Why is an alpha particle high ioniser

[ehabmozart]

What is the main cause that alpha particle has the highest ionisation out of the beta and gamma... Is it because of it's LARGE MASS or LARGE MAGNITUDE OF CHARGE?? This leads me to the general question.. How does ionistation occur and what affects it.. Mass or CHarge??

 

[Bob S]

There are several reasons. Charged particles from radioactive decay lose energy by scattering off the electrons in materials. This is commonly referred to as the Bethe-Bloch dE/dx or ionization loss equation. See Eq 27.1 and Fig 27.1 in http://pdg.lbl.gov/2011/reviews/rpp2011-rev-passage-particles-matter.pdf

The dE/dx ionization rate goes as the square of the incident particle charge, and also rises at low energies (Bragg peak) (See Fig. 27.1)

 

[Drakkith]

I believe it is because an alpha particle is much more massive than an electron and also has much more momentum after being ejected from the nucleus than an electron typically has.