T.O. 33B-1-1
Glossary 47
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A casting made by the process.
ION (RT): An ion is an atom or group of atoms that is not electrically neutral but instead carries a positive or negative
electric charge. Positive ions are formed when neutral atoms or molecules lose valance electrons; negative ions are
those which have gained electrons.
ION PAIR (RT): A positive ion and a negative ion or electron having charges of the same magnitude, and formed
simultaneously from a neutral atom or molecule with energy supplied by radiation or any other suitable source.
ION PAIRS: A positive ion and a negative ion or electron having charges of the same magnitude, and formed from a
neutral atom or molecule by the action of radiation or by any other agency that supplies energy.
ION SOURCE (ION GUN) (RT): A device by which gaseous ions are produced, focused, and accelerated, and are
emitted as a narrow beam.
IONIC (RT, PT): Relating to, existing in the form of, or characterized by ions.
IONIZATION: The process of adding electrons to, or knocking electrons from, atoms or molecules, thereby creating
ions. High temperatures, electrical discharges, and nuclear radiation can cause ionization.
IONIZATION CHAMBER: An instrument that detects and measures ionizing radiation by observing the electrical
current created when radiation ionizes gas in the chamber, making it a conductor of electricity.
IONIZING RADIATION: Any radiation that directly or indirectly displaces electrons from the outer domains of atoms.
Examples: alpha, beta, and gamma radiation.
IQI SENSITIVITY (RT): The sensitivity (quality level) of a radiographic process, as determined by the use of an image
quality indicator (IQI). Properly called radiographic sensitivity.
IRIDIUM-192: A radioactive isotope of the element Iridium that has a half life of 75 days. It is used extensively as a
source of gamma radiation.
IRRADIATION: Exposure to radiation, as in a nuclear reactor.
ISOMER: One or two or more nuclides having the same atomic number, but existing for measurable time intervals in
different quantum states, with different energies and radioactive properties.
ISOMER (RT): One of two or more nuclides that are both isotopes (same atomic number) and isobars (same mass
number) of each other, but which have some measurably different physical property, such as half life.
ISOMERIC TRANSITION (RT): The transition of an isomer to a lower energy state. It is accompanied by the
emission of gamma radiation that may be internally converted.
ISOTOPE (RT): One of several nuclides having the same number of protons in their nuclei, and hence belonging to the
same element, but differing in the number of neutrons, and therefore in mass number. Small quantitative differences in
chemical properties exist between elements and isotopes. Isotopes may or may not be unstable. Unstable isotopes
undergo transitions to other isotopes or elements with a loss of energy. Such energy is usually given off in the form of
electromagnetic or particle radiation. Isotopes are used as source of radiation for radiography.
ISOTROPY: Quality of having identical properties in all directions.
ITEMS: An item is one of the compounds necessary to make up a family of penetrant materials. For example:
penetrant, emulsifier, remover, or developer.
