Does every photopeak orginate a Compton edge?

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In summary, the conversation discusses the analysis of energy spectrums of nuclides and the observation of photopeaks and Compton edges. The speaker notes that they only see one Compton edge on all spectrums, regardless of the number of photopeaks. They initially thought that only photopeaks under 1022 keV would create a Compton edge, but the solved example contradicts this. The speaker asks why there is only one Compton edge and why it corresponds to the largest energy peak. They also mention a mislabeled figure and the use of a germanium detector for higher resolution. They conclude that Compton scattering can occur above the pair production threshold.
  • #1
carllacan
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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:
Screenshot_from_2015_12_12_14_50_23.png


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.
 
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  • #3
Compton scattering happens above the pair production threshold as well. Pair production is just an additional process.
 

1. What is a photopeak?

A photopeak is a characteristic energy peak in a gamma-ray spectrum that represents the direct detection of a gamma-ray photon by a detector.

2. What is a Compton edge?

A Compton edge is the lower energy limit of a photopeak, which occurs due to the Compton scattering of a gamma-ray photon within the detector material.

3. Does every photopeak originate a Compton edge?

No, not every photopeak originates a Compton edge. The presence of a Compton edge depends on the energy of the gamma-ray photon and the material of the detector.

4. How does a Compton edge affect the gamma-ray spectrum?

A Compton edge appears as a sharp decrease in the intensity of gamma-ray photons at a specific energy, which can affect the accuracy of the gamma-ray spectrum analysis.

5. How can we minimize the presence of Compton edges in a gamma-ray spectrum?

To minimize the presence of Compton edges, it is important to use a detector material with high atomic number, as this increases the probability of photoelectric absorption and decreases the likelihood of Compton scattering.

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