Characterisation of the Beamstrahlung radiation at FCC-ee

TL;DR

This paper characterizes beamstrahlung radiation at FCC-ee across various energies, analyzing its impact on machine-detector interface, background noise, and the need for photon dumps in high-luminosity lepton colliders.

Contribution

It provides a detailed analysis of beamstrahlung effects at different energies and discusses mitigation strategies for associated backgrounds and high-power photon management.

Findings

Beamstrahlung power ranges in the hundreds of kilowatts.

Significant background from incoherent e+e- pairs at the interaction point.

Necessity for a photon dump due to high beamstrahlung power.

Abstract

Beamstrahlung is a dominant effect in the beam dynamics of the high luminosity next-generation lepton collider FCC-ee. We characterize the beamstrahlung radiation for the beam parameters at the four working energies, from the Z-pole to the $t\bar{t}$ threshold, and present the effect of this radiation in the Machine-Detector-Interface region. We discuss the conceptual need for a photon dump due to the high power produced, which is in the order of hundreds of kilowatts. We also discuss the detector induced backgrounds due to the incoherent $e^+e^-$ pairs produced by the interaction of the beamstrahlung photons at the IP.