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How to distinguish two isotopes?

  1. Oct 13, 2011 #1

    If we had available for some two isotopes such as plutonium.
    One produced artificially, and the other not as example Pluton-238 and Pluton-242.
    If these isotopes would be protected by coating with a layer of absorbing radiation such as lead in what the easiest way we could identify them if we did not know which is which. Assume that they are in the form of spheres with the same radii and weight.

    I thought the mass spectrometry, but whether this method would be possible when these isotopes are covered with this coating, which can not be damaged?

    Although best if it is a simple method.

    Last edited: Oct 13, 2011
  2. jcsd
  3. Oct 13, 2011 #2
    I really care about, to know what it could be a method. If anyone of you has an idea I would be grateful.
  4. Oct 13, 2011 #3
    So you don't want to have to dig pieces of them out and send them through a mass spectrometer? Ok, well your examples are highly radioactive, so you would pretty easily be able to stick them in front of a gamma detector and examine their emission spectra, which will surely be different. I don't know what their decay modes are but depending what it is there are alpha and beta detectors also.

    For non radioactive samples I think Mossbauer spectroscopy would work, although it is hard to get the right source for the job as you only get a tiny width of gamma spectrum to work with per source, so you have to know exactly what you are looking for. It is not a nice general technique like mass spectroscopy.

    Probably there is some less extreme thing you could do too, for some reason I just think of the hard stuff first :).

    edit: Actually the Mossbauer thing might not work as I imagine you won't have pure samples of each isotope, in which case a Mossbauer spectrometer tuned to either isotope will see the lines you are looking for, and not the other ones.You would need the lines to be in the same energy range, so you could see their relative heights.
  5. Oct 13, 2011 #4
    Unfortunately, this coating of lead absorbs the radiation, but in the description of the problem has not been specifically written, only that absorbs radiation and, ironically, it comes even with the simplest method to distinguish between these isotopes.
  6. Oct 13, 2011 #5
    Oh, I didn't read that bit. That must be serious lead coating to block out everything. You wouldn't need very high intensity of gamma's to tell the isotopes apart.

    Well anyway, do you have time on your hands and a really sensitive scale? If you wait a really long time their masses will change by different amounts :p. Also the radiation will heat them differently, so you might just be able to measure their temperatures if the difference is big enough.

    There might also be some interesting magnetic thing you could do with the nuclear magnetic moments, I'm not sure. Probably there are loads more things you could do too.
  7. Oct 13, 2011 #6
    Might rely on this? Lead should nevertheless increase the temperature?
  8. Oct 14, 2011 #7
    My guess, is look at the activity of the two isotopes. The activity should be related to the temperature change of the container.
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