Radioactivity Calibrations Gamma Ionization Chamber

1 Page 1 NBSMeasurementServices: RadioactivityCalibrations withthe"47r"GammaIonization ChamberandOtherRadioactivity CalibrationCapabilities U.S.DepartmentofCommerce NationalBureauofStandards Open at page → 2 Page 2 CenterforRadiationResearch TheCenterforRadiationResearchisamajorcomponentoftheNationalMeasurementLaboratory intheNational BureauofStandards. TheCenterprovidestheNationwithstandardsandmeasurementservicesforionizing radiat... Open at page → 3 Page 3 NBSMEASUREMENTSERVICES: RADIOACTIVITYCALIBRATIONS WITHTHE"471"GAMMA IONIZATIONCHAMBER ANDOTHERRADIOACTIVITY CALIBRATIONCAPABILITIES JacquelineM.Calhoun CenterforRadiationResearch NationalMeasurementLaboratory NationalBur... Open at page → 4 Page 4 LibraryofCongressCatalogCardNumber:87-619870 NationalBureauofStandardsSpecialPublication250-10 Natl.Bur.Stand.(U.S.),Spec.Publ.250-10,41pages(Oct.1987) CODEN:XNBSAV Commercialproducts—materialsandinstruments—areidentifie... Open at page → 5 Page 5 PREFACE Thecalibration andrelatedmeasurement servicesoftheNationalBureau ofStandardsareintendedtoassistthemakersandusersofprecision measuringinstruments inachievingthehighestpossiblelevelsof accuracy,quality,andproductiv... Open at page → 6 Page 6 ABSTRACT ThispaperdescribestheuseoftheNBS"4u"yionizationchamber—an instrumentwhichprovidesanindirectmethodofcomparingtheactivity(decays persecond)ofgamma-ray-emitting radionuclides withnationalstandardsfora routinecalibr... Open at page → 7 Page 7 TABLEOFCONTENTS Page Abstract iv ListofTables vi ListofFigures vii 1.Introduction 1.1GeneralInformation: 1 1.2Description ofService 1 1.3Specifications forSamplesSubmittedforCalibration inthe NBS"4tt"yIonizationChamber 2... Open at page → 8 Page 8 LISTOFTABLES Page Table 1Specifications forCalibrationofGamma-RayEmittingSolutions WhichareSubmittedforCalibration(Radionuclides havinghalf livesgreaterthan15days) 3 Table2Specifications forCalibration ofGamma-RaySolutio... Open at page → 9 Page 9 LISTOFFIGURES Page Fig.1. SectionalViewofaOne-InchDiameterreentrant-well 7 Fig.2a.RelativeResponseofChamber vs.Gamma-RayEnergy0-500keV.... 8 Fig.2b.RelativeResponseofChamber vs.Gamma-RayEnergy500-3000keV. 8 Fig.3. Schema... Open at page → 11 Page 11 1.Introduction 1.1.GeneralInformation TheN6S"4Tr"Yionizationchamber (IC)isawel 1-typepressurized instrumentwhichisusedformeasuringtheactivity(decayspersecond)of gamma-ray-emitting radionuclides. Scheduledcalibrationservi... Open at page → 12 Page 12 a)theprincipalradionuclide b)referencetimeanddate c)methodofcalibration d)certifiedvalueofactivity e)decay-scheme assumptions f)assessmentofradionuclidicpurity g)overalluncertainty Whenthecalibrationserviceiscompleted,th... Open at page → 13 Page 13 Hi z o h- 3 -I o (0 o ilo >• UJ<u) K£ u E o u E e £ O o o M e o> O) 3 0) e <o zt5< H§IOn £ujS oT (0^ < o >>xs _ c^cr .20>ffi <oc ® CjQ« -S 1^<DO O£ ^9JS ocrS c« 3aO N o a. (0 o ooo_ o^z OOXOOOOZOOXZUOOOOOOOOX77X XX2XXXXX... Open at page → 14 Page 14 CO UJ I o (0 —w >» CO 5 >- if) < ^ ss O o> U.= Z g g> I-> s CDS < O o u. CO z g < o UJ Q, CO o 3 •o (0 o E o <0 o 1 o o (/) 0) O) O) 3 c o o 0> (0 o CM LU _l GQ < > 0)ffi <cc o CO ^(0o o-c .OS N T3 c (D CO o oo XX T-CM «... Open at page → 15 Page 15 1.3.2 Packagijig. Packagingforallsourcesmustbeincompliancewith theDepartment ofTransportation (DOT)andNuclearRegulatoryCommission (NRC) regulations. Copiesoftheseregulations maybeobtainedfromOperations Division,OfficeofH... Open at page → 16 Page 16 Sampleswhicharetoolowinactivityproduce acurrentinsufficiently differentfrombackground;sampleswhicharetoostrongmayproducesomany ionpairsthatrecombination canoccurbeforetheelectricfieldsweepsthem away. Anychangeincontainer... Open at page → 17 Page 17 I I Fig.1.Sectionalviewofaone-inchdiameterreentrant-well IG=11pressure ionizationchamber. (FromCentronic, 20thCenturyElectronics Ltd., KingHenry'sDrive,NewAddington,CroydonCR9OBG,England.) 7 Open at page → 18 Page 18 ENERGY,keV Fig.2a.RelativeResponseofChambervs.Gamma-RayEnergy0-500keV. 500 1000 1500 2000 2500 3000 ENERGY,keV Fig.2b.RelativeResponseofChambervs.Gamma-RayEnergy500-3000keV. 8 Open at page → 19 Page 19 2.3CommentsonDirectActivityMeasurements Alldirectmeasurements dependtosomedegreeonexistingnuclear-decay- schemedata.Forexample,calorimetric measurements requireaknowledgeofthe averageenergyperdecay. Theassociateduncertai... Open at page → 20 Page 20 Subsequent totheprimarydecay,excitedlevelsinthedaughternuclide thendecaybygamma-rayemissionorbyinternalconversion. Thelatterpro- cessalsogivesrisetoxraysandAugerelectrons. Long-livedexcitedstates cancontributeextracounts... Open at page → 21 Page 21 2.5.3 InternalGasCounters .Radionuclides inthegaseousformcanbe introduceddirectlyintothecountinggasofproportional counters. With precautions forquantitative mixingandhandling,andcompensation for boundaryeffects,lowuncert... Open at page → 22 Page 22 2.6.2Anticoincidence Counting .Iftheefficiency ofonedetector is veryhigh,thenitisreasonabletocountthosepulsesfromtheotherdetector whichdonothaveacoincidentpulse.Asapplied,thismethodhasthe technicaladvantagethatthetimingi... Open at page → 23 Page 23 2.7Radioactivity GroupInstrumentation attheU.S.NationalBureauof Standards Some40countingsystemsareinusebytheNBSRadioactivity Groupfor thedirectcalibration ofradionuclides, checkingforimpurities, retaining calibrations, c... Open at page → 24 Page 24 TABLE3INSTRUMENTSFORNBSBASICCALIBRATIONSNOTUSINGCASCADERADIATIONS ConntingSystem Label Description andReferences O.lnascintillation counter O.lna Acarefullymeasuredexternalbaffleabout 11cmindiameterestablishes thesolid a... Open at page → 25 Page 25 4nproportional counter 47rp Table3cent. Ametallizedfilmcarrying athinsource formstheboundrybetweentwohemispherical proportional counters,eachwithaloop electrode. Itisusedprimarilyfor high-energypure-beta-ray-emitt ing ra... Open at page → 26 Page 26 TABLE4INSTRUMENTSFORBASICNBSCALIBRATIONSUSINGCASCADERADIATIONS CotintingSystem Label DescriptionandReferences Thin-crystal scintillation system Largesodium iodidesystem Liquidscintillation system Thin-Xtal ANal(Tl)crysta... Open at page → 27 Page 27 o Pi H oi u 0 O Ti M W s o U «> >» at f-H O CO o I o o + O ,H o + o I + o + O tH o + o I in o o 1 00 o o + in o 1 00 MO M U U u e SI Ml <aa ft u CO iHO rH CO Oo o T so rH rH oo 00 o rH 00 o in m in • « • rH o rHo o M 3 C... Open at page → 28 Page 28 t w (A 5J o *^ o C5 OB (J M H o Q o e ca O o u (A 1 OB G8 B B ^ c o ?^ 1 1 1 L>, >fc § c: OS CB o W OS i 1 00 eS <d S S r B 6 nl c2 cs « o >B o •oB| o o + o o + o m o cs +> «a o o o B o 4) 1^ U o o « <M V V JS a cs a, on... Open at page → 29 Page 29 a o >«l oEl wcl C3ui 2 1^1O 9\ 1-1 ON cs <s CO 00 O Ooo oo o + -^ + + 1 1 + o u c; o i J. o T-1 CS ooo o o^ o O-"I O rl 00 o t-(o ao p~o "1 f-H i-( tS 1-1 -I 11 oo e^ •J .-a «»H o O •a •a «a a u u M «9 ea u U u & o o o o... Open at page → 30 Page 30 M O O a u 4> B o o + <4-l o * 5 00 o o 4> O 61 + !> i-t ••-> at O -1-1 .rH CD ^» d P ,-1n 4>O s^ «>H >» o a> o-H O at0 0(ia 00 O s•o •o ct gS u u u 1/1M M in Oh ca ed M CJ U Ma (3 O U 1U ax •o rH CLiu K B si OS CL, XT 00... Open at page → 31 Page 31 3.2Characteristics andFunctions Severalimportantcharacteristics oftheNBS"47r"Yionizationchamber include: sensitivity, long-termstability,simplicity ofoperation, and simplesourcepreparation [2],Theinstrument isnotonlyused... Open at page → 32 Page 32 Theelectrometer hasasensitivitystatedtobelOyV. Theinput amplifierprovideshighinputresistance (2x10^'*ohms),lowoffsetcurrent (lessthan5xlO"!^A),andlownoise. Thedouble-shielded inputsection permitsfloatingoperationsupto100... Open at page → 33 Page 33 Theactivity, A,oftheradionuclide inasample, S,tobemeasured is givenbyKDR3,whereR5istheresponse(current)forthesamplerelativeto thatfortheradiumsource. Backgroundcurrentsmeasuredjustbeforeand aftercountingthesampleandradiu... Open at page → 34 Page 34 Questionsareasfollows: NewBkg-0;Skip 1 #BKGS=-1 Time: Day# InputStartofCalenderScalarHR,MIN,SEC Resetclockonclockscalar ComputerTime:HR:MIN:SEC Statementofagreementbetweencomputerandcalenderclock Answer YoryifOK,Norntore... Open at page → 35 Page 35 Table6.SensitivityRangeSettings CapacitorRatio RadiumReferenceSource* 1.0 Background 10.0 3,10,20 100.0 20,60,100,200 1000.0 200,500,1000,5000 * Thenumberoftheradiumreferencesourceusedinapproximately equivalent to thenum... Open at page → 36 Page 36 4.3.5MeasuringtheSample .Whenplacingthesolutionsampleinthe chamber,observetheampouletomakecertainthatnoliquidisintheneckof theampoule. Thesampleisthencountedthesamenumberoftimesineachset ofmeasurements astheradiumreferen... Open at page → 37 Page 37 4.5FormatofCalibrationReport ThefollowingtwopagesshowanexampleofaReportofCalibration. As statedinsection1.2,attheendofacalibrationexercise,thetechnical userwillbegivenaReportofCalibrationstatingprimarily[3]: a)theprincip... Open at page → 38 Page 38 NBS-443 (Rev.2-8S) U.S.DEPARTMENTOFCOMMERCE NATIONALBUREAUOFSTANDARDS OAITHERSBURQ.MARYLAND20899 REPORTOFCALIBRATION for COMPANYNAME ADDRESS R&dionuclide s Sourceidentification Sourcedescription Solutioncomposition Activ... Open at page → 39 Page 39 NOTES Approximately fivemilliliters ofsolution. Ampoulespecifications bodydiameter vailthickness bariumcontent leadoxidecontent otherheavyelements 16.5±0,5mm 0.60±0,04mm lessthan2.5percent lessthan0.02percent tracequanti... Open at page → 40 Page 40 Theoriginoftheuncertaintyestimates (asstandarddeviations ofmeans, orsuitableapproximations) inadirectcomparisonareshowninthefollowing excerptfromthereportingformforaninternational intercomparisonof activitymeasurements o... Open at page → 41 Page 41 Discussions amongrepresentatives ofseveralnationalstandardizing laboratories, followingthedistribution ofaquestionnaire aboutuncertainty statements bytheBureauInternational desPoidsetMesures,ledtoa suggestionthatanapproa... Open at page → 42 Page 42 1231 percent a)60ionization-chambermeasurements onthissample 0.01 ^)solutioncomposition anddensity 0.05 c)fivecoincidencemeasurements 0.11 d)efficiencyextrapolation 0.10 e)gravimetricmeasurements 0.03 9)resolvingtime 0.0... Open at page → 43 Page 43 6.References 1.NBSSpecialPublication 260,NationalBureauofStandards,Standard ReferenceMaterialsCatalog1986-1987ed.[Availablefromthe Superintendent ofDocuments, U.S.GovernmentPrintingOffice,Washington, D.C.20402]. 2.NBSSpe... Open at page → 44 Page 44 NBS-n4A(REV.2-8C) U.S.DEPT.OFCOMM. 1.PUBLICATIONOR 2.PerformingOrgan.ReportNo.3.PublicationDate BIBLIOGRAPHICDATA REPORTNO. October1987\HFPl/^o#ain^tmrt'irin^) NT^c;/qp_9SO/in 4.TITLEANDSUBTITLE NBSMeasurementServices: R... Open at page → 47 Page 47 PUBLICATIONS INTHESP250SERIESFROMTHECENTERFORRADIATIONRESEARCH SP250-1 NBSMeasurement Services: SP250-12 SpectralRadianceCalibrations J.H.Walker,R.D.Saunders, andA.T.Hattenburg SP250-2 NBSMeasurement Services: SP250-13 F... Open at page → 48 Page 48 U.S.DepartmentofCommerce NationalBureauofStandards Gaithersburg,MD20899 OfficialBusiness PenaltyforPrivateUse$300 Open at page →