Half-Angle Beam Spread:

Calculates the half-angle beam spread “Φ” for a given velocity “V”, frequency “F”, transducer diameter “D”, and “K”is constant.Beam spread is a measure of the whole angle from side to side of the main lobe of the sound beam in the far field. Beam divergence is a measure of the angle from one [...]

Narrow Banded - A relative term denoting a restricted range of frequency response.

Natural Frequency - The frequency at which an object will vibrate freely when set in motion.
Naturally Occurring Radiation - cosmogenic (extraterrestrial) and terrestrial radiation with an activity [...]

Occupational Dose - Includes exposure of an individual to radiation (1) in a restricted area; or (2) in the course of employment in which the individual’s duties involve exposure to radiation; provided, the “occupational dose” [...]

Pair Production - An absorption process for X and gamma radiation in which the incident photon is annihilated in the vicinity of the nucleus of the absorbing atom, with subsequent production of an electron and [...]

Quantum - If the magnitude of a quantity is always an integral multiple of a definite unit, then that unit is called the quantum of the electromagnetic field and the meson is considered to be the quantum of the nuclear field.

Quantum Mechanics - A system [...]

Rad - radiation absorbed dose. The basic unit of absorbed dose of ionizing radiation. One rad is equal to the absorption of 100 ergs of radiation energy per gram of matter.

Radial - In the direction of a radius between the center and the surface of [...]

Safelight - A special lamp used in the darkroom to provide working visibility without affecting the photosensitive emulsion of the radiographic film.

Samarium 145 - A radioisotope of the element samarium.
Saturation (Magnetic) - A condition where incremental magnetic permeability [...]

Tangential - See circumferential.

Target - A material bombarded by any radiation, as the target is bombarded by electrons in an x-ray tube.

Temporary Magnet - A body of a soft steel or piece of iron which is readily magnetized but [...]

UT - Abbreviation for the ultrasonic method of nondestructive testing.

Ultrasonic - A term referring to acoustic vibration frequencies greater than about 20,000 hertz.

Ultrasonic Absorption - The damping of ultrasonic waves as they pass through a medium. See attenuation coefficient.

Ultrasonic [...]

V-Path - In angle beam tests of plate or cylindrical sections, the path of the ultrasonic beam in the test object from point of entry on the front surface to the back surface and reflecting to the front surface again. See also skip distance.

Valence Shell [...]