Momentum bandwidth of the KEK Accelerator Test Facility 2

Abstract

Momentum bandwidth is an important characteristic for final focus systems (FFS) of future high-energy colliders. A large momentum bandwidth is a notable feature of the novel local-chromaticity-correction FFS, being demonstrated at the KEK Accelerator Test Facility 2 (ATF2), owing to the locality of chromaticity correction. In this article, analytical estimations and simulations of momentum bandwidth for various optics of ATF2 are presented. Possible deviations of the momentum bandwidth due to realistic machine imperfections are studied. Experimental measurements at ATF2 following successful tuning of small vertical beam size at the interaction point (IP) are also described, which agree well with numerical predictions and further verify the robustness of the local chromaticity correction scheme.