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FCC-ee optics tuning WG meeting
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FCC-ee optics tuning WG meeting
IP knobs and luminosity, Leon
IP knobs generated as presented in the past. Knobs are scanned by computing luminosity versus knob settings in Xsuite.
Luminosity versus vertical waist shows the expected behaviour in the range of 1 cm. In the horizontal plane weaker dependence is found over 4 cm.
Next studies involve scans for other knobs and in presence of errors, checking cross terms between the knob scans in different IPs.
FCC-ee tuning simulations with pyAT, Elaf
Elaf introduced some updates as the number of singular values for orbit correction and new tune correction function. For LOCO 20 orbit correctors are used.
As outcome from last meeting she started implementing phase advance correction between BPMs and also coupling resonance driving terms. This shows an improved performance compared to only using LOCO specially in horizontal beta-beating and vertical emittance.
80um misalignment errors in the arcs are introduced giving good optics but still needing some improvements.
Next steps: continue the investigations and implementations for phase and coupling corrections. Ramping errors to simulate beta* squeeze. Include orbit corrections to mitigate emittance growth during corrections. Include vertical dispersion in the coupling correction. Hopefully, Satya and Elaf could coordinate among themselves to progress with phase advance and coupling correction developments.
MAD-NG, Laurent
MAD-NG extended to read beam-line syntax to read Pantaleo's lattice. It will also be extended to read MAD8 syntax, as provided by Pantaleo. SR not considered for now. One typo was identified in the MADX lattice. Optics must agree very well between all codes to validate a conversion. Crab sextupoles were checked to be off in this study.
Octupolar RDTs are computed in MADNG including their derivatives to sextupole strengths (parameters).
Next steps: Add RF cavities, synchrotron radiation (that needs some fix) and solenoid.
Oide-san asked about 6D RDTs as currently presented only 4D RDTs. This can be looked at in the future.
Future FCC-ee optics tuning meetings can be found here: https://indico.cern.ch/category/18470/
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