 [R]- R Symbol for the roentgen.
- RABBIT A small container propelled pneumatically or hydraulically through a tube leading between the laboratory and a location in a nuclear reactor or other device where irradiation of a sample can take place.
- RAD A unit of absorbed dose. (Not a SI unit.) 1 rad is 0.01 J absorbed per kg of any material. 1 rad =.01 gray). NCRP. RADIATION A term embracing electromagnetic waves as well as fast moving particles.
- RADIATION, ANNIHILATION See annihilation radiation.
- RADIATION, BACKGROUND See background radiation.
- RADIATION, CERENKOV See Cerenkov radiation.
- RADIATION CHEMISTRY That part of chemistry which deals with the chemical effects of ionizing radiation , as distinguished from photochemistry associated with visible and ultraviolet electromagnetic radiation.
- RADIATION COUNTER See counter, radiation.
- RADIATION DETECTOR See detector, radiation.
- RADIATION EFFECTS Any of several effects brought about by the interactions of radiation with matter; effects such as radiolysis, ionization , excitation, and defect formation.
- RADIATION, HARD See hard radiation.
- RADIATION HAZARD Hazard that exists in a region where there is a radiation field, other than what is considered to be normal background radiation.
- RADIATION INACTIVATION METHOD A method for estimating protein size based on the correlation between the radiation dose applied and the amount of protein activity surviving the dose. { Anal. Bioch. ~May 1990.}
 RADIATION, IONIZING See ionizing radiation.- RADIATION LENGTH The distance traveled by a charged particle through matter over which its energy is decreased by a factor e.
- RADIATION, MONOENERGETIC See monoenergetic radiation.
- RADIATION, NATURAL Radiation originating from natural radioactivity.
- RADIATION, PENETRATING Gamma-rays, x-rays or neutrons with low interaction cross sections.
- RADIATION, SOFT See soft radiation.
- RADIATION SOURCE An apparatus or material emitting or capable of emitting ionizing radiation.
- RADIATION SPECTRUM The components of radiation arranged in order of their wavelengths, frequencies or quantum energies. For particle radiation they are arranged in order of their kinetic energies.
- RADIATIVE CAPTURE See capture, radiative.
- RADICAL A molecular entity possessing an unpaired electron such as €CH3, €SnH3, €Cl (or Cl€). (In these formulae the dot, symbolizing the unpaired electron, should be placed so as to indicate the atom of highest spin density, if this is possible.) Paramagnetic metal ions are not normally regarded as radicals. C.
- RADIOACTIVE The property of unstable nuclides of undergoing spontaneous nuclear transformations with the emission of radiation.
- RADIOACTIVE AGE Of an object, the time, estimated from measurement of the isotopic composition, during which the content of a radioactive species within that object has remained unchanged except for nuclear decay.
- RADIOACTIVE CHAIN See decay chain.
- RADIOACTIVE CONTAMINATION A radioactive substance in a material or place where it is undesirable.
- RADIOACTIVE COOLING See cooling, radioactive.
- RADIOACTIVE DATING See dating, radioactive.
- RADIOACTIVE DECAY See decay, radioactive.
- RADIOACTIVE EQUILIBRIUM See equilibrium, radioactive.
- RADIOACTIVE FALLOUT See fallout, radioactive.
- RADIOACTIVE HALF-LIFE See half-life, radioactive.
- RADIOACTIVE INDICATOR See indicator, radioactive.
- RADIOACTIVE PERIOD See radioactive mean life.
- RADIOACTIVE SERIES See decay chain.
- RADIOACTIVE SOURCE Any quantity of radioactive material which is intended for use as a source of ionizing radiation.
- RADIOACTIVE TRACER A tracer containing a radioactive label.
- RADIOACTIVE TRACER TECHNIQUE In analysis: a technique for investigating recovery, loss, behavior, and speciation of a microcomponent, in which a radioactivelylabeled element or compound chemically identical with the microcomponent is added to the sample, and its behavior is followed by radioactivity measurements.
- RADIOACTIVE WASTE Unwanted radioactive materials obtained in the processing or handling of radioactive materials.
- RADIOACTIVITY The property of certain nuclides of showing radioactive decay.
- RADIOACTIVITY, ARTIFICIAL See induced radioactivity.
- RADIOACTIVITY, INDUCED See induced radioactivity.
- RADIOACTIVITY, NATURAL See natural radioactivity.
- RADIOALLERGO(AD)SORBENT TEST (RAST) An isotopic technique for the demonstration of reagins (a class of antibody) directed against specific allergens. B
- RADIOANALYTICAL CHEMISTRY That part of analytical chemistry in which the application of radioactivity is an essential step in the analytical procedures. Synonymous with analytical radiochemistry. See analytical radiochemistry.
- RADIOANALYTICAL PURIFICATION See radiochemical purification.
- RADIOANALYTIC IMAGING A technique of separation and analysis of reaction products from a radiolabeled starting material. The products are separated by thin layer chromatography using an autoradiograph to quantitatively and qualitatively visualize the results. The technique can be used to study photodegradation, for example. { W. Fostiak et al. Am. Env. Lab. (Feb. 1991) 10}
- RADIOAUTOGRAPH See autoradiograph.
- RADIOCHEMICAL PURIFICATION Chemical separation applied to a radioactive preparation in order to improve the radiochemical purity.
- RADIOCHEMICAL PURITY See purity, radiochemical.
- RADIOCHEMICAL SEPARATION Separation by a chemical means of the radioactive isotopes of (a) specified element(s) from a mixture of isotopes.
- RADIOCHEMICAL YIELD 1. For the isotopes of a specified element, the yield of a radiochemical separation , expressed as a fraction of the activity originally present. Also called the recovery. 2.) In radiation chemistry, the number of species transformed by radiation per eV of absorbed energy: represented by the symbol G, the G-value.
- RADIOCHEMISTRY That part of chemistry which deals with radioactive materials. It includes the production of radionuclides and their compounds by processing irradiated or naturally occurring radioactive materials, the application of chemical techniques to nuclear studies, and the application of radioactivity to the investigation of chemical, biochemical or biomedical problems.
- RADIOCHEMISTRY, ANALYTICAL That part of analytical chemistry in which the application of radioactivity is an essential step in the analytical procedures. Synonymous with radioanalytical chemistry.
- RADIOCHROMATOGRAM A graphical or other representation of a radiation detector response as a function of time produced by chromatographic separation of a mixture of radioactive species.
- RADIOCHROMATOGRAPH A measuring assembly designed to measure the spatial or time distribution of the activity of a mixture of radioactive components after separation by a chromatographic method.
- RADIOCOLLOID A radioactive substance in colloidal form. The radioactivity usually has little effect on the physicochemical properties of the colloid. See also pseudoradiocolloid.
- RADIOECOLOGY The scientific discipline dealing with the migration, transfer, and concentration of radionuclides in the environment and with the effect of environmental radioactivity on living organisms.
- RADIOELEMENT An element having no stable isotope. Also used to indicate an element which is naturally radioactive. NM.
- RADIOENZYMATIC ASSAY An assay of the enzymatic activity of a substance based on the use of a radioactive substance.
- RADIOEXCHANGE An exchange reaction in which one of the exchanging species is radioactive.
- RADIOGENIC Resulting from radioactive decay, usually in reference to natural products such as lead.
- RADIOGRAPH A visual representation of an object produced by placing the object between a source of ionizing radiation and a photographic plate or film.
- RADIOGRAVIMETRIC ANALYSIS An analytical procedure in which the activity of a precipitate is used as a measure of its mass.
- RADIOIMMUNOASSAY An analytical procedure based on the reversible and noncovalent binding of an antigen (hapten) by a specific antibody employing radioactively labeled antigen (hapten) to measure the fraction of the antigen (hapten) bound to a substoichiometric amount of antibody.
- RADIOIMMUNOASSAY, SOLID PHASE ANTIBODY Method of radioimmunoassay employing an antibody bound to a solid phase.
- RADIOIMMUNOELECTROPHORESIS Immunoelectrophoresis in which either the antibodies or antigens are radioactively labeled. B.
- RADIOIODINATION The process of incorporating the radionuclides of iodine (usually 125I, 131I or 123I) in, or of covalently linking a radioiodinated substance to, a substance.
- RADIOISOTOPE A radioactive isotope of a specified element.
- RADIOISOTOPE DILUTION ANALYSIS A method of isotope dilution analysis making use of a radionuclide.
- RADIOISOTOPE GENERATOR A system in which a long-lived radioisotope is permanently bound and decays to a shorter-lived daughter radioisotope that may be chemically removed or eluted. The latter process is referred to as milking the generator. The radioisotope generator is colloquially termed a "cow". KE.
- RADIOLIGAND Radioactive ligand
- RADIOLUMINESCENCE Light emissions caused by radiations from radioactive materials. NM.
- RADIOLYSIS The chemical decomposition of materials by ionizing radiation.
- RADIOMETRIC ANALYSIS A method of analysis in which measurement of the activity is an essential step.
- RADIOMETRIC ASSAY A non- competitive binding assay in which the receptor is labeled instead of the ligand. Synonymous with immunoradiometric assay. KE.
- RADIOMETRIC TITRATION A titration in which a radioactive indicator is used to monitor the end-point of the titration.
- RADIONUCLIDE A nuclide that is radioactive.
- RADIONUCLIDIC PURITY See purity, radionuclidic.
- RADIOPHARMACEUTICAL A radioisotopically labeled pharmaceutical.
- RADIOPHARMACOLOGY The study of the preparation and properties of radioactive drugs and their therapeutic and diagnostic uses.
- RADIOPOLAROGRAPHY A tool for studying electrochemical phenomena in which labeled ions are reduced polarographically and the resulting drop is counted. The radioactivity of a given number of drops is proportional to the amount of the element deposited and also to the current. It is a low concentration technique. KE.
- RADIOREAGENT Reagent labeled with radioactivity. KE.
- RADIORELEASE ANALYSIS An analytical procedure based on the release of radioactivity from the reagent by reaction with the analyte.
- RADIORECEPTOR ANALYSIS See radioreceptor assay.
- RADIORECEPTOR ASSAY Competitive binding assay employing a receptor protein that is not an antibody.
- RADIOTHERMOLUMINESCENCE The reappearance of luminescence in radioluminescent materials brought about by heating. Quartz and certain types of glass show the effect. NM.
- RADIOTOXICITY The ability of a substance to give rise to adverse biological toxic effects as a result of the ionizing radiation it emits. NM.
- RADIOTRACER TECHNIQUE See radioactive tracer technique.
- RADWASTE Radioactive waste.
- RAFFINATE In solvent extraction between an organic phase and an aqueous phase, the aqueous phase after equilibrium has been established. Ch.
- RANDOM COINCIDENCE See coincidence, random.
- RANGE The distance from a radiation source to the point where the flux density has vanished. A more explicit term is the mean linear range.
- RANGE, EXTRAPOLATED See extrapolated range.
- RANGE, MEAN LINEAR In a given material, for specified charged particles of a specified energy, the average displacement of the particles before they stop.
- RANGE, MEAN MASS The mean linear range multiplied by the mass density of the material.
- RANGE, RESIDUAL The penetration depth of a charged particle yet remaining to be traveled before the particle is stopped in the material.
- RANGE-ENERGY RELATION The dependence of the mean linear range of a charged particle in a particular substance on the particle's initial energy.
- RANGE STRAGGLING The stochastic dispersion of displacement (range) of charged particles about their mean linear range.
- RARE EARTH See lanthanide.
- RAST See radioallergosorbent test.
- RATEMETER An electronic sub-assembly which gives a continuous indication proportional to the average counting rate over a predetermined time interval (time constant).
- RBE Relative biological effectiveness.
- RBS Rutherford backscattering spectroscopy.
- RCP Radiochemical purity.
- REACTION, NUCLEAR A transmutation or nuclear excitation induced by radiation from an external source.
- REACTION ENERGY See Q-value.
- REACTION CHAIN ACTIVATION See secondary particle activation analysis.
- REACTOR, NUCLEAR A device in which a self-sustaining nuclear fission chain reaction can be maintained and controlled. The term is sometimes applied to a device in which a nuclear fusion reaction can be produced and controlled.
- RECEPTOR A chemical compound on a cell membrane or in a cell that binds other chemicals. NM.
- RECOIL The motion acquired by a particle through a collision with or the emission of another particle or electromagnetic radiation.
- RECOIL ATOM The atom struck by a particle with which it is has undergone either elastic or inelastic scattering or reaction, or an atom or ion remaining after a radiation has been emitted.
- RECOVERY In trace analysis: the yield of a preconcentration step expressed as quantities of the concentrated component. C. See also yield, radioactive.
- REE Rare earth element(s); that is, lanthanides.
- REFERENCE MATERIAL A homogeneous material, available in sufficient amounts, which can be used for comparing analysis results obtained at different laboratories and/or with different techniques.
- RELATIVE ATOMIC MASS See atomic mass, relative.
- RELATIVE BIOLOGICAL EFFECTIVENESS The ratio of the appropriate value of the biological effectiveness of the radiation in question to that of x-radiation with an average specific ionization of ion pairs per micron of water, for the particular biological effect under consideration and for the condition under which the radiation is received.
- RELATIVE COUNTING A measurement in which the activity of a sample is derived from the ratio between the count rates observed for the sample and for a source of known activity.
- REM See Roentgen equivalent man.
- RESOLUTION The use of the word resolution should be restricted to peak resolution. The concept should be distinguished clearly from that of resolving power , which should be restricted to instruments. The resolving power of an instrument used in an analytical procedure may well have its impact on the selectivity of the overall procedure. C.
- RESOLUTION ENHANCER 1.) Detector designs that reduce degradation of resolution by compensating for ballistic effects) or charge trapping , for example. 2.) Mathematical procedures, usually called "filters", for improving the ability to accurately resolve close peaks.
- RESOLVING POWER The central position of the response curve of a spectrometer of monoenergetic radiation divided by the width at one half of its height. Sometimes the width at the 1/eth of its height, sometimes the inverse of the above definition is used.
- RESOLVING TIME The smallest time interval which must elapse between the occurrence of two consecutive ionizing events or signal pulses, in order that the measuring device be capable of detecting each of them separately.
- RESOLVING TIME, COINCIDENCE See coincidence resolving time.
- RESOLVING TIME CORRECTION Correction to be applied to the observed number of pulses in order to take into account the number of pulses lost during the resolving time.
- RESONANCE The enhancement of the response of a system to a periodic driving force when the driving frequency is equal to a natural frequency of the system. For nuclear systems, this manifests itself as a particular reaction having a cross section maximum.
- RESONANCE ENERGY The energy of a particle entering a nuclear reaction, this energy being just sufficiently high to lead to the formation of reaction products in one of their excited states.
- RESONANCE INTEGRAL The integral, over all or some specified portion of the resonance energy range, of the cross section divided by the energy of a radiation.
- REST MASS The mass of a particle in its ground state and at rest. It represents the Newtonian mass and does not include the additional mass acquired by a particle in motion due to the relativistic effect.
- RETENTION Of atoms undergoing a nuclear transformation , that fraction which remains in or reverts to its initial chemical form.
- REVERSED PHASE CHROMATOGRAPHY A term of historical interest in liquidliquid chromatography referring to an elution procedure in which the stationary phase is non-polar, e.g. paper treated with hydrocarbons or silicones. C.
- RIA Radioimmunoassay
- RNAA Radiochemical neutron activation analysis. See activation analysis, radiochemical.
- ROENTGEN A unit of exposure. 1 roentgen = 1 R = 2.58 X 10-4 C/kg. (Not a SI unit.
- ROENTGEN EQUIVALENT MAN (rem) A unit of dose equivalent which depends on linear energy transfer and a quality factor. (Not a SI unit.) 1 rem =.01 J/kg = 1 rad X quality factor. 1 rem = 0.01 sievert (Sv).
- RRA Radioreceptor analysis.
- RSMR Rayleigh scattering of Mössbauer resonance.
- RUTHERFORD An obsolete unit of activity equal to 106 disintegrations per second. NM.
- RUTHERFORD SCATTERING OR RUTHERFORD BACKSCATTERING SPECTROSCOPY Any technique using high-energy particles directed toward a sample, in which the bombarding particles, after scattering, are detected and recorded as a function of energy and/or angle. The technique is mostly used for determining the depth distributions of elements based on the energy of the backscattered particle. C.
|
