Particle radiation is the radiation of energy by means of small fast-moving particles that have energy and mass.

Particle radiation can be emitted from within an unstable atomic nucleus (radioactive decay) in the form of a positively charged Alpha particle (α), a positively or negatively charged (the latter being more common) Beta particle (β), or a neutron. Other forms of particle radiation include neutrons, positrons and neutrinos.

Cosmic rays are subatomic particles falling naturally on the Earth. Most originate in the Sun and are part of the solar wind.

Radiation is often separated into two categories, ionizing and non-ionizing, to denote the energy and danger of the radiation. Ionization is the process of removing electrons from atoms, leaving two electrically charged particles (an electron and a positively charged ion) behind. The negatively charged electrons and positively charged ions created by ionizing radiation may cause damage in living tissue. The term radioactivity generally refers to the release of ionizing radiation.

See also

• radioactivity
• radiation
• physics
• nuclear physics
• nuclear engineering
• radiation therapy