The challenges of beam polarization and keV-scale centre-of-mass energy calibration at the FCC-ee
IN2P3/CNRS, LPNHE, Paris, France
2 University of Geneva, Geneva, Switzerland
3 Fermilab, Batavia, IL, USA
Accepted: 22 September 2021
Published online: 2 November 2021
The capability to determine the FCC-ee centre-of-mass energies (ECM) at the ppm level using resonant depolarization of the beams is essential for the Z line shape measurements, the W mass and the possible observation of the Higgs boson s-channel production. A first analysis (Blondel A et al Polarization and centre-of-mass energy calibration at FCC-ee. arXiv:1909.12245) demonstrated the feasibility of this programme, conditional to careful preparation and a number of further developments. The existing simulation codes must be unified; the analysis and design of the instrumentation must be developed; and a detailed planning must be developed for the simultaneous and coordinated operation of the accelerator, of the continuous polarization and depolarization measurements, and of the beam monitoring devices, ensuring a precise extrapolation from beam energies to centre-of-mass energy and energy spread.
© The Author(s) 2021. corrected publication 2022
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