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I High Energy Photon Recieved as Lesser Energy Photons?

  1. Jul 18, 2016 #1
    Is it possible (and has it been observed) where a single high energy photon is emitted, but then is received as multiple lower energy photons?
  2. jcsd
  3. Jul 18, 2016 #2
    This can happen when the photon is absorbed and re-emitted through some "non-linear" materials. See Spontaneous parametric down-conversion.

    I don't know if at high photon energies (gamma rays) in vacuum you could get pair production and then recombination producing different number of photons. Maybe someone else can answer that.
  4. Jul 19, 2016 #3


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    Pair production requires something in addition to the gamma ray. At high enough density (right after the big bang) it can be photon+photon.

    On earth pair production takes place by interacting with nuclei (necessary for momentum conservation). Typical result is production of electron-positron pair. The positron gets annihilated with an electron to produce two 511 kev photons, which is less than the original gamma ray (> 1022 kev).
  5. Jul 19, 2016 #4
    Thank you both!
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