Electromagnetic physics vectorization in the GeantV transport framework

¹ CERN, Meyrin 1211, Switzerland
² University of Pittsburgh, PA 15260, USA
³ Bhabha Atomic Research Centre, Mumbai 400085 IN
⁴ Fermi National Accelerator Lab, IL 60510, US
⁵ Institute of Space Science, Magurele 077125, RO
⁶ Tomsk State University, Tomsk 634050, Russia
⁷ University of Nebraska, NE 68588, US
⁸ Centro de Investigación en Computación, 07738 Gustavo A. Madero,, Mexico

^* e-mail: marilena.bandieramonte@cern.ch

Published online: 17 September 2019

Abstract

The development of the GeantV Electromagnetic (EM) physics package has evolved following two necessary paths towards code modernization. A first phase required the revision of the main electromagnetic physics models and their implementation. The main objectives were to improve their accuracy, extend them to the new high-energy frontier posed by the Future Circular Collider (FCC) programme and allow a better adaptation to a multi-particle flow. Most of the EM physics models in GeantV have been reviewed from theoretical perspective and rewritten with vector-friendly implementations, being now available in scalar mode in the alpha release. The second phase consists of a thorough investigation on the possibility to vectorise the most CPU-intensive physics code parts, such as final state sampling. We have shown the feasibility of implementing electromagnetic physics models that take advantage of SIMD/SIMT architectures, thus obtaining gains in performance. After this phase, the time has come for the GeantV project to take a step forward towards the final proof of concept. This takes shape through the testing of the full simulation chain (transport + physics + geometry) running in vectorized mode. In this paper we will present the first benchmark results obtained after vectorizing a full set of electromagnetic physics models.