Cf-252 spontaneous fission prompt neutron and photon...

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

[email protected]

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


MotivationImprovedfissionmodelsenablesnovelsystemdesign

• Keyneutronandphotoncorrelationstomeasure:– Multiplicity– Energyspectra– Relativeangleofemission

• Improvedmodelsofnuclearfissionwouldbenefitnuclearnonproliferationandsafeguardsapplications.

• Specifically,thecorrelatedneutronandgammarayemissiondataforimportantisotopessuchasU-235andPu-239arenotwellknown.

• Thereisaneedforexperimentaldatatocomparetofissionmodelsunderdevelopment.

2

MeasuredPu-240SFneutrondoublesversusdetectorangle.

ExperimenttomeasurePu-240SFneutroncorrelationswithanorganicscintillatorarray.


NuclearfissionNuclearfissionproducescorrelatedneutronsandphotons

3

Fast-neutronmultiplicitycounter

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

Neutronemission

Photonemission

Neutronandphotoncorrelationsarisefromthetransitionfromneutrontophotonemission.


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.


ExperimentdetailsLANLChi-NuarraywithCf-252

• 54- 17.78Øx5.04EJ-309organicliquidscintillatorsinthearray,45areused.

• Cf-252fissionchambersignalsplittoeachdigitizerboardforcoincidencetriggering.

• 1mflightpath.• 3- CAENV1730’swereusedfordigital

waveformacquisition.• 33TBofwaveformdataacquired.

5

Chi-Nuorganicliquidscintillatorarrayof54-17.78Øx5.04 EJ-309s.

Tail-to-totalratioagainstpulseheightwheretheupperbandincludesprimarilyneutrondetectionsandthebottomgamma-raydetectionsseparatedbythediscriminationlineinred.


• 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

6

FissionmodelneutronmultiplicitydistributionsforCf-252.

FissionmodelneutronspectraforCf-252.

Cf-252SF

Cf-252SF


• 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

7

PoliMi

CGMF

FREYA

EmittedCf-252SFpromptneutron(y-axis)andphoton(x-axis)multiplicityfromthefissionmodelswithoverlaid

E[ν|γ](x)andE[γ|ν](o).


FissionmodelevaluationPhysics-basedfissioneventgeneratorsarecoupledtoMCNPX-PoliMi

8

MCNPX-PoliMi.exe

MPPost.exe

Listofdetectedevents

Labgeometry,physics

Modelgenerated

fissionevents• PoliMi• CGMF• FREYA

Detectorresponseparameters

UserinputsExecutables

Thisapproachfacilitatesdirectcomparisonofsimulationandmeasurementresults.


ModelingandsimulationdetailsLaboratorygeometry

9

Side Top

Ionizationchamberdetail


• Experimentandsimulationpulseheightdistributionsshowgeneralagreement.

• MCNPX-PoliMiagreesbestforbothneutronandphotondistributions.

10

Neutrons

Photons

ResultsPulseheightdistributionsfromexperimentandsimulations

Neutronpulseheightdistributionsofsimulatedandexperimentalresults(left)andsimulatedoverexperiment(right).Theuncertaintiesaresmallerthanthepoints.

Photonpulseheightdistributionsofsimulatedandexperimentalresults(left)andsimulatedoverexperiment(right).Theuncertaintiesaresmallerthanthepoints.


ResultsHigh-ordercoincidencedistributionsfromexperimentandsimulations

11

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

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

• High-ordercoincidencesfromexperimentshowmixedagreementtosimulations.

• FREYAbestcapturesneutroncoincidences.

• PoliMibestcapturesphotoncoincidences.


ResultsNeutron-photonmultiplicitycorrelationsfromexperimentandsimulations

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

• Nosimulationresultagreeswellwiththeexperiment.

12

Averagenumberofdetectedphotonsgivenνneutronsdetectedincoincidence,E[γ|ν].

Averagenumberofdetectedneutronsgivenγphotonsdetectedincoincidence,E[ν|γ].


Conclusions

• Adedicatedexperimenttoobserveneutron-photonmultiplicitycorrelationswasperformedandresultsfromsimulationsusingcorrelatedemissionfissionmodelswerealsoshown.

• Theexperimentshowedsmallnegativeneutron-photonmultiplicitycorrelationonanevent-by-eventbasis,suggestingneutronandphotoncompetitionforemission.

• FutureworkwithPu-240andU-235measurementsusingorganicscintillatorarrayscouldfurtherimprovemodelcomparisons,particularlyinneutronenergymeasurements.

13

U-235parallelplateavalanchechamber.

Chi-Nuarraywithliquidorganicscintillators.

Chi-NuarraywithliquidorganicscintillatorsandaCf-252ionization

chamber.


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.

14


15

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

[email protected]

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

Cf-252 spontaneous fission prompt neutron and photon...

Documents

Transcript of Cf-252 spontaneous fission prompt neutron and photon...