Impact of beam asymmetries at the Future Circular Collider e+e-

TL;DR

This study uses detailed simulations to analyze the effects of beam asymmetries at the FCC-ee, comparing results with analytical models and assessing operational tolerances for asymmetric beam parameters.

Contribution

First comprehensive simulation of beam asymmetries at FCC-ee including beam-beam collisions and injection, with analysis of sensitivity and operational tolerances.

Findings

Good agreement between simulations and analytical models for small perturbations

Identified sensitivity of beam parameters to asymmetries

Estimated tolerances for initial asymmetries in machine parameters

Abstract

In this paper we present detailed simulations with asymmetric initial beam settings in the context of the proposed Future Circular Collider e+e- (FCC-ee) using the Xsuite framework. We compare simulated equilibrium bunch sizes and luminosities against an already existing analytical model, which shows remarkably good agreement for realistic small perturbations. We investigate the longitudinal top-up injection, the currently preferred injection scheme for the FCC-ee, using self-consistent simulations featuring beam-beam collisions with beamstrahlung and the injection process, for the first time. We present and assess the sensitivity and required precision of the nominal beam parameters in a potential real-life operation by providing first estimates of the tolerances in the initial asymmetry of several machine parameters, with respect to the 3D flip-flop mechanism, obtained from parameter scan simulations.