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FCC-FS EPOL group and FCCIS WP2.5 meeting 29
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Europe/Zurich
Description
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 16:30 on Thursday typically every three weeks.
FCC-FS EPOL group meeting
Zoom Meeting ID
63437787216
Host
Alain Blondel
Alternative host
Jacqueline Keintzel
Useful links
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Zoom URL
R. Kieffer explains that discussions with K. Oide and G. Roy are foreseen if the polarimeter could be integrated in the RF section. He suggests that for now PA will be assumed for the baseline. K. Oide comments that installing the polarimeter next to the IP would be advantageous. R. Kieffer informs that for beam dumps after all IPs the bypass tunnel would need to be roughly 600m, so only additional 200m would be required for the laser. I. Koop comments that with polarimeters next to each IP the phase of spin precession could be measured between the IPs, and thus, allowing to measure the beam energy at each IP. R. Kieffer suggests to write a document explaining all advantageous, before September.
M. Roney presents polarization proposal at SuperKEKB. He reminds on merits for particle physics experiments of collison with polarized beams. The goal is 70% polarization at the IP for the electron ring. Spin rotators would be placed around the IP for longitudinal polarization. A compton polarimeter could be installed close to Tsukuba straight section. A polarization measurement via Touschek lifetime is being foreseen end of 2025. For this polarized electron beams would be injected into HER. Dedicated hardware (spin rotators, ...) could be installed in LS2 from 2027. K. Oide reminds that SBL is the challenge of SKEKB.
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