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Geant4 and MCNPX: Comparison of Electron Beam Transport Simulation

Geant4 and MCNPX: Comparison of Electron Beam Transport Simulation. Shawn Kang (JPL/ CalTech ) Giovanni Santin (ESA) Insoo Jun (JPL/ CalTech ) Petteri Nieminen (ESA). Outline. Europa Jupiter System Mission (EJSM) Goal of Analysis Benchmarking Study Description Slab Shields

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Geant4 and MCNPX: Comparison of Electron Beam Transport Simulation

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  1. Geant4 and MCNPX: Comparison of Electron Beam Transport Simulation Shawn Kang (JPL/CalTech) Giovanni Santin (ESA) Insoo Jun (JPL/CalTech) PetteriNieminen (ESA)

  2. Outline • Europa Jupiter System Mission (EJSM) • Goal of Analysis • Benchmarking Study Description • Slab Shields • Slab Shield with Slab Si detector • Spherical Shell Shield with solid sphere Si detector • Status on Electron Beam Test at IAC • Geant4 and MCNPX Input Setup • Analysis Results • Conclusion and Future Work

  3. Europa Jupiter System Mission (EJSM) http://opfm.jpl.nasa.gov/europajupitersystemmissionejsm/ • EJSM consists of NASA-led Jupiter Europa Orbiter (JEO) and ESA-led Jupiter Ganymede Orbiter (JGO) • Launches: 2020 • Jovian system tour phases: 2–3 years • Moon orbital phases: 6–12 months • End of Prime Missions: 2029 • Flexibility if either flight element is delayed or advanced

  4. Brief EJSM Mission Definition • NASA and ESA: Shared mission leadership • Independently launched and operated orbiters • NASA-led Jupiter Europa Orbiter (JEO) • ESA-led Jupiter Ganymede Orbiter (JGO) • Complementary science and payloads • JEO concentrates onEuropa and Io • JGO concentrates onGanymede and Callisto • Synergistic overlap • 11-12 instruments each • Science goals: • Icy world habitability • Jupiter system processes

  5. Goal of Analysis • To compare and better understand the predictive capability of commonly used radiation transport tools • To provide a set of benchmark problems that potential instrument providers can use to validate their own choice of transport tools • To provide the radiation environment behind various shielding materials and thicknesses so as to estimate nominal background noise levels expected in detectors and sensors • To provide a guideline of using graded shield (i.e., low-Z/high-Z) materials

  6. Benchmarking Study Description 25 MeV e- incident beam Case 1: Electron source Unidirectional, pencil beam Case 2: Tantalum (1 cm=16.6 g/cm2) Bottom surface (tally/score surface) Aluminum or Tantalum Particle energy spectra Silicon (5 micron) Energy deposition (total and by particle) Silicon (5 micron) 100 cm Silicon (620 micron) 100 cm Case 3: Beam Test At IAC JEO Electron Spectrum or JGO Electron Spectrum 7g/cm2 Al or Ta

  7. Geant4/GRAS Physics and Scoring Physics Scoring

  8. 2 MeV e- on 5g/cm2 Aluminum Slab Beam Direction Aluminum Tally Surface No secondary neutron generated

  9. 100 MeV e- on 50g/cm2 Aluminum Slab Beam Direction Aluminum Tally Surface

  10. 3 MeV e- on 5g/cm2 Tantalum Slab Beam Direction Tantalum Tally Surface No secondary neutron generated

  11. 30 MeV e- on 5g/cm2 Tantalum Slab Beam Direction Tally Surface Tantalum

  12. 25 MeV e- on Tantalum and Silicon Slab

  13. 25MeV e- on Tantalum and Silicon Slab

  14. Spherical Shell Geometry

  15. Electron Beam Test at IAC • Electron beam tests were performed at Idaho Accelerator Center (IAC) in June of 2010. • APL (David Roth, Alan Tipton, and Fazel) – lead the test • 23MeV electron source beam • Aluminum and Tantalum shield were used. • Si(Li) detector was used • JPL (Shawn Kang) – will perform Geant4 simulation

  16. Conclusion • As shown, when comparable physics models and data were chosen, results produced for electron, gamma, neutron fluxes and energy deposition by the two codes show generally good agreement. • The agreements in the differential gamma spectra are much better than neutron spectra. • it appears that neutron results manifest the different photonuclear reaction modeling in the two codes. Further investigation is needed to resolve the differences in secondary neutron generations by two codes.

  17. Backup 1 The surface flux is defined as   Where W= particle weight, µ = Ω·n, cosine of angle between surface normal n and particle trajectory Ω MCNPX sets µ= 0.05 when µ < 0.10 to avoid 1/ µ becomes too large for the particles that graze the surface; however, it is unknown how G4FlatSurfaceFlux takes care of this issue. Tantalum (1 cm=16.6 g/cm2) Particle energy spectra Silicon (5 micron) Silicon (5 micron) Cell Flux & Energy Deposit Silicon (620 micron)

  18. Backup 2 • Goal 1: Determine if the Jupiter system harbors habitable worlds • Ocean characteristics • Ice shells and subsurface water • Deep internal structure, and (for Ganymede) intrinsic magnetic field • External environments • Global surface compositions • Surface features and future landing sites • Goal 2: Characterize Jupiter system processes • Satellite system • Jupiter atmosphere • Magnetodisk/magnetosphere • Jovian system Interactions • Jovian system origin

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