DEVELOPMENT AND INTEGRATION OF A FISSION EVENT GENERATOR INTO THE GEANT4 FRAMEWORK FISSION FRAGMENT GENERATOR Brycen L. Wendt Tatsumi Koi

FISSION SAMPLING Fission Event Generation Operation Parameters

FISSION EVENT GENERATION FISSION SAMPLING 3 Goal: single event perspective Accurately reproduce single fission event Maintain overall fission statistics Conservation Mass Momentum Energy

FISSION EVENT GENERATION FISSION SAMPLING 4 1.Generate ternary fission particles 2.Select primary fission fragment 3.Generate neutrons 4.Determine secondary fission fragment 5.Sample particle energies 6.Generate fission γ’s 7.Sample angles for γ’s and neutrons 8.Sample angles for ternary particles 9.Calculate fission fragment angles

FISSION SAMPLING 5

Geant4 kernel defines Fission isotope Fission isomer Incident particle Incident particles provide Fission type Energy Momentum FISSION EVENT GENERATION FISSION SAMPLING 6

OPERATION PARAMETERS FISSION SAMPLING 7 File based Uses internal data in Geant4 neutron data files Maintains internal ability to parse pure ENDF data tapes Hard-coded values ν – prompt neutron production Ternary particle angular distributions

OPERATION PARAMETERS FISSION SAMPLING 8 Fission fragment sampling method Ternary fission Probability Yields Fission cause Spontaneous Neutron induced

INTEGRATION INTO GEANT4 NeutronHP Stand-Alone Model

NEUTRONHP INTEGRATION INTO GEANT4 10 Two fission models available Activated by environment variables G4NEUTRONHP_PRODUCE_FISSION_FRAGMENTS G4NEUTRONHP_USE_WENDT_FISSION_MODEL Selected at runtime in NeutronHPChannel

NEUTRONHP INTEGRATION INTO GEANT4 11 Demonstrated in example New in Geant beta extended/hadronic/FissionFragment

STAND-ALONE MODEL INTEGRATION INTO GEANT4 12 Location: neutron_hp/ Class: G4FissionFragmentGenerator Initialized with default values

STAND-ALONE MODEL INTEGRATION INTO GEANT4 13 Change parameters: G4SetIsotope() G4SetMetaState() G4SetCause() G4SetIncidentEnergy() G4SetTernaryProbability() G4SetAlphaProduction() G4SetSamplingScheme()

RESULTS Fission Fragment Production Fission Fragment Energies

FISSION FRAGMENT PRODUCTION RESULTS 15

FISSION FRAGMENT PRODUCTION RESULTS 16

FISSION FRAGMENT ENERGIES RESULTS 17

FUTURE WORK

19 Physics Spontaneous fission as stand-alone model High energy neutron models (>10 MeV) Symmetric fission Model for fragment angular distributions Photo- and proton-induced fission Sampling model to improve fission fragment reproduction Utility Allow user-constraint on fission fragment angles Internal test module (test29)

This research is being performed using funding received from the Integrated University Program ACKNOWLEDGEMENTS FUTURE WORK 20

BIBLIOGRAPHY APPENDIX 21 D. N. POENARU et al., “Multicluster accompanied fission,” Phys. Rev. C, 59, 3457 (1999). H. SOODAK, Reactor Handbook: Physics, John Wiley & Sons (1962). Z. FRAENKEL and S. G. THOMPSON, “Properties of the Alpha Particles Emitted in the Spontaneous Fission of Cf252,” Physical Review Letters, 13, 438 (1964).