Experiences from the CBM collaboration: CAD to ROOT conversion for Detector Geometries

Fully automated conversion from CAD geometries directly into their ROOT geometry equivalents is a topic of wide interest in particle physics experiment communities for some time. Tessellation of the surface of an intricate geometry is a powerful approach towards this goal, by potentially providing a shared geometrical representation with very good convergence even for the case of complex geometries. However, using tessellated geometries also requires significant computational effort for particle tracking inside and through tessellated objects. In this paper, we first discuss the experiment and the methodology involved in tessellation and conversion. We report on the application and first experience of using two different software approaches. The two tools, VecGeom and TGeoArbN, were used for simulation of the same tessellated subdetector component. Our observations in this simulation with respect to obtained results and simulation speed are reported along with our general observation about the handling of these tools.