| Routine ID: GEOM020 | |
|---|---|
| Author(s): | Submitted: 22.03.94 |
| Origin: | Revised: 22.03.94 |
The topology of
GEANT is given by 16 general shapes which are used to represent
solids in the design of detectors. These shapes are bounded by 2-nd order
surfaces for reasons of speed at tracking time. New tools have been
introduced to extend the power of the GEANT geometry: boolean operations
(union, intersection and subtraction) between such shapes are now allowed, so
that an infinity of new shapes can be built; divisions along arbitrary axis
are now possible, allowing to exploit any simmetry in the design.
The tracking is now able to handle overlapping volumes in the most general
sense: the concept of MANY volumes has been extended to automatic
clipping
for protuding objects. Thanks to this MANY technique,
any 3D or 2D geometrical
pattern can be reduced to a single dimensional structure, basically cancelling
the need for GUNEAR at tracking time.
Finally, more than one order of magnitude in speed has been gained compared
to the old step search algorithm used to track in MANY volumes.