- In nuclear physics, irradiation is the exposure of a sample or object to nuclear or short-wavelength electromagnetic radiation, usually for a definite
purpose. Biological and pharmaceutical materials may have their properties
altered by exposure to ultraviolet radiation; X-rays are widely used in medicine and
industry. Materials may be irradiated directly with radiation of a given
type and energy by placing them in a particle accelerator or nuclear reactor, but it is
often more practical to use the radiation from manufactured radioactive isotopes to change their physical and
chemical properties as required. Neutrons and gamma rays are used to sterilize
foodstuffs and control the reproduction of insect pests.
The outer layers of a supernova are
irradiated by neutrons produced as the core collapses to form a neutron
star; these neutrons react with atomic nuclei to form heavier elements.
See also ionizing radiation.
AND NUCLEAR PHYSICS
- In optics, irradiation is an effect of contrast that
makes bright objects viewed against a dark background appear to be larger
than they really are.