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Science

Dark Matter Particles May Have Been Detected 156

Posted by kdawson
from the who-you-callin'-a-wimp dept.
During two seminars at Stanford and Fermilab on Thursday, researchers described signals for two events detected deep in an old iron mine in Minnesota that might mark the first detection of dark matter — or not. The presenters said the chances that the signals they detected were caused by something other than "neutralino" dark matter particles was 23 percent. "One source indicates that we'd need less than 10 total detections within the CDMS' range in order to have a high degree of confidence in the results." The NY Times describes the Cryogenic Dark Matter Search methodology: "The cryogenic experiment is nearly half a mile underground in an old iron mine in Soudan, Minn., to shield it from cosmic rays. It consists of a stack of germanium and silicon detectors, cooled to one-hundredth of a degree Kelvin. When a particle hits one of the detectors, it produces an electrical charge and deposits a small bit of energy in the form of heat, each of which are independently measured. By comparing the amounts of charge and heat left behind, the collaboration’s physicists can tell so-called wimps from more mundane particles like neutrons, which are expected to flood the underground chamber from radioactivity in the rocks around it." Here are the research team's summary notes of the latest results (PDF).
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Dark Matter Particles May Have Been Detected

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  • by Anonymous Coward on Friday December 18, 2009 @09:54AM (#30486452)
    As a 49 yo feminist grandmother, I reject these results, since they are done by an old boys network of grey haired caucasian scientists.
    • Re: (Score:3, Funny)

      by Anonymous Coward

      As a 49 yo feminist grandmother, I reject these results, since they are done by an old boys network of grey haired caucasian scientists.

      Marie Jo, I told you to dust of my PC, not to surf the web.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      As a 49 yo feminist grandmother, I reject these results, since they are done by an old boys network of grey haired caucasian scientists.

      http://www.fnal.gov/pub/presspass/press_releases/CDMS_Photos/cdms_2_collaboration.JPG

      Yep, sure looks like an entire pack of grey haired Caucasian scientists to me -- if I squint really hard and cover up a few people in the photo.

    • by ceoyoyo (59147)

      Now that's fame: to become a Slashdot meme.

    • by jo42 (227475) on Friday December 18, 2009 @11:14AM (#30487432) Homepage

      White male science has been looking in the wrong place for dark matter. They should try looking between the ears of politicians. Mod away... :p

      • They should try looking between the ears of politicians.

        It's true that alot of politicians are corrupted, and not much gets done.

        But have you worked in a large company yet, where in order to complete a project different seperated departments with different stakes are involved and all have an own opinion and different expertises?

        Enlarging that to "projects in a country" or even on a larger scale, it amases me anything gets done at all, disregarding the intelligence of many trying to push their agenda, stakes

    • Maybe you should have went to college and got a degree in physics then?
  • As I understand it, the chances of it being some other (extra-solar) particle detected is about 1 in 4. They need a 1:1000 to have a valid argument. Although interesting, I can't help but wonder when the next funding cycle starts.
    • Re: (Score:3, Funny)

      by wanerious (712877)
      Their fiendishly clever plan to get more money hopefully flew under the radar of the other standing-room-only particle physicists and cosmologists in attendance at the seminar where the results were announced.
    • Re:1:4? (Score:5, Insightful)

      by marcosdumay (620877) <marcosdumay@@@gmail...com> on Friday December 18, 2009 @10:10AM (#30486638) Homepage Journal
      No, 1:4 is enough for a good argument. They need 1:1000 or lower to end the argument.
    • by bmearns (1691628)

      Which is exactly what they specified in the article. They're not making any argument, they're reporting on their findings, and very specifically say:

      ...we can make no claim to have discovered WIMPs

    • by mrtommyb (1534795)

      They need a 1:1000 to have a valid argument.

      Well, the IPCC report into climate change only reported a 9:1 chance of global warming being due to humans [wikipedia.org]. I think most people would agree that climate change being anthropogenic is a valid arguement, even those who sceptical of the science.

    • The chance that "nothing" (as in, no dark matter around here) would generate a signal as "big" as they saw (2 events) is 23%. If they had so many events that the chance of "nothing" generating that number of events was under 0.1% (they'd need 5 or more events on this analysis), they would be able to say the "null hypothesis", or the absence of dark matter, was proven wrong. With their current equipment, they can't do that, and now I'm sure this will be the same result when they analyse the full data set. It

  • by mseeger (40923) on Friday December 18, 2009 @10:17AM (#30486724)

    All detected particles are due to abnormal solar activity.

    The detected particles will melt the crust within the next three years. Buy tickets for the arch from me now! Just 1.000.000 Euro each... No checks

    CU, Martin

    P.S. Guess which movie i watched yesterday :-)

  • by Anonymous Coward on Friday December 18, 2009 @10:29AM (#30486898)

    The paper pre-print will appear on the arxiv as 0912.3592, but is already available as on the CDMS homepage [berkeley.edu]. Two events or 23% seems a bit low for all the hysteria... Pentaquarks went away after 50 events were discovered at more than 10 different labs...

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      Pentaquarks went away after 50 events were discovered at more than 10 different labs...

      The difference between pentaquarks and this experiment is that CDMS did their analysis blind. That is, they agreed on what a positive signal would look like before they looked at the data. There's much less chance of making a stupid systematic error when you do a blinded analysis. The pentaquark folk went wrong when they did hundreds of cuts on previously gathered data trying to find anomalies. When you look at a bunch of data and pick out blips, the chance that they're random fluctuations instead of real s

  • Tours available. (Score:3, Informative)

    by mpaulsen (240157) on Friday December 18, 2009 @11:25AM (#30487596) Journal
    If you're ever in the neighborhood, a tour of the mine and the lab are well worth the visit.

    http://maps.google.com/maps?q=Soudan,+mn [google.com]
    http://www.dnr.state.mn.us/state_parks/soudan_underground_mine/index.html [state.mn.us]
    http://www.dnr.state.mn.us/soudan/physics_tour.html [state.mn.us]

    (Generally open June-September -- check before you come.)
  • by hesaigo999ca (786966) on Friday December 18, 2009 @11:40AM (#30487844) Homepage Journal

    I watched maybe too many star trek episodes, but I thought this dark matter stuff was in outer space and that any item touching it would implode (sort of). I am not a science expert, but would not finding dark matter inside earth's core insinuate that it was partially made of the stuff and that what we know about dark matter makes no sense??? I am sure there are no real dark matter exerts per se, as it is something we never really had contact with, however, what science knows about it to me seems very limited, and for what I do know ....dark matter should not be something we can just mine and tap into, it should be something that has a lot more involvement environmentally then I see here.

  • One in two (Score:3, Funny)

    by SoVeryTired (967875) on Friday December 18, 2009 @12:24PM (#30488490)

    I don't understand where they got 23% from. There are two possibilities: either it is dark matter or it isn't. Therefore the probability is 50%.

    • by jfengel (409917)

      See, suppose there were a million doors...

      • So either the door you open is the right door, or it's not. Therefore, the odds of opening the right door are 1:2 or 50%. You're just not getting this new math.
    • No, there are the following possibilities
      1) both excess events are dark matter events
      2) the first excess event is a dark matter event, the second isn't
      3) the first excess event is not a dark matter event, the second is
      4) both excess events aren't actually dark matter events

      Hence, in one out of four cases there is no dark matter which gives their 23% after subtracting 2% since we actually know that there is dark matter.

    • There are two possibilities: either the Earth is flat or it isn't. Therefore the probability is 50%.

    • by dcollins (135727)

      "There are two possibilities: either it is dark matter or it isn't. Therefore the probability is 50%."

      Hidden assumption of equally likely events.

  • by sexconker (1179573) on Friday December 18, 2009 @12:33PM (#30488630)

    That's dangerously low!

    My home town nearly went to zero Kevins back in 1978.

    It was a particularly cold winter, and we were already down to 3 Kevins (due to their low popularity at the time).

    Kevin Thomas had flown out to be with his son's family for a wedding and got stuck in Boston for a whole week due to the weather. 2 Kevins left.

    Kevin Lemmer was rushed to the hospital during my shift. I still remember the call from the EMTs as the ambulance was rushing toward us. "It's Lemmer. He's in bad shape. Drove right into the fucking ditch." We called the time of death at 6:15 PM.

    At 6:16, all eyes turned to room 2217. Kevin Spencer was 82 and on his death bed with leukemia. His family being Catholic, he had already been given his last rights. If he couldn't hold out until Kevin Thomas returned, we would be at zero Kevins. Sure, we had 4 perfectly healthy Calvins, but they're just not the same.

    It was 7:15 when Carla Brooks and her husband James burst through the main entrance. "She's not due for 2 weeks!", James exclaimed. As the staff bustled around getting the Brookses settled, they exchanged darting glances with each other. This was their first child, and they wanted to keep the baby's sex a secret. Of course, in a small town, secrets don't get kept. Nearly all of the hospital staff new that the child about to rip open Mrs. Brooks was indeed a boy.

    The delivery was routine, and Kevin Brooks was born healthy, if a tad underweight, at 10:52 PM. Kevin Spencer was pronounced dead at 10:54.

    It was, as they say, a close one. Kevin Thomas arrived two days later, the weather having finally cleared up. To this day, we still rib him about it.

    Cedar Falls is currently at 5 Kevins.

  • Supersymmetry lives? (Score:3, Interesting)

    by SloWave (52801) on Friday December 18, 2009 @01:29PM (#30489506) Journal

    If they have really found neutralinos [wikipedia.org] then wouldn't that would mean supersymmetry is confirmed? It that case it is a whole new ballgame in particle physics. There are blogs out there that are saying that CERN is about to announce something big too.

    • by Chris Burke (6130)

      If they have really found neutralinos then wouldn't that would mean supersymmetry is confirmed? It that case it is a whole new ballgame in particle physics.

      Pretty much. It would really only be a confirmation of one prediction of supersymetry, but it's a pretty damn impressive prediction to see born out, and smart money would be on the other particles predicted to eventually be discovered.

      The only sad thing is that to really nail down the evidence for the neutralino will probably take years at CDMS. Oh w

  • No longer dark? (Score:3, Interesting)

    by mooingyak (720677) on Friday December 18, 2009 @02:31PM (#30490686)

    If we can detect it, does that mean we have to stop calling it dark matter?

    • No. The name has to do with the fact that it does not interact electromagnetically.

    • Probably, with enough confidence astronomers will start talking about neutralino clouds, or something like that.
    • by IICV (652597)

      If you can feel the shape of a dark statue in a dark room with your hands, does it stop being dark?

      No? Then no.

Facts are stubborn, but statistics are more pliable.

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