Minutes of the G4 Technical Forum  1/12/05

- Review of the open user requirements.

  John Apostolakis reported progress with open user requirements.  Several requirements
  were being delivered (in Geant4 8.0) including particle properties from an
  external,  nested parameterisations, and others closed as delivered in
  release 7.1 (polarised Rayleigh scattering, and user limits per region.)
  Progress in reducing printout from electromagnetic processes upon initialisation
  was discussed, noting a key remaining difficulty. Improvement in physics
  list to use standard EM-physics components was reported.  An example for
  new exotic particles is suspended, as requestor have another solution.

  LHCb reminded us on their request for reduced verbosity, ie being able to
  reduce the printout to a minimum during production runs. They
  refined the item, by requesting a single 'global' verbose command.
  This will be looked into by G4.

- G4 Release Validation Procedure
  
  Alberto Ribon showed the present release validation procedure, using regression
  testing of a set of simplified calorimeter setups. The goal is to be able
  to compare two G4 versions and use physics variables to check automatically if 
  there are statistically  significant differences. As a start, calorimeter
  observables sensitive to  hadronic physics have been used. A statistics 
  package  is needed for a  clever search to find such differences. The results
  with large differences are examined by eye.  The computing effort is large,
  hence the GRID is used.
  A request was made to have a summary of the (most sensitive) histograms 
  available on the web, so the users could have a look at it as well,
  after the release.


- Report on the Recent G4  collaboration workshop               Alex
  The workshop was held from 7-10 November 2005 in Bordeaux
  For the detailed report see, the slides.
  There were reports from many areas including accelerator applications,
  space aplication, medical applications. Furthermore there were
  parallel session on physics lists, overviews of the physics packages, 
  shower parametrizations, geometry (new solids),ion physics, new physics 
  models. The latter contained a presentation of the Intra Nuclear Cascade 
  Liege model and interesting new results from CHIPS in lepton scattering.
  PYTHONization was discussed, as well as G4 in a distributed computing 
  environment.
  The workshop was conceived as beneficial and productive, and very well 
  organized
 
- Particle properties, A proposal from Herwig                  Peter

  Peter Richardson gave an overview of the current thinking for Herwig++.
  It was explained that the PDG tables cannot be used directly, due 
  to its incompleteness (particularly branching ratios for many particles 
  do not sum up to one). Examples are given.
  While Herwig is now revising its own tables and adopting a more 
  transparent and easy to maintain  data base approach, Peter believes that 
  such tables will remain generator dependend and thus there will be no  
  universal tables that could eg. be used by Geant4 or other simulation 
  engines.
  Hence this discussion is deferred to the MC4LHC workshop at CERN in 
  summer and no action needs to be scheduled for G4 before a conclusion  
  emerges from that workshop.


New and upcoming items in Geant4                              John 

  John Apostolakis reported on new features being included in Geant4 8.0,
  schedule for December 16th, 2005.  Key improvements include the improvement
  of the stability of energy deposition and resolution in sampling calorimeters,
  resulting from the revision of multiple scattering and the ability
  to revise particle properties at the start of a simulation.  Physics
  lists were revised to work with the revised particle-properties use
  cases and to incorporate gamma-nuclear and electro-nuclear reactions,
  which were available only in some list.   In addition there is a
  new options to check the overlap of a geometrical volume when it is
  constructed, and an extention to  parameterisations enabling nesting by
  utilise grand-parent volume information to compute the material.

Next meetings                                                 Albert
 
The next meeting is Tuesday 7/2/06
Regular meetings after that are planned for
April
June
September
November
the proposal for the April Meeting is April 25th


MC truth information in Geant4                               Witek

A meeting with the experiments was held and the result presented and 
included in the write-up attached in Appendix 1


2/5/06
J. Apostolakis
A. De Roeck

Final revisions 1/3/06, JA