ASTM E170-2016a 8856 Standard Terminology Relating to Radiation Measurements and Dosimetry《有关辐射测量和剂量测定的标准术语》.pdf

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1、Designation: E170 16aStandard Terminology Relating toRadiation Measurements and Dosimetry1This standard is issued under the fixed designation E170; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis terminology generally covers terms that apply to radiation measurements and dosimetryassociated with energy deposition and radiation eff

3、ects, or damage, in materials caused by interactionsby high-energy radiation fields. The common radiation fields considered are X-rays, gamma rays,electrons, alpha particles, neutrons, and mixtures of these fields. This treatment is not intended to beexhaustive but reflects special and common terms

4、used in technology and applications of interest toCommittee E10, as for example, in areas of radiation effects on components of nuclear power reactors,radiation hardness testing of electronics, and radiation processing of materials.This terminology uses recommended definitions and concepts of quanti

5、ties, with units, for radiationmeasurements as contained in the International Commission on Radiation Units and Measurements(ICRU) Report 85a on “Fundamental Quantities and Units for Ionizing Radiation,” October 2011.2Those terms that are defined essentially according to the terminology of ICRU Repo

6、rt 85a will befollowed by ICRU in parentheses. It should also be noted that the units for quantities used are the latestadopted according to the International System of Units (SI) which are contained in Appendix X1 astaken from a table in ICRU Report 85a.2This terminology also uses recommended defin

7、itions of twoJCGM documents,3namely “International vocabulary of metrology” (VIM, 2012, unless indicatedotherwise) and “Guide to the expression of uncertainty in measurement” (GUM, 2008). Those termsthat are defined essentially according to the terminology of these documents will be followed by eith

8、erVIM or GUM in parentheses.A term is boldfaced when it is defined in this standard. For some terms, text in italics is used justbefore the definition to limit its field of application, for example, see activity.1. Referenced Documents1.1 ASTM Standards:4E380 Practice for Use of the International Sy

9、stem of Units(SI) (the Modernized Metric System) (Withdrawn 1997)5E722 Practice for Characterizing Neutron Fluence Spectra inTerms of an Equivalent Monoenergetic Neutron Fluencefor Radiation-Hardness Testing of ElectronicsE910 Test Method for Application and Analysis of HeliumAccumulation Fluence Mo

10、nitors for Reactor VesselSurveillance, E706 (IIIC)1.2 Joint Committee for Guides in Metrology (JCGM)Reports:3JCGM 100:2008, GUM 1995 , with minor corrections,Evaluation of measurement data Guide to the expressionof uncertainty in measurementJCGM 200:2012, VIM International vocabulary of metrol-ogy B

11、asic and general concepts and associated terms1This terminology is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.93 on Editorial.Current edition approved Oct. 1, 2016. Published November 2016. Originallyapproved

12、in 1963. Last previous edition approved in 2016 as E170 16. DOI:10.1520/E0170-16A.2ICRU Report 60 has been superseded by ICRU Report 85a on “FundamentalQuantities and Units for Ionizing Radiation,” October 2011. Both of thesedocuments are available from International Commission on Radiation Units an

13、dMeasurements (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3Document produced by Working Groups of the Joint Committee for Guides inMetrology (JCGM). Available free of charge at BIPM website (http:/www.bipm.org).4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon

14、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.5The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive,

15、 PO Box C700, West Conshohocken, PA 19428-2959. United States11.3 ICRU Documents:2ICRU 60 Fundamental Quantities and Units for IonizingRadiation, December 30, 1998ICRU 85a Fundamental Quantities and Units for IonizingRadiation, October, 20111.4 NIST Document:6NIST Technical Note 1297 Guidelines for

16、Evaluating andExpressing the Uncertainty of NIST MeasurementResults, 19941.5 ISO Standard:7ISO 10012 Measurement management systems Require-ments for measurement processes and measuring equip-ment2. Terminologyabsorbed dose (D)quotient of d by dm, where d is themean incremental energy imparted by io

17、nizing radiation tomatter of incremental mass dm. (ICRU), thusD 5 d/dm (1)DISCUSSIONThe SI unit of absorbed dose is the gray (Gy), where 1gray is equivalent to the absorption of 1 joule per kilogram of thespecified material (1 Gy = 1 J/kg). The unit rad (1 rad = 100 erg/g =0.01 Gy) is still widely u

18、sed in the nuclear community; however, itscontinued use is not encouraged. For a photon source under conditionsof charged particle equilibrium, the absorbed dose, D, may be ex-pressed as follows:D 5 Een/, (2)where: = fluence (m2),E = energy of the ionizing radiation (J), anden/ = mass energy absorpt

19、ion coefficient (m2/kg).If bremsstrahlung production within the specified material isnegligible, the mass energy absorption coefficient (en/) is equal to themass energy transfer coefficient (tr/), and absorbed dose is equal tokerma if, in addition, charged particle equilibrium exists.absorbed dose r

20、ate (D)quotient of dD by dt where dD is theincrement of absorbed dose in the time interval dt (ICRU),thusD5 dD/dt (3)SI unit: Gys1.DISCUSSIONThe absorbed-dose rate is often specified as an averagevalue over a longer time interval, for example, in units of Gymin1orGyh1.accuracycloseness of agreement

21、between a measured quan-tity value and a true quantity value of a measurand (VIM).DISCUSSION(1) The concept “accuracy” is not a quantity and is notgiven a numerical quantity value. A measurement is said to bemore accurate when it offers a smaller measurement error.(2) The term “accuracy” should not

22、be used for measure-ment trueness and the term “precision” should not be used for“accuracy,” which, however, is related to both these concepts.(3) “Accuracy” is sometimes understood as closeness ofagreement between measured quantity values that are beingattributed to the measurand.activation cross s

23、ectioncross section for a specific direct orcompound nuclear interaction in which the product nucleusis radioactive.DISCUSSIONFission and spallation processes produce a statisticalensemble of outgoing nuclear channels, but they are not considered tobe activation reactions.activity (A)of an amount of

24、 radionuclide in a particularenergy state at a given time, quotient of dN by dt, where dNis the mean change in the number of nuclei in that energystate due to spontaneous nuclear transformations in the timeinterval dt (ICRU), thusA 52dN/dt (4)Unit: s1The special name for the unit of activity is the

25、becquerel(Bq), where1Bq5 1s21(5)DISCUSSIONThe former special unit of activity was the curie (Ci),where1Ci5 3.7 31010s21exactly!. (6)The negative sign in Eq 4 is an indication that the activity is de-creasing with time. The “particular energy state” is the ground state ofthe nuclide unless otherwise

26、specified. The activity of an amount ofradionuclide in a particular energy state is equal to the product of thedecay constant for that state and the number of nuclei in that state (thatis, A=N). (See decay constant.)aleatory uncertaintyuncertainty representing random un-certainty contributors where

27、there is little possibility ofreducing this uncertainty contributor by consideration of amore controlled scenario.DISCUSSION(1) One paradigm decomposes uncertainty into epistemicand aleatory components. This division of uncertainty catego-ries is very dependent upon what question is being posed in a

28、given application. Aleatory uncertainties can be transformedinto epistemic uncertainties depending upon the application.The uncertainties underlying a quantity may be classified asaleatory or epistemic according to the goals of the process.(2) Aleatory uncertainty, also referred to as variability,st

29、ochastic uncertainty or irreducible uncertainty, is used todescribe inherent variation associated with a quantity orphenomenon of interest. The determination of material prop-erties or operating conditions of a physical system typicallyleads to aleatory uncertainties; additional experimental charac-

30、terization might provide more conclusive description of thevariability but cannot eliminate it completely. Aleatory uncer-tainty is normally characterized using probabilistic approaches.analysis bandwidthspectral band used in an instrument,such as a densitometer, for a measurement.analysis wavelengt

31、hwavelength used in a spectrophotomet-ric instrument for the measurement of optical absorbance orreflectance.annihilation radiationgamma radiation produced by theannihilation of a positron and an electron.6Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070

32、, Gaithersburg, MD 20899-1070, USA, http:/www.nist.gov7Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.E170 16a2DISCUSSIONFor particles at rest, two photons are p

33、roduced, eachhaving an energy corresponding to the rest mass of an electron (511keV).backscatter peakpeak in the observed photon spectrumresulting from large-angle (110) Compton scattering ofgamma rays from materials near the detector.DISCUSSIONThis peak is normally below about 0.25 MeV. Also, itwil

34、l not have the same shape as the full-energy peaks (being wider andskewed toward lower energy).benchmark neutron fieldwell-characterized irradiation en-vironment which provides a fluence or fluence rate ofneutrons suitable for the validation or calibration of experi-mental techniques and methods as

35、well as for validation ofcross sections and other nuclear data, where followingclassification for reactor dosimetry has been made:8controlled neutron fieldneutron field physically well-defined, and with some spectrum definition, employed for arestricted set of validation experiments.reference neutro

36、n fieldpermanent and reproducible neu-tron field less well characterized than a standard field butaccepted as a measurement reference by a community of users.standard neutron fieldpermanent and reproducible neutronfield that is characterized to state-of-the-art accuracy in termsof neutron fluence ra

37、te and energy spectra, and their associatedspatial and angular distributions, where important field quan-tities need to be verified by interlaboratory measurements.DISCUSSIONA type of neutron field is considered to be a “standard”over a specified energy range and there is only one type of “standardn

38、eutron field” for a given energy range. Currently, the252Cf spontane-ous fission field is a “standard neutron field” from 0.5 MeV to 8 MeV.The deuterium-tritium (DT) accelerator field is considered to be the“standard neutron field” from 13.5 to 15 MeV. The thermal Maxwellianand epithermal 1/E slowin

39、g-down field are also considered to be“standard neutron fields.”bremsstrahlungbroad-spectrum electromagnetic radiationemitted when an energetic charged particle is influenced bya strong electric field, such as the Coulomb field of an atomicnucleus.DISCUSSIONIn radiation processing, bremsstrahlung ph

40、otons aregenerated by the deceleration or deflection of energetic electrons in atarget material. When an electron passes close to an atomic nucleus, thestrong Coulomb field causes the electron to deviate from its originalmotion. This interaction results in a loss of kinetic energy by theelectron wit

41、h the emission of electromagnetic radiation; the photonenergy distribution extends up to the maximum kinetic energy of theincident electron. This bremsstrahlung spectrum depends on the elec-tron energy, the composition and thickness of the target, and the angleof emission with respect to the inciden

42、t electron.buildup factorfor radiation passing through a medium,ratio of the total value of a specified radiation quantity (suchas absorbed dose) at any point in that medium to thecontribution to that quantity from the incident uncollidedradiation reaching that point.cadmium ratioratio of the neutro

43、n reaction rate measuredwith a given bare neutron detector to the neutron reactionrate measured with an identical neutron detector enclosed bya particular cadmium cover and exposed in the same neutronfield at the same or an equivalent spatial location.DISCUSSIONIn practice, meaningful experimental v

44、alues can beobtained in an isotropic neutron field by using a cadmium filterapproximately 1 mm thick.calibrated instrumentinstrument that has been through acalibration process at established time intervals.DISCUSSIONMeasurements carried out by this instrument havemetrological traceability to the ref

45、erence standard if calibration isproperly carried out.calibrationset of operations that establish, under specifiedconditions, the relationship between values of quantitiesindicated by a measuring instrument or measuring system, orvalues represented by a material measure or a referencematerial, and t

46、he corresponding values realized by standards(VIM: 1993).DISCUSSION(1) Calibration conditions include environmental and irra-diation conditions present during calibration.(2) These standards should have metrological traceabilityto a national or international standard.(3) To be reliable, calibration

47、should be carried out atregular time intervals frequency may depend on the final useof the data. Often, the frequency is specified by regulatoryauthorities.calibration source or fieldsee electron standard field,gamma-ray standard field, and X-ray standard field.calorimeterinstrument capable of makin

48、g measurements ofenergy deposition (or absorbed dose) in a material throughmeasurement of change in its temperature and knowledge ofthe characteristics of the material and the details of itsconstruction.DISCUSSIONCalorimeter is generally designated as a primary-standard dosimeter.certified reference

49、 material (CRM)reference material, ac-companied by documentation issued by an authoritativebody and providing one or more specified property valueswith associated uncertainties and traceabilities, using validprocedures (VIM).DISCUSSION“Certified reference material” should be differentiatedfrom “Standard Reference Material” which is a National Institute ofStandards and Technology (NIST) trademarked nomenclature.charged particle equilibriumcondition that exists in anincremental volume within a material un