 [E]- EC Electron capture (q. v.)
- ECD See electron capture detector.
- EDTA A metal chelating agent , ethylenediaminetetraacetic acid.
- EDXRF See energy dispersive x-ray fluorescence analysis.
- EFFECTIVE CADMIUM CUT-OFF (ENERGY) In a given experimental configuration, the energy value determined by the condition that the detector response would be unchanged if the cadmium cover surrounding the detector was replaced by a fictitious cover opaque to neutrons with energy below this value and transparent to neutrons with energy above this value.
- EFFECTIVE THERMAL CROSS-SECTION See cross section, effective thermal.
- EFFICIENCY (OF A COUNTER) See counting efficiency.
- EFFICIENCY, INTRINSIC See detector efficiency, intrinsic.
- EFFLUENT, RADIOACTIVE Any solid, liquid or gaseous radioactive waste material discharged from a system.
- EKA Prefix to an element indicating another element in the same column but one row lower in the periodic table having the light elements located at the top. Derived from the Sanskrit word for "one". This nomenclature scheme has been used historically for designating new, or unknown elements. Thus, gallium was eka-aluminum; element 118 would be eka-radon.
- ELASTIC RECOIL DETECTION ANALYSIS A type of ion beam analysis and Rutherford backscattering spectroscopy in which an ion beam strikes a sample at a grazing angle and recoiling ions are detected. The technique is used for depth profiling, particularly for light-elements in a heavy matrix. C.
- ELASTIC SCATTERING See scattering, elastic.
- ELECTRODEPOSITION A method of thin sample preparation in which an electric current is used to deposit sample material.
 ELECTROMAGNETIC RADIATION Electromagnetic waves and the associated energy; photons.- ELECTROMETER A device for measuring electric charges or electric currents.
- ELECTRON A stable elementary particle having an electric charge of ±1.60219 X 10-19 C and a rest mass of 9.1095 X 10-31 kg. When used without specification the term means the negatively charged electron, which is also called the negatron. Its anti-particle , the positively charged electron, is called positron.
- ELECTRON, AQUEOUS A hydrated electron; an electron solvated by water molecules. M.
- ELECTRON ACCELERATOR An accelerator in which the beam particles are electrons
- ELECTRON CAPTURE See capture, electron.
- ELECTRON CAPTURE DETECTOR 1.) A very sensitive detector for the presence of certain classes of molecules, most notably chlorine-containing molecules. It is based on a steady current produced by a long-lived beta-emitter and the measurable perturbations in that current caused by the presence of small quantities of molecules that scavenge or capture the electrons. 2.) A detector for electron capture decay.
- ELECTRON, COMPTON See Compton electron.
- ELECTRON, CONVERSION See conversion electron.
- ELECTRON, SECONDARY An electron emitted as a result of momentum transfer from some primary radiation. M.
- ELECTRON SPECTROSCOPY FOR CHEMICAL ANALYSIS Type of spectroscopy involving the measurement of the kinetic energy of electrons emitted by chemical substances usually as a result of excitation by monochromatic X-rays. C.
- ELECTRON VOLT A unit of energy corresponding to 1.6022X10-19 J.
- ELECTROSCOPE A device for measuring very small electrostatic charges.
- ELECTROSPRAYING A soft (non-violent) sample ionization technique, applicable particularly to large and complex species in solution, for producing intact ions in vacuo. Solutions pass through a needle maintained at a few kilovolts relative to a chamber. The resulting field at the needle tip charges the surface of the emerging liquid, dispersing it by Coulomb forces into a spray of small charged droplets.
- ELEMENT A substance in which the nucleus of each atom is characterized by having exactly the same number of protons.
- ELEMENTARY PARTICLE See particle, elementary.
- ELUANT Liquid used to extract one material from another as in chromatography. The term eluent is preferred.
- ELUATE The effluent emerging from a chromatographic bed when elution is carried out.
- ELUENT The liquid or gas entering a chromatographic bed and used to effect a separation by elution. C.
- ELUTE To remove or separate by elution chromatography.
- EMANATION 1. Radon 2. Any radioactive gas released by another radioactive substance.
- EMANATION POWER A ratio of the amount of radon escaping a solid or solution, to the amount being formed.
- EMANATION THERMAL POWER A thermoanalytical technique in which the release of radioactive emanation from a substance (and/or its reaction products) is measured as a function of temperature while the substance is subjected to a controlled temperature program. C.
- EMANOMETRIC ANALYSIS A method of quantitative analysis which uses measurement of the radioactive isotopes of inert gases for the determination of appropriate elements. HRC.
- EMULSION, NUCLEAR An ionization-sensitive material such as a photographic emulsion used for permanently recording the tracks of charged particles. GNST
- ENAA Epithermal neutron activation analysis.
- END LABELING Procedure in which terminal phosphate groups of DNA are removed and enzymatically replaced with radiolabeled groups. J.
- END PRODUCT The final product of a nuclear reaction or process. M.
- ENERGY (OF A RADIATION) Energy of the individual particles or photons of which radiation consists.
- ENERGY, BINDING See binding energy.
- ENERGY DISPERSIVE X-RAY FLUORESCENCE ANALYSIS A method of X-ray fluorescence analysis where element specificity is obtained by measuring the energy spectrum of the induced X-radiation.
- ENERGY FLUX DENSITY See flux density, energy.
- -- ENERGY, IONIZING --
- ENERGY LEVEL The stable energy state that an atom or molecule or nucleus can assume. NM.
- ENERGY RESOLUTION A measure, at given energy, of the smallest difference between the energies of two particles or photons capable of being distinguished by a radiation spectrometer. It is usually expressed as FWHM. See full-width at half-maximum.
- ENERGY THRESHOLD The limiting kinetic energy of an incident particle or energy of an incident photon (both expressed in the laboratory system) below which a specified process cannot take place.
- ENRICHMENT Any process by which the isotopic abundance of a specified isotope in a mixture of isotopes of an element is increased.
- ENRICHMENT FACTOR For a material enriched in a specified isotope , the ratio between the isotopic abundance and the natural abundance of that isotope.
- ENRICHMENT, ISOTOPIC Any process by which the isotopic abundance of a specified isotope in a mixture of isotopes of an element is increased. C.
- EOB End-of-bombardment.
- EPICADMIUM NEUTRONS See neutrons, epicadmium.
- EPITHERMAL NEUTRON ACTIVATION ANALYSIS Activation analysis using epithermal neutrons, i. e., those with energies usually just above thermal.
- EPITHERMAL NEUTRONS See neutrons, epithermal.
- EPSILON RAYS Tertiary electrons. See delta rays.
- EQUILIBRIUM ISOTOPE EFFECT See isotope effect.
- EQUILIBRIUM, RADIOACTIVE Among the members of a decay chain , the state which prevails when the ratios between the activities of successive members remain constant.
- EQUILIBRIUM, SECULAR Radioactive equilibrium where the half life of the precursor isotope is so long that the change of its activity can be ignored during the period of interest and all activities remain constant.
- EQUILIBRIUM, TRANSIENT Radioactive equilibrium where the ratio of the (longerlived) parent to (shorter-lived) daughter activity as a function of time is a constant less than unity.
- ERD or ERDA Elastic recoil detection analysis.
- ESCA Electron spectroscopy for chemical analysis.
- ESCAPE PEAK, DOUBLE In a gamma-ray spectrum , the peak due to pair production in the detector and escape, from the sensitive part of the detector, of the two photons of 511 keV resulting from annihilation.
- ESCAPE PEAK, IODINE The x-ray escape peak in a gamma-ray spectrum using a NaI scintillation spectrometer and due to the escape of the 28 keV X-ray of the iodine in the scintillation crystal.
- ESCAPE PEAK, SINGLE In a gamma-ray spectrum , the peak due to pair production in the detector and escape, from the sensitive part of the detector, of one of the photons of 511 keV resulting from annihilation.
- ESCAPE PEAK, X-RAY In a gamma or X-ray spectrum , the peak due to the photoelectric effect in the detector and escape, from the sensitive part of the detector, of the X-ray photon) emitted as a result of the photoelectric effect.
- EXCHANGE RATE The rate at which an exchange reaction occurs.
- EXCHANGE REACTIONS Reactions in which two atoms or ions exchange places, either in two molecules or in the same molecule. M.
- EXCITATION Process causing the transition of a system from one state to another of higher energy.
- EXCITATION ENERGY Minimum energy required to bring a system to a specified higher energy level.
- EXCITATION FUNCTION In nuclear reactions the dependence of the cross section for the reaction upon the energy of the projectile.
- EXCITED STATE State of a system with energy higher than that of the ground state.
- EXPONENTIAL DECAY Variation of a quantity (generally the activity of a radionuclide) according to the law A=Aoe-lt where A and Ao are the values of the quantity being considered at time t and zero respectively, and l is an appropriate constant.
- EXPOSURE For X- or gamma radiation in air: the sum of the electrical charges of all the ions of one sign produced after all electrons liberated by photons in a suitably small volume element of air are completely stopped, divided by the mass of the air in the volume element.
- EXTRACTABLE SPECIES Any chemical species which can be separated through an extraction procedure.
- EXTRACTION A separation method in which a liquid solvent causes the transfer of one or more analytes into it from contact with a second liquid or solid phase mixture. M.
- EXTRACTION CHROMATOGRAPHY Synonymous with liquid-liquid chromatography. One liquid can be a film adsorbed on a solid stationary packing material.
- EXTRACTION CYCLE A series of steps involving solvent extraction , stripping , and in some cases scrubbing. GNST
- EXTRAPOLATED RANGE The distance from a radiation source at which the flux density has decreased to one-half of its initial value. It is calculated by extrapolation of the tangent to the flux density) versus distance curve to zero flux density.
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