Accurate Spin Tracking on Modern Computer Architectures for Electron-Ion Colliders

Electron-ion colliders (EICs) are the best microscopes for studying the structure of nuclear matter, particularly the nature and origin of spin in nuclei. To be effective, such machines require electron and ion beams with polarizations as high as 80%. Comprehensive end-to-end simulations to study the spin dynamics and optimize the beam polarization require exorbitant computational effort. We will enhance the open source spin-tracking code Zgoubi to take advantage of new capabilities in modern computer architectures. We will also develop new algorithms that improve the accuracy, speed and stability of long-time simulations. This work will make accessible, with a time-scale of hours instead of days, the design studies required to validate, optimize, and compare EIC designs. We will also develop a browser-based graphical interface that will make Zgoubi easier to use. During Phase I, we will evaluate the computational bottlenecks in Zgoubi, and begin porting the code's physics kernels to take advantage of modern architectures such as GPUs or MIC co- processor chips. We will also develop a symplectic tracking algorithm for elements whose fields are known through field maps. This will improve the accuracy and speed of particle tracking through field maps. Finally, we will implement a prototype browser-based GUI for Zgoubi. Commercial Applications and Other Benefits: Digital courseware is a growing market, estimated to be above $1.5 Bn, and fragmented with many approaches. Interactive software enables numerical experiments that would be impossible in the classroom. RadiaSoft will develop educational modules for accelerator physics during Phase II, based on our open source Sirepo framework. During Phase III, we will generalize to other scientific topics, appropriate for science classes at the high school, college and graduate level.