Hello, So I assume, ionization occurs, when an electron has enough energy to either overcome the potential (Coulomb) barrier, or tunnel right through it (or can the overcoming of the barrier even be described as a 100% chance of tunneling?). If an alpha particle interacts with an atom, it conveys some of its kinetic energy to an electron, raising its energy level to a point where it is either capable of moving over the energy barrier of its atom or at least the difference between the barrier and the electrons' energy decreases and thus the chances of tunnel ionization increase. However, that doesn't take into account that different ionizing radiation particles have different electric charges. Electrical fields can distort the potential barrier of an atom so that electrons are more likely to escape. So does the fact that those particles have different charges have any effect on the ionization process or don't they really matter? Even if they don't, how exactly is the kinetic energy transfered? The particles are not really "bumping" into each other, it's quantum mechanics acting at this level, so are there some virtual photons or how does the ionization exactly work?