GEOM001 The geometry package

The geometry package has two main functions:

1. define, during the initialisation of the program, the geometry in which the particles will be tracked;
2. communicate, during the event processing phase, to the tracking routines the information for the transport of the particles in the geometry which has been defined.

The present section reviews the concepts of the geometry package and explains how the geometrical information should be provided by the user. It is important to point out that, once the geometry has been defined, the tracking of particles through the different volumes proceeds without any intervention from the user [TRAK].

The connection between the geometry and tracking packages is established by the subroutines GMEDIA/GTMEDI, GTNEXT/GNEXT and GINVOL which answer respectively the questions:

• In which volume is a given point ?
• What is the distance to the nearest volume along the trajectory of the particle ?
• What is the distance to the nearest volume ?
• Is a given point still in the current volume ?

• The volume definition
• Volumes with contents
• Overlapping volumes, see also [GEOM020]
• The physical tree
• The data structures JVOLUM and JGPAR and the common /GCVOLU/
• The user tools
• Geometrical information retrieval