1、The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 1995 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Published1995. Printed in the United States of America.IEEE is a registered trademark in the U.S. Pa
2、tent the assay for radioactivity; and thedetermination of gamma ray energies and intensities are established. Both energy calibration andefficiency calibration are coveredKeywords: calibration, efficiency calibration, energy calibration, gamma-ray energy, radioactivity,radionuclidesCopyright The Ins
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13、ssions.Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-iiiIntroduction(This introduction is not a part of ANSI N42.12-1994, American National Standard Calib
14、ration and Usage of Thallium-Activated Sodium Iodide Detector Systems for Assay of Radionuclides.)This standard, a revision of ANSI N42.12-1980, is the responsibility of the Accredited Standards CommitteeN42 on Radiation Instrumentation. Committee N42 delegated the development of this standard to it
15、s Sub-committee N42.2. Drafts were reviewed by Committee N42, Subcommittee N42.RM on Radioactivity Mea-surements, and other interested parties, and the comments received were utilized in producing the standardas finally approved. The standard was approved by N42 letter ballot of 11 April 1994.At the
16、 time it approved this standard, the Accredited Standards Committee on Radiation Instrumentation,N42, had the following members:Louis Costrell,ChairLuigi Napoli,Administrative SecretaryOrganization Represented Name of RepresentativeAmerican Conference of Governmental Industrial HygienistsJesse Liebe
17、rmanHealth Physics Society.George CampbellJoseph R. Stencel (Alt.)Institute of Electrical and Electronics Engineers.Louis CostrellJulian Forster (Alt.)Anthony J. Spurgin (Alt.)Lawrence Berkeley LaboratoryEdward J. LampoLawrence Livermore National Laboratory.Paul L. PhelpsNational Institute of Standa
18、rds and TechnologyLouis CostrellMichael P. Unterweger (Alt.)Oak Ridge National Laboratory.Hugh R. BrashearPacific Northwest LaboratoriesKenneth L. SwinthUS Army Center for EW/RSTA.Edward GroeberUS Department of EnergyGerald GoldsteinUS Federal Emergency Management Agency .Carl R. SiebentrittUS Nucle
19、ar Regulatory Commission.Edward C. Wenzinger, Sr.Members-at-LargeJoseph C. BellianErnesto A. CorteMorgan CoxJohn M. GallagherJack M. SelbyAl N. TschaecheEdward J. VallarioLee J. WagnerSanford Wagner At the time this standard was approved, Subcommittee N42.RM had the following members: Frank X. Masse
20、,ChairJ. M. R. Hutchinson,SecretaryRobert Ayres Bert M. Coursey Y. KobyashiJoseph G. Bellian Michael Devine David McCurdyJohn D. Buchanan Roger Ferris D. M. MontgomeryR. F. Coley Robert J. Gehrke Carl W. SeidelCopyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS unde
21、r license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ivThe working group for this standard had the following members:Joseph G. Bellian,Project LeaderRod Dayton Tom Jenkins Robert KinzerJ. M. R. Hutchinson Peter Paul Ernesto A. CorteMelvyn Halbert Don
22、W. Miller Frank X. Massey The following persons were on the balloting committee:Joseph G. Bellian Gerald Goldstein Anthony J. SpurginHugh R. Brashear Edward Groeber Joseph R. StencilGeorge Campbell Edward J. Lampo Kenneth L. SwinthErnesto A. Corte Jesse Lieberman Al N. TschaecheLouis Costrell Paul L
23、. Phelps Michael UnterwegerMorgan Cox Jack M. Selby Edward J. VallarioJulian Forster Carl L. Siebentritt Sanford WagnerJohn M. Gallagher Edward C. Wenzinger, Sr.Mary Lynne NielsenIEEE Standards Project EditorCopyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under
24、license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-vContentsCLAUSE PAGE1. Overview 11.1 Scope 11.2 Purpose. 12. References 23. Definitions 24. Procedure . 34.1 Total spectrum counting systems. 34.2 SCA counting systems . 54.3 MCA counting systems 65.
25、Sources of systematic error 86. Precautions. 96.1 Assay for a radionuclide for which no radioactivity standard is readily available 96.2 Assay of mixtures of radionuclides 96.3 Thin-Window detectors . 96.4 Count rates . 96.5 Geometric correction factors 96.6 Counting statistics 96.7 Dead-Time correc
26、tions. 96.8 Correction for decay during the counting period. 106.9 Counting geometry. 116.10 Spectral features. 116.11 Full-Energy-Peak efficiency versus energy function or curve 116.12 Net count rate. 126.13 Temperature effects . 126.14 Linearity. 127. Bibliography 12Copyright The Institute of Elec
27、trical and Electronics Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction
28、or networking permitted without license from IHS-,-,-American National Standard Calibration and Usage of Thallium-Activated Sodium Iodide Detector Systems for Assay of Radionuclides1. Overview1.1 ScopeThis standard establishes methods for performance testing, calibration, and usage of thallium-activ
29、atedsodium iodide NaI(Tl) detector systems for the measurement of gamma ray emission rates of radionu-clides; the assay for radioactivity; and the determination of gamma ray energies and intensities. It coversboth energy calibration and efficiency calibration. The following three techniques are cons
30、idered:a) Total spectrum counting (see 4.1) employs a system that counts all pulses above a low-energythreshold (see 6.1, 6.2, and 6.3).b) Single-channel analyzer (SCA) counting (see 4.2) employs a system with a counting “window,”which establishes upper and lower energy boundaries (see 6.1, 6.2, and
31、 6.3).c) Multichannel analyzer (MCA) counting (see 4.3) employs a system in which multiple counting win-dows are utilized. This technique allows measurements for which the continuum under the full-energy peak may be subtracted without introducing unacceptable error.In case of overlapping peaks in th
32、e spectrum, it is realized that an MCA with access to a spectrum-strippingprogram is necessary. Such cases are not covered by this standard.1.2 PurposeThe purpose of this document is to provide a standardized basis for the calibration and usage of sodiumiodide detector systems for the measurement of
33、 gamma ray emission rates of radionuclides. Typical applica-tions include radionuclide identification and assay in various industrial, environmental, and medical applica-tions. An NaI(Tl) detector system consists of three major components: a scintillating medium that producesa flash of light when io
34、nizing radiation interacts with it; one or more photomultipliers, optically coupled tothe scintillator, which converts the light flash to an amplified electrical impulse; and associated electronicinstrumentation that powers the photomultiplier and processes the output signal. (See IEEE Std 398-1972.
35、1)1Information on the reference can be found in clause 2.1ANSIN42.12-1994 AMERICAN NATIONAL STANDARD CALIBRATION AND USAGE OF THALLIUM-ACTIVATEDCopyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction or networking per
36、mitted without license from IHS-,-,-The theory of operation of NaI(Tl) detectors is presented in numerous publications, including B3, B5,and B9 in clause 7.2. ReferencesThis standard shall be used in conjunction with the following publication:IEEE Std 398-1972 (Reaff 1990), IEEE Standard Test Proced
37、ures for Photomultipliers for ScintillationCounting and Glossary for Scintillation Counting Field (ANSI).23. Definitions3.1 accuracy: The degree of agreement of the measured value with the true value of the quantity beingmeasured.3.2 assay: The determination of the activity of a radionuclide in a sa
38、mple.3.3 ambient background: Those counts that can be observed, and thereby allowed for, by measuring a sam-ple that is identical to the unknown sample in all respects except for the absence of radioactivity. Thesecounts are attributable to environmental radioactivity in the detector itself, the det
39、ector shielding material,and the sample container; cosmic rays; electronic noise pulses; etc.3.4 check source: A radioactive source, not necessarily calibrated, that is used to confirm the continuing sat-isfactory operation of an instrument.3.5 correlated gamma ray summing: The simultaneous detectio
40、n of two or more gamma rays originatingfrom a single atom disintegration.3.6 dead time (td): The time after a triggering pulse during which the system is unable to retrigger.3.7 efficiency: The net number of counts registered by the detector system per unit of time, divided by thenumber of photons o
41、f interest originating in the radioactive source during the same unit of time.3.8 energy calibration: The relationship between the height of the amplifier output pulse and the energy ofthe photons originating in the radioactive source.3.9 full-energy peak: The peak in a pulse height spectrum that co
42、rresponds to total absorption of a gammaphoton in the NaI(Tl) detector.3.10 full width at half maximum (FWHM): The full width of a gamma photon peak distribution measuredat an ordinate halfway between the maximum ordinate of the peak and the background.3.11 live time: The total time of the measureme
43、nt minus the total dead time.3.12 precision: The degree of agreement of repeated measurements of the same property, expressed quanti-tatively as the standard deviation computed from the results of the series of measurements.3.13 pulse height radiation: See 3.16.2IEEE publications are available from
44、the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway,NJ 08855-1331, USA.2ANSISODIUM IODIDE DETECTOR SYSTEMS FOR ASSAY OF RADIONUCLIDES N42.12-1994Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEENo
45、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.14 radioactivity standard source: A radioactivity standard, as used in this document, shall be either aradioactivity standard that has been certified as to absolute radioactivity by a laboratory recognized as theNatio
46、nal Standardizing Laboratory of a country for radioactivity measurements or a radioactivity standardthat has been obtained from a supplier who participates in measurement assurance activities with theNational Standardizing Laboratory when such standards are available. In such measurement assurance a
47、ctiv-ities, the radioactivity calibration value of the suppliers should agree with the National Standardizing Labo-ratory value within the overall uncertainty stated by the supplier in its certification of the same batch ofsources or in its certification of similar sources.3.15 random photon summing
48、: The simultaneous detection of two or more photons originating from thedisintegrations of more than one atom.3.16 resolution, pulse height: The measured FWHM, after ambient background subtraction, of a gamma-ray peak distribution, expressed as a percentage of the pulse height corresponding to the c
49、entroid of the dis-tribution.3.17 sensitivity response: The net number of counts registered by the detector system per unit of time,divided by the activity of the radionuclide.3.18 shall: A verb indicating an action required by this standard.3.19 should: A verb indicating an action that is to be included when practical.3.20 simulated source: A radioactive source consisting of one or more long-lived radionuclid
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