GPU-Accelerated Optical Physics in Celeritas

Celeritas is a Monte-Carlo based particle transport code developed for computationally intensive applications in the energy and intensity frontier experiments. With the upgrade of the High Luminosity Large Hadron Collider (HL-LHC) and the increasing scale of neutrino and rare event detectors, the demand for high-fidelity, large-scalesimulations is increasing. Celeritas addresses these challenges through GPU-optimization and platform portability, providing electromagnetic physics and is currently extending its capabilities to optical simulation, with seamless integration into existing Geant4 applications by offloading particles to Celeritas. In this work, we present the current status, focusing on GPU optical photon simulation. To demonstrate performance gains, we perform benchmark comparisons of optical photon generation and transport between Celeritas and Geant4 for different experimental setups, positioning Celeritas as a scalable solution for the next-generation experiments.