Gamma - when is pair production dominant

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SUMMARY

For gamma rays with energies above 10 MeV, pair production is the dominant interaction mechanism, particularly in most elements. While pair production can occur at energies as low as 1.022 MeV, it typically becomes the primary interaction at around 5 MeV for lead and 10 MeV for air. The interaction type is influenced by both the energy of the photon and the atomic number of the medium. This establishes pair production as a critical concept in high-energy photon interactions.

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  • Understanding of pair production in high-energy physics
  • Knowledge of photon interactions, including Compton scattering and the photoelectric effect
  • Familiarity with the significance of atomic number in radiation interactions
  • Basic concepts of gamma ray energy levels
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  • Research the specifics of pair production thresholds in various materials
  • Study the differences between Compton scattering and pair production
  • Explore the role of atomic number in photon interaction mechanisms
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Physicists, radiation safety professionals, and anyone involved in high-energy photon research or applications will benefit from this discussion.

lavster
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hi,
am i right in saying that for gamma rays of energies above 10MeV, the main interaction mechanism is pair production? and this is independent on energy? (or is it compton scattering for example?)
thanks
 
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While pair production is possible for photon energies of 1.022 MeV or higher, it is not usually dominant until the incident photon energy is, very generally, about 5 MeV.

The incident photon energy which dominantly results in pair production depends on the element/medium being considered. Here are two pictures, for lead and air, illustrating my point.

3776093624_ed9dc620c0.jpg


3775266331_983d0a3243.jpg


As you can see, pair production is the predominant mechanism of interaction between photons and electrons for energies at about 5 Mev in lead, and at about 10 MeV in air (when considering the photoelectric effect, Compton scattering, and pair production).

EDIT: Sorry, got carried away. A more concise answer: For photons with energies above 10 MeV, pair production is the most dominant interaction mechanism for most elements. The type of interaction depends on energy AND atomic number.
 

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