CATIA-GDML Geometry Builder. S. Belogurov 1,2 ([email protected]), Yu. Berchun 2 , A. Chernogorov 1 , P. Malzacher 3 , E. Ovcharenko 1,2 , A. Semennikov 1. 1- Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia
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S. Belogurov1,2([email protected]), Yu. Berchun2, A. Chernogorov1, P. Malzacher3, E. Ovcharenko1,2, A. Semennikov1
1- Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia
2- Bauman Moscow State Technical University, (BMSTU) Moscow, Russia
3- GSI - Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
Geometry representation in CAD and G4/ROOT
The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies.
Design optimization of complex, densely packed systems in severe radiation conditions (lke FAIR experiments) requires iterative exchange of geometry and material info
, L3, 2L4)
Solids: CSG vs. “arbitrary”
In CAD hierarchy a minimal unit is a solid body (part).
Products (assemblies) and subproducts are only logical units – all the materials are assigned to solid bodies inside the part files or to parts
For mechanical, thermal, and some of electromagnetic software the transfer is automated.For radiation simulation packages that’s not a case.
In some cases automated geometry transfer is possible, but result is not optimized for simulations and computations are too slow for big assemblies and complex shapes.
Implementation of primitives as parameterized User Defined Features (UDF) in CATIA.
The UDFs are placed into G4Catalog.
For realization of Boolean combinations CATIA operations Add, Remove and Intersect are used.
3 methods of multiple instantiation are implemented
Replica - matches with G4ReplicaVol
Array - copied objects can be inserted into an intermediate logical volume
SimplePlacement Array - intermediate volume is only a convenient reference frame
File structure for representation of a LogicalVolume.
PartBody contains a parameterized solid and material form G4Material CATIA catalog.
Unparameterized solid copy of the PartBody is published
Solids, published in files corresponding to smaller LogicalVolumes can be inserted into the tree with positioning. They represent daughter volumes
1. Implement G4 – like geometry in CATIA2. Extend construction and measurement functionality of CATIA by special tools for building G4 – like representation of the existing CAD model3. Make simulation optimized geometry4. Exchange geometry via GDML
LHCb VELO CAD model
Running export Macro
LHCb VELO read from GDML
Use material of mother volumes
Crystal calorimeter for R3B
GLAD for R3B
Consists of 4 SS and Cu layers of complicated shapes with ribs.
All transferred to G4/ROOT. One of the shells is discussed here
General and partial views of the crystal array for R3B calorimeter
Cylinders, Tori, and Ellipsoids:
General shape is OK, but the shell has slits – bad for simulations
Radii and heights of cylinders are modified, Ellipsoid -> Sphere, but no slits: good for simulations
G4/ROOT-like representation of a slice of CFC boxes and entire crystal array
- Enhancement of the set of implemented primitives
- Improvement of the G4Materials catalog in CATIA
- Implementation of checkers for CSG tree structure and volume overlaps
- Adaptation of the CATIA Digital Mockup (DMU) optimizer for automatic fit of parameterized CSG models to existing parts
- Case study and best practice elaboration
The authors are grateful to Drs. F. Carminati, R. Brun, A. Gheata (CERN), and D. Bertini (GSI) for stimulating interest and discussions and to A. Markin (BMSTU) for his contribution into the project. The work was supported by INTAS grant 06-1000012-8778and by FAIR-Russia Recearch Center.