Beta-delayed proton emission

The animation presents an example of beta-delayed particle emission. In this particular case the decay process consists of the following steps:

β⁺ decay:

²⁶₁₅P₁₁ → ²⁶₁₄Si₁₂ + e⁺ + ν,

followed by proton emission (proton decay):

²⁶₁₄Si₁₂ → ²⁵₁₃Al₁₂ + p.

In the rollover image of the picture below you can see the decay processes starting from ²⁶P. After the first β⁺ decay we get 100% ²⁶S. Then the main branch is β⁺ decay again (denoted by ε in the chart). However thare is also a thin branch (~1%) where the ²⁶S nucleus gets rid of its high excitation energy by emitting a proton rather than a γ photon. The product of this decay is ²⁶Si which does not normally decay by proton emission although it is still relatively rich in protons (otherwise it would not show β⁺ activity after all). This shows that the excited state of the nucleus is important for the proton to conquer the Coulomb barrier.

Proton decay – in the sense of spontaneous proton emission by a ground-state nucleus – only occurs near the proton dripline on the table of nuclides.