1、Designation: E170 14aE170 15Standard 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 20112Those terms that are defined essentially according to the terminology of ICR
6、U 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 recommende
7、d definitions 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
8、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 Internati
9、onal System of Units (SI) (the Modernized Metric System) (Withdrawn 1997)5E456 Terminology Relating to Quality and StatisticsE706 Master Matrix for Light-Water Reactor Pressure Vessel Surveillance Standards, E 706(0) (Withdrawn 2011)5E722 Practice for Characterizing Neutron Fluence Spectra in Terms
10、of an Equivalent Monoenergetic Neutron Fluence forRadiation-Hardness Testing of ElectronicsE910 Test Method for Application and Analysis of Helium Accumulation Fluence Monitors for Reactor Vessel Surveillance,E706 (IIIC)1.2 ISO Standards:3GUM Guide to the Expression of Uncertainty in Measurement, IS
11、O 1995VIM International Vocabulary of Basic and General Terms in Metrology, ISO 20081 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 approved Oct. 15, 2014Marc
12、h 15, 2015. Published November 2014April 2015. Originally approved in 1963. Last previous edition approved in 2014 asE170 14.E170 14a. DOI: 10.1520/E0170-14A.10.1520/E0170-15.2 ICRU Report 60 has been superceded by ICRU Report 85a on “Fundamental Quantities and Units for Ionizing Radiation,” October
13、 2011. Both of these documents areavailable from International Commission on Radiation Units and Measurements (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3 Available from International Organization for Standardization (ISO), 1 Rue de Varembe, Case Postale 56, CH-1211, Geneva 20, Switze
14、rland, http:/www.iso.ch.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 approved version of this h
15、istorical 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 depict all changes accurat
16、ely, 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 19428-2959. United States
17、11.3 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 Uncertainty of NIST Measureme
18、nt Results, 19942. Terminologyabsorbed dose (D)quotient of d by dm, where d is the mean incremental energy imparted by ionizing radiation to matterof incremental 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
19、 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; however, its continued use is not encouraged. Fora photon source under conditions of charged particle equilibrium, the absorbed dose, D, may be expr
20、essed as follows:D 5Een/, (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 is negligible, the mass energy absorption coefficient (en/) is equal to the mass energytransfer
21、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 where 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 sp
22、ecified as an average value over a longer time interval, for example, in units of Gymin1 or Gyh1.accuracycloseness of agreement between a measurement result and an accepted reference value (see Terminology E456).activation cross sectioncross section for processes in which the product nucleus is radi
23、oactive (see cross section).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), thusA 52dN/dt (4)
24、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 decreasing with time. The “particular energy
25、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 decay constant.)analysis bandwidthspec
26、tral band used in a photometric instrument, such as a densitometer, for the measurement of opticalabsorbance or reflectance.6 Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, USA, http:/www.nist.govE170 152analysis waveleng
27、thwavelength used in a spectrophotometric instrument for the measurement of optical absorbance orreflectance.annihilation radiationgamma radiation produced by the annihilation of a positron and an electron. For particles at rest, twophotons are produced, each having an energy corresponding to the re
28、st mass of an electron (511 keV).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 (normally below about 0.25 MeV) resulting from large-angle (110)Compton scatt
29、ering of gamma rays from materials near the detector. This peak will not have the same shape as the full-energypeaks (being wider and skewed toward lower energy).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 skew
30、ed toward lowerenergy).benchmark neutron fieldwell-characterized neutron field which will provide a fluence of neutrons for validation or calibrationof experimental techniques and methods and for validation of cross sections and other nuclear data. The following classificationof benchmark neutron fi
31、elds for reactor dosimetry has been made:7controlled neutron fieldneutron field physically 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 f
32、ield but accepted asa measurement reference by a community of users.standard neutron fieldpermanent and reproducible neutron field with neutron fluence rate and energy spectra, and theirassociated spatial and angular distributions characterized to state-of-the-art accuracy. Important field quantitie
33、s must be verified byinterlaboratory measurements and calculations.bremsstrahlungbroad-spectrum electromagnetic radiation emitted when an energetic charged particle is influenced by a strongelectric field, such as the Coulomb field of an atomic nucleus.DISCUSSIONIn radiation processing, bremsstrahlu
34、ng photons are generated by the deceleration or deflection of energetic electrons in a target material. When anelectron passes close to an atomic nucleus, the strong Coulomb field causes the electron to deviate from its original motion. This interaction resultsin a loss of kinetic energy by the elec
35、tron with the emission of electromagnetic radiation; the photon energy distribution extends up to the maximumkinetic energy of the incident electron. This bremsstrahlung spectrum depends on the electron energy, the composition and thickness of the target, andthe angle of emission with respect to the
36、 incident electron.buildup factorfor radiation passing through a medium, ratio of the total value of a specified radiation quantity (such as absorbeddose) at any point in that medium to the contribution to that quantity from the incident uncollided radiation reaching that point.cadmium ratioratio of
37、 the neutron reaction rate measured with a given bare neutron detector to the neutron reaction ratemeasured with an identical neutron detector enclosed by a particular cadmium cover and exposed in the same neutron field atthe same or an equivalent spatial location.DISCUSSIONIn practice, meaningful e
38、xperimental values can be obtained in an isotropic neutron field by using a cadmium filter approximately 1 mm thick.calibrated instrumentinstrument for which the response has been documented upon being directly compared with the responseof a standard instrument, both having been exposed to the same
39、radiation field under the same conditions; or one for which theresponse has been documented upon being exposed to a standard radiation field under well-defined conditions.calibration source or fieldsee electron standard field, -ray standard field, and X-ray standard field.calorimeterinstrument capab
40、le of making absolute measurements of energy deposition (or absorbed dose) in a material throughmeasurement of its change in temperature and a knowledge of the characteristics of its material construction.7 Neutron Cross Sections for Reactor Dosimetry, International Atomic Energy Agency, Laboratory
41、Activities, Vienna, 1978, Vol 1, p. 62.E170 153certified reference materialmaterial that has been characterized by a recognized standard or testing laboratory, for some of itschemical or physical properties, and that is generally used for calibration of a measurement system, or for development oreva
42、luation of a measurement method.DISCUSSIONCertification of a reference material can be obtained by one of the following three established routes of measurement of properties: (1) using apreviously validated reference method; (2) using two or more independent, reliable measurement methods; and (3) us
43、ing an ad hoc network ofcooperating laboratories, technically competent, and thoroughly knowledgeable with the materials being tested. The certified reference materialsprovided by the United States National Institute of Standards and Technology are called Standard Reference Materials.charged particl
44、e equilibriumcondition that exists in an incremental volume within a material under irradiation if the kineticenergies and number of charged particles (of each type) entering that volume are equal to those leaving that volume.DISCUSSIONWhen electrons are the predominant charged particle, the term “e
45、lectron equilibrium” is often used to describe charged particle equilibrium. See alsothe discussions attached to the definitions of kerma and absorbed dose.coincidence sum peakpeak in the observed photon spectrum produced at an energy corresponding to the sum of the energiesof two or more gamma- or
46、x-rays from a single nuclear event when the emitted photons interact with the detector within theresolving time of the detector.Compton edge (Ec)maximum energy value of electrons of the Compton scattering continuum. The energy value of the Comptonedge is continuum, which is given by:Ec 5E2 E11 2E0.5
47、11(7)Ec5E2 E11 2E0.511(7)which corresponds to 180 scattering of the primary photon of energy E (MeV). For a 1 MeV photon, the Compton edge isabout 0.8 MeV.DISCUSSIONThis value corresponds to 180 scattering of the primary photon of energy E (MeV). For a 1 MeV photon, the Compton edge is about 0.8 MeV
48、.Compton scatteringelastic scattering of a photon by an atomic electron, under the condition of conservation of momentum, thatis, the vector sum of the momenta of the outgoing electron and photon is equal to the momentum of the incident photon. Thescattered photon energy, E, is given byE5 E11E 12 co
49、s !0.511(8)where E is the incident photon energy in MeV and is the angle between the direction of the primary and scattered pho-ton. The electron energy, Ee, is equal to E E.continuumsmooth distribution of energy deposited in a gamma detector arising from partial energy absorption from Comptonscattering or other processes (for example, Bremsstrahlung). See Compton scattering.cross section ()of a target entity, for a particular interaction produced by incident charged or uncharged
