1、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-,-,-The Institute of Electrical and Electronics Engineers, Inc.345 East 47th Street, New York, NY 10017-2394, US
2、ACopyright 1999 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Published 1 June 1999. Printed in the United States of America.Print: ISBN 0-7381-1412-X SH94702PDF: ISBN 0-7381-0740-9 SS94702No part of this publication may be reproduced in any form, in an electroni
3、c retrieval system or otherwise, without the prior written permission of the publisher.ANSI N42.14-1999 (R2004)(Revision ofANSI N42.14-1991)American National Standard forCalibration and Use of Germanium Spectrometers for the Measurement of Gamma-Ray Emission Rates of RadionuclidesSponsorAccredited S
4、tandards Committee on Radiation Instrumentation, N42Accredited by theAmerican National Standards InstituteSecretariatThe Institute of Electrical and Electronics Engineers, Inc.Reaffirmed December 2, 2004American National Standards InstituteAbstract: Methods for the calibration and use of germanium s
5、pectrometers for the measurementof gamma-ray energies and emission rates over the energy range from 59 keV to approximately3000 keV, and for the calculation of source activities from these measurements, are established.Minimum requirements for automated peak finding are stated. Methods for measuring
6、 the full-energy peak efficiency with calibrated sources are given. Performance tests that ascertain the prop-er functioning of the Ge spectrometer and evaluate the limitations of the algorithms used for locatingand fitting single and multiple peaks are described. Methods for the measurement of, and
7、 thecorrection for pulse pileup are suggested. Techniques are recommended for the inspection of spec-tral-analysis results for large errors resulting from summing of cascade gamma rays in the detector.Suggestions are provided for the establishment of data libraries for radionuclide identification, d
8、e-cay corrections, and the conversion of gamma-ray rates to decay rates.Keywords: calibration, cascade summing, decay rates, gamma-ray emission rates, germaniumspectrometers, radionuclides, spectrometersAmerican National StandardAn American National Standard implies a consensus of those substantiall
9、y concerned with its scopeand provisions. An American National Standard is intended as a guide to aid the manufacturer, theconsumer, and the general public. The existence of an American National Standard does not in anyrespect preclude anyone, whether he has approved the standard or not, from manufa
10、cturing, market-ing, purchasing, or using products, processes, or procedures not conforming to the standard. Amer-ican National Standards are subject to periodic reviews and users are cautioned to obtain the latesteditions.CAUTION NOTICE:This American National Standard may be revised or withdrawn at
11、 any time.The procedures of the American National Standards Institute require that action be taken to reaf-firm, revise, or withdraw this standard no later than five years from the date of publication. Purchas-ers of American National Standards may receive current information on all standards by cal
12、ling orwriting the American National Standards Institute.Authorization to photocopy portions of any individual standard for internal or personal use isgranted by the Institute of Electrical and Electronics Engineers, Inc., provided that the appropriatefee is paid to Copyright Clearance Center. To ar
13、range for payment of licensing fee, please contactCopyright Clearance Center, Customer Service, 222 Rosewood Drive, Danvers, MA 01923 USA;(508) 750-8400. Permission to photocopy portions of any individual standard for educational class-room use can also be obtained through the Copyright Clearance Ce
14、nter.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-,-,-Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license wit
15、h IEEENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Introduction(This introduction is not part of ANSI N42.14-1999, American National Standard for Calibration and Use of GermaniumSpectrometers for the Measurement of Gamma-Ray Emission Rates of Radionuclides.)This
16、 standard covers the techniques for the calibration and use of germanium spectrometers for the measure-ment of gamma-ray emission rates of radionuclides to assure the reliability of such measurements.This standard is the responsibility of the Accredited Standards Committee N42 on Radiation Instrumen
17、ta-tion. Committee N42 delegated the development of the standard to its Subcommittee N42.RM. Drafts werereviewed by members of Committee N42, Subcommittee N42.RM, and other interested parties, and thecomments received were utilized in producing the standard as finally approved and issued. The standa
18、rd wasapproved by Committee N42 letter ballot of 17 December 1997.ParticipantsAt the time it approved this standard, the Accredited Standards Committee on Radiation Instrumentation,N42, had the following members:Louis Costrell, Chair Michael P. Unterweger, Vice ChairNaeem Ahmad, SecretariatOrganizat
19、ion Represented Name of RepresentativeAmerican Conference of Governmental Industrial Hygienists.Jesse LiebermanApplied Safety Technology.Edward J. Vallario*Battelle Pacific NW Laboratories .Joseph C. McDonaldBicronJoseph G. BellianEberline Instruments .James K. HeschEGb) Coincidence (cascade) summin
20、g;c) The decay of the source during sampling (e.g., with air filters) and counting;d) The decay of the source from a previous time to the counting period;e) Attenuation of photons within and external to the source that is not accounted for by the full-energypeak efficiency calibration.2. ReferencesT
21、his standard shall be used in conjunction with the following publications. When the following standards aresuperseded by an approved revision, the revision shall apply.ANSI N13.30-1996, American National Standard Performance Criteria for Radiobioassay.3ANSI N42.23-1996, American National Standard Me
22、asurement and Associated Instrument Quality Assur-ance for Radioassay Laboratories.4IEEE Std 100-1996, IEEE Standard Dictionary of Electrical and Electronics Terms.5IEEE Std 325-1996, IEEE Standard Test Procedures for Germanium Gamma-Ray Detectors.3ANSI publications are available from the Sales Depa
23、rtment, American National Standards Institute, 11 West 42nd Street, 13th Floor,New York, NY 10036, USA (www.ansi.org/).4This publication is available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ08855-1331, USA (www.standards.ieee.org/).5IEE
24、E publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway,NJ 08855-1331, USA (www.standards.ieee.org/).2 Copyright 1999 IEEE. All rights reserved.ANSIFOR THE MEASUREMENT OF GAMMA-RAY EMISSION RATES OF RADIONUCLIDES Std N42.14-19
25、99Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS3. DefinitionsThe word “shall” denotes a requirement, the word “should” denotes a recommendation, and the word
26、“may”denotes permission. To conform to this standard, Ge spectrometry shall be performed in accordance with therequirements of this standard, but not necessarily with its recommendations; however, justification should bedocumented for deviations from a recommendation.For the purposes of this standar
27、d, the following terms and definitions apply. IEEE Std 100-1996 should bereferenced for terms not defined in this clause.3.1 abundance: See: emission probability per decay P(E) or Pg(E).3.2 activity (A): The expected number of spontaneous nuclear decays (transformations) in unit time from aspecified
28、 energy state (excluding prompt decays from a lower nuclear level) for a given amount of a radionu-clide. Its standard unit (SI) is the becquerel (Bq), where one Bq equals one decay per second. Activity hasoften been expressed in curies (Ci), where 3.7 1010Bq equals 1 Ci, exactly.3.3 ADC conversion
29、gain: The number of channels over which the full amplitude span can be spread; usu-ally 20488192 channels are used for Ge gamma-ray spectrometry.3.4 analog-to-digital converter (ADC): An electronic device used to convert the amplitude of a voltagepulse from analog to digital format.3.5 attenuation:
30、The net loss at the detector of primary photons of a given energy resulting from their inter-action with matter either due to the occurrence of scattering or absorption in the sample or in materialbetween the sample and the detector crystal.3.6 background: Spectral data including peaks not caused by
31、 the source but rather resulting from radioac-tive decay occurring in the surrounding environment or resulting from cosmic-ray interactions in or adjacentto the detector. See also: continuum.3.7 baseline: See: continuum.3.8 calibration: The determination of a value that converts a measured number in
32、to a desired physical quan-tity (e.g., pulse height into photon energy, or counts per second into emission rate).3.9 cascade summing: See: coincidence summing of x and gamma rays.3.10 cascade transitions: Gamma rays in the radioactive decay of a single atom that are emitted sequen-tially and within
33、the resolving time of the spectrometer.3.11 coincidence summing of x and gamma rays: The simultaneous detection of two or more photonsoriginating from a single nuclear disintegration that results in only one observed (summed) pulse. Syn: cas-cade summing; true coincidence summing.3.12 combined uncer
34、tainty: The uncertainty resulting from combining category A and category B uncer-tainties, as defined by the Bureau International des Poids et Mesures (BIPM), using standard statisticalmethods. Category A uncertainties are evaluated by applying statistical methods to a series of repeated mea-suremen
35、ts and are characterized by the estimated standard deviation, sA; category B uncertainties areassigned to quantities whose variation is not explicitly observed. Category B uncertainties are determined byestimating from other information an approximation to a corresponding “standard deviation,” sB, w
36、hoseexistence is assumed. They are combined as if they are all standard deviations.Copyright 1999 IEEE. All rights reserved. 3-,-,-ANSIStd N42.14-1999 AMERICAN NATIONAL STANDARD CALIBRATION AND USE OF GERMANIUM SPECTROMETERSCopyright The Institute of Electrical and Electronics Engineers, Inc. Provid
37、ed by IHS under license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS3.13 continuum: The part of the pulse-height distribution lying underneath a peak, including contributionsassociated with the source, detector, and measuring conditions that affect the spec
38、tral shape. Syn: baseline.3.14 counting rate: The rate at which detector pulses are being registered in a selected voltage interval. Theunit is reciprocal seconds (i.e., s-1).3.15 crossover transition: A gamma ray occurring between two nonadjacent nuclear levels.3.16 dead time: The time during which
39、 the ADC is unable to process input pulses because it is processing aprevious pulse.3.17 detection efficiency: The ratio between the number of selected pulses recorded per unit time to thenumber of photons emitted by the source per unit time. See also: full-energy peak efficiency; totalefficiency.3.
40、18 direct current (dc) level: The input or output voltage level on a dc-coupled instrument when there areno pulses present. For Ge spectrometer systems, the dc level of an output signal from a linear amplifiershould be matched to the input requirements for dc levels of an ADC if the gain conversion
41、scale is toinclude the origin.3.19 elapsed time (Tr): Counting time uncompensated for periods in which an instrument might be unableto respond. Elapsed time of a count equals live time plus dead time.3.20 emission probability per decay P(E) or Pg(E): The probability that a radioactive decay will be
42、fol-lowed by the emission of the specified radiation. Gamma-ray emission probabilities are often expressed per100 decays. Syn: yield; abundance.3.21 energy resolution, full width at half maximum (FWHM): The width of a peak at half of the maxi-mum peak height with the baseline removed.3.22 energy res
43、olution, full width at tenth maximum (FWTM): The width of a peak at one-tenth of themaximum peak height with the baseline removed. For a normal (Gaussian) distribution, FWTM is 1.823times its FWHM.3.23 full-energy peak: A peak in the spectrum resulting from the complete (total) absorption of a photo
44、n ofa given energy in the active volume of the Ge crystal and the collection of all of the resulting charge.Syn: photopeak.3.24 full-energy peak efficiency e (E): The ratio between the number of counts in the net area of the full-energy peak to the number of photons of that energy emitted by a sourc
45、e with specified characteristics for aspecified source-to-detector distance.3.25 gamma-ray branching ratio f(E): For a given excited state, the ratio of the emission rate of a partic-ular gamma ray to the total transition rate from the level (not to be confused with emission probability perdecay).3.
46、26 gamma-ray emission rate R(E): The rate at which a gamma ray of a given energy from the decay ofa particular radionuclide is emitted from a given source. The gamma-ray emission rate is the activity timesthe gamma-ray emission probability.3.27 live time (TL): The time interval of a count during whi
47、ch a counting system is capable of processinginput pulses. Elapsed (or real) time equals live time plus dead time.4 Copyright 1999 IEEE. All rights reserved.-,-,-ANSIFOR THE MEASUREMENT OF GAMMA-RAY EMISSION RATES OF RADIONUCLIDES Std N42.14-1999Copyright The Institute of Electrical and Electronics
48、Engineers, Inc. Provided by IHS under license with IEEENot for ResaleNo reproduction or networking permitted without license from IHS3.28 Monte Carlo: A modeling technique in which the interaction of a gamma-ray of energy E with matteris predicted by simulation.3.29 multichannel analyzer: See: multi
49、channel pulse-height analyzer.3.30 multichannel pulse-height analyzer (MCA): An electronic device that records and stores pulsesaccording to their height. It consists of three function segments: an ADC to provide a means of measuringpulse amplitude; memory registers (one for each channel of the spectrum) to tally the number of pulseshaving an amplitude within a given voltage increment; an input/output section that permits transfer of thespectral information to ot
