Particle Tracking for FCC-ee Top-up Injection

FCC-ee (Future Circular e$^+$e$^-$ Collider) is the next generation highest-luminosity energy frontier lepton collider, designed to deliver record luminosity for the precision studies of Z, W, H and t. To maintain the stored beam current and maximize luminosity throughout the physics run, top-up injection scheme is needed for the collider. In this study several aspects of FCC-ee collider top-up injection (such as injection efficiency, dynamic aperture, momentum acceptance, nonlinear dispersion, on-axis injection and hybrid on-off axis injection, twiss parameter error tolerance) were studied in Z mode using particle tracking. By optimizing twiss parameters and emittance of the injected beam, injection efficiency was substantially improved. For the particle tracking simulations mentioned, a newly developed Python package called Xsuite was used. Computationally expensive jobs with high number of particles and turns were performed on CERN's Batch Service based on HTCondor.