Neutron Source Strength Calibrations

1 Page 1 NBSMeasurement Services: ResearchInformationCenter fVationalBureauofStandards Gaitheraburg,Alarykad20899 Neutron SourceStrength , , ,,,, Calibrations U.S,DepartmentofCommerce NationalBureauofStandards Open at page → 2 Page 2 CenterforRadiationResearch TheCenterforRadiationResearchisamajorcomponentoftheNationalMeasurementLaboratoryintheNational BureauofStandards. TheCenterprovidestheNationwithstandardsandmeasurementservicesforionizing radiati... Open at page → 3 Page 3 NBSMEASUREMENTSERVICES: NEUTRONSOURCESTRENGTH CALIBRATIONS E.DaleMcGarry EdwardW.Boswell CenterforRadiationResearch NationalMeasurementLaboratory NationalBureauofStandards Gaithersburg,MD20899 U.S.DEPARTMENTOFCOMMERCE,C.... Open at page → 4 Page 4 LibraryofCongressCatalogCardNumber:88-600510 NationalBureauofStandardsSpecialPublication250-1 8 Natl.Bur.Stand.(U.S.),Spec.Publ.250-18,58pages(Mar.1988) CODEN:XNBSAV Commercialproducts—materialsandinstruments—areidentifi... Open at page → 5 Page 5 PREFACE ThecalibrationandrelatedmeasurementservicesoftheNationalBureau ofStandardsareintendedtoassistthemakersandusersofprecision measuringinstruments inachievingthehighestpossiblelevelsof accuracy,quality,andproductivit... Open at page → 6 Page 6 ABSTRACT Themanganesesulfate(MnSO^)bathmethodofneutronsourcestrength calibration atNBSisdescribedandcomparedbrieflywithotherMnSO^ bathtechniquesusedinternationally. Theaccuracyofsource calibration isdiscussedfromtheviewp... Open at page → 7 Page 7 TABLEOFCONTENTS Page 1.DESCRIPTION OFCALIBRATIONSERVICESANDACCURACIES 1.1ServicesAvailable 1.1.1 AllowableSourceStrengthRange 1.1.2MethodinGeneral 1.2SummaryofAccuracy 1.2.1AccuracyofNBS-ISourceStrength 1.2.2OtherUncerta... Open at page → 8 Page 8 5.1 Countingthe*®MnGammaRays 20 5.1.1 Scintillators andPhotomultiplierTubes 20 5.1.2Preamplifiers 20 5.1.3LinearAmplifiers 20 5.1.^Discriminators 20 5.1.5Scalers 21 5.1.6PrintoutModules 21 5.2ResponseRatioofCountersandSy... Open at page → 9 Page 9 LISTOFFIGURES Fig.No. BriefDescription PageNo. 1 RadiumBerrylliumPhotoneutronSource NBS-I 3 2 CirculatingManganeseSulphateBathand ShieldedGammaRayDetectors 6 3 PhotographofMnSO^Bath 7 4 SchematicofNuclearEventsinMnS04 8... Open at page → 11 Page 11 1.DESCRIPTION OFCALIBRATIONSERVICESANDACCURACIES 1.1ServicesAvailable Theavailableservicesaredescribed inthecurrenteditionofthe IonizingRadiationSectionofNBSSpecialPublication 250,"NBS CalibrationServicesUsersGuide,1986-... Open at page → 12 Page 12 1.2.2OtherUncertaintyComponentsofInterest 1)Dependingupontheactivityofthesource,differentscintillation countersareused. Theuseofseparatecountersforhighlevel (>2x10®n/s)sourcesintroducesanadditionalO.H%uncertaintybecause... Open at page → 13 Page 13 3 Open at page → 14 Page 14 calibrations. Inthefirstcalibration, thethermalneutrondensity wasdeterminedfromtheactivityinducedinthinindiumandmagnesium foilsasafunctionofdistancefromthesourcewhenboththesource andfoilswereunderwater. Thesecondcalibrat... Open at page → 15 Page 15 TABLE 1 NBS-1EMISSIONRATETABLEBASEDONTHECALIBRATIONOF1,257E£ INJUNc.1961ANDAHALFLIFEOF1600YcARS 1976 1977 1978 1979 4#%A^ 1980 JAN 1.2491E+06 12485E+06 4OAA^pj.y\y 1«2480Et06 l»2475E+06 1.2469E+06 FEB l,2490E+06 1•2485Et... Open at page → 17 Page 17 FIG.3.Aphotographofthealuminumshellwhichsupportsthe polyethylenelinerandMnSO/^solution. Sourcesarepulledintothe centerofthesolutionbyaTefloncanattachedtoaropeonapulley, above,andashortsteelbaratthebottomoftheinsideofthe... Open at page → 18 Page 18 7^ UJ CO UJ o _UJ a:< 3< UJUJ X QQO UJ I- 3 O) UJ CO UJ < q:^ GOo <5 (JUJ X UJ9 oi2 0) (0 0) cx: o t. 3c <D Cc m0) o • cc co0) o nq0) .-4 o x: •tH • *j4J mt, 03 • o0>, CO £> c> s:<D (u • ijTD0) Oa: cO •>HbOCO 0)*J o30) J... Open at page → 19 Page 19 However,thereisnowsufficientevidence (5)toshowthatdifferent ^'^Cfsourcesexhibitmeasurablydifferent"effective"^^^Cfhalflives intherangeof2.635to2.657years. Consequently, qualitycontrol proceduresarerelatedtomeasurements o... Open at page → 20 Page 20 TABLE2.AtomDensitiesofElementsinEachCompositionoftheMnSO^ SolutionsReferredtoinTables3and Density(g/cm') 1.382 1.257 1.093^ N^/Nj^^ 35.47 55.65 162.15 AmountofMnSO^ 320.7 231.3 93.68 (g/kgsolution) Concentrations (inunit... Open at page → 21 Page 21 TABLE4.AbsorptionRatesperSourceNeutronforElementsOtherThan ManganeseintheNBSMnS04BathAssumingaConcentration Densityof 1.374kg/Landa^^^CfFissionNeutron-Energy Spectrum. Bathis1.27m inDiameter(SeeRef.7). TypeandEnergy Rang... Open at page → 22 Page 22 CD - CD CD CO OQ .O Tr\ \JJ ooC_)ooO TJ <D c: tz o 1 O — < r *-« CO CD C\J CD CQ oon Q-H rrt (— • 1 rr\ *jJ o frt M-J * * COC ' cc _ f~^ C_) r— CO —J rrt ill frt cr 111o O LO '~1 (0 1 oCY^ Cu CD E * OO O* oCDOCD rrt W <D... Open at page → 23 Page 23 Table5.ResultsofIntercomparison BetweenCalculationand Measurement ofSourceAbsorption Calculateddifferencebetween bareandcadmiumcovered sourceabsorption Experimentally measured difference(frombath irradiations) . Pu-Be-B... Open at page → 24 Page 24 (0.08±0.03)%. Theuncertainties ofthesefourquantitiesare estimatesthatareintendedtohavethecharacterofonestandard deviationandarebaseduponthefollowing: 1)forfastneutroncapture insulfurandoxygen,theuncertaintystemsprimarily... Open at page → 25 Page 25 varietyofmeasurements atNBSintheyears1976-198^. Thissourceis identifiedasNS-100. TheuncertaintyestimatedfortheCf-252source NS-100is±1.1?do). Theuncertainty isderivedasfollows. 4.1Recapitulation ofUncertaintyComponents NS... Open at page → 26 Page 26 Table7.SummaryofUncertainties AssociatedwithCalifornium NeutronSourceStrengthCalibrations SourceStrengthNBS-I ±0.85% 3 * Main-to-Remote CounterResponseRatio ±0.H0% s Fastneutroncapturebyoxygenandsulfur ±0.08% s fortheCfn... Open at page → 27 Page 27 wasassumedtobebiasedandwasalsoexcluded. Oftheremainingresults,multipledatapointsfromanylaboratorywere averagedtoyieldthevalueslistedinTable8.TheNBSresultswere treatedsomewhatdifferently, however,becausetheveryfirstNBSdat... Open at page → 28 Page 28 < o I. o N s « N _l I • 1 I • 1 I • 1 00 J I I I : L C 2 Sc <s o <z 03 11 1 1 c < S3 ii < Ec ffi u- < £ 3 Q. ^ OD (O in ^ COM ^ (%)lenpisdJaAiieia^ O T- (0 g-o a.2 CO(U 4-)0) CO> in 21 18 Open at page → 29 Page 29 Table8. AReviewoftheMostRecentInternational SourceStrength Intel—Comparison(seeRef.10). Uncertainties (inpercent) Result(xlO^n/s) (ata6Q%confidencelevel) 1NBS(1978) 2.09557 0.945 2BIPM 2.098U 0.322 3ENEA 2.11161 O.i^OH 4... Open at page → 30 Page 30 5.OPERATIONALDESCRIPTION OFFACILITY Themanganesesulfatebathmethodofneutronsourcecalibrationatthe NBSinvolvesmechanicalmanipulations necessarytopositioneither NBS-Ioranunknownsourceintothebathformeasurements, electronics... Open at page → 31 Page 31 5.1.5Scalers Allscalarsarecontained inasingleTennelecmodule,whichisatinner andtriplescalar. ThescalarchannelsareA,BandC. A&Barethe mainreadout,withAbeingthemost-significant-digit overflowfromB. Cisfortheremoteoutput. 5.1... Open at page → 32 Page 32 enclosedinMonelof 1-mmthickness (9).Thesourcehavingthe originalcapsule(NBS-I)hasbeenchosenastheprimarystandardfor theabsolutecalibration. Ithashadanaluminumprotectivejacket placedaroundit.TheothersourceisknownasNBS-II. T... Open at page → 33 Page 33 thedetailsforsettingtheelectronics andthediscriminator. The positionofthe**Mnpeakisperiodicallycheckedbytheoperatorand manualadjustmentstotheamplifiergainaremadeasnecessary. After acquiringsomeexperiencewiththesystem,gai... Open at page → 34 Page 34 4)Fromthelargeroftheabove-mentioned uncertainties andthenumber ofobservations, thecodedeterminestheuncertainty ofthemean countrate. 5)Thecodeliststhesystemdead-time(orcountingloss)correction, andthebackgroundrate. 6)Thec... Open at page → 35 Page 35 5)Finally,thefollowingarecomputed: TN=(TEMP/100)*(meancountrate) TB=0.06*(meanbackgroundrate) ERR=SQRT(TN^+TB^ ) where:TNistheabsolute, asopposedtorelative,uncertaintyonthe averagecountingrate; TBistheuncertaintyonavaria... Open at page → 36 Page 36 7. IMPROVEMENTS INOPERATIONSBECAUSEOFBETTERNEUTRONANDGAMMA-RAY SHIELDING Twoareasofimprovementhaveresultedfromtheinstallation ofbetter neutronandgammashielding. Previously,scintillation counterscould beactivatedbyexposur... Open at page → 37 Page 37 8.SAFETY Thecalibration ofneutronsourcesinvolvesseveraldifferent safetyaspects: 1)Theradiationsafetyaspectemphasizesminimization of personnelexposure. BecausetherearenohotcellsatNBS,the magnitudeofneutronsourcestrengthst... Open at page → 38 Page 38 9.REFERENCES 1. J.A.DeJuren, D.W.Padgett,andL.F.Curtiss,J.Res.NBS40,63 (1955). 2. J.A.DeJurenandJ.Chin,J.Res.NBS40,311(1955). 3. R.H.Noyce,E.R.Mosburg,Jr.,J.B.Garfinkel,andR.S. Caswell,"AbsoluteCalibrationoftheNationalBu... Open at page → 39 Page 39 V.Naggiar,Rapportsurlacomparaisoninternationale delamesure dutauxd'emissiondelasouredeneutronsRa-Be(a,n)duConseil NationaldeRecherches n200-1parlamethodederalentissement des neutronsdansunesolutiondesulfatedemanganese, _... Open at page → 41 Page 41 APPENDIXA-OutputfromtheMn-56DataProcessingCodeandExampleTest Report riLEMAMI18EDl.LOa THIRANCOUIITIMaDATAMIRK(«!•lalaaacoadm)! 1 «0. 0. lt7627. 101136. 92. 11.4.48. 2 40. 0. 187429. 100293.—92. 11.3.28. 3 «0. 0. 187334.... Open at page → 42 Page 42 UNITEDSTATESDEPARTMENTOFCOMMERCE NationalBureauofStandards Gaithersburg,Maryland2D899 REPORTOFCALIBRATION TestNo.536-98765-4 Date: 13May1985 SUBMITTEDBY:ABCDECorporation FOR:JohnP.Doe 9999S.SouthAvenue Anywhere,US66666 D... Open at page → 43 Page 43 APPENDIXB-ComputerCodeforProcessingRawCountingDatafrom theManganeseSulfateBathElectronics PROGRAMANALYZE.FTN CHARACTERAN1 ,AN2,AN3,AN4,AN5,INFILE* 12 ,OUFILE*12 ,M0NTH*9 REALC(8),CMAIN(100).CREMOTdOO),NB ,DTIME( 100 ),SE... Open at page → 44 Page 44 PROGRAMANALYZE.FTN READ(6 , '(A) •)AN2 IF(AN2.EQ.'Y')THEN NB=1 . ELSE NB=0. ENDIF WRITE(5,*) 'WhatisthecurrentvalueofNBS-IinCPS?' READ(6,*)NBS1 WRITE(5,*) 'Inputthedeadtimeinmicroseconds:' READ(6,*)TAU TAU=TAU* 1.OE-6 WR... Open at page → 45 Page 45 PROGRAMANALYZE.FTN BAK=BKG*DELTAT DTZ=TAU/DELTAT DO501=1,N0 X(I)=X(I)/(1-X(I)*DTZ) 50 CONTINUE LAMBDA=AL0G(2.) /(2.6^15*365.25*8.64E4) IF(CF2.EQ. 1)THEN DO601= 1,N0 X(I)=X(I)-BAK X(I)=X(I)»EXP(LAMBDA »DTIME(I)) X(I)=X(I)... Open at page → 46 Page 46 PROGRAMANALYZE.FTN IF(PASS.EQ. 1)THEN WRITE(4,1008) WRITE(M,1009) WRITE(5,1008) WRITE(5,1009) ELSE WRITE(i4,1010) WRITE(M,101 1) WRITE(5,1010) WRITE(5,101 1 ) ENDIF F0RMAT(22X,'MAINCOUNTERRESULTS') F0RMAT(22X, '*********... Open at page → 47 Page 47 PROGRAMANALYZE.FTN 1012 F0RMAT(12X,'Theuncorrectedmeanofallthedatais',F25.3) 1013 F0RMAT(12X,'Its expectedstandarddeviation(in%)is',F23.3) 1014 F0RMAT(12X,'Itsobservedstandarddeviation (in%)is',F23.3) 1015 F0RMAT(12X,'Th... Open at page → 48 Page 48 PROGRAMANALYZE.FTN SUBROUTINECHANGE(DAY,MONTH ,IDAY ,YEAR) DETERMINEMONTHANDDAYOFTHEMONTHWHENGIVENTHEDAYOFTHEYEAR CHARACTER*9MONTH INTEGERDAY,YEAR IF(DAY.LE.31)THEN MONTH='JANUARY' IDAY=DAY ENDIF IF(IM0D(YEAR,4) .NE.0)TH... Open at page → 49 Page 49 PROGRAMANALYZE.FTN CLEAPYEAR ELSE IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH= IDAY = ENDIF IF(DAY MONTH = IDAY = EN... Open at page → 50 Page 50 PROGRAMANALYZE.FTN SUBROUTINEECALC(NO ,X,AVE,SIG,STD) REALX(100) SMW=0. S=0. AMT=FLOAT(NO)- 1 DO101=1,N0 S=S+X(I) 10 CONTINUE AVE=S/FL0AT(N0) SIG=SQRT(AVE) DO201=1,N0 SMW=SMW+(X(I)-AVE)*«2 20 CONTINUE STD=SQRT(SMW/AMT) S... Open at page → 51 Page 51 APPENDIXC-CaliforniumSourceDecayCodeListing C CFYLD—CALIFORNIUM YIELD6/26/82. DIMENSIONKCOM(66) CHARACTER*! REP CHARACTER*'4 A C THISPROGRAMUSES2.645YRHALFLIFEFOR252CFANDNU=3.766. C FOR250CFITUSES13.2YRSAND3.53.FOR254CFI... Open at page → 52 Page 52 CALIFORNIUMSOURCEDECAY WRITE(7,4) READ(5,3)ID,M,IYR0 CALLIDAYS(ID,M,IYRO,IDAYO) WRITE(7,5) READ(5,1)X050 ,X052 ,X054 C NORMALIZETHENEUTRONEMMITTERSTO 1 . SN=X050+X052+X054 X50=XO50/SN X52=X052/SN X54=X054/SN WRITE(7,6) R... Open at page → 53 Page 53 CALIFORNIUMSOURCEDECAY ACCEPT22,REP IF ((REP.EQ.'Y').OR.(REP.EQ.'y ') )GOTO70 WRITE(7,10) READ(5,3)ID,M,IYR2 IF(ID.EQ.O)GO TO200 CALLIDAYS(ID,M,IYR2,IDAY2) WRITE(7,8) READ(5,3)ID,M,IYR3 CALLIDAYS(ID,M,IYR3 ,IDAY3) CALLLP... Open at page → 54 Page 54 CALIFORNIUMSOURCEDECAY SUBROUTINEIDAYS(ID,M ,lYR,IDAY) C THISSUBROUTINECALCULATESTHEJULIANCALENDARDAYOFTHEYEAR C 1FORMAT(7X'YOUTYPEDMONTHANDDAY.TYPEDAYANDMONTHV) 3FORMAT(15) IF(IYR.LT.1900)IYR=IYR+1900 IF(M.GT.12)WRITE(7... Open at page → 55 Page 55 CALIFORNIUMSOURCEDECAY C IDYMUSTNOTBECHANGEDBECAUSEITISRETURNEDTOMAINPGM C IDAY=IDY IMOD=MOD(IYR,^) IF(IDAY-31)10,10,20 10A=AJAN ID=IDAY GOTO1000 20IF(IDAY-59)30,30,^0 30A=AFEB ID=IDAY-31 GOTO1000 i|0IF(IDAY.EQ.60.AND.IM... Open at page → 56 Page 56 CALIFORNIUMSOURCEDECAY 190A=ASEP ID=IDAY-2^3 GOTO1000 200IF(IDAY-304)210,210,220 210A=A0CT ID=IDAY-273 GOTO1000 220IF(IDAY-33^)230,230,240 230A=AN0V ID=IDAY-304 GOTO1000 240A=ADEC ID=IDAY-334 GOTO1000 1000RETURN END C6 Open at page → 57 Page 57 EXAMPLEOUTPUT NBS118(TYPEIII)SOURCESTRENGTHPER14FEB1985CALIBRATION THEATOMPERCENTCOMPOSITIONOFCF250,252AND254= 8.160000 86.260002 0.021000 THEHALFLIVESUSEDINYEARSFORCF250ANDCF252, ANDINDAYSFORCF254= 13.200000 2.645000 61... Open at page → 59 Page 59 Appendix D 1.INTERFACEOFCOUNTINGELECTRONICSTOMICROCOMPUTER Thecounterelectronicsareconnectedtoamicrocomputer fordata storageandanalyses. Theprincipalinterfacecomponent isthe Tennelec"TC-588"BufferedPrintoutControlInterfa... Open at page → 60 Page 60 TABLED-2 SwitchSettingsInTheTC-588 Switch Name SWl SW1 SWl SWl SWl SWl SWl Function TTYorRS-232 (Notused) Parity StopBits NumberofBits Tl TT TT (doesn'tmatter) Switch Number 1 2 3 4 5 6 7 Onor Off "ON"=RS232 "OFF"=Nopari... Open at page → 61 Page 61 2.DATACOLLECTION Thefollowing istheprocedureforcollectingdatafromtheMNSO^ activitycountingelectronics, usingaDigitalEquipmentCorporation (DEC)Pro-350computer. 2.1 ToStartDataTaking 2.1.1 OnthePRO-350: 1)Select"PROTOOLKIT... Open at page → 62 Page 62 2)Type"COPY"(togettheprintoutoftheoutputfile) FROM: Filename.ext TO: LP: 3.110VOLTSUPPLYANDTHEUNINTERRUPTABLE POWERSUPPLY Partofthesystemisonanuninterruptable powersupplywhichwill keepthesystem(mainelectronicsandmicrocom... Open at page → 63 Page 63 NBS-114A(REV.2-8C) U.S.DEPT.OFCOMM. 1.PUBLICATIONOR 2.PerformingOrgan.ReportNo.3.PublicationDate BIBLIOGRAPHICDATA REPORTNO. SHEET(Seeinstructions) NBS/SP-250/18 March1988 4.TITLEANDSUBTITLE NBSMEASUREMENTSERVICES: NEUTR... Open at page → 67 Page 67 THESP250SERIESONNBSMEASUREMENTSERVICES* SP250-1 SpectralRadianceCalibrations 003-003-02792 $3.50 SP250-2 FarUltravioletDetectorStandards 003-003-02810-0 $4.25 SP250-3 RadiometricStandardsIntheVacuum Ultraviolet 003-003-0... Open at page → 68 Page 68 U.S.DepartmentofCommerce NationalBureauofStandards Gaithersburg,MD20899 OfficialBusiness PenaltyforPrivateUse$300 StimulatingAmerica's 1913-1988 Open at page →