1、Designation:D364906(Reapproved 2014)An American National StandardStandard Practice forHigh-Resolution Gamma-Ray Spectrometry of Water1This standard is issued under the fixed designation D3649;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the measurement of gamma-rayemitting radionuclides in water by means of gamma-raysp
3、ectrometry.It is applicable to nuclides emitting gamma-rayswith energies greater than 45 keV.For typical counting systemsand sample types,activity levels of about 40 Bq are easilymeasured and sensitivities as low as 0.4 Bq are found for manynuclides.Count rates in excess of 2000 counts per secondsho
4、uld be avoided because of electronic limitations.Highcount rate samples can be accommodated by dilution,byincreasing the sample to detector distance,or by using digitalsignal processors.1.2 This practice can be used for either quantitative orrelative determinations.In relative counting work,the resu
5、ltsmay be expressed by comparison with an initial concentrationof a given nuclide which is taken as 100%.For quantitativemeasurements,the results may be expressed in terms of knownnuclidic standards for the radionuclides known to be present.This practice can also be used just for the identification
6、ofgamma-ray emitting radionuclides in a sample without quan-tifying them.General information on radioactivity and themeasurement of radiation has been published(1,2).2Informa-tion on specific application of gamma spectrometry is alsoavailable in the literature(3-5).See also the referenced ASTMStanda
7、rds in 2.1 and the related material section at the end ofthis standard.1.3 This standard does not purport to address the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicabil
8、ity of regulatorylimitation prior to use.2.Referenced Documents2.1 ASTM Standards:3D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Clo
9、sed ConduitsD3648 Practices for the Measurement of RadioactivityD4448 Guide for Sampling Ground-Water Monitoring WellsE181 Test Methods for Detector Calibration and Analysis ofRadionuclides3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,refer to Terminology D1129.For terms
10、not defined inthis practice or in Terminology D1129,reference may be madeto other published glossaries.4.Summary of Practice4.1 Gamma ray spectra are measured with modular equip-ment consisting of a detector,high-voltage power supply,preamplifier,amplifier and analog-to-digital converter(or digi-tal
11、 signal processor),multichannel analyzer,as well as acomputer with display.4.2 High-purity germanium(HPGe)detectors,p-type orn-type,are used for the analysis of complex gamma-ray spectrabecause of their excellent energy resolution.These germaniumsystems,however,are characterized by high cost and req
12、uirecooling.Liquid nitrogen or electromechanical cooling,or both,can be used.4.3 In a germanium semiconductor detector,gamma-rayphotons produce electron-hole pairs.The charged pair is thencollected by an applied electric field.A very stable low noisepreamplifier is needed to amplify the pulses of el
13、ectric charge1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved June 1,2014.Published July 2014.Originally approvedin 1978.Last previous edition approved in 2006 a
14、s D3649 06.DOI:10.1520/D3649-06R14.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,r
15、efer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 resulting from gamma photon interactions.The output from thepreamplifier is directly proportional to the energy deposited bythe
16、 incident gamma-ray.These current pulses are fed into anamplifier of sufficient gain to produce voltage output pulses inthe amplitude range from 0 to 10 V.4.4 A multichannel pulse-height analyzer is used to deter-mine the amplitude of each pulse originating in the detector,and accumulates in a memory the number of pulses in eachamplitude band(or channel)in a given counting time.Com-puterized systems with stored programs and interface hardwarecan accomplish the same functions as hardwired multich
