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    ABP-HSS Section meeting

    → Europe/Zurich
    Description
    https://cern.zoom.us/j/7288039887
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    HSS News, Rogelio, slides.
    COVID news updated, see https://hse.cern/news-article/coronavirus-information-measures-and-recommendations
    From 10/8 all staff at CERN.
    For those concerned by Asbestos  on teleworking indicate in EDH "Exceptional measures and Asbestos removal".
    Absence will require medical certificates as before COVID.
    European strategy and FCC, see Michael Benedikt presentation in https://indico.cern.ch/event/936623/. FCC feasibility study : high priority for tunnel and infrastructure. Plans to produce a CDR+ .
    MAD-NG time line presented : beta release planned for 1. August. Sep-Nov testing by selected users, names given on slides. In December decide about review. International review planned for March-April 2021.

    Round table:
    Related to experiments, Helmut: preparation started for the next LHCC week, 31/8 - 3/9. Open LHCC with status talks on 2/9 https://indico.cern.ch/event/939299/. Short summary by Helmut planned for following LMC.
    Collimation, Roderik: 2nd TCLD installed
    Codes, MAD, Laurent + Tobias. Work on MAD-NG beta version.  MAD-X : preparing new release, expected within two weeks.
    Injectors, Massimo: working with Alex + RF on paper on bucket barrier test.
    OMC, Tobias: had first meeting chaired by Tobias, discussing improved software for IR non-linear correction, which before was in FORTRAN and not it is in Python and takes feeddown into accout.

    Aperture measurements with AC dipoles, Nuria Fuster-Martinez, slides.
    Nuria studied aperture measurements using AC dipole to generate losses, as possible alternative to the
    standard method that uses the transverse damper (ADT) to blowup the beams, in both cases combined with collimator scans.
    Reporting from 2017-2018 measurements, giving overall good agreement and promising results.  

    First observed discrepancy between AC dipole and ADT techniques was at beta*=30cm in vertical plane.  Most likely related to kicking wrongly in both planes (H&V) with  AC-dipoles.

    A second observed discrepancy at beta*=25cm in the horizontal plane. Simulations with coupling or dp/p could not explain the latter discrepancy. A hypothesis was made that uncaptured particles with large dp/p in the machine could be kicked with the AC dipole to get lost in unexpected locations.
    Ewen mentions detuning with amplitude coming from IR crossing angles as possible source of differences by ADT blow-up and AC dipole oscillations. Roderik clarified that ADT measurements are performed without octupoles but usually a quick test with octupoles on is performed to confirm that aperture is not significantly deteriorated. This test should be performed in Run 3 when revisiting the technique. Roderik also argued that the dp/p used in simulations is too small. Nuria replied that particles were lost at larger dp/p. This should be investigated. 

    Next meeting probably in two weeks (for those around during this holiday period).
     

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