Study of alternative ILC final focus optical configurations

TL;DR

This paper explores alternative final focus optical configurations for the ILC to optimize beam sizes and reduce beamsstrahlung emission, using simulations to evaluate luminosity impacts and beam-beam interactions.

Contribution

It introduces and evaluates new optical configurations for the ILC final focus system that aim to improve beam parameters and reduce unwanted emissions.

Findings

Alternative configurations can increase horizontal beam size and decrease vertical size.

Simulations show potential for reduced beamsstrahlung emission.

Luminosity can be maintained with optimized bunch lengths.

Abstract

The role of the ILC final focus system (FFS) is to demagnify the beam to the sizes at the IP required to meet the ILC luminosity goals. The current design of final focus performs perfect chromaticity correction in both horizontal and vertical planes. Based on this design a set of alternative optical configurations were studied in which the horizontal beam size at the IP is increased while at the same time the vertical one is decreased, with the goal of reducing beamsstrahlung emission. Luminosity reduction due to the hour glass effect must be considered because betay*/sigmaz* becomes much smaller in this case. The beam-beam interaction simulation by Guineapig++ was used for evaluation. Reduced bunch lengths are used to make sure that the obtained luminosities are not lower than those of the ILC original (nominal) configuration.