OMC homecoming
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Tobias, IP2 missing events
Lower lumi in IP2 corrected with the MQSX knob. Lumi simulations cannot explain all lumi loss only with the coupling knob. A waist shift could include some tilts in the beams. A waist shift of 40cm would increase beam size to 40-50% level.
The lumi loss scales with the square of the strength of the knob.
Next steps:
- What k-mod is doing ?
- Big tilts from survey, what do they do?
- VdM knob and observations
- Jaime to check automatic matching code
- Reinforce local coupling correction:
+ Single BPM
+ Local coupling correction with Q1
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Ewen , some non-linear activities in MDs
Losses in the start were due to k-modulation (!). The global linear optics correction knob blew-up the beam (!).
It seems b4 correction improved tune measurement. b3/a3 settings made a huge impact on lifetime.
Nice data of lifetime over 20min without changing anything.
The dump on the HL-LHC DA MD was not on the reported tune on the slide, there was a mistake.
Conclusion was that by optimizing working point forced DA improves.
Interesting to see that we did not see blow-up after AC dipole excitations in 2018, contrary to 2017.
Maybe was due to the smaller DA.
Is the effect with large Q' due to islands?
Would be nice to kick into the island instead for future MDs.
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Pending MD notes:
-Tobias, coupling decay
-Josch, MD1 amplitude detuning
-Michael, uncorrected b3 DA
-MD2 and MD3 and MD4, Islands MD, Adecta, HL-LHC DA (1st part linear Josch)
-Jaime, Lumi scans
-3D forced kicks
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Joschua, 10 Hz spectral line.
in the ion measurements the 11 Hz line has an amplitude of about 10-20 um.
In protons 6 um - 7 um.
Higher in flat ...
At injection lots of polution.
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Elena, isolation forest for bad BPMs
Simulations identify well bad BPMs.
To be seen, input errors. tobias: What would happen with lattice errors.
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Andreas, Lobster
robustness checks, 2nd order!
best combination?