CERN Accelerating science

Minutes Technical Forum 17-Jan-2020

Minutes of 16 January 2029 Meeting of Geant4 Technical Forum
Editor: A. Morsch, 17 January 2020
- Starting at 16:00

General introduction and prospects
+ see slides for details
- Next TF to discuss 2020 workplan end of March 2020
- User input on requirements is welcome

What's new in 10.6  - non–physics
+ see slides for details

What's new in 10.6 - EM physics
+ see slides for details

What's new in 10.6 - Hadronic physics 
+ see slides for details

Status of open requirements 
+ see slides for details
+ New requirements from the JLAB collaboration meetting are presented

**** New Requirements from Experiments

+ see slides for details
- S08: Clarification: All official productions are done inside ISF. Only tests have been performed also standalone.
- S12: Clarification: 0-lifetime is defined by primary particle generator and not by G4
- G4 suggestion to move to 10.6; no difefrence for EM and little difference for hadronic physics
  Use FTFP_BERT. In the past response was too high but Birk's constant tuning will bring it down.

+ see slides for details
- There used to be good agreement between data and MC for the
physics list FTFP_BERT_EMM which is used by CMS. However, the agreement for the version
10.6 is significantly worse than the earlier version 10.4.p03. It can be partly
restored by tuning the overlaps among the models or constants for Birk’s law.
- G4 recommendation: Concentrate on tuning Birk's constant instead of varying the transition region between 
  FTF and Bertini.

Geant4 in LArTPC simulation
+ see slides for details
- G4 feedback: Subprocess for hadron inelastic interaction identified by integer code (documented in the G4 manual)
- G4 recommendation on physics lists: QGSP_INCLXX, Shielding

PYG4ometry load/manipulate/save/visualise/convert GDML/Fluka/CAD geometry
+ see slides for details
- Tesselation used in conversion from CAD
- Converted FLUKA geometry allows placement of new volumes 

Proposal for Adoption of Tetrahedral Mesh Navigator
+ see slides for details
- G4 suggestion: G4 10.6 supports external navigation module for easy prototyping
- G4 suggestion: Implement the porposed setters instead of recerating the objects (S20).
  This should improve the performance significantly.