Glossary cont'd - hdbk11080140

DOE-HDBK-1108-97

Radiological Training for Accelerator Facilities

Student's Guide

GLOSSARY (continued)

Fail-Safe: A design feature built into a system or system component so that the most likely mode of

failure causes the production of X-rays to be turned off. If fail-safe design is not possible or cost-

effective, the system or system component should be designed so that no single failure will cause unsafe

operation.

Interlock: A safety device that automatically renders an area safe from prompt radiation when the device

is actuated.

Linear accelerator: A device that accelerates charged particles along a straight line.

Mixed Waste: Waste containing both radioactive and hazardous components as defined by the Atomic

Energy Act and the Resource Conservation and Recovery Act, respectively.

Muon: An elementary particle apparently identical to the electron except for being 200 times heavier.

Neutron: Elementary particle with a mass approximately the same as that of a hydrogen atom and

electrically neutral.

Nucleus: The small, central, positively charged region of an atom that carries essentially all the mass.

Pion: A cosmic particle with a mass about 273 times that of an electron and a half-life of 2/100,000,000

(2 x 10-8) of a second. Positive, negative, and neutral pions exist.

Primary Beam: Radiation that passes through the window, aperture, cone, or other collimating device of

the source housing. Sometimes called useful beam.

Prompt radiation: Radiation resulting from the accelerator beam or the interaction of the accelerator

beam with surrounding matter that ceases shortly after the beam is removed. Activation products and

area contamination are not considered prompt radiation.

Proton: An elementary nuclear particle with a positive electric charge and an atomic weight of

approximately one.