A CAD interface for GEANT4

Abstract

Often CAD models already exist for parts of a geometry being simulated using GEANT4. Direct import of these CAD models into GEANT4 however, may not be possible and complex components may be difficult to define via other means. Solutions that allow for users to work around the limited support in the GEANT4 toolkit for loading predefined CAD geometries have been presented by others, however these solutions require intermediate file format conversion using commercial software. Here within we describe a technique that allows for CAD models to be directly loaded as geometry without the need for commercial software and intermediate file format conversion. Robustness of the interface was tested using a set of CAD models of various complexity; for the models used in testing, no import errors were reported and all geometry was found to be navigable by GEANT4.

Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source

“…CADMesh is a C++ library for loading CAD based geometries into Geant4. 31 The conversion of the mesh balloon wall geometry into a CADmesh-compatible assembly was performed using Tetnest, 31 a python-based script that imports surface meshes and creates the nested tetrahedral mesh. The balloon wall material was assigned to the geometry.…”

Semiconductor neutron detectors

“…Thanks to the different toolkits present on the kernel, it was possible to import the geometry directly from the layout [29], and to define the physics to be used and running the simulations of different events using the defined environment [30] [31]. The physics section was defined using a pre-existent model called QGSP_BERT_HP using the neutron cross section contained in the GDML library.…”

GUIMesh: A tool to import STEP geometries into Geant4 via GDML

“…This can be done using Geant4 native class G4Tesselation or by a Geometry Description Markup Language (GDML) [4][5] file, a geometry description format based on XML. The CADMesh [6] [7] tool already allows to interface Stereolithography (STL is a CAD mesh format) [8] files with Geant4. However, there are currently no non-commercial tools capable of interfacing STEP [9] described geometries, the most widely used data exchange CAD format, to Geant4 by converting them to GDML.…”