Choose timezone
Your profile timezone:
FCC-ee optics tuning WG meeting
→
Europe/Zurich
FCC-ee optics tuning WG meeting
E. Musa presents updates on tuning simulations. Compared to before the phase difference between 2 BPMs is measured and corrected. Using only arc trim quads or quads yields worse results compared to using elements also in the IR. Using trim quads at sextupoles yields the best results. The noise added is the absolute noise of the measurement parameters. R. Tomas suggests using quadrupoles close to sextupoles, since he suggests that the response matrix calculation could be improved. Studies point that corrector coils in the IR would be required to correct leakage from the arcs. In any case skew quadrupoles are added to sextupoles. C. Carli suggests checking with magnet experts if having both skew and normal quadrupoles at the sextupoles. K. Oide suggest to touch only the quadrupoles outside the -I sextupole pair.
B. Dalena et al. present anomaly detector and signal denoising of TbT BPM data. 3 diffrent techniques are used, including LSTM. The latter reduces the noise the most, but it takes about 1h. R. Tomas suggests to also look at the phase shift. J. Keintzel suggests to also look at the amplitde.
M. Li presents on investigation of injection-related beam losses at SuperKEKB. 2 types of beam losses are identified. Large and fast within the first 100 turns which affects injection efficiency and the second one smaller and continous beam loss until 1000 turns, which affects injection background. Injection angle affects injection efficiency. Cancel coil errors reduce injection efficiency from ~70 ro 60%. Injection feedback leads to small stored beam loss. IR beam loss can be suppressed by minor collimator aperture adjustment. Injection efficiency depends also on working point. K. Oide comments that for ee colliders where Qy is lower than Qx is not usable for luminosity and suggests to check luminosity and lifetime. R. Tomas asks from where the cancel coil errors are obtained, M. Li answers that Y. Ohnishi provides them. J. Keintzel agrees to ask Y. Ohnishi if they are now included in the SKEKB model. R. Tomas comments that the cancel coil error affects only a3 and a4 components of QC1. P. Bambade comments that KEK colleauges are investigating the cancel coil errors, e.g. by H. Koiso. R. Tomas gives an example of switching polarity is discussed as an option.
W. Yuanyuan presents IP tuning for CEPC. Knobs are defined for R1, R2, R3, R4, Dy and Dy'. They are applied after global optics corrections. Several 10s of microns are applied at the IR quadrupoles. R. Tomas suggests to update the table afterwards.
There are minutes attached to this event.
Show them.
