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Looking for waves to detect a specific material exclusively

  1. Feb 16, 2015 #1
    hello!

    is there a material or substance that can be detected using some kind of waves (magnetic, electromagnetic, ultrasound, infrared, whatever, etc)
    with extreme specificity (ie. no other materials or substances are to be mistaken)
    with extreme sensitivity (ie. a nanometer of that material or substance can be distinguished from two nanometers)
    and where the waves that detect it can penetrate most materials and detect the material or substance we are talking about beneath most materials regardless of the thickness

    is there any 'material/substance and waves' couple that satisfies these conditions?

    thanks!
     
  2. jcsd
  3. Feb 16, 2015 #2

    PeterDonis

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    I don't know of any. Your requirements seem very strict, and not really compatible with one another. In particular, the "regardless of thickness" requirement and the "extreme sensitivity" requirement seem virtually impossible to satisfy at the same time.
     
  4. Feb 17, 2015 #3

    e.bar.goum

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    By requiring extreme position resolution "a nanometer of that material or substance can be distinguished from two nanometers", you get in trouble. (unless you meant "nanogram")

    If you relax that a bit, but still require extreme *abundance* sensitivity, with extreme specificity, there are a few techniques that come to mind - Accelerator Mass Spectrometry gives you extreme sensitivity -- you are talking about sensitivities on the order of 10-16 -- literal atom counting, and it is certainly bulk, but you invariably destroy what you are looking so it doesn't have total utility. Most results are also relative to another ion. Isobars are also a problem, but in a lot of cases, if you're clever, you can deal with them.

    If you're interested in ppm levels, you have a lot more options - neutron activation analysis is good if you don't mind making your material radioactive for some time. PIXIE is essentially non-destructive. Rutherford Back-scattering gives you information about the bulk. Neutron scattering is also good for a few centemeters, but I couldn't tell you what the sensitivity is. I suspect it's a matter of how long you count for.

    Basically, there are a bunch of options, but you've got to pick the right one for the job.
     
  5. Feb 17, 2015 #4
    can't I just scan things for magnetic distortions and detect a material that distorts magnetism in a specific manner?
    or if magnetic waves cannot penetrate things, maybe them radiowaves? or something other?
     
  6. Feb 17, 2015 #5

    russ_watters

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    The method of detection depends on what you are trying to detect. Steel submarines, for example, are detected using magnetism.
     
  7. Feb 17, 2015 #6
    I alraedy said that I am trying to detect a material or substance that can be detected by waves that pass through most things!
    eg, pass through water, flesh, bone, wall, metal if possible!
     
  8. Feb 17, 2015 #7
    for example, can raman spectroscopy see inside things? and does it have sensitivity to see small traces of a specific substance?
     
  9. Feb 18, 2015 #8
    ok, let's find waves that can see through things, are there any?
     
  10. Feb 18, 2015 #9

    Bystander

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    Do you have something specific in mind? Niven's "deep radar?" Neutrino shadows? Gravity waves?
     
  11. Feb 18, 2015 #10
    I want to detect an item that passes through a detector
    I can patch anything to that item
    but the detector should be able to detect it even if it is inside a pocket or between books or inside a metal box (ok, not the latter if it's not possible)
     
  12. Feb 18, 2015 #11

    Bystander

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    We gathered that much --- you want to tag elephants with radioactive bowling balls? Minnows with radioactive iodine? Merchandise from the local "Big Box" to catch shop lifters? Hi-mu 80 in explosives for mine detectors? Something someone's lost? Tag things to track people/animals/vehicles?
     
  13. Feb 18, 2015 #12
    Merchandise from the local "Big Box" to catch shop lifters
     
  14. Feb 18, 2015 #13

    Bystander

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    They've figured out how to kill the inventory control tags? So you need a new marker that can be "killed" or "cleared" at the scanner to let paying customers out --- oh, wow. Or, a scanner at the door that counts a particular sale, as it's leaving, and compares it to register "ticket." Got it. Good problem to play with --- and we want it "unspoofable."

    Edit: Going to have to have the ticket in hand to get out of the store, aren't we.?
     
    Last edited: Feb 18, 2015
  15. Feb 18, 2015 #14
    I don't understand you, is this some kind of banter?
     
  16. Feb 18, 2015 #15

    Bystander

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    No. I'm just rephrasing the problem in my mind, and maybe for some others following the thread. You've set us a "poser" in terms of what is "state of the art" for both the store, and the "discount shoppers." It's going to take a little thinking.
     
  17. Feb 18, 2015 #16

    PeterDonis

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    The specifications you give in your OP are a lot more stringent than this use case implies. Is the item really going to be as small as one nanometer? (Do you know how small one nanometer is?) Do you really need detection through most materials regardless of the thickness? (You realize that implies detection through, say, a foot or a hundred feet or a mile of material, right?)
     
  18. Feb 18, 2015 #17
    the item is not going to be a nanometer, but the MARK on it is going to be that, the mark with that specific detectable substance

    yes, I need detection of that specific substance regardless thickness of materials, but thickness won't be more than 1-2 meters
     
  19. Feb 18, 2015 #18

    davenn

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    and why cannot you use the current RFID tagging systems ?


    EDIT ... oops not likely to work through metal, but I cant think of anything else that would either
     
    Last edited: Feb 18, 2015
  20. Feb 18, 2015 #19

    PeterDonis

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    How are you planning to make nanometer-sized marks with a specific substance? Once again, do you realize how small a nanometer is?
     
  21. Feb 18, 2015 #20
    ok, if not nanometer, definately millimeter
     
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