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Consortium for Verification Technology
Cf-252spontaneousfissionpromptneutronandphoton
correlationsM.J.Marcath1,*,P.Schuster1,P.Talou2,I.Stetcu2,T.Kawano2,M.Devlin2,R.C.Haight2,R.Vogt3,4,J.Randrup5,S.D.Clarke1,S.A.Pozzi1
1DepartmentofNuclearEngineeringandRadiologicalSciences,UniversityofMichigan,AnnArbor,MI,USA
2LosAlamos National Laboratory,LosAlamos,NewMexico 87545,USA3Physics Division,LawrenceLivermore National Laboratory,Livermore,California94551,USA4PhysicsDepartment,UniversityofCalifornia,Davis,California95616,USA5NuclearScienceDivision,LawrenceBerkeleyNationalLaboratory,Berkeley,California94720,USA
Consortium for Verification Technology
MotivationImprovedfissionmodelsenablesnovelsystemdesign
• Keyneutronandphotoncorrelationstomeasure:– Multiplicity– Energyspectra– Relativeangleofemission
• Improvedmodelsofnuclearfissionwouldbenefitnuclearnonproliferationandsafeguardsapplications.
• Specifically,thecorrelatedneutronandgammarayemissiondataforimportantisotopessuchasU-235andPu-239arenotwellknown.
• Thereisaneedforexperimentaldatatocomparetofissionmodelsunderdevelopment.
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MeasuredPu-240SFneutrondoublesversusdetectorangle.
ExperimenttomeasurePu-240SFneutroncorrelationswithanorganicscintillatorarray.
Consortium for Verification Technology
NuclearfissionNuclearfissionproducescorrelatedneutronsandphotons
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Fast-neutronmultiplicitycounter
http://www.int.washington.edu/talks/WorkShops/int_13_3/
Neutronemission
Photonemission
Neutronandphotoncorrelationsarisefromthetransitionfromneutrontophotonemission.
Consortium for Verification Technology
ExperimentandmethodsMeasureandsimulatecorrelatedneutronsandphotonsfromCf-252
• MeasureCf-252spontaneousfissionneutronandphotoncorrelationsrelevanttononproliferationandsafeguardsforthefirsttime.
• Evaluatenewfissionmodelsusingexperimentallymeasuredcorrelations.
– MCNPX-PoliMi
– CGMF(LANL)[1]
– FREYA(LLNL&LBNL)[2]
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New,physicsbasedfissionmodelswithcorrelations.
Chi-NuarraywithliquidorganicscintillatorsandaCf-252ionizationchamber.
[1]P.Talou,et.al,LA-UR-12-25059,LosAlamos,NM(UnitedStates),2012.[2]J.Randrup andR.Vogt,Phys.Rev.C,vol.80,no.2,p.024601,2009.
Consortium for Verification Technology
ExperimentdetailsLANLChi-NuarraywithCf-252
• 54- 17.78Øx5.04EJ-309organicliquidscintillatorsinthearray,45areused.
• Cf-252fissionchambersignalsplittoeachdigitizerboardforcoincidencetriggering.
• 1mflightpath.• 3- CAENV1730’swereusedfordigital
waveformacquisition.• 33TBofwaveformdataacquired.
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Chi-Nuorganicliquidscintillatorarrayof54-17.78Øx5.04 EJ-309s.
Tail-to-totalratioagainstpulseheightwheretheupperbandincludesprimarilyneutrondetectionsandthebottomgamma-raydetectionsseparatedbythediscriminationlineinred.
Consortium for Verification Technology
• Research is underway to develop models that exhibit fission-particle correlations.
• CGMF (LANL) and FREYA (LLNL & LBNL) are event-by-event Monte Carlo codes.
• Model output was integrated with MCNPX-PoliMi to enable comparison with measured data.
NuclearfissionmodelsPhysics-basedevent-by-eventfissionmodeldevelopmentisongoing
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FissionmodelneutronmultiplicitydistributionsforCf-252.
FissionmodelneutronspectraforCf-252.
Cf-252SF
Cf-252SF
Consortium for Verification Technology
• Research is underway to develop models that exhibit fission-particle correlations.
• CGMF (LANL) and FREYA (LLNL & LBNL) are event-by-event Monte Carlo codes.
• Model output was integrated with MCNPX-PoliMi to enable comparison with measured data.
NuclearfissionmodelsPhysics-basedevent-by-eventfissionmodeldevelopmentisongoing
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PoliMi
CGMF
FREYA
EmittedCf-252SFpromptneutron(y-axis)andphoton(x-axis)multiplicityfromthefissionmodelswithoverlaid
E[ν|γ](x)andE[γ|ν](o).
Consortium for Verification Technology
FissionmodelevaluationPhysics-basedfissioneventgeneratorsarecoupledtoMCNPX-PoliMi
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MCNPX-PoliMi.exe
MPPost.exe
Listofdetectedevents
Labgeometry,physics
Modelgenerated
fissionevents• PoliMi• CGMF• FREYA
Detectorresponseparameters
UserinputsExecutables
Thisapproachfacilitatesdirectcomparisonofsimulationandmeasurementresults.
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ModelingandsimulationdetailsLaboratorygeometry
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Side Top
Ionizationchamberdetail
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• Experimentandsimulationpulseheightdistributionsshowgeneralagreement.
• MCNPX-PoliMiagreesbestforbothneutronandphotondistributions.
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Neutrons
Photons
ResultsPulseheightdistributionsfromexperimentandsimulations
Neutronpulseheightdistributionsofsimulatedandexperimentalresults(left)andsimulatedoverexperiment(right).Theuncertaintiesaresmallerthanthepoints.
Photonpulseheightdistributionsofsimulatedandexperimentalresults(left)andsimulatedoverexperiment(right).Theuncertaintiesaresmallerthanthepoints.
Consortium for Verification Technology
ResultsHigh-ordercoincidencedistributionsfromexperimentandsimulations
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Detectednumberofphotons,P(γ),forsimulationandexperimentresults(left).Thesimulatedresultdividedbyexperimentisalsoshown(right).
Detectednumberofneutrons,P(ν),forsimulationandexperimentresults(left).Thesimulatedresultdividedbyexperimentisalsoshown(right).
• High-ordercoincidencesfromexperimentshowmixedagreementtosimulations.
• FREYAbestcapturesneutroncoincidences.
• PoliMibestcapturesphotoncoincidences.
Consortium for Verification Technology
ResultsNeutron-photonmultiplicitycorrelationsfromexperimentandsimulations
• ExperimentE[νd|γd]andE[γd|νd]indicatesnegativeneutron-photoncorrelation.
• Nosimulationresultagreeswellwiththeexperiment.
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Averagenumberofdetectedphotonsgivenνneutronsdetectedincoincidence,E[γ|ν].
Averagenumberofdetectedneutronsgivenγphotonsdetectedincoincidence,E[ν|γ].
Consortium for Verification Technology
Conclusions
• Adedicatedexperimenttoobserveneutron-photonmultiplicitycorrelationswasperformedandresultsfromsimulationsusingcorrelatedemissionfissionmodelswerealsoshown.
• Theexperimentshowedsmallnegativeneutron-photonmultiplicitycorrelationonanevent-by-eventbasis,suggestingneutronandphotoncompetitionforemission.
• FutureworkwithPu-240andU-235measurementsusingorganicscintillatorarrayscouldfurtherimprovemodelcomparisons,particularlyinneutronenergymeasurements.
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U-235parallelplateavalanchechamber.
Chi-Nuarraywithliquidorganicscintillators.
Chi-NuarraywithliquidorganicscintillatorsandaCf-252ionization
chamber.
Consortium for Verification Technology
Acknowledgements
TheauthorsthankP.Talou (LANL),R.C.Haight(LANL),M.Devlin(LANL),R.Vogt(LLNL),andJ.Randrup (LBNL)fortheircollaborationtothisresearch.
Thisworkwasfundedin-partbytheConsortiumforVerificationTechnologyunderDepartmentofEnergyNationalNuclearSecurityAdministrationawardnumberDE-NA0002534.
M.J.Marcath issupportedbytheU.S.DepartmentofEnergyNuclearNonproliferationInternationalSafeguardsGraduateFellowshipProgramsponsoredbytheNationalNuclearSecurityAdministration’sOfficeofNonproliferationandInternationalSecurity.
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Consortium for Verification Technology
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Cf-252spontaneousfissionpromptneutronandphoton
correlationsM.J.Marcath1,*,P.Schuster1,P.Talou2,I.Stetcu2,T.Kawano2,M.Devlin2, R.C.Haight2,R.Vogt3,4,J.Randrup5,S.D.Clarke1,S.A.Pozzi1
1DepartmentofNuclearEngineeringandRadiologicalSciences,UniversityofMichigan,AnnArbor,MI,USA
2LosAlamos National Laboratory,LosAlamos,NewMexico 87545,USA3Physics Division,LawrenceLivermore National Laboratory,Livermore,California94551,USA4PhysicsDepartment,UniversityofCalifornia,Davis,California95616,USA5NuclearScienceDivision,LawrenceBerkeleyNationalLaboratory,Berkeley,California94720,USA