My question is related to this topic: Tunneling of alpha particles. Unfortunately it didn't quite solve my doubts.
My professor and the book I'm reading (Particles and Nuclei: An Introduction to the Physical Concepts by Povh et al.) says that "The emitted nucleons are primarily neutrons since they are not hindered by the Coulomb threshold" which means that a neutron has a separation energy lower than a proton. They take this as true, indeed for example when a nucleus decays to another nucleus in an excited state, we compare the energy of this excited level and the separation energy of neutron to check if it's bonded for nucleons' emission (like in the $\beta$-decay $^{60}_{27}$Co $\to$ $^{60}_{28}$Ni).
I still don't get how, although the Coulomb force between protons is repulsive, the existence of this force makes it harder to separate a proton from a nucleus. I'd expect the proton to see something which reduce the confinement inside the well (of the nucleus) but this is not the true, it sees a barrier caused by this force. Instead a neutron doesn't see a barrier because there's no Coulomb force and therefore (I guess?) it's easier to separate.
So, why the Coulomb force, which should facilitate the separation as it's repulsive, makes it harder for a proton to be separated than a neutron?
