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FCC-FS EPOL group meeting 46
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Europe/Zurich
18/3-008 - CLIC Meeting room (CERN)
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 15:00 on Friday.
FCC-FS EPOL group meeting
Zoom Meeting ID
63437787216
Host
Alain Blondel
Alternative host
Jacqueline Keintzel
Useful links
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Zoom URL
J. Keintzel reminds about the FCC physics workshop:
https://indico.cern.ch/event/1588696/
J. Burvill presents frist steps on the photon sensor for the polarimeter. ToyMC and BDSIM differ by a factor of 2. The measurement accuracy DeltaA/A is in the order of 8e-3. E. Torrence suggests to not have more than 1 radiation length of tungsten. The goal is to perform RDP simulations with realsitic polarimeters in BDSIM. A. Blondel suggests including the background from the beam. He expresses his opinion that no fit might be needed.
R. Kieffer presents on the digitization for the polarimeter. J. Keintzel suggests that the particles lost inside the beampipe should be checked by e.g. the collimation team.
R. Kieffer presents on the LCC GHC optics comparison for the polarimeters. For LCC there might be background from the IP. Currently the inter-beam distance is about 1 m. It needs to be defined if shielding would be required and if possibly there are implications on the inter-beam distance. More background from SR from the arcs is exptected. For LCC the pattern is a bit thinner, since the beam size is a bit bigger at the GHC. C. Carli points out that beam divergence impacts the performance of the polarimeter. E. Torrence suggests to look at the optics functions at the point of the detector. A. Blondel and C. Carli suggest to evaluate if upstream or downstream of the IP would be better.
J. Keintzel presents simulations of RDP for KARA.
J. Keintzel shows the EPOL chapter for the comparison report. A. Blondel suggests highlighting the differences between GHC and LCC. C. Carli suggests to evaluate which depolarizer strength we need in the future, since currently it is more difficult to judge. R. Kieffer adds that the difference between the location is described.
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