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May 8 – 12, 2023
Norfolk Waterside Marriott
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CaTS: Integration of Geant4 and Opticks

May 8, 2023, 2:00 PM
Marriott Ballroom VII (Norfolk Waterside Marriott)

Marriott Ballroom VII

Norfolk Waterside Marriott

235 East Main Street Norfolk, VA 23510


Wenzel, Hans (Fermilab)


CaTS is a Geant4 advanced example that is part of Geant4[1] since version 11.0. It demonstrates the use of Opticks[2] to offload the simulation of optical photons to GPUs. Opticks interfaces with the Geant4 toolkit to collect all the necessary information to generate and trace optical photons, re-implements the optical physics processes to be run on the GPU, and automatically translates the Geant4 geometry into a GPU appropriate format. To trace the photons Opticks
uses NVIDIA® OptiX7™ [3]. In this presentation we shall describe CaTS and the work performed to integrate Opticks with Geant4 using the tasking mechanism and the work to include CaTS in the software framework used by liquid Argon TPC neutrino experiments. We shall demonstrate that the generation and tracing of optical photons represents an ideal application to be offloaded to GPUs, fully utilizing the high degree of available parallelism. In a typical liquid Argon TPC simulation, a speedup of several hundred times compared to single threaded Geant4 is observed.


Keywords: Simulation of optical photons, GPUs.

Consider for long presentation No

Primary author

Wenzel, Hans (Fermilab)


Presentation materials