Beam-beam effects in the Super Proton-Proton Collider

TL;DR

This paper investigates beam-beam interactions in the proposed Super Proton-Proton Collider, analyzing their impact on beam stability and exploring methods to optimize dynamic aperture through crossing angle adjustments.

Contribution

It provides a detailed analysis of beam-beam effects, including empirical scaling laws and optimization strategies for dynamic aperture in the collider design.

Findings

Long-range interactions limit dynamic aperture.

Scaling laws relate aperture to transverse separation and interaction count.

Increasing crossing angles can significantly improve dynamic aperture.

Abstract

The Supper Proton-Proton Collider is a next-generation hadron collider that is now being designed. A baseline design aims for a peak luminosity of about 1*10^35 cm^-2 s^-1. The focus of this article is the effect of beam-beam interactions which are expected to strongly influence stability in the beams. We start with a discussion of a scheme to generate the crossing angles at the interaction points while also correcting the dispersion thus created. The optics constraints on the achievable \b{eta}* were studied. Weak-strong simulations were performed to study single particle dynamics via tune footprints, frequency map analysis and dynamic aperture calculations. The long-range interactions with the smallest separations are shown to determine the dynamic aperture. Empirical scaling laws for the dependence of the dynamic aperture on the transverse separations and on the number of long-range interactions are found. A tune scan shows several alternative working points with slightly better dynamic aperture than the baseline choice. Finally an option to significantly increase the dynamic aperture by increasing the crossing angle for different choices of \b{eta}* was studied.