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Luciano Pandola discusses new developments in EM modeling at the 16th Geant4 Workshop, including a new de-excitation scheme, interface improvements, and radiation chemistry modeling. The discussion also covers the development and validation of release 9.5.
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Highlight from Parallel 7ANew EM model developments Luciano Pandola for the EM Working Groups 16th Geant4 Workshop, SLAC, September 19th-23rd, 2011
New de-excitation scheme • New interface developed during the last year • No basic change in physics • Base class is virtual: multiple models can be accomodated • New features: • De-excitation alongStep • In the past, it was available only for PostStep • comes for free if the model derives from G4VEnergyLossProcess • De-excitation per Region • De-excitation in StdEm and DNA models • Cutomized cross sections can be used for shell ionisation • Can be managed via UI and G4EmOptions • But: de-excitation per process is lost
Modeling radiation chemistry in Geant4 • Necessary to estimate biological damages due to radicals from ionizing radiation • Chemistry stage: >10-12 s • Need to allow the track-track interaction • Develop a customized SteppingManager • Need time step AND space step • G4VITProcess : public G4VProcess • Freeze and save the process state • Prototype ready and working • Long computing time • Within 10% wrt other dedicated MC codes
Discussion on release 9.5: development and validation • Open issues in Standard: not sure which ones can be ready for the next release • Fix bremsstrahlung model (< 10 MeV) • New Rayleigh scattering (CPU-effective) • MSC with WentzelVI for GeV particles • Apparently not trivial to mix-and-match different MSC in different energy range • G4Exception migration • CPU optimization for m/hadron bremsstrahlung • Fix Coverity reports Ok for release
Discussion on release 9.5: development and validation • What if fixed bremsstrahlung and new Rayleigh are not ready? • Use temporarily Livemore models in opt3 • Important to check performances and problems at the boundary of the energy region • Use also Livermore Ionisation below 10 keV in opt3 • CPU benchmarks, run tests regularly • Report from LHCb to be understood • Check regularly cross sections and stopping powers • Dose kernel in water ( medical applications)
Discussion on release 9.5: development and validation • UI interface for the atomic de-excitation. Now two flags: one for g-induced fluorescence, one for charged particle- induced fluorescence (e-, p, ions) • But usually one wants g-induced and e--induced fluorescence to operate at the same time • Try to unify the two flags in order to have only one • Overhead due to the building of XS tables for protons and alphas?