Minutes of the Computing meeting held on 3 November 1999

Present: G.Corti, G.Gracia, J.Harvey, P.Binko, M.Merk, E. Van Herwijnen, I.Belyaev, I.Korolko,
              M.Needham, R.Van Der Eijk, R. Hierck, S.Probst, G.Barrand, E.Tcherniaev, F.Ranjard

Minutes : Florence Ranjard

      1. Detector Description persistent and transient model (R.Chytracek) (ppt)

  Rado has presented the detector description (persistent and transient models) presently implemented into Gaudi.

• The same description will be used by every LHCb programs: simulation, reconstruction, analysis, visualization.
• The Geant4 geometry will be filled from this description.
• The transient model defines:
  • logical volumes, mother volume, daughter volumes.
  • solids
  • physical volumes
  • materials:isotopes, elements, mixtures.
• The Persistent detector description is in XML
  • standard
  • widely supported and maintained outside CERN
  • application and programming language independent
  • XML data are self-descriptive
  • allow us to use several existing tools.

        2. Navigation in geometry tree and transformation (I.Belyaev) (ps)

Vanya has presented the 2 trees : Geometry and Detector Description and their relations.

• The geometry tree is:

  • a detailed tree of geometry volumes
  • without up-links
  • no unique location

• The Detector Description tree is:
  • a simplified tree
  • with full hierarchy
  • represents the structure of detector
  • unique location of elements

Both trees are  defined and implemented, the connection between trees is defined and implemented.
Solids are defined, some primitive solids are implemented as well as some simple boolean solids.
Vanya set a list of possible improvements such as:
Do we need other kinds of solid? other shapes, more sophisticated boolean?

For more details please look at the set of ps files avalaible at  :

http://lhcb.cern.ch/computing/offline/postscript/ibelyaev/

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next meeting : 10 November 1999 at 9:00 room B
                      agenda -  RICH OO Software: The first milestone  (D.Liko)