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FCC-ee optics tuning WG meeting
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FCC-ee optics tuning WG meeting
R. Tomas reports there were discussions on 100 µm BPM alignment, but BI could probably do better.
An IPAC 2025 paper will be written.
A solid draft of the Feasibility Study Report should be completed by the end of this year, however, no Overleaf document has been shared for now.
S. Sai presents updates on his tuning simulations. Compared to the last meeting, linear coupling is also corrected. Errors on the FF quadrupole are reduced to 10 µm, but other IR quadrupoles remain at 40 to 60 µm. No IP tuning on top of that is performed for now.
L. van Riesen-Haupt presents DA updates with beam-beam and vertical misalingment errors on all sextupoles and all quadrupoles for ttbar-optics. With increasing rms errors, DA drops, however, no major impact of beam-beam on DA is found. R. Tomas suggests to show the correlation of the same seeds with and without beam-beam. C. Carli points out starting from 0.1µm misalingment the DA starts to drop and suggests to use lattices with corrections. T. Pieloni suggests to check if beam-beam introduces some orbit itself. R. Tomas suggests to also study MA.
L. van Riesen-Haupt presents general thoughts about DA. In addition to x,y, he also introduced x',y' on the same unit circle. Compared to "typical" DA studies, fewer particles survive. With radiation this new technique reduces the DA by about 20 sigma compared to the old technique. Also, DA depends strongly on the location were it is evaluated. K. Oide suggest to also evaluate the ellipse at s1 and track back to s0.
J. Keintzel presents updates on optics measurements with 50k turns. 1µm BPM resolution seems challenging for the IR region, but fine for the arcs. R. Tomas suggests to look at the coupling resolution too.
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