 [B]- BACKGROUND The term employed to designate the value indicated by a radiation measuring device in the absence of the source whose radiation is to be measured, when the device is placed under its normal conditions of operation.
- BACKGROUND RADIATION Radiation from any source other than the one to be detected or measured.
- BACK EXTRACTING See stripping.
- BACKSCATTER Scattering of radiation in a generally backward direction. In the assay of radioactivity , it applies to the scattering of radiation into the radiation detector from any material except the sample and the detector.
- BACKWASHING In an ion-exchange column, an upward flow of eluant through the resin bed serving to clean and reconstitute the exchanger bed. M. BADGE A dosimeter that is clipped onto clothing or worn as a "ring" on the finger and which is later processed to quantify exposure to radiation.
- BALLISTIC DEFICIT In proportional counters , when pulses are shaped using time constants adjusted so that the slow component of the drift of ions do not contribute to the pulse amplitude, the shaped pulse has a lower amplitude than that corresponding to an infinite time constant by an amount known as the "ballistic deficit".
- BARN A unit of area used in expressing nuclear cross sections : 1 barn = 10-28m2.
- BATCH PROCESS A process, particularly in reference to separations, that is not continuous and which is conducted with discrete quantities of materials or a limited number of reagents. M.
- BATEMAN EQUATIONS The set of coupled differential equations that expresses the amounts of reactants and products as a function of time as these species are undergoing both production and loss by nuclear reaction and radioactive decay.
- BEAM Collimated radiation for the purpose of irradiation.
 BEAM CURRENT In a charged particle accelerator, the electric current determined by the number, velocity, and charge of the particles.- BEAM DUMP See beam stop.
- BEAM HOLE In a reactor, a hole through the shielding which allows a beam of radiation, especially fast neutrons, to escape. M.
- BEAM MONITORING Measuring the intensity or energy flux density of a beam.
- BEAM STOP Material at the end of a beam placed there to completely stop and absorb the remaining beam particles.
- BEAM TRAP See beam stop
- BECQUEREL SI unit of activity or nuclear transition rate equal to one per second (symbol 1 Bq). Caveat illustration: The activity of 1 nanomole of 40K (half life = 1.25 X 109 years) would be approximately 10.5 Bq but the gamma activity of that same nanomole would be only 1.13 Bq because only 10.7% of 40K's decays involve a gamma branch. To avoid ambiguity, the latter should be referred to as 1.13 gamma Bq.
- BETA DECAY Nuclear decay in which a beta particle is emitted or in which orbital electron capture occurs.
- BETA EMITTER An atom or nucleus which undergoes radioactive decay by emitting a beta particle (b) and an antineutrino or neutrino. The former accompanies a b- and the latter a b+.
- BETA PARTICLE A negative or positive electron which has been emitted by a nuclear particle in a nuclear transformation.
- BGO DETECTOR A solid scintillation detector material based on bismuth germanate.
- BETA STABILITY LINE On a graph of neutron number or of mass number vs atomic number and displaying one or more properties of each nucleus, the locus of stable nuclei. (Synonym: Segre curve)
- BIASED LINEAR PULSE AMPLIFIER See amplifier, biased linear pulse.
- BI-ISOTOPIC MONITOR The use of 95Zr and 97Zr for determination of the thermal to epithermal neutron flux ratio by activation analysis.
- BIFUNCTIONAL CHELATE Complexing agent with two sites for complexation. NM.
- BINDING In competitive radioassay , the reactive forces between ligand and binding agent describable by the mass action law and measurable by the fraction of reagent tracer bound in the ligand-binding agent complex. NM.
- BINDING AGENT In competitive radioassay , the test reagent chosen, most commonly antibody, to react specifically with the substance under test via mass action, reversible reaction. NM.
- BINDING CAPACITY The amount of specific binding sites available per quantity of binding reagent. The extrapolated point of the X-axis of a Scatchard plot performed under defined conditions. NM.
- BINDING ENERGY The energy necessary to break a nucleus into specified constituents; the total binding energy is the energy requirement to disassemble the nucleus entirely into protons and neutrons.
- BIOCONJUGATE An agent (usually a chelate used to conjugate radionuclide to an antibody.
- BIOLOGICAL HALF-LIFE For a substance the time required for the amount of that substance in a biological system to be reduced to one half of its value by biological processes, when the rate of removal is approximately exponential.
- BNCT Boron neutron capture therapy.
- BOILING WATER REACTOR A nuclear power reactor with enriched 235U fuel and boiling light water as moderator and coolant.
- BOLUS A contiguous mass, such as a medically administered dose of labeled compound.
- BOMBARDMENT Irradiation in a beam of particles or photons.
- BORON CARBIDE FILTER In epithermal neutron activation analysis , a thickness of boron carbide (B4C) that is used instead of the more usual cadmium filter which is used to achieve the cadmium cutoff. In this way, one may avoid the induced activity that grows into the cadmium with use.
- BORON CHAMBER An ionization chamber that is lined or filled with boron or boron compounds. M.
- BORON NITRIDE FILTER In epithermal neutron activation analysis , a thickness of boron nitride (BN) can replace the more usual cadmium filter used to achieve the cadmium cutoff. In this way, one may avoid the induced activity that grows into the cadmium with use.
- BOWEN'S STANDARD KALE A reference material for the analysis of plant materials with known concentration values and ranges for a group of macroelements (Na, K, Ca, Mo, O, P, S, N, and Cl) as well as 30 trace elements. HRC. Bq The symbol for the becquerel unit of activity of a radioactive substance.
- BRAGG CURVE A graph of specific ionization due to a charged particle passing through a material as a function of the penetration depth of that particle relative to its range; that is, as a function of its residual range. FFKM.
- BRAGG PEAK A peak in a Bragg curve showing that the amount of ionization per millimeter of tissue or other stopping medium traversed by charged particles increases sharply as the particles slow down near the ends of their tracks. NM.
- BRAGG RULE The mass stopping power of a compound or mixture for charged particles is approximately given by the weighted sum of the stopping powers of all the components atoms. FFKM.
- BRANCHING DECAY Nuclear decay which can proceed in two or more different ways.
- BRANCHING FRACTION In branching decay the fraction of nuclei which decay in a specified way.
- BRANCHING PROBABILITY See branching fraction.
- BRANCHING RATIO The ratio of the branching fraction for two or more specified modes of decay.
- BREIT-WIGNER FORMULA A formula describing the rapidly varying cross section for a nuclear reaction in the vicinity of one or more resonances. NM + FKMM.
- BREMSSTRAHLUNG The electromagnetic radiation associated with the acceleration or deceleration of charged particles in the presence of a Coulomb field.
- BREMSSTRAHLUNG, INNER Bremsstrahlung which may accompany the emission or absorption of a charged particle by a nucleus.
- BUILD-UP FACTOR In the passage of radiation through a medium, the ratio of the total value of a specified radiation quantity at any point to the contribution to that value from radiation reaching the point without having undergone a collision. NM.
- BURIAL GROUND A place for burying unwanted radioactive objects to prevent their escape or escape of their radiations. M.
- BURN-UP Induced nuclear transformation of atoms during reactor operation.
- BURN-UP FRACTION The fraction of an initial quantity of a given nuclide that has undergone burn-up.
- BURN-UP, SPECIFIC The total energy released through induced nuclear transformations divided by the mass of a nuclear fuel.
- BURST A sudden increase or appearance of particles or fragments emitted, of short duration, as in a nuclear bomb explosion.
- BWR See boiling water reactor.
- BY-PRODUCT Any radioactive material (except special nuclear material) yielded in or made radioactive by exposure to the radiation incident to the process of producing or utilizing special nuclear material. The tailings or waste products produced by the extraction or concentration of uranium or thorium from any ore processed primarily for its source material content. NM.
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