BARIUM TITANATE TRANSDUCER (UT): (Polycrystalline Barium Titanate BaTiO3). A ceramic material
composed of many individual crystals fired together, and polarized by the application of a D.C. field for use as a
BARK: The decarburized layer just beneath the scale that results from heating steel in an oxidizing atmosphere.
BARN (RT): A very small unit of area used in measuring the cross sections of atoms, nuclei, electrons, and other
particles. One barn is equal to 10-24 square centimeter. The term is a measure of the probability that a given nuclear
reaction will occur.
BARRIER (PROTECTIVE) (RT): Barrier of attenuating materials used to reduce radiation exposure.
BASE DENSITY (RT): The slight density that is due only to the film base and the blue dye in it. It is measured with
the emulsion layer removed, or on a film which has been fixed without prior development.
BASE PLUS FOG (RT): The density of a films base material plus the darkening of its emulsion caused by fog. The
base plus fog level brings no useful information to the film and merely creates a high background that reduces contrast
and image visibility.
BASELINE (UT): The horizontal trace across the A-scan CRT display for a no signal condition.
BATH (colloquial) (PI, MT):
The liquid penetrant inspection materials (penetrant, emulsifier, developer) into which parts are immersed
during the inspection process.
Penetrant materials retained in bulk in immersion tanks intended for re-use.
Term used to designate a suspension of ferromagnetic particles with oil or water.
BEAM: A directed flow of energy into space or matter.
BEAM ANGLE (RT): The smallest angle between the central axis of the radiation beam and the plane of the
BEAM DIVERGENCE (RT): The solid angle of the beam of radiation as it emerges from the X-ray tube or gamma-ray
BEAM QUALITY (RT): An expression used to describe the penetrating power (energy spectrum) of a beam of
radiation. The quality of an X-ray beam is usually expressed in terms of the half-value layer of some reference
material, such as aluminum or copper.
BEAM SPREAD (UT): Divergence of a sound beam as it travels through material.
BERNOULLI EFFECT (PT): A law of hydrodynamics: a liquid will flow through a conduit at a constant velocity
governed by the pressure. When a section of the conduit is decreased in size, the velocity of the liquid flow in the
reduced section is increased. If a small opening is placed in the reduced section, a vacuum or suction will be created at
BETA PARTICLE (RT): An electron or positron emitted from a nucleus during decay. The term beta particle is
reserved for electrons and positrons.
BETA RAY (RT): A stream of high speed electrons that is of nuclear origin. This radiation is more penetrating than
alpha radiation, but it ionizes less strongly.