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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

mmarcath@umich.edu

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

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MotivationImprovedfissionmodelsenablesnovelsystemdesign

• Keyneutronandphotoncorrelationstomeasure:– Multiplicity– Energyspectra– Relativeangleofemission

• Improvedmodelsofnuclearfissionwouldbenefitnuclearnonproliferationandsafeguardsapplications.

• Specifically,thecorrelatedneutronandgammarayemissiondataforimportantisotopessuchasU-235andPu-239arenotwellknown.

• Thereisaneedforexperimentaldatatocomparetofissionmodelsunderdevelopment.

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MeasuredPu-240SFneutrondoublesversusdetectorangle.

ExperimenttomeasurePu-240SFneutroncorrelationswithanorganicscintillatorarray.

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NuclearfissionNuclearfissionproducescorrelatedneutronsandphotons

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Fast-neutronmultiplicitycounter

http://www.int.washington.edu/talks/WorkShops/int_13_3/

Neutronemission

Photonemission

Neutronandphotoncorrelationsarisefromthetransitionfromneutrontophotonemission.

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ExperimentandmethodsMeasureandsimulatecorrelatedneutronsandphotonsfromCf-252

• MeasureCf-252spontaneousfissionneutronandphotoncorrelationsrelevanttononproliferationandsafeguardsforthefirsttime.

• Evaluatenewfissionmodelsusingexperimentallymeasuredcorrelations.

– MCNPX-PoliMi

– CGMF(LANL)[1]

– FREYA(LLNL&LBNL)[2]

4

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.

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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.

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• 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

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• 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).

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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.

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ResultsHigh-ordercoincidencedistributionsfromexperimentandsimulations

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Detectednumberofphotons,P(γ),forsimulationandexperimentresults(left).Thesimulatedresultdividedbyexperimentisalsoshown(right).

Detectednumberofneutrons,P(ν),forsimulationandexperimentresults(left).Thesimulatedresultdividedbyexperimentisalsoshown(right).

• High-ordercoincidencesfromexperimentshowmixedagreementtosimulations.

• FREYAbestcapturesneutroncoincidences.

• PoliMibestcapturesphotoncoincidences.

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ResultsNeutron-photonmultiplicitycorrelationsfromexperimentandsimulations

• ExperimentE[νd|γd]andE[γd|νd]indicatesnegativeneutron-photoncorrelation.

• Nosimulationresultagreeswellwiththeexperiment.

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Averagenumberofdetectedphotonsgivenνneutronsdetectedincoincidence,E[γ|ν].

Averagenumberofdetectedneutronsgivenγphotonsdetectedincoincidence,E[ν|γ].

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Conclusions

• Adedicatedexperimenttoobserveneutron-photonmultiplicitycorrelationswasperformedandresultsfromsimulationsusingcorrelatedemissionfissionmodelswerealsoshown.

• Theexperimentshowedsmallnegativeneutron-photonmultiplicitycorrelationonanevent-by-eventbasis,suggestingneutronandphotoncompetitionforemission.

• FutureworkwithPu-240andU-235measurementsusingorganicscintillatorarrayscouldfurtherimprovemodelcomparisons,particularlyinneutronenergymeasurements.

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U-235parallelplateavalanchechamber.

Chi-Nuarraywithliquidorganicscintillators.

Chi-NuarraywithliquidorganicscintillatorsandaCf-252ionization

chamber.

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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

mmarcath@umich.edu

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