Minutes of 8 November 2011 Meeting of Geant4 Technical Forum



Editor: A. Morsch, 11 November 2011





- Starting at 16:00



Geant4 9.5 Highlights

=====================

+ See slides

John comments on the performance of the parallel layered mass geometry (slide 4):

This depends strongly how the geometry has been drafted. The performance 

decreases with increasing number of intersections between the different layers.



Updates on EM Physics

======================

+ See slides





Updates in Hadronic Physics

===========================

+ See slides

John on slide 12 (physics list status supported/experimental): these are the proposed

changes. Users should give feedback.



V. Ivantchenko clarifies slide 8 (energy/momentum conservation): CHIPS conserves within

~10 keV. User should check experimental Physics List CHIPS 

John explains (slide 12 CHIPS->experimental): this is not a change, it was always experimental.



John comments on slide 5 (improved neutron models): old neutron libraries cannot be used

with new Geant4 and new libraries cannot be used with old Geant4. This has to be clear

to the users and he expects that not all experiments will like this. Need feedback.



Tatsumi confirms that the old Neutron-HP *can* use the new G4NDL data library, 

though new component in the new library is of course not seen by the old Newtron-HP.







Open requirements

=================

+ See slides

 



Requirements from LHCb

=======================

+ See slides

Slide 2 Error Messages together with run and event numbers

Have to understand to which extend the internal G4 run and event number is useful.

Relevant for reproducing a problem ("crash") is the seed.

User may change the format.



Slide 3 Signature of Physics Builders.

More details are needed from Gloria Corti.





Requirements from ALICE

=======================

+ See slides

Concerning the anti-triton problem, V. Ivantchenko explains that cross-section for nuclei and 

anti-nuclei have been extracted from different sources. The fact that anti-triton seems to 

have a lower x-section than triton reflects the systematic error.

A more consistent approach for parametrization both cross-sections is needed. 





Requirements from non-LHC experiments

=====================================

* On the simulation requirements of the Max-Planck-Institut fuer extraterrestrische Physik

and the Max-Planck Halbleiterlabor, on our development plans, and on requests for future Geant4 releases.



* Simulation requirements from Catholic University of Rio Grande do Sul, 

Federal University of Pernambuco and State University of Rio de Janeiro



* On the simulation requirements of the Hanyang University in Korea, on our development plans, 

and on requests for future Geant4 releases



*On the simulation requirements of TU Darmstadt in the context of our participation in the ATHENA X-ray telescope project, 

on our development plans, and on requests for future Geant4 releases



+See slides





The TF chair observes that the four talks prepared by four collaborating individuals 

have essentially the same contents and request: 



"Keep Livermore based low energy processes in future releases

If these processes can not be maintained by the G4 working group, move them to pii package instead so that they can be

maintained by our collaborators."



He recommends that in the future this should be summarized in a single presentation.



S. Incerti confirms that Livermore-based low-energy EM processes are kept in 9.5 release.

He also comments that requirements have been discussed with ATHENA and they are actually satisfied

with the current Geant4 low-energy EM implementation. 

M. Verderi reminds us that this is also the official position of ESA.

M. Asai points out that PII in Geant4 is one of PIXE models. 

It cannot contain different physics processes such as ionization.



From this point on M.G. Pia starts to disturb the meeting with a constant forced giggling and the chair 

has to call the meeting to order. Further discussion of the subject becomes difficult.



The TF chair makes the remark that at the TF users are invited to provide feedback and substantiate their problems with the 

existing G4 versions. It is not the appropriate place to discuss general strategies of core development (eg maintenance of 

obsolete packages and compatibility with external simulation software development projects).