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I Dark Matter Detection Experiment Results?

  1. Mar 20, 2016 #1
    In 2011 Dr. Gerald Guralnik of Brown University was involved in an ongoing Dark Matter Detection experiment, perhaps LUX? It was an international collaboration involving underground detectors. He was certain DM would be detected in 5 years - i.e., now. I was dubious, so we bet "bragging rights" on it.

    Tragically, Jerry passed away in 2014. He was a great physicist and a great guy as well.

    Now, I'm wondering what the status of that experiment is. Obviously nothing dramatic or I would have seen it in the news; and don't see up-to-date info on the net (if it was LUX). Can anyone tell me how it's doing, whether work is ongoing, and whether I would have won my bet?
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  3. Mar 20, 2016 #2


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  4. Mar 20, 2016 #3
    thanks Orodruin, that's exactly what I needed. I'd noticed this before on the net: "We present constraints on WIMP-nucleus scattering from the 2013 ... LUX"); 2013 is a long time ago. But the crucial information I was missing is: "last revised 26 Jan 2016". It's pretty clear what's happened between 2013 and 2016 ...
  5. Mar 20, 2016 #4


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    As far as I know, only the DAMA/LIBRA and DAMA/NaI experiments have made claims of a direct detection, by way of an annual modulation in signal around 40 keV. These results are in tension with the other direct detection experiments. There is a new experiment called SABRE that will have active background suppression (http://www.pa.ucla.edu/sites/default/files/webform/jingke_xu.pdf [Broken]) that will test the DAMA/LIBRA claims. Happily, there will be a southern hemisphere component that should deal with seasonal background contributions.
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  6. Mar 20, 2016 #5


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    For a summary of the status of dark matter searches see; http://arxiv.org/abs/1509.00869, Dark matter searches.
  7. Mar 21, 2016 #6


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    Chapter 2 of Emily Shields thesis is very informative and pedagogical, it doesn't need a high level of prior knowledge. She has worked with Jing ke Xu and they use some of the same graphs. You may have seen it.

    She seems to be part of the group working on SABRE.
    Last edited by a moderator: May 7, 2017
  8. Mar 21, 2016 #7
    Thanks for responses, e.bar.goun, Chronos, marcus

    Just to clarify, I mainly wanted to know if I'd won my bet re. LUX. I made one other bet with Dr. Guralnik, that the Higgs boson wouldn't be found by LHC! Of course I lost. As you probably know he was one of the people, as well as Peter Higgs, who helped work out the Higgs symmetry-breaking mechanism back in 1964, and deserved the Nobel as much as anyone. So it's great that he lived long enough to see the July 4, 2012 announcement.

    marcus, Emily Shields thesis is great for getting up to speed on DM detection, very readable and covers all the bases. Having looked at it all of a sudden I'm much more interested in the whole question.

    I'm afraid the DAMA work is not too convincing yet, but let's hope SABRE backs it up. DAMA is obviously very difficult and subject to uncertainties, and of course I know little about it (just this thesis). But one thing I can say, Dr. Guralnik worked on LUX, and it seems to conflict with DAMA. Just as a general rule, if his work disagrees with anyone at all - I'll put my money on him. (If he told me God made a mistake, I'd believe him.)

    Can't help making a comment ... The thesis contains 10 pages (!) of acknowledgements, including this: "I thank you. Words cannot express how much you mean to me, but fortunately I think you already know. I love you, and I can’t wait to meet our next adventure together." - to Jason. I shudder to think what would have happened, back in the day, if I'd included 10 pages of such acknowledgements. The world has changed.

    The following is not Ms. Shield's statistic, but some other worker's; she's just summarizing results:

    "The Planck results are the most statistically significant evidentiary results for non-baryonic dark matter to-date, constituting a 42σ result for the existence of cold dark matter."

    42 sigma is meaningless statistically, and surely is due to the 6-parameter model used for fitting a pretty simple power curve - you can fit almost anything with 6 fudge factors. Anything over 6-8 sigma or thereabouts shouldn't even be mentioned. It's like having a result with 4 significant digits, say 1.000, dividing it by 3, and reporting your answer as .333333...recurring for 42 digits.

    As I said, excellent, comprehensive survey, thanks for pointing it out; I'm just addicted to picking nits.
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