Alpha radiation is made up of a stream of alpha particles emitted from unstable nuclei within a radioactive substance. An alpha particle is also a helium-4 nucleus.

Darmstadt team member Stefan Typel has calculated that alpha particles should form in the neutron-rich skins of heavy nuclei. Now, his prediction has been confirmed by his colleagues who used the 392 ...

For example lead, lead-206 has 82 protons and has 124 neutrons. Nuclei with too many, or too few, neutrons do exist naturally but are unstable and will disintegrate (or decay) by emitting radiation.