FCC EPOL polarimeter dipole chat

Friday 28 Aug 2026, 13:45 → 14:45 Europe/Zurich

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.

A. Martens in last EPOL meeting:

• 2.3 e-4 field stability over the full aperture and full length
• horizontal beam field 2.9 e-5 Tm
• longitudinal bending field 7.4e-3 Tm
• Dipole roll 94 mu rad (factor 10 smaller as for tuning)

 

Presentation by J. Burvill at FCC week 2026:

https://indico.cern.ch/event/1552126/contributions/7128827/attachments/3289677/5942462/2026_06_11_FCC_Week.pdf

 

Recent alignment parameters:

See e.g. here: https://indico.cern.ch/event/1717066/contributions/7244642/attachments/3333088/5971374/20260828_KeintzelTomas_CellLayout.pdf

13:45 → 14:05 Discussion

Speakers: Aurelien Martens (Université Paris-Saclay (FR)), Dirk Mergelkuhl (CERN), Prof. Eric Torrence (University of Oregon (US)), Guy Wilkinson (University of Oxford (GB)), Jacqueline Keintzel (CERN), Jeremie Bauche (CERN), Melvin Liebsch (TE-MSC-NCM), Dr Robert Kieffer (CERN)

20260828_Keintzel_DiscussionPolDip.pdf