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IEEE NSS 2007 Honolulu, HI Best Student Paper (A. Lechner )

IEEE NSS 2007 Honolulu, HI Best Student Paper (A. Lechner ). IEEE TNS April 2009. Geant4 8.1p02 Geant4 9.1. Same geometry, primary generator and energy deposition scoring reused for the results presented in this talk

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IEEE NSS 2007 Honolulu, HI Best Student Paper (A. Lechner )

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  1. IEEE NSS 2007 Honolulu, HI Best Student Paper (A. Lechner) IEEE TNS April 2009 Geant4 8.1p02 Geant4 9.1 Same geometry, primary generator and energy deposition scoring reused for the results presented in this talk Verification of consistency: published/new results in same configuration

  2. High precision measurements intended for simulation validation Traditionally considered a reference for Monte Carlo codes

  3. Experimental set-up Beam energy: 25 keV – 1 MeV Incidence angles: 0o, 30o, 60o Targets: Measure: [Sandia79] Be, C, Al, Fe, Cu, Mo, Ta, U Energy deposition profile [Sandia80] Be, C, Al, Ti, Mo, Ta, U Total deposited energy Experimental uncertainties: 1.2 - 2.2% (nominal)

  4. Simulation configuration Calorimeter and front/infinite layers: same material Geometry: as in experiment Mass geometry + readout geometry front foil • e/g physics • low energy EEDL/EPDL (“Livermore”) • low energy – Penelope • Standard infinite layer e- beam • Multiple scattering • Urban* • Goudsmit-Saunderson calorimeter Sandia79: calorimeter placed at different depths • Secondary production threshold • 250 eV (low energy) • 1 keV (standard) Sandia80: whole volume is sensitive Geant4 versions 8.1, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6-b (with latest patch applied) • Step limitation • 1, 10, 1000 mm • no step limitation

  5. Validation analysis Compatibility of experiment-simulation: c2 test c2 test case = target material, beam energy, beam angle Significance of the c2test: a = 0.01 efficiency of a Geant4 physics model fraction of test cases in which simulation is compatible with experiment Na>0.01 eG4model = Categorical analysis to determine whether two Geant4 physicsmodels, or two Geant4 versions differ significantly in accuracy N tot • Fisher’s exact test • Barnard’s exact test • Pearson’s c2test • c2 test with Yates continuity correction • McNemar’s test (matched pairs) • Contingency tables • whole sample • matched pairs

  6. Energy deposition profile C, 1 MeV Geant4 9.6-b similar to 9.5 Most accurate Geant4 version: 9.1 Most accurate Geant4 model: Livermore-9.1 p-value Geant4 9.1-9.5 equivalence: 0.008 p-value Livermore-Penelope: 0.002 p-value Livermore-Standard: <0.001

  7. Total energy deposition in a single volume of elemental material (the simplest test case one can think of) Efficiency vs. Geant4 version Dependency on step limitation observed in Geant4 9.4

  8. Multiple scattering models Further tests in progress to evaluate the effects of different parameter values and models in the Sandia79/80 test configuration

  9. Goudsmit-Saundersonmultiple scattering model Al 521 keV G4GoudsmitSaundersonModel - for electrons and positrons O. Kadri, V. Ivanchenko, F. Gharbi, A. Trabelsi Incorporation of the Goudsmit–Saunderson electron transport theory in the Geant4 Monte Carlo code NIM B, Vol. 267, no .23–24, pp. 3624–3632, Dec. 2009 Experimental data from Sandia-79 report c2test Geant4 9.3p02 (Sep. 2010): p-value = 1.6 10-34 Geant4 9.5p01 (Mar. 2012): p-value = 1.8 10-22 Efficiency (with “Livermore” e/g models)

  10. Penelope 2001-2008 re-implementation Geant4 9.1: Penelope 2001 Geant4 9.5: Penelope 2008(default) Penelope 2001 (available) Penelope 2008 model does not appear to have improved Geant4 simulation accuracy w.r.t. Penelope 2001, nor w.r.t. EEDL/EPDL (“Livermore”) models

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