1. Subscribersonhouse
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    17 Apr '08 16:14
    This will be just a tiny bit controversial I bet:
    http://space.newscientist.com/article/dn13726-dark-matter-may-have-been-found-on-earth.html
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    18 Apr '08 03:12
    Originally posted by sonhouse
    This will be just a tiny bit controversial I bet:
    http://space.newscientist.com/article/dn13726-dark-matter-may-have-been-found-on-earth.html
    Interesting article, thanks.

    Do you know what a 100kg or 250kg detector actually is or how it works? I like to read about this sort of stuff, although its not my branch of science, so certainly no expert.

    How do they know the particles are dark matter?

    If you can shed any more light, it will be much appreciated.
  3. Subscribersonhouse
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    18 Apr '08 03:292 edits
    Originally posted by timebombted
    Interesting article, thanks.

    Do you know what a 100kg or 250kg detector actually is or how it works? I like to read about this sort of stuff, although its not my branch of science, so certainly no expert.

    How do they know the particles are dark matter?

    If you can shed any more light, it will be much appreciated.
    Right now I think its a statistical game, the results will have to be independently verified. I think the detector is a photomultiplier tube or avalanche diode detector, the solid state equivalent and detects brief flashes of light when one particle interacts with another head on.
    Its how they detect neutrino's, same idea. They mentioned in the article there would be seaonal variations if its dark matter so they hope to corrolate cycling up and down of hits depending on what part of the year the planet is aiming at, so its a long boring road collecting flashes. Like the first neutrino detector, it was not very sensitive and you might get one hit a week or so making it a very long term affair and these dark matter particles are even less reactive than neutrino's so you can see the problem, need lots of detectors shielded by about a mile of solid rock to keep out stray cosmic rays and such. The Neutrino detectors now are giant pools of ultra pure liquid, might just be DI water but not sure. Sometimes a neutrino (very seldom) it hits a particular atom dead nuts and turns into another atom, but in the process the breakdown causes a tiny flash which the photomultiplier tube amplifies enough to record. So you build up a track record of where they originate, mostly from the sun, but there are other experiments that are detecting neutrino's emitted by nuclear reactors, a detector or string of them a few miles from the reactor, I think the fluid is C CL4, Carbon Tetrachloride, the cleaning fluid. I think one way used to be if the chlorine atom takes a direct hit it transmutates into something else and they can be detected by running all the fluid through a spectrum analyzer, looking for a needle in a haystack for sure, 3 or 4 atoms gotten zonked from Chlorine to ??, anyway detectable. That was the old way I think. Now they just use sensitive light detectors.
    Ok, the detector in this case is Sodium Iodide, presumably transparent, a solid block of it 100Kg and 250 Kg, not sure how big that would be but its probably one extremely pure crystal grown into a boule. So a dark matter whacks one of the atoms, they didn't say which, and it interacts, not sure if it actually transmutates or not but gives of a pulse of light barely detectable and maxes in June and minumized signals in december as the theory goes, the earth is either running into them or away from them relatively speaking as the sun makes its way around the galaxy so every 6 months there will be a minima and maxima and thats what they claim to have seen after a 7 year run. And of course these results are met with more than a little bit of scepticism­čÖé
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    18 Apr '08 03:39
    Originally posted by sonhouse
    Right now I think its a statistical game, the results will have to be independently verified. I think the detector is a photomultiplier tube or avalanche diode detector, the solid state equivalent and detects brief flashes of light when one particle interacts with another head on.
    Its how they detect neutrino's, same idea. They mentioned in the article the ...[text shortened]... 7 year run. And of course these results are met with more than a little bit of scepticism­čÖé
    Appreciate the explanation.

    Sounds like an expensive field of research.
  5. Subscribersonhouse
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    18 Apr '08 03:441 edit
    Originally posted by timebombted
    Appreciate the explanation.

    Sounds like an expensive field of research.
    And boring for the most part, eh. Like HEY, last week I got a hit, and by jimini, today I just got ANOTHER ONE!!!. Third time this month­čÖé
    The one problem they will have till some newer detector technology gets developed, is they are getting one hit from a single collision giving one flash. That means they don't know what direction the signals are coming from, they can only count flashes and like they said, look for a differant # in June (more) and a smaller # in December. That is a fundamental problem. Like in the old cloud chambers, you saw a particle make a long track and it is at least easy to see what direction it came from since its a one dimensional affair, a line of detection. The detects on this experiment is a zero dimension detect, a single flash so you need other ways to determine directionality.
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    18 Apr '08 04:08
    Originally posted by sonhouse
    And boring for the most part, eh. Like HEY, last week I got a hit, and by jimini, today I just got ANOTHER ONE!!!. Third time this month­čÖé
    The one problem they will have till some newer detector technology gets developed, is they are getting one hit from a single collision giving one flash. That means they don't know what direction the signals are coming f ...[text shortened]... is a zero dimension detect, a single flash so you need other ways to determine directionality.
    Is it possible to setup multiple detectors which all shield the particles from different directions i.e. so each detector can only be hit from particles in one direction...........
  7. Subscribersonhouse
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    18 Apr '08 07:121 edit
    Originally posted by timebombted
    Is it possible to setup multiple detectors which all shield the particles from different directions i.e. so each detector can only be hit from particles in one direction...........
    That would be nice but the particles pass through everything and if they hit, they hit just one atom, nucleus actually, they are lucky to be detecting anything at all. What would you suggest as a shield? It is already under a mile of rock.
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    18 Apr '08 08:05
    Originally posted by sonhouse
    That would be nice but the particles pass through everything and if they hit, they hit just one atom, nucleus actually, they are lucky to be detecting anything at all. What would you suggest as a shield? It is already under a mile of rock.
    Maybe not a physical shield like a "solid" barrier, but a virtual shield that can repel or redirect the particles? Really just thinking aloud here........
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    18 Apr '08 08:55
    So what is dark matter? Do we know what particles builds up drk matter?

    Or do they just pick up high energy cosmic particles? Then, what's new with that?
  10. Subscribersonhouse
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    18 Apr '08 11:40
    Originally posted by timebombted
    Maybe not a physical shield like a "solid" barrier, but a virtual shield that can repel or redirect the particles? Really just thinking aloud here........
    Well the only thing we have is electric or magnetic fields to manipulate the stuff and as far as I know they are extremely neutral, don't react to either kind of force. That would only seem to leave gravity, and the whole planet is a sink for them that way.
  11. Subscribersonhouse
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    18 Apr '08 11:421 edit
    Originally posted by FabianFnas
    So what is dark matter? Do we know what particles builds up drk matter?

    Or do they just pick up high energy cosmic particles? Then, what's new with that?
    That would be the 64,000 dollar question. The big guys haven't a clue either, Dark Matter, Dark Energy, Quintessence, all of these puppies we know next to nothing about so the idea that some dude in Italy manages to capture some is going to be quite contentious, to say the least. I think they know for sure it's not cosmic rays, which are just helium atoms or nuclei going within a hairbreaths of the speed of light.
    I think the thinking goes this dark matter stuff is going very slow.
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    19 Apr '08 05:13
    Originally posted by sonhouse
    That would be the 64,000 dollar question. The big guys haven't a clue either, Dark Matter, Dark Energy, Quintessence, all of these puppies we know next to nothing about so the idea that some dude in Italy manages to capture some is going to be quite contentious, to say the least. I think they know for sure it's not cosmic rays, which are just helium atoms o ...[text shortened]... s of the speed of light.
    I think the thinking goes this dark matter stuff is going very slow.
    So what did they find? Some reactions with atoms, and that's it?

    We can rule out cosmic radiation of 'known' type. And I would think they would differ neutrino interaction (?).

    So what kind of reaction do they have that couldn't be explained in another way that dark matter?

    I think they can't explain the reactions, so they label it 'dark matter' not knowing better. But that is my hypothesis...
  13. Subscribersonhouse
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    19 Apr '08 05:38
    Originally posted by FabianFnas
    So what did they find? Some reactions with atoms, and that's it?

    We can rule out cosmic radiation of 'known' type. And I would think they would differ neutrino interaction (?).

    So what kind of reaction do they have that couldn't be explained in another way that dark matter?

    I think they can't explain the reactions, so they label it 'dark matter' not knowing better. But that is my hypothesis...
    Yours and everyone elses at this point. Like I said, it's a contentious issue, and will be until independent verification or falsification takes place. Extraordinary claims and extraordinary evidence and all that.
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    30 Apr '08 05:20
    so from my understanding dark matter and dark energy and all that good stuff is what you see in space and what everything is floating in? and so there may be some of that empty black space on the earth? if that is correct, that sounds pretty awesome
  15. Subscribersonhouse
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    01 May '08 05:19
    Originally posted by EcstremeVenom
    so from my understanding dark matter and dark energy and all that good stuff is what you see in space and what everything is floating in? and so there may be some of that empty black space on the earth? if that is correct, that sounds pretty awesome
    It's not 'empty black space', it's something but so far unknown that is like neutrino's in that they penatrate everything with ease through the earth, through people, we don't even know how fast theses buggers go or their mass per particle, any of that basic stuff. So anything we learn puts us one step closer to understanding what it is we are dealing with, what it is that makes up most of the mass in the universe. Remember, the stuff we are made of, carbon, hydrogen, iron and so forth only makes up 4 percent of the mass of the universe so we are definitely in the minority mass wise.
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