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    252th HiLumi WP2 Meeting

    → Europe/Zurich
    Description

    Chair: Nicolas Mounet

    Minutes: Rogelio Tomas

    HiLumi WP2 Meeting Room
    Zoom Meeting ID
    67218398114
    Host
    Hannes Bartosik
    Alternative host
    Andrea Fornara
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    HLMC tomorow with various topics relevant for WP2.

    JAP next week.

     

    Max, DA and stability

    In single beam crabbing with round optics, B1 DA better when B1 is crabbing. B2 DA also better when B1 is crabbing.

    In flat optics this preference for crabbing B1 is not seen.

    Nominal end of collapse: Octupole scan gives very good DA between -375 and 100A. Q'=15, ppb=2.2e11. CCs off. Worst bunch selected. Joanna confirms that the point she studied is consistent.

    Nicolas suggests to have the plot also for Q'=20, where Joanna found strong sensitivity on DA.

    First stability diagram studied, to be reviewed.

    Phase advanced between IPs and RDTs could be check to see if this helps understanding the preference for B1 crabbing. Also doing the DA studies with machine errors will also give more statistics.

     

    Andrea, DA with beam-beam

    Field quality has no effect at injection DA.

    Baseline: End of collapse and end of leveling have small deterioration of DA by max ~0.5sigma when adding field quality and corrections. 

    Flat 50/15 has about 50% of the amplitude detuning of round 15/15cm. DA is also much better.

    In summary: Field quality makes almost no impact for 

    Nicolas notices that DA at end of collapse is a bit optimistic. Sofia and Joanna notice that the dp/p=2.3e-4 instead of 2.7e-4 usually at FT with 15 MV.

    The behaviour of DA versus dp/p shoud be reviewed as it appears to be more pronounced for the end of collapse.

    The amplitude detuning without corrections, and without MO, for the 50/15 has various large values up 178000 m-1, which is a factor 3 larger than the typical comfortable values seen in LHC. Probably some more studies with sensitivities to errors in the correction

      

    Joanna, Flux jumps

    New studies reproduce past results.

    Using new pessimistic measurements orbit jumps up to 0.1 sigma are seen. DQ max 3.4e-5. Max relative emittance growth of 1e-4. Probably all still OK, but now orbit should be visible.  

    Joanna comments that the current scenario assumes that jumps are fully independent, however they could interfere.

    A model looking at the possibility of this intereference shows that orbit could be much larger. The most realistic assumption points to visible orbit jumps, probably causing losses.

    Direct tracking confirms analytical estimates!

    Further tracking to be done, specially with the most precise model to predict if there would be important losses in the ramp.

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

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