Alpha, Beta, and Gamma Decay Mechanisms

Manual: General · Subject: Physics

Go beyond definitions to understand decay energetics, selection rules, and emission spectra.

Decay Mechanisms in Detail

Alpha decay

Alpha decay occurs in very heavy nuclei because emitting an $\alpha$ particle can move the parent toward a more stable region. The process is governed by quantum tunneling through the Coulomb barrier.

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Tunneling

Even when the alpha particle does not have enough classical energy to escape, it may tunnel through the barrier with a small but nonzero probability.

Beta decay

In $\beta^-$ decay, a neutron converts to a proton with emission of an electron and antineutrino. In $\beta^+$ decay, a proton converts to a neutron with emission of a positron and neutrino. These processes are mediated by the weak interaction.

Beta decay comparison

Mode	Nuclear change	Leptons emitted
$\beta^-$	$n \to p$	$e^-$ and $\bar\nu_e$
$\beta^+$	$p \to n$	$e^+$ and $\nu_e$
Electron capture	$p + e^- \to n$	$\nu_e$

What physical interaction mediates beta decay?

Strong Electromagnetic Weak Gravitational

What causes alpha particles to escape from the nucleus?

Gamma decay

Gamma decay typically follows alpha or beta decay when the daughter nucleus is left in an excited state. The nucleus sheds excess energy by emitting a high-energy photon without changing composition.

Why does gamma decay not change the element?

It changes only energy, not

Z

A

It removes protons It adds neutrons It converts photons into nucleons

What particle accompanies beta minus decay along with the electron?

Neuroanatomy Explorer

Memory Deck

Match the Pairs

Concept Constellation

Alpha, Beta, and Gamma Decay Mechanisms

Decay Mechanisms in Detail

Alpha decay

Beta decay

Gamma decay