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Does every photopeak orginate a Compton edge?

  1. Dec 12, 2015 #1

    I have to analyse the energy spectrums of several nuclides and observe their photopeaks and the Compton edges originated by these. I only see one Compton edge on all the spectrums, no matter how many photopeaks they are.

    At first I thought I should only expect photopeaks under 1022 keV to originate a Compton edge, since photons above this energy would also undergo pair production, but in the solved example we are provided the Compton edge for the Co-60 is marked as corresponding to the 1,33 MeV peak, which contradicts my reasoning:

    Why do we only see one Compton edge? And why is the one for the largest energy peak?

    Thank you for your time.

    PD: I'm not sure if this should be in homework: I think it doesn't, since while I need to know this to solve the problem it is mainly a question about Compton scattering, but I apology otherwise.
  2. jcsd
  3. Dec 12, 2015 #2
  4. Dec 13, 2015 #3


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    Staff: Mentor

    Compton scattering happens above the pair production threshold as well. Pair production is just an additional process.
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