Which involves interaction between an incident photon and an atomic nucleus?

Which involves interaction between an incident photon and an atomic nucleus?

• A. Photoelectric interaction
• B. Compton interaction
• C. Coherent scatter
• D. Pair production

Answer: (D)

Pair production is the interaction where a photon is transformed into an electron-positron pair in the electromagnetic field of a nucleus. The nucleus must participate to conserve momentum, which is why this process specifically involves the atomic nucleus. The photon must have at least 1.022 MeV of energy to create the two rest masses, and any excess energy becomes kinetic energy of the electron, positron, and the recoiling nucleus. Other processes involve electrons rather than producing new particles with the nucleus’s help: the photoelectric effect happens when a photon is absorbed by an atomic electron, ejecting it from the atom; Compton scattering is a photon scattering off a bound electron, transferring some energy to that electron; and coherent (Rayleigh) scattering is elastic scattering from the entire atom with negligible energy loss. Thus, the interaction that explicitly requires the nuclear field to create particle-antiparticle pairs is the one described here.

Pair production is the interaction where a photon is transformed into an electron-positron pair in the electromagnetic field of a nucleus. The nucleus must participate to conserve momentum, which is why this process specifically involves the atomic nucleus. The photon must have at least 1.022 MeV of energy to create the two rest masses, and any excess energy becomes kinetic energy of the electron, positron, and the recoiling nucleus.

Other processes involve electrons rather than producing new particles with the nucleus’s help: the photoelectric effect happens when a photon is absorbed by an atomic electron, ejecting it from the atom; Compton scattering is a photon scattering off a bound electron, transferring some energy to that electron; and coherent (Rayleigh) scattering is elastic scattering from the entire atom with negligible energy loss. Thus, the interaction that explicitly requires the nuclear field to create particle-antiparticle pairs is the one described here.