all argue about. The statistical analysis is hard, and may contain errors, hence the move to a "gapped" pulse, with a big feature in the middle, a more distinctive profile.

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    3. defiler
      Reply Icon

      That seems to be the point

      By modulating the neutrinos on a distinct pattern, they should be able to show that it's the same stream. And also they'll be able to see if the modulation smears or any such. That's the way I see it anyway. Tea anyone?

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  5. Clive Galway

    My guess

    Just a layman's stab, and I am not that well informed on the news item, but aren't the neutrinos meant to be passing through the centre of the earth?

    As mass warps space-time, then thinking of the rubber sheet with a ball on it analogy, aren't the neutrinos maybe taking the straight short route (following the line where the undeformed rubber sheet would be if the ball wasnt there) rather than the long bendy route down the dip in the sheet, through the ball and up the other side.

    Is there anything else that we can detect going in one side of the earth and coming out the other? If not, how can we attribute this FTL phenomenon to neutrinos? Maybe anything that has the ability to ignore matter is not following the same rules as everything else and so will appear to be travelling FTL.

    Just wild speculation from someone with no more qualifaction to be asking the question apart from hair rather like Albert Einsteins - But hey, if you have the mad scientist look about you, that qualifies you in my book ;)

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  6. Neil Barnes Silver badge
    Boffin

    Why are they bothering doing it all again?

    Surely - cause occurring before effect - they already know the result?

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  7. FredScummer
    Paris Hilton

    Blimey!

    Reading all the responses relating to these naughty neutrinos which won't be guided by a fibre optic cable and I realise that I've obviously entered the wrong club. I didn't see a sign indicating that only Albert Einstein's could enter. Very sorry, will exit and see if I can find the room I want.

    Paris because I hope she'll be in the room I'm looking for, as I want to practice being a neutrino.

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  8. JeffyPooh
    Pint

    Suggestion:

    Use these neutrinos to provide short-cut-through-the-Earth communications between European, Asian and USA stock markets for real-time traders and their evil programmed trading clusters.

    We will only know that this has been done when it's too late - after some anonymous brokerage house wakes up one morning to find they've captured *all* the money in the world.

    Don't laugh - they're digging trenches across New England to save a few milliseconds...

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  9. Anonymous Coward
    Anonymous Coward

    this might...

    "as far as I can tell"? - without even looking you mean.

    here's how they do it:

    A conceptual design is presented for a high-power pion production target and collection system, which is suggested to be used as source for the proposed CERN muon-neutrino factory. A relatively low-energy proton beam of 2.2 GeV which is pulsed at 50 Hz with ∼1014 ppp and 4 MW average power has been chosen as driver. The deleterious effects of the up to 1 kW/g power densities deposited in the target and its surroundings by the proton beam are a major technical challenge since it seriously limits the lifetime of all solid components. A target, which consists of a free surface mercury-jet with a high axial velocity, allows efficiently to carry the heat away from the production region without need for beam windows. The secondary pions are collected and injected into the pion decay channel by means of a magnetic horn. This horn which has to surround the Hg-jet target is known to be very radiation resistant as well as light and easy to exchange. The suggested mechanical layout and technical parameters of the target, horn and cooling system are discussed.

    So, they know when the target protons are released and that the rest of the reaction is pretty much as fast as light. Hence they can infer the time density of the neutrino pulse.

    As for the last remark, "Fire them at a different detector .. same result" - how the fuck would you know?

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  10. Alex C
    Thumb Up

    What I like about this is that Cern's response was (paraphrased) "ooh - interesting. That shouldn't happen - it's probably an error somewhere, though we were pretty careful. Lets run it again in a simpler way and see if it happens again. "

    They tend not to start shouting about how they've made something travel faster than light, but can't prevent the journalists from inferring it.

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  11. ChaosFreak
    Black Helicopters

    How can this be replicated?

    If I recall correctly, the hallmark of the scientific method is to verify an experiment by having an independent experimenter replicate the results using the same experimental setup.

    How is that possible with the LHC since there is only one in existence?

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  12. Mountearl
    Gimp

    I can't believe you have all missed the obvious....

    It's because the so-called experts at CERN used a Denon AKDL-1 to connect their detector to the timing circuit. As it can transmit the whole of the internet in 8 picoseconds, running faster than light with a few megabits of data is no sweat.

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  13. Paolo Marini
    Happy

    light neutrinos?

    are neutrinos affected by light and if so could the detector equipment actually be taking a "snapshot" of their reflection instead of the real ones?

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