Gamma decay involves which type of emission?

• A. The emission of neutrons from a nucleus.
• B. The emission of alpha particles from a nucleus.
• C. The emission of beta particles from a nucleus.
• D. The release of gamma rays from a nucleus.

Answer: (D)

Gamma decay is the process in which an excited nucleus sheds excess energy by emitting a gamma photon. Gamma rays are high-energy photons, so this emission carries energy away without carrying charge or changing the numbers of protons or neutrons. That means the atomic number and mass number stay the same after gamma emission. This is different from emitting neutrons (which reduces the mass number by 1), alpha particles (which remove two protons and two neutrons, changing both Z and A), or beta particles (which transform one type of nucleon into another and change Z). Gamma emission often occurs after another decay leaves the nucleus in an excited state, and it serves to bring the nucleus down to its ground state.