1. CATIA-G4/Root Geometry Builder. S. Belogurov 1,2, * (belogurov@itep.ru), Yu. Berchun 2, A. Chernogorov 1, *, P. Malzacher 3, E. Ovcharenko 1,2, *, A. Semennikov 1 * - FRRC fellows 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 ( Helmholtz Center for Heavy Ion Research)

2. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk2 Outline Introduction Motivation The method An example Plans

3. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk3 CAD system Introduction 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. simulation tools Design optimization requires iterative exchange of geometry and material info

4. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk4 Introduction The most popular software for simulation of particle interactions and propagation in matter and data analysis are GEATN4 and ROOT. Both Geant4 and ROOT use the same geometry representation which differs a lot form one in CAD systems. Geant4/ROOT geometry can be transferred via GDML files We are presenting a tool, which allows to facilitate creation of G4/ROOT- compatible geometry from the CAD system CATIA v.5 (used in CERN, GSI and other labs) The work was reported at SECESA2010 and CHEP2010 conferences

5. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk5 Motivation In CAD systems solid bodies are built using a wide class of surfaces and curves in advanced boundary representation (BRep). Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies.

6. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk6 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In G4/ROOT the Constructive Solid Geometry (CSG) is used. Building blocks are primitives. Currently 21 primitives are implemented. Some of them are shown

7. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk7 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In G4/ROOT the Constructive Solid Geometry (CSG) is used. Simple solids can be combined using Boolean operations ( union, subtraction, intersection ) Result of Boolean operation is a solid. It can participate in further Boolean operations

8. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk8 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. 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

9. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk9 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother L1(Box1,Vacuum)

10. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk10 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother L1(Box1,Vacuum L2(Box2, Plastic) )

11. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk11 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother L1(Box1,Vacuum,3L2) L2(Box2, Plastic)

12. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk12 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother L1(Box1,Vacuum L3(Cyl1,Cu) L4(Box3,Fe),3L2) L2(Box2, Plastic)

13. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk13 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother L1(Box1,Vacuum L2(Box2, Plastic L3(Cyl1,Cu) L4(Box3,Fe),3L2) L3, 2L4), L3, 2L4)

14. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk14 Motivation Geometry representation in CAD and G4/ROOT The difference is twofold: in the description of solid bodies and in the hierarchy of assemblies. In the G4/ROOT hierarchy there are three conceptual layers: –G4VSolid: shape, size –G4LogicalVolume: material, MF, sensitivity, daughter volumes, etc. –G4VPhysicalVolume: position and rotation of an instance of the logical volume inside its mother - Any logical volume is made of a material - Unlike a part in CAD systems, any logical volume may be a mother for placing smaller volumes inside. - Any intersections of volumes’ boundaries are forbidden. - The World is the biggest logical volume, it can not be positioned. L1(Box1,Vacuum L3(Cyl1,Cu) L4(Box3,Fe),3L2) L2(Box2, Plastic L3, 2L4), L3, 2L4)

15. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk15 Motivation Preparing any geometry for MC simulations one has to keep in mind two issues: 1. Required Detalization For a detector with poor position resolution, description should be less accurate than for more precise device. Choosing appropriate level of detalization, one can reduce significantly required computational time and memory. Examples: a threaded hole in a flange with a screw inside is equivalent for MC to a bulk piece of metal; for peripheral equipment, sometimes, just a simple solid filled with a correct mixture of materials is sufficient.

16. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk16 Motivation Preparing any geometry for MC simulations one has to keep in mind two issues: 2. Optimization for simulations A couple of tricks. - Minimization of the number of volumes. E.g. a module of the sampling calorimeter: In CAD model – lead and scintillator plates. For G4 simulations scintillator plates are inserted into the bulk Pb mother volume.

17. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk17 Motivation Preparing any geometry for MC simulations one has to keep in mind two issues: 2. Optimization for simulations A couple of tricks. - Avoiding unions helps to accelerate simulations. E.g. CAD and G4/ROOT representations of a section of the beampipe for CBM experiment at FAIR (Cylinder, Sphere, Cone. No overlaps, no unions)

18. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk18 Motivation Thus, our tool allows to facilitate creation of G4/ROOT- compatible geometry from the CAD system CATIA v.5. It is targeted on scientists who understand what geometry representation and level of detalization are optimal for given simulation task. Sacrificing automation of the geometry transfer we gain optimization For usage of the tool one should get familiar with limited (but powerful) measurement, construction, and visualization functionality of CATIA and our plugins.

19. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk19 The method 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.

20. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk20 The method File structure for representation of a LogicalVolume. PartBody contains a parameterized solid and material. 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 M d d d

21. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk21 The method Initially, files containing only PartBodies with material and publication should be prepared. Then specially designed VBA macro helps to insert with positioning a copy of a LogicalVolume as a daughter PhysicalVolume into a destination part.

22. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk22 The method 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

23. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk23 The method At the end the tree is analyzed and GDML file is exported. Import of GDML files into CATIA is implemented as well

24. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk24 The method Illustration of the procedure. a)Three Part files are loaded. b)Slice is twice inserted and positioned inside the Cylinder c)Cylinder is positioned inside the World (Box) d)Geometry exported to GDML and read by ROOT

25. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk25 For transferring geometry, one has to load an existing CAD model first. Then, using powerful measurement, construction, and visualization functionality of CATIA and our tool, a G4/ROOT compatible geometry can be built. The method Examples of measurements in CATIA

26. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk26 Examples GLAD – Large Aperture SC Diplole Magnet for R3B experiment at FAIR. Consists of 4 SS and Cu layers of complicated shapes with ribs. All transferred to G4/ROOT. One of the shells is discussed here

27. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk27 Examples Cylinders, Tori, and Ellipsoids: General shape is reproduced, but the shell has slits – bad for simulations  Cylinders, Tori, and Spheres, but length and radii of cylinders are modified : General shape is violated, but no slits – good for simulations

28. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk28 Examples LHCb VELO read from GDML LHCb VELO CAD model

29. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk29 Crystal calorimeter for R3B. General and partial views Examples

30. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk30 Examples Crystal calorimeter for R3B. G4/ROOT-like representation of a slice of CFC boxes and entire crystal array

31. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk31 - 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 Plans for further development

32. S. Belogurov et al. FRRC session, Dec. 12-th, 2010, Obninsk32 - 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 Plans for further development Thank you for your attention !