SLIDE 36 Introduction to Geant4 Introduction to Geant4 -
M.Asai (SLAC) -
Oct.27, 2003 @ Fermi Lab 36 36
Cuts Cuts in Geant4 in Geant4
A Cut in Geant4 is a production threshold production threshold. .
- Only for physics processes that have infrared divergence
Only for physics processes that have infrared divergence
- Not tracking cut, which does not exist in Geant4
Not tracking cut, which does not exist in Geant4
- Energy threshold must be determined at which discrete
Energy threshold must be determined at which discrete energy loss is energy loss is replaced by continuous loss replaced by continuous loss
Old way:
- Track primary particle until cut
Track primary particle until cut-
- off energy is reached,
- ff energy is reached, calculate
calculate continuous loss and dump it at that point, continuous loss and dump it at that point, stop tracking primary stop tracking primary
Create secondaries secondaries only above cut
- nly above cut-
- off energy, or add to
- ff energy, or add to
continuous loss of primary for less energetic continuous loss of primary for less energetic secondaries secondaries
Geant4 way:
- Specify range (which is converted to
Specify range (which is converted to energy for each material) at energy for each material) at which continuous loss begins, track which continuous loss begins, track primary down to zero range primary down to zero range
Create secondaries secondaries only above specified range, or add to
- nly above specified range, or add to
continuous loss of primary for continuous loss of primary for secondaries secondaries of less energetic
and not reaching to the volume boundary not reaching to the volume boundary
