Alpha, beta and gamma radiation are produced when a nucleus decays. Their properties are summarised in the following table.
| Property | Alpha | Beta | Gamma |
| Nature | Helium Nucleus - two protons and two neutrons | Fast moving electron | Energetic photon |
| Effect on photographic film | Yes | Yes | Yes |
| Approximate number of ion – pairs produced in air per mm |
|
| 1 |
| Typical material needed to stop it | 0.01 mm thickness of aluminium Piece of paper Few cm air | A few mm aluminium | 10 cm lead |
| Penetration ability | Low | Medium | High |
| Typical path length in air | A few cm. Alpha paprticles have the important proprty that most energy is lost at the end of the path - this is useful in the treatment of cancer. | Less than 1 m | Infinity |
| Deflection by magnetic or electric fields | Deflected since positively charged | Deflected since negatively charged | No deflection |
| Speed | About | About |
|
| Typical energy, eV | About 5 MeV | A few KeV to a few MeV | A few keV |
| Mass, kg |
|
| 0 |
but very variable
