Hi. 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.