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Test67 for the verification of EM models

Test67 for the verification of EM models. Luciano Pandola INFN – LNGS. Intercomparison exercise. In 2007 a “comparison exercise” has been performed within the g -ray spectrometry community

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Test67 for the verification of EM models

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  1. Test67 for the verification of EM models Luciano Pandola INFN – LNGS

  2. Intercomparison exercise • In 2007 a “comparison exercise” has been performed within the g-ray spectrometry community • Goal: compare detection efficiencies predicted by different MC codes for a given (simplified) geometry of interest • each participant submitted the results calculated with his/her favourite MC code • participants used Geant4, Geant3, PENELOPE, MCNP, EGS et al. • Appl. Rad. Isotopes 66 (2008) 764 • found differences up to 10% at very low energy. Typically < few % • Use this setup as a benchmark for the existing and new EM models in Geant4  test67

  3. Check EM physics with test67 • The same test67 job issistematicallyrunateachnew referencetag, usingseveral EM builders • 6 energiesbetween 45 keV and 2000 keV • 5·106 events/run • Convenient wayto: • test for anomalies/bugs, possibly introduced in the development • Cross-check the stability of results and the consistency of the EM builders • Benchmark the CPU performances of each builder and track for improvements • Results available at • /afs/cern.ch/sw/geant4/user/vnivanch/verification/electromagnetic/test67

  4. Stability of results vs. tag, G4EmPenelopePhysics Full peak efficiency at 120 keV (nominal geometry configuration) stable vs. Geant4-ref tag 09-04-ref-01 Penelope v2008 Full peak efficiency at 120 keV (%) 09-05-ref-09 Penelope v2001

  5. Stability of results vs. tag, G4EmStandardPhysics_option3 Full peak efficiency at 120 keV (%) 09-05-ref-09 09-04-ref-05 Major variation in result seen in 09-05-ref-09 feedback to Vladimir. Due to a bug, immediately fixed intags emstand-V09-05-53 and emutils-V09-05-43

  6. Benchmark of CPU performances At each new reference tag, the same test67 job is executed on pcgeant08@CERN using different EM builders. Absolute numbers are meaningless, but it is interesting to check for relative differences between different models and/or different Geant4 tags Clear improvement for Opt3 and Livermore between ref-06 and ref-07 (new Rayleigh scattering model)

  7. Backup

  8. Comparison with other codes • Results from Geant4-sim can be compared also with reference values obtained with other codes in the intercomparison exercise • error bars in the reference values are the spread of results provided by participants who used the same code • Good agreement with EGS, Geant4 (of course!), Penelope (of course!) Total efficiency at 120 keV Peak efficiency at 120 keV

  9. Summary • Test (test67) available in Geant4 to implement the intercomparison exercise of Appl. Rad. Iso. 66 (2008) 764 • well-defined geometry, typical use-case of g-ray spectroscopy • Results obtained with the dev version of Geant4 can be compared with the reference results reported in the intercomparison and obtained with different MC tools • way to quickly check for (big) bugs during the development • scripts and processing tools already available • Convenient way also to monitor the stability vs. reference tag of several parameters • not only efficiencies, but also fluorescence yield, spectra, etc. • The application is able to handle all sets of EM models, though more focus was given to Penelope, up to now • good performance of EM models (results and stability)

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