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