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Updated CMS application physics list settings

Mihaly Novak requested to merge mnovak/CMSUpdate into master

The CMS application settings have been updated:

  1. Updated region list for the activation of the 2 physics list:

    • ~ 85-90 % of the steps are done in the "EcalRegion" that contains only 25 out of the 425 material-cuts couples
    • the physics list, that contains EM models with "sampling-table" based final state sampling has been set to be used only in this "EcalRegion"
    • the physics list, that contains EM models with "rejection" based final state sampling has been set to be used in all other regions
    • this minimises the memory usage (by the sampling tables) while maximises the potential gain
    • also, this will make the initialisation fast (as without using any sampling tables)

  2. The default EM physics setting was changed to be closer to the one used by the CMS experiment:

    • in their Geant4 simulation, the CMS experiment uses the EM-opt1 Geant4 EM physics constructor everywhere except the hadronic calorimeter region "HcalRegion" where the EM-opt0 is used
    • the main difference in the 2 constructors is that the MSC model in opt1 has a less strict step limit parameter (good for crystal calorimeters) while opt0 contains the default, more strict MSC step limit parameter value (good for sampling calorimeters)
    • therefore, opt1 is a faster simulation with longer steps for changed particles compared to opt0
    • in the current settings, the GeantV/Geant4 CMS applications has opt0 settings everywhere
    • this has been changed by adding to MSC models to the MSC processes:
      • one being active only in the "HcalRegion" with a range-factor of 0.06 (opt0)
      • one being active everywhere except the "HcalRegion" with a range-factor of 0.2 (opt1)
    • this will bring the CMS applications (both GeantV and Geant4) closer to the real CMS simulation settings/steppings
    • also demonstrates the feature of having multiple models in a given process being active in different region of the detectors i.e. the possibility of combining different physics description per-detector region within a single physics list (beyond the feature of having different physics list per-detector region)

Note, that warnings are reported by the GeantV physics framework but everything is correct including these warnings!

Edited by Mihaly Novak

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