Collision-energy calibration and monochromatisation studies at FCC-ee

The Future Circular Collider (FCC) technical and financial Feasibility Study (FS) includes a workpackage on Energy Calibration, Polarisation and Monochromatisation (EPOL), which is concernedwith the precision determination of the centre-of-mass energy at the e+e− machine, FCC-ee. Toachieve this goal it is proposed to use resonant depolarisation and possibly spin precession meas-urements, in conjunction with precise measurement by the detectors of the energy spread and otherparameters with physics events. Beam diagnostics, provided by polarimeters and beam-positionmonitors, play an essential role in monitoring the polarisation level and controlling numerous beamparameters at the interaction point. Specific items of accelerator equipment include polarisationwigglers and depolarising RF-kickers. The target is to achieve a precision commensurate to theremarkable statistical precision achievable in the physics experiments. The possible monochromat-isation of colliding beams in view of a measurement of the e+e− → H(125) process is also beingstudied, with the specific requirements of this procedure under investigation. A review is presentedof the status of these activities at the end of the FS, together with the outlook for future work.