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Can photovoltaic cells capture gamma photons?

  1. Oct 9, 2011 #1
    I am by no means well versed in nuclear power, but from my limited exposure I have gathered that a very large portion of nuclear energy (and antimatter) is expressed in high energy gamma radiation. All forms of electromagnetic radiation are expressed as photons, correct?

    Taking the concept of photovoltaic cells, which capture photons in the visible spectrum, can that not be applied to high energy gamma photons to capture some of that energy?

    I would imagine that significant damage would occur to the cells from the ionizing radiation. But from what i gather from the source of all accurate* knowledge (wikipedia), even non-photoelectric effect interactions would produce smaller (less energetic photons) that through enough iterations would be low enough in energy to be absorbed through the cells.

    Granted I know nothing of the engineering of such photovoltaic cells, but the concept itself seems to lend itself rather well.

    Would this be feasible in anyway whatsoever?
     
  2. jcsd
  3. Oct 11, 2011 #2

    Drakkith

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    One of the problems is that while visible light will easily be asborbed in a thin layer on a solar cell, gamma radiation will easily penetrate large layers of shielding.
     
  4. Oct 11, 2011 #3
    I am aware. However I would think that if it were possible to absorb a significant amount given a thick enough cell then the energy absorbed might be worth the costs of making such a thick photoelectric cell.

    Again, I don't know if it is feasible, I was more or less just asking whether it is a possibility.
     
  5. Oct 11, 2011 #4

    Drakkith

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    Maybe, but I don't think a photovoltaic cell would even work for gamma radiation. Not sure though.
     
  6. Oct 11, 2011 #5
    perhaps not at first because they are too high energy, but after multiple matter reactions it might have split enough to become several photons of a low enough energy so that they can be absorbed by the photoelectric effect when hitting a cell.

    Really, it would initially seem that the hardest part would be making something that could capture photons of that wavelength and something thick enough to capture them once they have lost enough energy and then convert it usefully.

    EDIT:
    after the latter two matter interactions it can be absorbed through the photoelectric effect theoretically.
    from wikipedia:

     
    Last edited: Oct 11, 2011
  7. Oct 12, 2011 #6

    Hepth

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    But its also a question of how much the sun emits of what frequency, and it falls of pretty fast :
    http://www.vicphysics.org/documents/events/stav2005/spectrum.JPG

    So it's not worth going after those high energy photons as there are so few of them, at least from the sun.

    Now if you make a photovoltaic material that is dense enough to stop high energy radiation with only a few feet thick of material, and to capture its energy at least to some decent efficiency, then I'd say use them to build reactor shells. Though I'm not sure its even worth going after.
     
  8. Oct 12, 2011 #7
    It was the reactor shell idea that I was going for. If there were appreciable amounts of gamma radiation hitting us from the sun, i'm pretty sure we'd be dead.

    I recall seeing a number as to how much energy is emitted as gamma radiation that we just cant use. I recall it being rather high as well. If we can even capture a decent fraction of that extra energy it would increase the overall efficiency of the reactor while getting rid of some of the potentially harmful radiation.

    I dont know if its worth going after either. I had hoped someone on here could give insight into that. I think that it would be worthwhile though, because unless the cells degrade relatively fast or they are simply insanely expensive, I believe the extra electricity generated could cover the costs over time
     
  9. Oct 12, 2011 #8

    QuantumPion

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    You may be confusing gammas with neutrinos. Energy lost by neutrinos accounts for about 5% of the reactor's fission energy and cannot be recovered. Energy released by gammas however IS recovered, in the form of heat.
     
  10. Oct 12, 2011 #9

    ZapperZ

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    No. At some point, if the penetration depth is too deep, it will be longer than the electron escape depth. This means that even if you create electrons that have enough energy to escape, it is created too deep into the material that it loses energy first before it can migrate to the surface.

    This is why we have no photodetector for gamma photos, and why such photovoltaic cell doesn't quite work.

    Zz.
     
  11. Nov 24, 2013 #10
    Gamma vs photovoltaic


    Hey Logannc,
    I had the same thoughts back in 2005. I looked around and found no info. I did speak to a few ppl in PV research at two of our Uni's and at our Nuclear Science facility. I got silence!

    I even took a PV down to our radiation store to see any current was generated. I don't think I had put a load on the cell correctly. However nil output!

    I started searching the net again and found your post, along with other pubs.

    http://www.publish.csiro.au/?act=view_file&file_id=PH610443.pdf

    http://nvlpubs.nist.gov/nistpubs/jres/64A/jresv64An4p297_A1b.pdf

    My guess is would a lower energy emitter along with a higher Z value semiconductor work?
     
  12. Nov 24, 2013 #11

    Drakkith

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    The last post in this thread was over 2 years ago.
     
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