An alpha particle is essentially a helium nucleus; two protons and two neutrons held together by strong nuclear forces. Alpha particles are emitted when large unstable nuclei undergo alpha decay to become smaller and more stable. Alpha radiation is highly ionising, although the radiation can not pass through the barrier of skin, so inhalation or consumption of the radioactive source are the main causes of harm from alpha particle emission.
- ↑ Breithaupt J. AQA physics A A2: student’s book. UK: Nelson Thornes. 2008.