Tuesday, July 10, 2012

Physics List 1 Notes

• Slide 12
  • To aid in ConstructProcess() a function ConstructEM() may be defined to construct all the ElectroMagnetic Processes. In this function, it is recommended that you use the G4PhysicsListHelper to take care of initializing the process in the proper order!!! This is new starting with 9.5

Tuesday, July 10th, 2012 - see talks online as well

Morning Talks

Physics I

• slide 10 - can explicitly list particles
• Need to tell the particles that they need to move
• can group EM physics and all other physics if you would like
• slide 12 - while writing methods in Physics list - use physics list helper (new 4.9.5)
  • helps with ordering
  • list processes, it will put them in correct order
  • you do need to instantiate a particle iterator
• ConstructGeneral is "fictitous" - you can make it anything you like
  • need to loop over all particles (not just those that can decay)
  • check to make sure decay process is applicable for that particle
• Cuts
  • final mandatory method you have to implement
  • 0.7*mm recommended for most applications
  • needed for all 4 (gamma, e-, e+, proton) and no others (even neutrons)
  • can change cut for individual particles (don't have to be the same)
  • if you use a standard package, it wll be set

• Modular physics lists
  • some nice features, like certain things automatic
  • basically a bookkeeping device for EM vs hadronic processes
  • for example proton, electron, decay physics all separate
  • still have to do setCuts, but it is simpler

• Prepackaged physics lists - the "easy" way to do it
• adding hadronic physics is more involved than EM physics
  • need to use models
  • for example - for neutrons - there is a basic model, then there are HP_neutron model
  • there are several physics lists which have been validated by experiment
• geant4.cern.ch/support/proc_mod_catalog/physics_lists/physicsLists.html
• really are a "best guess" of the physics needed in a given use case
• may not do exactly what you want
• possible to use prepackaged physics lists and remove one process and replace it

• Reference Physics Lists
  • subset of prepackaged physics lists

• Questions
  • Hadronic - Bertini vs. binary cascade - you have to decide - need to validate
    • Bertini handles more particles
    • Binary better for lower energies
  • photonuclear - EM or Hadronic - both! - see future talk

Afternoon Talks

Hands On II

Return to JLAB GEANT4 Workshop, July 9-13, 2012
Return to MOLLER GEANT4 Simulations
Return to MOLLER at 11 GeV E09-005