1、Designation: E170 15aE170 16Standard 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
2、 number 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 radiat
3、ion effects, 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
4、 terms 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
5、 quantities, 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 IC
6、RU Report 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.2 This terminology also uses recommend
7、ed definitions of twoJCGM documents,3 namely “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 followe
8、d by eitherVIM 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 Interna
9、tional System of Units (SI) (the Modernized Metric System) (Withdrawn 1997)5E456 Terminology Relating to Quality and StatisticsE722 Practice for Characterizing Neutron Fluence Spectra in Terms of an Equivalent Monoenergetic Neutron Fluence forRadiation-Hardness Testing of ElectronicsE910 Test Method
10、 for Application and Analysis of Helium Accumulation Fluence Monitors for Reactor Vessel Surveillance,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 expression of uncertaintyin measu
11、rementJCGM 200:2012, VIM International vocabulary of metrology Basic and general concepts and associated terms1 This terminology is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibility of Subcommittee E10.93on Editorial.Current edition
12、approved Sept. 1, 2015Feb. 15, 2016. Published October 2015February 2016. Originally approved in 1963. Last previous edition approved in 2015 asE170 15.E170 15a. DOI: 10.1520/E0170-15A.10.1520/E0170-16.2 ICRU Report 60 has been superseded by ICRU Report 85a on “Fundamental Quantities and Units for I
13、onizing Radiation,” October 2011. Both of these documents areavailable from International Commission on Radiation Units and Measurements (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3 Document produced by Working Groups of the Joint Committee for Guides in Metrology (JCGM). Available fr
14、ee of charge at BIPM website (http:/www.bipm.org).4 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.5 The last
15、approved version of this historical standard is referenced on www.astm.org.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. Becauseit may not be technically possible to adequately
16、depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
17、 19428-2959. United States11.3 ICRU Documents:2ICRU 60 Fundamental Quantities and Units for Ionizing Radiation, December 30, 1998ICRU 85a Fundamental Quantities and Units for Ionizing Radiation, October, 20111.4 NIST Document:6NIST Technical Note 1297 Guidelines for Evaluating and Expressing the Unc
18、ertainty of NIST Measurement Results, 19941.5 ISO Standard:7ISO 10012 Measurement management systems Requirements for measurement processes and measuring equipment2. Terminologyabsorbed dose (D)quotient of d by dm, where d is the mean incremental energy imparted by ionizing radiation to matterof inc
19、remental mass dm. (ICRU), thusD 5d/dm (1)DISCUSSIONThe SI unit of absorbed dose is the gray (Gy), where 1 gray is equivalent to the absorption of 1 joule per kilogram of the specified material (1 Gy= 1 J/kg). The unit rad (1 rad = 100 erg/g = 0.01 Gy) is still widely used in the nuclear community; h
20、owever, its continued use is not encouraged. Fora photon source under conditions of charged particle equilibrium, the absorbed dose, D, may be expressed as follows:D 5Een/, (2)where: = fluence (m2),E = energy of the ionizing radiation (J), anden/ = mass energy absorption coefficient (m2/kg).If brems
21、strahlung production within the specified material is negligible, the mass energy absorption coefficient (en/) is equal to the mass energytransfer coefficient (tr/), and absorbed dose is equal to kerma if, in addition, charged particle equilibrium exists.absorbed dose rate (D)quotient of dD by dt wh
22、ere dD is the increment of absorbed dose in the time interval dt (ICRU), thusD 5dD/dt (3)SI unit: Gys1.DISCUSSIONThe absorbed-dose rate is often specified as an average value over a longer time interval, for example, in units of Gymin1 or Gyh1.accuracycloseness of agreement between a measurementmeas
23、ured result quantity value and an accepted reference value (seeTerminologya true quantity value of a E456).measurand (VIM).DISCUSSION(1) The concept “accuracy” is not a quantity and is not given a numerical quantity value. A measurement is said to be moreaccurate when it offers a smaller measurement
24、 error.(2) The term “accuracy” should not be used for measurement 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 of agreement between measured quantity values that are being att
25、ributedto the measurand.activation cross sectioncross section for a specific direct or compound nuclear interaction in which the product nucleus isradioactive.DISCUSSIONFission and spallation processes produce a statistical ensemble of outgoing nuclear channels, but they are not considered to be act
26、ivation reactions.activity (A)of an amount of radionuclide in a particular energy state at a given time, quotient of dN by dt, where dN is themean change in the number of nuclei in that energy state due to spontaneous nuclear transformations in the time interval dt(ICRU), thus6 Available from Nation
27、al Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, USA, http:/www.nist.gov7 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, h
28、ttp:/www.iso.org.E170 162A 52dN/dt (4)Unit: s1The special name for the unit of activity is the becquerel (Bq), where1Bq51s21 (5)DISCUSSIONThe former special unit of activity was the curie (Ci), where1Ci53.731010 s21 exactly!. (6)The negative sign in Eq 4 is an indication that the activity is decreas
29、ing with time. The “particular energy state” is the ground state of the nuclideunless otherwise specified. The activity of an amount of radionuclide in a particular energy state is equal to the product of the decay constant forthat state and the number of nuclei in that state (that is, A = N). (See
30、decay constant.)aleatory uncertaintyuncertainty representing random uncertainty contributors where there is little possibility of reducing thisuncertainty contributor by consideration of a more controlled scenario.DISCUSSION(1) One paradigm decomposes uncertainty into epistemic and aleatory componen
31、ts. This division of uncertainty categories isvery dependent upon what question is being posed in a given application.Aleatory uncertainties can be transformed into epistemicuncertainties depending upon the application. The uncertainties underlying a quantity may be classified as aleatory or epistem
32、icaccording to the goals of the process.(2) Aleatory uncertainty, also referred to as variability, stochastic uncertainty or irreducible uncertainty, is used to describeinherent variation associated with a quantity or phenomenon of interest. The determination of material properties or operatingcondi
33、tions of a physical system typically leads to aleatory uncertainties; additional experimental characterization might providemore conclusive description of the variability but cannot eliminate it completely. Aleatory uncertainty is normally characterizedusing probabilistic approaches.analysis bandwid
34、thspectral band used in a photometric an instrument, such as a densitometer, for the measurement of opticalabsorbance or reflectance.a measurement.analysis wavelengthwavelength used in a spectrophotometric instrument for the measurement of optical absorbance orreflectance.annihilation radiationgamma
35、 radiation produced by the annihilation of a positron and an electron.DISCUSSIONFor particles at rest, two photons are produced, each having an energy corresponding to the rest mass of an electron (511 keV).backscatter peakpeak in the observed photon spectrum resulting from large-angle (110) Compton
36、 scattering of gamma raysfrom materials near the detector.DISCUSSIONThis peak is normally below about 0.25 MeV. Also, it will not have the same shape as the full-energy peaks (being wider and skewed toward lowerenergy).benchmark neutron fieldwell-characterized irradiation environment which provides
37、a fluence or fluence rate of neutronssuitable for the validation or calibration of experimental techniques and methods as well as for validation of cross sections andother nuclear data, where following classification for reactor dosimetry has been made:8controlled neutron fieldneutron field physical
38、ly well-defined, and with some spectrum definition, employed for a restricted setof validation experiments.reference neutron fieldpermanent and reproducible neutron field less well characterized than a standard field but accepted asa measurement reference by a community of users.standard neutron fie
39、ldpermanent and reproducible neutron field that is characterized to state-of-the-art accuracy in terms ofneutron fluence rate and energy spectra, and their associated spatial and angular distributions, where important field quantities needto be verified by interlaboratory measurements.8 The followin
40、g three definitions are derived from: Neutron Cross Sections for Reactor Dosimetry, International Atomic Energy Agency, Laboratory Activities, Vienna,Vol 1, 1978, p. 62 and Vlasov, M., IAEA Program on Benchmark Neutron Fields Applications for Reactor Dosimetry, Report INDC(SEC)-54/L+Dos, IAEA, Vienn
41、a, 1976.E170 163DISCUSSIONA type of neutron field is considered to be a “standard” over a specified energy range and there is only one type of “standard neutron field” for a givenenergy range. Currently, the 252Cf spontaneous fission field is a “standard neutron field” from 0.5 MeV to 8 MeV. The deu
42、terium-tritium (DT)accelerator field is considered to be the “standard neutron field” from 13.5 to 15 MeV. The thermal Maxwellian and epithermal 1/E slowing-down fieldare also considered to be “standard neutron fields.”bremsstrahlungbroad-spectrum electromagnetic radiation emitted when an energetic
43、charged particle is influenced by a strongelectric field, such as the Coulomb field of an atomic nucleus.DISCUSSIONIn radiation processing, bremsstrahlung photons are generated by the deceleration or deflection of energetic electrons in a target material. When anelectron passes close to an atomic nu
44、cleus, the strong Coulomb field causes the electron to deviate from its original motion. This interaction resultsin a loss of kinetic energy by the electron with the emission of electromagnetic radiation; the photon energy distribution extends up to the maximumkinetic energy of the incident electron
45、. This bremsstrahlung spectrum depends on the electron energy, the composition and thickness of the target, andthe angle of emission with respect to the incident electron.buildup factorfor radiation passing through a medium, ratio of the total value of a specified radiation quantity (such as absorbe
46、ddose) at any point in that medium to the contribution to that quantity from the incident uncollided radiation reaching that point.cadmium ratioratio of the neutron reaction rate measured with a given bare neutron detector to the neutron reaction ratemeasured with an identical neutron detector enclo
47、sed by a particular cadmium cover and exposed in the same neutron field atthe same or an equivalent spatial location.DISCUSSIONIn practice, meaningful experimental values can be obtained in an isotropic neutron field by using a cadmium filter approximately 1 mm thick.calibrated instrumentinstrument
48、that has been through a calibration process at established time intervals.DISCUSSIONMeasurements carried out by this instrument have metrological traceability to the reference standard if calibration is properly carried out.calibrationset of operations that establish, under specified conditions, the
49、 relationship between values of quantities indicated bya measuring instrument or measuring system, or values represented by a material measure or a reference material, and thecorresponding values realized by standards (VIM: 1993).DISCUSSION(1) Calibration conditions include environmental and irradiation conditions present during calibration.(2) These standards should have metrological traceability to a national or international standard.(3) To be reliable, calibration should be carried out at regular time
