How does gamma decay differ from alpha and beta decay?

Gamma decay differs fundamentally from alpha and beta decay in its nature, mechanism, and the particles involved. While alpha and beta decay involve the emission of matter, gamma decay is a process of energy dissipation.12

• Nature of Emission: Alpha decay involves the emission of alpha particles (helium-4 nuclei), and beta decay involves the emission of electrons or positrons. In contrast, gamma decay involves the emission of gamma rays, which are high-energy photons with no rest mass or electric charge.23
• Mechanism: Alpha and beta decay are processes that change the identity of the nucleus by altering the number of protons or neutrons. Gamma decay typically occurs when a nucleus is in an excited state—often as a result of a previous alpha or beta decay—and needs to dissipate excess energy to reach its stable ground state.143
• Energy Spectra: Unlike beta decay, which exhibits a continuous distribution of particle energies, gamma rays are emitted with discrete energy levels corresponding to the transitions between specific nuclear energy states.15

Because gamma rays lack charge and mass, they possess significantly higher penetrating power than charged alpha or beta particles.4