ASTM D7902-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7902 − 18 D7902 − 20
Standard Terminology for
Radiochemical Analyses
This standard is issued under the fixed designation D7902; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This standard describes terminology commonly used in radiochemistry and radioanalysis.
1.2 The values stated in SI units are to be regarded as standard. Other units of measurement, including some units that are not
accepted for use with the SI, are also defined.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D7282 Practice for Set-up, Calibration, and Quality Control of Instruments Used for Radioactivity Measurements
2.2 BIPM Documents:
GUM Guide to the Expression of Uncertainty in Measurement (GUM), 100:2008
2.3 Code of Federal Regulations:
40 CFR 141.25 Analytical Methods for Radioactivity
40 CFR Appendix B to Part 136 Definition and Procedure for the Determination of the Method Detection Limit
2.4 ANSI Documents:
ANSI N42.22 Traceability of Radioactive Sources to the National Institute of Standards and Technology (NIST) and Associated
Instrument Quality Control
3. Significance and Use
3.1 This terminology standard describes terms and definitions used in standards for radiochemical analysis maintained by
ASTM Committee D19 on Water. The terminology is also recommended for general use in the radiochemistry community.
4. Terminology: Terms and Definitions
4π geometry, n—geometry in which the radiation detector has essentially the same probability of detecting radiation from the
source emitted in any direction.
absorption (of radiation), n—transfer of some or all of the energy of a radiation to matter it traverses.
This terminology is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical
Analysis.
Current edition approved Feb. 1, 2018May 1, 2020. Published March 2018June 2020. Originally approved in 2014. Last previous edition approved in 20162018 as D7902
– 16.18. DOI: 10.1520/D7902-18.10.1520/D7902-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Bureau International des Poids et Mesures (BIPM), Pavillon de Breteuil F-92312 Sèvres Cedex, France, http://www.bipm.org.
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
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Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7902 − 20
abundance, (1) n—probability of emission of a given radiation during the decay of an atom of a given radionuclide; radiation
emission probability—also called intensity;
(2) see isotopic abundance.
actinide, n—any element with atomic number between 89 and 103, including actinium, thorium, protactinium, uranium,
neptunium, plutonium, americium, and curium.
activation, n—inducement of radioactivity by irradiation.
activation analysis, n—analysis based on the characteristic radiations emitted by nuclides formed by activation.
−1
activity (for radionuclides), A [T ], n—mean rate of radioactive decay in a quantity of material.
DISCUSSION—
The term activity may be qualified by specifying one or more radionuclides (for example, U activity) or the type of decay (for example, gross alpha
activity).
DISCUSSION—
−1
The SI unit of activity is the becquerel (Bq), which equals 1 s (one nuclear disintegration per second).
activity concentration, (1) n—quotient of the activity of a specified quantity of material and its volume; volumic activity;
(2) n—quotient of the activity of a specified quantity of material and its associated mass or size.
aliquant, n—fractional part that does not evenly divide the whole.
aliquot, n—fractional part that evenly divides the whole.
DISCUSSION—
Chemists commonly use the term aliquot to mean either an aliquant or aliquot of a sample.
alpha decay, n—radioactive decay accompanied by the emission of an alpha particle.
alpha particle, α particle, n—particle consisting of two protons and two neutrons (a He nucleus) emitted from a nucleus during
certain types of radioactive decay.
alpha-particle spectrometry, alpha spectrometry, n—measurement of components of a sample or system based on analysis of
alpha-particle spectra.
DISCUSSION—
In titles and summaries, the full name alpha-particle spectrometry is preferred. In other contexts, either name is often acceptable.
alpha scintillation cell, n—specially designed sealable container, whose walls are coated with silver-activated zinc sulfide (a
scintillator), having a transparent window at one end, which can be filled with a gas such as helium or nitrogen containing some
quantity of radon and used in conjunction with a scintillation counter to measure the alpha emissions of the radon and its
progeny.
analyst, n—person who performs analyses.
analyte, n—in an analysis, the component analyzed for.
ancestor (radionuclide), parent (radionuclide), n—radionuclide that produces a given nuclide in a series of one or more
radioactive decays.
DISCUSSION—
The term ancestor is often used in the context of indirect relationships involving a series of decays. The term parent is often used when there is a direct
relationship.
annihilation, n—interaction between a particle and its antiparticle in which the original particles disappear and new photons or
particles are produced.
annihilation peak, n—peak in a gamma-ray spectrum at 511 keV produced by annihilations of positrons and electrons.
D7902 − 20
DISCUSSION—
Each annihilation results in two 511 keV gamma-rays, at least one of which usually escapes from the detector without depositing its energy.
anticoincidence counting, n—radiometric counting technique that lowers interference levels by rejecting any event that is
accompanied by one or more other events occurring within a specified time interval.
DISCUSSION—
Anticoincidence counting requires two or more detectors, often of different types, operating simultaneously.
areic, adj—in proportion to area.
DISCUSSION—
The adjective areic, when applied to the name of a measurable quantity, indicates the quotient of that quantity and its associated area, as in areic activity
or areic mass.
attenuation (of radiation), n—decrease in intensity of radiation due to interactions with matter.
−1
attenuation coefficient, linear attenuation coefficient, μ or μ [L ], n—for a parallel beam of photons passing through a material,
l
the fraction of the photons removed in a short distance, divided by that distance (see also mass attenuation coefficient).
DISCUSSION—
The concept of an attenuation coeffıcient may be applied to other types of radiation provided the attenuation follows approximately an exponential law.
attenuation curve, n—plot of attenuation factors versus another quantity such as distance, mass, or areic mass.
attenuation factor, n—fraction of a beam of radiation remaining after the beam has passed through a given amount of material.
Auger effect, n—ejection of an electron, called an Auger electron, from an outer shell, accompanying the filling of a vacancy in
an inner shell.
DISCUSSION—
The Auger effect and X-ray emission are alternative means of releasing energy when such an inner shell vacancy is filled.
Auger electron, n—orbital electron ejected from an atom in the Auger effect.
background, (1) n—in general, the normal analyte concentration, radiation level, or instrument signal observed in the absence of
the analyte or in the absence of any analyte contributed by a given cause;
(2) n—instrument signal observed in the absence of a source (also instrument background or detector background).
DISCUSSION—
The unqualified term background has so many shades of meaning that it can be a source of confusion unless it is explained.
background subtraction count, BSC, n—a source count used to determine the background to be subtracted from the sample test
source count. D7282
backscatter(ing), n—deflection of radiation by matter at any angle greater than 90° from its original direction of motion.
backscatter peak, n—peak in a gamma-ray spectrum produced by photons resulting from Compton scattering in the material
surrounding the detector.
baseline, n—in the graph of a spectrum, the straight or curving line on which peaks are superimposed.
−1
becquerel, Bq, n—special name for the SI derived unit of activity, equal to 1 s (one nuclear disintegration per second).
− +
beta decay, β decay, n—radioactive decay that results in a change in atomic number but no change in mass number; β decay, β
decay, or electron capture.
− −
β decay, n—radioactive decay accompanied by the emission of a β particle and an antineutrino.
+ +
β decay, n—radioactive decay accompanied by the emission of a β particle and a neutrino.
D7902 − 20
− +
beta particle, β particle, n—electron (β ) or positron (β ) emitted from a nucleus during certain types of radioactive decay.
bias (voltage), n—for many types of radiation detector, a voltage applied to the detector to enable it to detect an ionizing event.
blank, (1) adj—containing little or no analyte; analyte-free;
(2) see blank sample.
blank sample, n—any of various types of real or artificial samples that are expected to contain little or no analyte, such as a method
blank or reagent blank.
DISCUSSION—
Use of the term blank sample without qualification or explanation may cause confusion.
blank source, n—source prepared to simulate a test source with no analyte present.
branching decay, n—radioactive decay that can proceed in more than one way.
branching fraction, branching ratio, n—in branching decay, the fraction of nuclei that decay in a specified way.
calibration source, CS, n—a known quantity of radioactive material, traceable to the SI via a national standards body,metrology
institute, prepared for the purpose of calibrating nuclear instruments. D7282, modified
carrier, n—an isotope or mixture of isotopes of an element, chemically identical or similar to the radionuclide(s) of interest, added
in a quantity sufficient to promote a desired chemical behavior and move the radionuclide(s) or an unwanted contaminant
through a chemical process.
DISCUSSION—
In radiochemistry the use of a carrier may also allow gravimetric measurement of the chemical yield.
cascade summing, (true) coincidence summing, n—summing produced when the energies of two or more radiations emitted by
the same atom are absorbed by the detector within a period of time shorter than the resolving time of the detector.
Čerenkov counting, n—radiation counting technique based on detection of Čerenkov radiation (also Cerenkov or Cherenkov).
Čerenkov radiation, n—electromagnetic radiation emitted by a charged particle moving through a medium at a speed greater than
the speed of light in that medium (also Cerenkov or Cherenkov).
channel, n—any of the data registers or memory locations used to record pulses in a single-channel or multichannel analyzer.
chemical yield, n—fraction of the amount of a given analyte or other substance remaining after specified chemical separations
(sometimes called recovery or chemical recovery).
DISCUSSION—
Use of the term recovery as a synonym for chemical yield may cause confusion and should be avoided. See recovery.
chemiluminescence, n—emission of electromagnetic radiation as a result of a chemical reaction – a possible cause of interference
in liquid scintillation counting.
coincidence counting, n—radiometric counting technique that lowers interferences by rejecting any event that is not accompanied
by one or more other events occurring within a specified time interval; for example, coincidence counting of the beta particle
and 364.5 keV gamma-ray from the decay of I.
DISCUSSION—
Coincidence counting requires two or more detectors, often of different types, operating simultaneously.
combined standard uncertainty, u , n—standard uncertainty of a measurement result obtained by uncertainty propagation.
c
Compton baseline, n—baseline in a gamma-ray spectrum, which is due largely to Compton scattering but also in part to tailing
and other effects.
Compton edge, n—feature of a gamma-ray spectrum which appears as an abrupt decrease in the baseline at the upper end of the
energy distribution of the Compton electrons associated with a gamma-ray photopeak.
D7902 − 20
DISCUSSION—
The Compton edge is found at the energy
2 2
E ⁄ E 1 m c ⁄ 2
~ !
γ γ e
where E is the energy of the photopeak.
γ
Compton effect, Compton scattering, n—scattering of a photon by a free or weakly bound electron in which the incident photon
imparts a portion of its energy and momentum to the electron, resulting in a free electron and a scattered lower-energy photon.
Compton electron, n—the energetic free electron resulting from the Compton effect.
Compton photon, n—the scattered photon resulting from the Compton effect.
conversion electron, n—the orbital electron ejected from an atom by internal conversion.
coprecipitation, n—precipitation of a normally soluble component by inclusion in the precipitate of another less soluble
component from the same solution.
cosmic radiation, n—radiation that originates outside Earth’s atmosphere.
count, (1) v—to perform a radiation counting measurement;
(2) n—a radiation counting measurement;
(3) n—a single pulse registered during counting;
(4) n—total number of pulses registered during counting.
counting effıciency—see detection efficiency.
counting period, counting interval, n—time interval from the beginning to the end of a radiation counting measurement.
counting uncertainty, n—in radiochemistry, the uncertainty of the result of a measurement due to the random nature of radioactive
decay, radiation emission, and radiation detection—also called counting error.
DISCUSSION—
The term counting uncertainty is preferred because of the emphasis in metrology on the distinction between error of measurement and uncertainty of
measurement.
count rate, n—quotient of the total count and the live time for a radiation counting measurement.
DISCUSSION—
If the count rate is corrected by subtracting a background or blank value, it is called a net count rate. The uncorrected count rate may be called the
gross count rate.
−1
counts per minute, n—unit for count rate, equal to 1 min .
DISCUSSION—
−1
The reciprocal minute (symbol min ) is accepted for use with the SI as a unit for count rate; however, the symbol cpm, which has sometimes been
used, is not accepted for use with the SI.
−1
counts per second, n—unit for count rate, equal to 1 s .
DISCUSSION—
−1
The SI symbol for this unit is s . The symbol cps, which has sometimes been used, is not accepted for use with the SI.
count time, counting time, count duration, n—either live time or real time, but often presumed to denote the live time.
DISCUSSION—
In contexts where the difference between the two meanings is important, the more specific term is preferred to avoid any ambiguity.
coverage factor, k,n—factor by which a standard uncertainty is multiplied to obtain an expanded uncertainty.
D7902 − 20
critical value, (1) n—threshold value that a measurement result must exceed in order to lead to the decision that the analyte is
present; detection threshold—also called critical level or decision level;
(2) n—in a statistical hypothesis test, a limiting value of the critical region for the test statistic.
crosstalk, n—phenomenon in gas proportional counting or liquid scintillation counting where an emitted alpha particle is
misidentified as a beta particle or vice versa.
curie, Ci, n—traditional non-SI unit of activity, equal to 3.7 × 10 Bq, which is approximately the activity of one gram of pure
Ra.
DISCUSSION—
The curie may be used with SI prefixes.
DISCUSSION—
The curie is such a large unit that its submultiples (from the picocurie to the millicurie) are more commonly used as units for laboratory analyses.
daughter (nuclide), daughter product, descendant (nuclide), decay product, n—nuclide produced from a given radionuclide
in a series of one or more radioactive decays.
DISCUSSION—
The term descendant is often used in the context of indirect relationships involving a series of radioactive decays. The term daughter is often used
when there is a direct relationship.
dead time, (1) n—time required for a radiation counter to process an event, during which additional events cannot be processed,
generally expressed in terms of absolute time (for example, 10 s); cf. resolving time;
(2) see total dead time.
dead water, n—water devoid of tritium (for example, fossil water).
decay chain, n—sequence of nuclides arranged so that each nuclide after the first is an immediate decay product of its predecessor
in the sequence.
−1−1
decay constant, radioactive decay constant, λλ [[T ],n—physical constant associated with a radionuclide, equal to the
radionuclide’s mean instantaneous fractional decay rate, or for a single atom, the probability of decay during a short time
interval, divided by the length of the interval.
DISCUSSION—
The decay constant λ also equals ~ln 2!⁄T , where T is the half-life of the radionuclide.
1⁄2 1/2
DISCUSSION—
The activity of a collection of N atoms of the radionuclide equals λN.
decay factor, n—expected fraction of the atoms of a radionuclide remaining after a specified time, or for a single atom the
probability of survival for a specified time.
decay scheme, n—graphical representation of the transitions that can occur during the decay of an atomic nucleus.
depleted uranium, DU, n—uranium in which the isotopic abundance of U is less than its natural abundance (cf. enriched
uranium).
delayed coincidence counting, n—radiometric counting technique that lowers interferences by accepting only an event that is
accompanied by one or more other events occurring within a specified short but measurable time interval following the initial
event; for example, delayed coincidence counting of the alpha particle from the decay of Rn followed by the alpha particle
from the decay of Po (0.148 second half-life) – the immediate decay progeny.
DISCUSSION—
D7902 − 20
Delayed coincidence counting may require the use of only one detector and is most advantageous where the detection efficiency of the initial and
follow-on event is relatively high. The overall count rate must also be sufficiently low to minimize occurrence of accidental delayed coincidences.
desiccator, n—container used to dry material or keep it dry, usually by enclosing it in a small space with a desiccant.
detect, (1) v—^radiation& to produce an indication of an emitted ray or particle;
(2) v—^analyte& to determine by measurement that an analyte is present (for example, in a source or sample).
detection capability, n—ability of a measurement process to discriminate between small positive amounts of an analyte and
zero—typically described by the minimum detectable value.
detection efficiency, n—probability that a radiation emitted by a radioactive source will be registered by the instrument—also
called counting efficiency.
detection limit, (1) see minimum detectable value;
(2) n—any of several other quantities defined as “detection limits” by various authorities, including the “method detection
limit” (40 CFR Appendix B to Part 136) and the “detection limit” for Safe Drinking Water Act compliance monitoring (40 CFR
141.25).
detector, n—device that indicates the presence of a phenomenon or the occurrence of an event without necessarily providing a
measured value for it.
dewar, Dewar, n—double-walled container with an evacuated space between the walls, often silvered on the innermost surface to
prevent heat transfer, used for storing liquefied gases.
−1
disintegrations per minute, dpm, n—non-SI unit of activity, equal to 1 min —never used with SI prefixes.
electron capture, EC, n—mode of radioactive decay in which the nucleus captures an orbital electron, causing the atomic number
to decrease by one while the mass number remains unchanged—considered to be a type of beta decay although no beta particle
is emitted.
emanation, n—release of a gas from a matrix; for example, emanation of Rn from soil, water, or other matrix.
enriched uranium, EU, n—uranium in which the isotopic abundance of U is greater than its natural abundance (cf. depleted
uranium).
equilibrium, n—state of a system in which positive and negative rates of change are balanced so that that the overall rate of change
is approximately zero (see also radioactive equilibrium).
error (of measurement), n—difference between the result of a measurement and the true value of the measurand.
DISCUSSION—
Error of measurement should not be confused with uncertainty of measurement. The error of a measurement is generally unknown because the true
value is unknown.
escape peak, n—peak in a gamma-ray spectrum produced when incident gamma-rays of a particular energy interact with the
detector and produce other photons, one or more of which escape from the detector without depositing their energy.
expanded counting uncertainty, n—product of the standard counting uncertainty and a coverage factor.
expanded uncertainty, U,n—quantity defining an interval about the result of a measurement that may be expected to encompass
a large fraction of the distribution of values that could reasonably be attributed to the measurand.
GUM
DISCUSSION—
The expanded uncertainty is obtained by multiplying the standard uncertainty of the result by a coverage factor.
fossil water, n—groundwater that has remained sealed in an aquifer for a long period of time, typically thousands of years or more.
full-energy peak, FEP, n—peak in a gamma-ray spectrum produced by those incident photons of a particular energy that deposit
all of their energy in the detector.
full width at half maximum, FWHM, n—width of a spectral peak at half its height above the baseline—often used as a measure
of resolution in spectrometry.
full width at tenth maximum, FWTM, n—width of a spectral peak at one-tenth its height above the baseline.
D7902 − 20
gamma-ray, n—photon emitted from a nucleus during certain types of radioactive decay, or produced by annihilation of a particle
and its antiparticle.
gamma-ray spectrometry, gamma spectrometry, n—measurement of components of a sample or system based on analysis of
gamma-ray spectra.
DISCUSSION—
In titles and summaries, the full name gamma-ray spectrometry is preferred. In other contexts either name is often acceptable.
gas-flow proportional counter, GFPC, n—gas proportional counter in which gas flows continuously through the ionization
chamber.
gas proportional counter, GPC, n—radiation counter based on an ionization chamber where the voltage applied to the chamber
electrodes is such that the amplitude of each pulse is proportional to the number of ion pairs generated by an incident radiation.
Gaussian, (1) adj—normally distributed;
(2) adj—shaped like the graph of the probability density function for a normal distribution (a “bell curve”).
geometry, n—overall configuration of a radioactive source and a radiation detector for a radiation measurement, including the
source’s size, shape, container, composition, density, and position and o
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