Speaker
Description
Next-generation High Energy Physics (HEP) experiments face unprecedented computational demands. The High-Luminosity Large Hadron Collider anticipates data processing needs that will exceed available resources, while intensity frontier experiments such as DUNE and LZ are dominated by the simulation of high-multiplicity optical photon events. Heterogeneous architectures, particularly GPU acceleration, offer a path to meet these challenges by reducing both compute time and power consumption. Celeritas is a GPU-optimized particle transport code designed for high-performance computing (HPC) environments. It supports cross-platform execution (CPU, CUDA, HIP) with reproducible results and has demonstrated significant speedups in electromagnetic shower simulations. For efficient GPU-based geometry traversal, Celeritas integrates the VecGeom and ORANGE libraries and is currently transitioning from volume-based to surface-based models. Generic detector geometries can be imported from Geant4 or GDML files and are handled through VecGeom or ORANGE, both of which are optimized for GPU performance. Optical photons from Cherenkov, scintillation, and custom sources are handled in a separate GPU stepping loop. Benchmarks show up to 150x speedup (CPU vs GPU) in photon generation, and up to 350x speedup for generation and tracing to boundaries in simple geometries (without physics interactions). Volumetric interactions, including wavelength shifting, are implemented and surface-level optical properties are in development. We will present Celeritas' performance, capabilities, and utility for detector simulation in HEP experiments, and discuss the status of ongoing integration efforts with ATLAS, CMS, and LZ.
References
Publications and presentations may be found here: https://celeritas-project.github.io/celeritas
The most recently released paper on Celeritas provides profiling and performance results specifically for electromagnetic showering simulations:
A. L. Lund, J. Esseiva, S. R. Johnson, E. Biondo, P. Canal, et al. “Accelerating detector simulations with Celeritas: profiling and performance optimizations”. Mar 2025. 10.48550/arXiv.2503.17608
Significance
This presentation will cover the new developments and benchmarking of optical physics simulations on the GPU with Celeritas, and its integration status with various experiments. The performance and validation results of optical physics in Celeritas have not been previously presented.
| Experiment context, if any | Celeritas is not tied directly to a single experiment, but has ongoing integration efforts with ATLAS, CMS, and LZ. |
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