| The range of the phosphorus P32 beta particle, which has a maximum energy of 1.71 MeV, is 2.8 mm of aluminium. |
| Next smaller in mass is the beta particle, which is identical in mass and charge to an electron. |
| Adding a neutron, which has one unit of mass, to 238 U gives 239 U, which decays rapidly to a new element by emitting a beta particle. |
| The weak nuclear force is involved, and the neutron is converted into a proton when the beta particle is emitted. |
| During this process the nucleus expels a negative beta particle as radiation. |
| When a nucleus ejects a beta particle, one of the neutrons in the nucleus is transformed into a proton. |
