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    FCC-ee optics tuning WG

    → Europe/Zurich
    18/3-008 - CLIC Meeting room (CERN)

    18/3-008 - CLIC Meeting room

    CERN

    20
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    FCC-ee optics tuning WG meeting
    Zoom Meeting ID
    65516078996
    Host
    Rogelio Tomas Garcia
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    Actions:

    • Simulate failure of correctors and BPMs 
    • Repository for tuning result seeds --> Space in EOS created: "fcc-ee-tuning", first step: put existing tuned seeds with descriptions there
    • Max BPM to quadrupole alignment --> more studies to be done
    • Including long-range misalignments: --> News presented today
    • Tuning simulations with larger H errors after BBA and split errors between arc and IR: --> news next tuning meeting
    • a4 correction to be studied:
    • Split arc and IR BPM resolution: --> news today
    • BPM resolution for RDTs measurements: --> news today

     

    Jack reports that EOS space for FCC-ee-tuning is already available.

     

    BPM tolerances, Patrick

    1 mrad rolls in arc BPMs is OK to provide 2.5e-4 error in f1001. Actually it is enough to remove about 5 BPMS either side of the IP to maintain 3e-4 rms in f1001.

    Exploring tuned lattices from Satya large loss in MA is observed. Worst seed has many large RDTs (sextupolar skew). The worse performance of tuning should be compared to Kevin's tuning.

     

    Chromatic beta* and energy shifts, Jacqueline

    Energy shift is positive for negative opposite sign dispersion. D and offset must be measured, controlled and corrected below tolerances. Since many new effects are contributing to this energy uncertainty, keeping the 100 keV as total (but added in quadrature) is very challengings. -> Put all contributions together 

    Off-momentum beta also contributes to the energy uncertainty. Current chromatic beta values give about 600 keV shift to the energy. This is without beam-beam. 0.38% resolution on the beta error would be needed for Z (0.28% for W), which is challenging. Need to measure beta* for a large energy range. Discrepanacy to previous estimate is being investigated.

    Going from non-colliision to beam-beam needs to be studied.

     

    Generation of realistic long-wavelength misalignments, Jürgen Gutekunst , Vincent Gerligand

    Goal to provide realistic misalignments of the machine from the alignment network, just instrument precision. In few km beam line can move by 10mm in H..

    Motion per year is 1mm in H and 1-2.5 in V. There is no special treatment of the FFS area.

    Realizations (seeds) are provided for testing in tuning simulations, available in gitlab.

     

     

     

     

     

     

     

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