How Does the Coulomb Barrier Affect Alpha Decay?

[Peter G]

Can you gurus help me understand in a qualitative way the nature of the Coulomb barrier as it applies to alpha decay? I can intuitively appreciate the Coulomb barrier as it applies to anincoming charged particle, but resources I have been reading apply the same term to the barrier felt by alphas, within the nucleus, inhibiting emission. I would have thought that any barrier that must be overcome by an alpha trying to escape would derive from the dominance of the strong force, binding the alpha to the nucleus, over the Coulomb force of the protons trying to push the alpha out. So, what am I missing here?

 

[Orodruin]

The strong force has a much shorter range than the electromagnetic force. When the alpha particle is part of the nucleus, it is strongly attracted to the rest of the nucleus, making the overall potential low. However, as soon as the particle leaves the nucleus, the strong part of the potential becomes essentially zero, meaning that the only remaining part of the potential is the large Coulomb potential - making it a potential barrier for the particle leaving the nucleus because it has to first leave the nucleus by climbing on top of that large potential.