Minutes2005 12 01

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
The workshop was conceived as beneficial and productive, and very well

- 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
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
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

J. Apostolakis
A. De Roeck

Final revisions 1/3/06, JA

Meeting Date: 

Thursday, December 1, 2005