FCC-FS EPOL group meeting 50
The FCC technical and financial feasibility study comprises a work package (EPOL) on precision determination of the centre of mass energy at FCCee. using resonant depolarisation of the beams, in conjunction with precise measurement of the energy spread and other parameters using physics events in the detectors, and other beam diagnostics in particular to control the collision parameters. Specific equipment involves polarimeters for both beams, polarisation wigglers, and depolarising RF kickers. The possible mono-chromatization of the beams in view of a measurement of the e+ e- —> H (125) process will also be studied and special requirements investigated.
Short group meetings are foreseen at 15:00 on Friday.
G. Willkinson reminds that the FCC week EPOL sessions are currently being organized and that an IPAC paper is being prepared.
A. Korsun gives an update on monochromatization for the LCC. Studies include beamstrahlung. The most promising strategy is enlarging horizontal beta-function at the IP to about 5 to 10m. K. Oide warns that large xi_x could introduce significant dynamic beta* and emittance.
A. Martens presents considerations on the polarization for colliding bunches. Pz is estimated to be below 1e-6. Measuring vertical polarization to 1e-4 should be envisaged. Asymptotic polarization could be in the order of 3.8e-4, assuming 10% top up every 30s.