ASTM E170-2008b 317 Standard Terminology Relating to Radiation Measurements and Dosimetry.pdf

1、Designation: E 170 08bStandard Terminology Relating toRadiation Measurements and Dosimetry1This standard is issued under the fixed designation E 170; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb

2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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

3、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 ter

4、ms 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 qua

5、ntities, with units, for radiationmeasurements as contained in the International Commission on Radiation Units and Measurements(ICRU) Report 33 on “Radiation Quantities and Units,” April 15, 1980.2Those terms that are definedessentially according to the terminology of ICRU Report 33 will be followed

6、 by ICRU in parentheses.It should also be noted that the units for quantities used are the latest adopted according to theInternational System of Units (SI).1. Referenced Documents1.1 ASTM Standards:3E 380 Practice for the Use of the International System ofUnits (SI) (The Modernized Metric System)4E

7、 456 Terminology Relating to Quality and StatisticsE 706 Master Matrix for Light-Water Reactor PressureVessel Surveillance Standards, E 706(0)E 722 Practice for Characterizing Neutron Energy FluenceSpectra in Terms of an Equivalent Monoenergetic NeutronFluence for Radiation-Hardness Testing of Elect

8、ronicsE 910 Test Method for Application and Analysis of HeliumAccumulation Fluence Monitors for Reactor Vessel Sur-veillance, E706 (IIIC)1.2 ISO Standards:5GUM Guide to the Expression of Uncertainty in Measure-ment, ISO 1995VIM International Vocabulary of Basic and General Termsin Metrology, ISO 199

9、31.3 ICRU Documents:6ICRU 33 Radiation Quantities and UnitsICRU 60 Fundamental Quantities and Units for IonizingRadiation, December 30, 19981.4 NIST Document:7NIST Technical Note 1297 Guidelines for Evaluating andExpressing the Uncertainty of NIST Measurement Re-sults, 19942. Terminologyabsorbed dos

10、e (D)Quantity of ionizing radiation energyimparted per unit mass of a specified material. The SI unit ofabsorbed dose is the gray (Gy), where 1 gray is equivalent tothe absorption of 1 joule per kilogram of the specifiedmaterial (1 Gy = 1 J/kg). The mathematical relationship isthe quotient of d by d

11、m, where d is the mean incrementalenergy imparted by ionizing radiation to matter of incremen-tal mass dm (see ICRU 33).1This terminology is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.93 on Editorial.Current e

12、dition approved May 1, 2008. Published May 2008. Originallyapproved in 1963. Last previous edition approved in 2008 as E 170 08a.2Available from International Commission on Radiation Units and Measure-ments (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.3For referenced ASTM standards, vis

13、it the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn.5Available from International Organization for Standardization (ISO), 1, ch. dela Voi

14、e-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.6Available from International Commission on Radiation Units and Measure-ments (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814.7Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., S

15、top 1070, Gaithersburg, MD 20899-1070, USA, http:/www.nist.gov1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 5 d/dm (1)DISCUSSION The discontinued unit for absorbed dose is the rad (1rad = 100 erg/g = 0.01 Gy). Absorbed dose is so

16、metimes referred tosimply as dose. For a photon source under conditions of chargedparticle equilibrium, the absorbed dose, D, may be expressed asfollows:D 5F E en/r, (2)where:F = particle fluence (particles/m2),E = energy of the ionizing radiation (J), anden/r = mass energy absorption coefficient (m

17、2/kg).If bremsstrahlung production within the specified material isnegligible, the mass energy absorption coefficient (en/r)isequal to the mass energy transfer coefficient (tr/r), andabsorbed dose is equal to kerma if, in addition, charged particleequilibrium exists.absorbed dose rate, Dthe absorbed

18、 dose in a material perincremental time interval, that is, the quotient of d D by d t(see ICRU Report 33).D5 dD/dt (3)SI unit: Gys1.DISCUSSIONThe absorbed-dose rate is often specified in terms of theaverage value of D over longer time intervals, for example, in units ofGymin1or Gyh1.accuracythe clos

19、eness of agreement between a measure-ment result and an accepted reference value (see Terminol-ogy E 456).activation cross sectionthe cross section for processes inwhich the product nucleus is radioactive (see cross section).activity, Aof an amount of radioactive nuclide in a particularenergy state

20、at a given time, the quotient of dN by dt, wheredN is the expectation value of the number of spontaneousnuclear transitions from that energy state in the time intervaldt (ICRU).A 5 dN/dt (4)Unit: s1The special name for the unit of activity is the becquerel(Bq).1 Bq 5 1s21(5)DISCUSSIONThe former spec

21、ial unit of activity was the curie (Ci).1 Ci 5 3.7 3 1010s21exactly!. (6)The “particular energy state” is the ground state of the nuclide unlessotherwise specified. The activity of an amount of radioactive nuclide in aparticular energy state is equal to the product of the decay constant for thatstat

22、e and the number of nuclei in that state (that is, A=Nl). (See decayconstant.)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 th

23、e measurement of optical absorbance orreflectance.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 peaka peak in th

24、e observed photon spectrum(normally below 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 fielda well-charact

25、erized neutron fieldwhich will provide a fluence 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:8controlled neutron

26、fielda neutron field physically well-defined, and with some spectrum definition, employed for arestricted set of validation experiments.reference neutron fielda permanent and reproducible neu-tron field less well characterized than a standard field butaccepted as a measurement reference by a communi

27、ty ofusers.standard neutron fielda permanent and reproducible neu-tron field with neutron fluence rate and energy spectra, andtheir associated spatial and angular distributions character-ized to state-of-the-art accuracy. Important field quantitiesmust be verified by interlaboratory measurements and

28、 cal-culations.buildup factorfor radiation passing through a medium, theratio 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 ratiothe ratio o

29、f the neutron reaction rate mea-sured with a given bare neutron detector to the neutronreaction rate measured with an identical neutron detectorenclosed by a particular cadmium cover and exposed in thesame neutron field at the same or an equivalent spatiallocation.DISCUSSIONIn practice, meaningful e

30、xperimental values can beobtained in an isotropic neutron field by using a cadmium filterapproximately 1 mm thick.calibrated instrumentan instrument for which the responsehas been documented upon being directly compared with theresponse of a standard instrument, both having been exposedto the same r

31、adiation field under the same conditions; or onefor which the response has been documented upon beingexposed to a standard radiation field under well-definedconditions.calibration source or fieldsee electron standard field,g-ray standard field, and X-ray standard field.calorimeteran instrument capab

32、le of making absolute mea-surements of energy deposition (or absorbed dose) in amaterial through measurement of its change in temperatureand a knowledge of the characteristics of its materialconstruction.8Neutron Cross Sections for Reactor Dosimetry, International Atomic EnergyAgency, Laboratory Act

33、ivities, Vienna, 1978, Vol 1, p. 62.E 170 08b2certified reference materiala material that has been char-acterized by a recognized standard or testing laboratory, forsome of its chemical or physical properties, and that isgenerally used for calibration of a measurement system, orfor development or ev

34、aluation 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 measurement methods; and (3) usi

35、ngan 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 ReferenceMaterials.charged particle eq

36、uilibriuma condition 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 predominatnt charged particle,the term “electr

37、on equilibrium” is often used to describe chargedparticle equilibrium. See also the discussions attached to the definitionsof kerma and absorbed dose in E 170.coincidence sum peaka peak in the observed photon spec-trum produced at an energy corresponding to the sum of theenergies of two or more gamm

38、a- or x-rays from a singlenuclear event when the emitted photons interact with thedetector within the resolving time of the detector.Compton edge (Ec)the maximum energy value of electronsof the Compton scattering continuum. The energy value ofthe Compton edge isEc5 Eg2Eg1 12Eg0.511(7)which correspon

39、ds to 180 scattering of the primary photonof energy Eg(MeV). For a 1 MeV photon, the Compton edgeis 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 and

40、photon is equal to the momentum ofthe incident photon. The scattered photon energy, E8g,isgiven byE8g5Eg1 1Eg1 2 cosu!0.511(8)where Egis the incident photon energy in MeV and u is theangle between the direction of the primary and scatteredphoton. The electron energy, Ee, is equal to Eg E8g.continuum

41、the smooth distribution of energy deposited in agamma detector arising from partial energy absorption fromCompton scattering or other processes (for example,Bremsstrahlung). See Compton scattering.cross section, sthe quotient of P by F, where P is theprobability of the interaction for one target ent

42、ity whensubjected to the particle fluence F (ICRU).s5P/F (9)Unit: m2The special unit of cross section is the barn, b.1b5 10228m2(10)decay constant, lof a radioactive nuclide in a particularenergy state, the quotient of dP by dt, where dP is theprobability of a given nucleus undergoing a spontaneousn

43、uclear transition from that energy state in the time intervaldt (ICRU).l5dP/d t (11)Unit: s1DISCUSSIONThe quantity (ln 2)/l is commonly called the half-life,T12 , of the radioactive nuclide, that is, the time taken for the activityof an amount of radioactive nuclide to become half its initial value.

44、depth-dose distributionvariation of absorbed dose withdepth from the incident surface of a material exposed to agiven radiation.displacement dose (Dd)the quotient of d dby dm, where ddis that part of the mean energy imparted by radiation tomatter which produces atomic displacements (that is, ex-clud

45、ing the part that produces ionization and excitation ofelectrons) in a volume element of mass dm.Dd5 d d/dm (12)Unit:Jkg1DISCUSSIONA more common unit is displacements per atom(dpa), (see definition).displacements per atom (dpa)the mean number of timeseach atom of a solid is displaced from its lattic

46、e site duringan exposure to displacing radiation, as calculated followingstandard procedures (see displacement dose).dosimetera device that, when irradiated, exhibits a quanti-fiable change that can be related to absorbed dose in a givenmaterial using appropriate measurement instrument(s) andprocedu

47、res.dosimetry systema system used for determining absorbeddose, consisting of dosimeters, measurement instrumentsand their associated reference standards, and procedures forthe systems use.effective cadmium cut-off energy (Ec)the energy at whicha specified cadmium container performs like a theoretic

48、allyperfect filter and, therefore, has the following properties:(1) for all energies below Ec, no neutron reactions occur,and(2) for all energies above Ec, neutron reactions occur at thesame rate as if the cadmium were not present.DISCUSSIONEcvaries with cadmium thickness, geometry of thecontainer,

49、angular distribution of incident neutrons, and ambienttemperature.effciencysee total efficiency and full-energy peak effi-ciency.electron equilibriumcharged-particle equilibrium for elec-trons.electron standard fieldan electron field whose particleenergy and direction, spatial uniformity, and particle fluenceE 170 08b3rate uniformity are well established and reproducible.energy calibrationa process of establishing the relationshipbetween photon or particle energy and channel number in thespectrome