Characterization of the International Linear Collider damping ring optics

TL;DR

This paper presents a method for characterizing and optimizing the damping ring optics of the ILC, considering errors and misalignments, to meet emittance and dynamic aperture specifications.

Contribution

It introduces a comprehensive methodology for evaluating and optimizing damping ring lattice performance considering realistic errors and measurement limitations.

Findings

BPM measurement errors and corrector placement limit emittance tuning.

Specifications for magnet alignment and errors are aligned with performance goals.

Minimum number of BPMs and their placement significantly affect emittance targets.

Abstract

A method is presented for characterizing the emittance dilution and dynamic aperture for an arbitrary closed lattice that includes guide field magnet errors, multipole errors and misalignments. This method, developed and tested at the Cornell Electron Storage Ring Test Accelerator (CesrTA), has been applied to the damping ring lattice for the International Linear Collider (ILC). The effectiveness of beam based emittance tuning is limited by beam position monitor (BPM) measurement errors, number of corrector magnets and their placement, and correction algorithm. The specifications for damping ring magnet alignment, multipole errors, number of BPMs, and precision in BPM measurements are shown to be consistent with the required emittances and dynamic aperture. The methodology is then used to determine the minimum number of position monitors that is required to achieve the emittance targets, and how that minimum depends on the location of the BPMs. Similarly, the maximum tolerable multipole errors are evaluated. Finally, the robustness of each BPM configuration with respect to random failures is explored.