Which gamma interaction is associated with high-energy photons and involves pair production?

Which gamma interaction is associated with high-energy photons and involves pair production?

• A. Photoelectric
• B. Pair Production
• C. Compton
• D. Electron capture

Answer: (B)

When gamma rays have enough energy, they can be converted into matter in the strong electromagnetic field of a nucleus. This process, called pair production, uses the photon’s energy to create an electron-positron pair. The energy must be at least 1.022 MeV (twice the electron rest mass), and a nearby nucleus is needed to conserve momentum. After creation, the electron and positron may carry away energy and, later, annihilate to produce photons again. This is the best match for high-energy photons creating a particle–antiparticle pair. The other interactions operate differently: the photoelectric effect absorbs the photon and ejects a bound electron, typically at lower energies; Compton scattering involves the photon scattering off an electron with energy transfer and a lower-energy scattered photon; electron capture is a nuclear decay process, not a gamma interaction with matter.

When gamma rays have enough energy, they can be converted into matter in the strong electromagnetic field of a nucleus. This process, called pair production, uses the photon’s energy to create an electron-positron pair. The energy must be at least 1.022 MeV (twice the electron rest mass), and a nearby nucleus is needed to conserve momentum. After creation, the electron and positron may carry away energy and, later, annihilate to produce photons again.

This is the best match for high-energy photons creating a particle–antiparticle pair. The other interactions operate differently: the photoelectric effect absorbs the photon and ejects a bound electron, typically at lower energies; Compton scattering involves the photon scattering off an electron with energy transfer and a lower-energy scattered photon; electron capture is a nuclear decay process, not a gamma interaction with matter.