The FCC-ee Interaction Region Magnet Design

TL;DR

This paper discusses the complex design challenges of the FCC-ee interaction region magnets, focusing on beam focusing, magnetic shielding, and minimizing emittance blow-up within spatial constraints.

Contribution

It introduces a novel magnet design approach that addresses the unique spatial and magnetic challenges of the FCC-ee interaction region.

Findings

Effective magnet configurations reduce emittance blow-up.

Design solutions improve beam screening from detector magnetic fields.

Minimized crosstalk between final focus quadrupoles.

Abstract

The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (+-15 mrad) in the high-field region of the detector solenoid. Moreover, the very low vertical beta_y* of the machine necessitates that the final focusing quadrupoles have a distance from the IP (L*) of around 2 m and therefore are inside the main detector solenoid. The beams should be screened from the effect of the detector magnetic field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized, while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized.