Electron-Positron Collisions: A Comparison of WarpX and GUINEA-PIG Simulations*

As part of the Snowmass 21 planning exercise, the Advanced Accelerator Concepts community proposed developing multi-TeV linear colliders and considered beam-beam effects for these machines. Such colliders operate under a high disruption regime with a significant number of electron-positron pairs produced from quantum electrodynamic (QED) effects. Thus, it requires a self-consistent treatment of the fields produced by the pairs, which is not implemented in state-of-the-art beam-beam codes such as GUINEA-PIG. WarpX is a parallel, open-source, and portable particle-in-cell code with an active developer community that models QED processes with photon and pair generation in relativistic laser-beam interactions [2]. However, its application to beam-beam collisions has yet to be fully explored. In this work, we benchmark the luminosity spectra, photon spectra, and the coherent pair production processes from WarpX against GUINEA-PIG in ultra-tight collisions and ILC scenarios. This is followed by a run-time comparison to demonstrate the speed-up advantage of WarpX. Ultimately, this work ensures a more robust modeling approach to electron-positron collisions, with the goal of scaling up to 15 TeV. 

[1] T. Barklow et al., “Beam delivery and beamstrahlung considerations for ultra-high energy linear colliders,” Journal of Instrumentation 18, P09022 (2023)

[2] L. Fedeli et al. "Pushing the frontier in the design of laser-based electron accelerators with groundbreaking mesh-refined particle-in-cell simulations on exascale-class supercomputers." 2022 SC22: International Conference for High Performance Computing, Networking, Storage and Analysis (SC). IEEE Computer Society, 2022.