ASTM E170-2014 5589 Standard Terminology Relating to Radiation Measurements and Dosimetry.pdf

1、Designation: E170 14Standard 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 effe

3、cts, 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 u

4、sed 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 quantit

5、ies, 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 20112Those terms that are defined essentially according to the terminology of ICRU Report

6、 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 definit

7、ions of twoISO documents3, namely “International Vocabulary of Basic and General Terms in Metrology.” (VIM,2008) and “Guide to the Expression of Uncertainty in Measurement” (GUM, 1995). Those terms thatare defined essentially according to the terminology of these documents will be followed by either

8、VIM 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 Syst

9、em of Units(SI) (the Modernized Metric System) (Withdrawn 1997)5E456 Terminology Relating to Quality and StatisticsE706 Master Matrix for Light-Water Reactor Pressure VesselSurveillance Standards, E 706(0) (Withdrawn 2011)5E722 Practice for Characterizing Neutron Fluence Spectra inTerms of an Equiva

10、lent Monoenergetic Neutron Fluencefor Radiation-Hardness Testing of ElectronicsE910 Test Method for Application and Analysis of HeliumAccumulation Fluence Monitors for Reactor VesselSurveillance, E706 (IIIC)1.2 ISO Standards:3GUM Guide to the Expression of Uncertainty inMeasurement, ISO 1995VIM Inte

11、rnational Vocabulary of Basic and General Termsin Metrology, ISO 20081.3 ICRU Documents:2ICRU 60 Fundamental Quantities and Units for IonizingRadiation, December 30, 1998ICRU 85a Fundamental Quantities and Units for IonizingRadiation, October, 20111This terminology is under the jurisdiction ofASTM C

12、ommittee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.93 on Editorial.Current edition approved Sept. 1, 2014. Published October 2014. Originallyapproved in 1963. Last previous edition approved in 2010 as E170 10. DOI:10.1520/E0170-14.2ICRU Report 60 h

13、as been superceded by ICRU Report 85a on “FundamentalQuantities and Units for Ionizing Radiation,” October 2011. Both of thesedocuments are available from International Commission on Radiation Units andMeasurements (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3Available from Internation

14、al Organization for Standardization (ISO), 1 Rue deVarembe, Case Postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information

15、, 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, PO Box C700, West Conshohocken, PA 19428-2959. United States11.4 NIST Document:6NIST Technical No

16、te 1297 Guidelines for Evaluating andExpressing the Uncertainty of NIST MeasurementResults, 19942. Terminologyabsorbed dose (D)quotient of d by dm, where d is themean incremental energy imparted by ionizing radiation tomatter of incremental mass dm. (ICRU), thusD 5 d/dm (1)DISCUSSIONThe SI unit of a

17、bsorbed 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 used in the nuclear community; however, itscontinued use is not encouraged. For a photon source under

18、 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 absorption coefficient (m2/kg).If bremsstrahlung production within the specified material isnegligible, the

19、 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 rate (D)quotient of dD by dt where dD is theincrement of absorbed dose in the time interval dt (ICRU)

20、,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 between a measurementresult and an accepted reference value (see TerminologyE456).activation cross s

21、ectioncross section for processes in whichthe product nucleus is radioactive (see cross section).activity (A)of an amount of 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 nucle

22、ar transformations in the timeinterval dt (ICRU), thusA 52dN/dt (4)Unit: s1The special name for the unit of activity is the 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 t

23、hat the activity is de-creasing with time. The “particular energy state” is the ground state ofthe nuclide unless otherwise 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 st

24、ate (thatis, A=N). (See decay constant.)analysis bandwidthspectral band used in a photometricinstrument, such as a densitometer, for the measurement ofoptical absorbance or reflectance.analysis wavelengthwavelength used in a spectrophotomet-ric instrument for the measurement of optical absorbance or

25、reflectance.annihilation radiationgamma radiation produced by theannihilation of a positron and an electron. For particles atrest, two photons are produced, each having an energycorresponding to the rest mass of an electron (511 keV).backscatter peakpeak in the observed photon spectrum(normally belo

26、w about 0.25 MeV) resulting from large-angle(110) Compton scattering of gamma rays from materialsnear the detector. This peak will not have the same shape asthe full-energy peaks (being wider and skewed toward lowerenergy).benchmark neutron fieldwell-characterized neutron fieldwhich will provide a f

27、luence of neutrons for validation orcalibration of experimental techniques and methods and forvalidation of cross sections and other nuclear data. Thefollowing classification of benchmark neutron fields forreactor dosimetry has been made:7controlled neutron fieldneutron field physically well-defined

28、, and with some spectrum definition, employed for arestricted set of validation experiments.reference neutron 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 an

29、d reproducible neutronfield with neutron fluence rate and energy spectra, and theirassociated spatial and angular distributions characterized tostate-of-the-art accuracy. Important field quantities must beverified by interlaboratory measurements and calculations.bremsstrahlungbroad-spectrum electrom

30、agnetic radiationemitted when an energetic charged particle is influenced bya strong electric field, such as the Coulomb field of an atomicnucleus.DISCUSSIONIn radiation processing, bremsstrahlung photons aregenerated by the deceleration or deflection of energetic electrons in atarget material. When

31、 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 with the emission of electromagnetic radiation; the photonenergy distribution extends up to the maximum

32、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 incident electron.6Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop

33、 1070, Gaithersburg, MD 20899-1070, USA, http:/www.nist.gov7Neutron Cross Sections for Reactor Dosimetry, International Atomic EnergyAgency, Laboratory Activities, Vienna, 1978, Vol 1, p. 62.E170 142buildup factorfor radiation passing through a medium,ratio of the total value of a specified radiatio

34、n 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 neutron reaction rate measuredwith a given bare neutron detector to the neutron reactionrate measured with an identica

35、l 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 values can beobtained in an isotropic neutron field by using a cadmium filterapproximately 1 mm thick.calibrated

36、instrumentinstrument for which the responsehas been documented upon being directly compared with theresponse of a standard instrument, both having been exposedto the same radiation field under the same conditions; or onefor which the response has been documented upon beingexposed to a standard radia

37、tion field under well-definedconditions.calibration source or fieldsee electron standard field, -raystandard field, and X-ray standard field.calorimeterinstrument capable of making absolute mea-surements of energy deposition (or absorbed dose) in amaterial through measurement of its change in temper

38、atureand a knowledge of the characteristics of its materialconstruction.certified reference materialmaterial that has been charac-terized by a recognized standard or testing laboratory, forsome of its chemical or physical properties, and that isgenerally used for calibration of a measurement system,

39、 orfor development or evaluation of a measurement method.DISCUSSIONCertification of a reference material can be obtained byone of the following three established routes of measurement ofproperties: (1) using a previously validated reference method; (2) usingtwo or more independent, reliable measurem

40、ent methods; and (3) usingan ad hoc network of cooperating laboratories, technically competent,and thoroughly knowledgeable with the materials being tested. Thecertified reference materials provided by the United States NationalInstitute of Standards and Technology are called Standard ReferenceMater

41、ials.charged particle equilibriumcondition that exists in anincremental volume within a material under irradiation if thekinetic energies and number of charged particles (of eachtype) entering that volume are equal to those leaving thatvolume.DISCUSSIONWhen electrons are the predominant charged part

42、icle,the term “electron equilibrium” is often used to describe chargedparticle equilibrium. See also the discussions attached to the definitionsof kerma and absorbed dose.coincidence sum peakpeak in the observed photon spec-trum produced at an energy corresponding to the sum of theenergies of two or

43、 more gamma- or x-rays from a singlenuclear event when the emitted photons interact with thedetector within the resolving time of the detector.Compton edge (Ec)maximum energy value of electrons ofthe Compton scattering continuum. The energy value of theCompton edge isEc5 E2E112E0.511(7)which corresp

44、onds to 180 scattering of the primary pho-ton of energy E(MeV). For a 1 MeV photon, the Comptonedge is about 0.8 MeV.Compton scatteringelastic scattering of a photon by anatomic electron, under the condition of conservation ofmomentum, that is, the vector sum of the momenta of theoutgoing electron a

45、nd photon is equal to the momentum ofthe incident photon. The scattered photon energy, E,isgiven byE5E11E1 2 cos !0.511(8)where Eis the incident photon energy in MeV and isthe angle between the direction of the primary and scatteredphoton. The electron energy, Ee, is equal to E E.continuumsmooth dis

46、tribution of energy deposited in agamma detector arising from partial energy absorption fromCompton scattering or other processes (for example,Bremsstrahlung). See Compton scattering.cross section ()quotient of P by , where P is theprobability of the interaction for one target entity whensubjected t

47、o the particle fluence (ICRU). 5 P/ (9)Unit: m2The special unit of cross section is the barn, b.1b5 10228m2(10)decay constant ()of a radionuclide in a particular energystate, quotient of dN/N by dt, where dN/N is the meanfractional change in the number of nuclei in that energy statedue to spontaneou

48、s nuclear transformations in the timeinterval dt (ICRU), thus 52dNNdt(11)Unit: s1DISCUSSIONThe quantity (ln 2)/ is commonly called the half-life,T12, of the radionuclide, that is, the time taken for the activity of anamount of radionuclide to become half its initial value.depth-dose distributionvari

49、ation of absorbed dose withdepth from the incident surface of a material exposed to agiven radiation.displacement dose (Dd)quotient of ddby dm, where ddisthat part of the mean energy imparted by radiation to matterwhich produces atomic displacements (that is, excluding thepart that produces ionization and excitation of electrons) ina volume element of mass dm, thusDd5 dd/dm (12)Unit:Jkg1DISCUSSIONA more common unit is displacements per atom(dpa), (see definition).E170