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Second Workshop on Wire Experiment for Long Range Beam-Beam Compensation

→ Europe/Zurich
La Villa du Lac - Divonne-les-Bains /France
Adriana Rossi (CERN), Hermann Schmickler, Yannis Papaphilippou
Description

Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller beta* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab-cavities. Both beam losses and emittance growth could be mitigated by compensating the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing Wires embedded into collimator jaws, installed either side of the high luminosity interaction regions. 

Following the LRBB mini-workshop in Lyon, in December 2015, we will review the machine configuration for the experiment with Wires planned in 2017, with the 2 Wires being installed in IP5 during the EYETS 2016-17.

In particular, basing on simulations and previous LRBB experiments, we would like to come to the definition of the operational parameters, the instrumentation, machine settings. We will be discussing LHC optics and parameter space in term of intensity, emittances, chromaticity, octupole current, damper gain, machine parameters envelope (collimator settings, maximum beam intensity for the weak beam, time spent with wire close to beam . . .), observables expected from simulations, instrumentation required and detection limits (or in turn the minimum bunch intensity to be able to measure the effect of the wire), other causes of beam losses or tune shift that may mask the effect of the wire, measurements needed prior the dedicated experiment, minimum time required . . .

Participants
  • Adriana Rossi
  • Alexander Valishev
  • Alexey Levichev
  • Axel Poyet
  • Belen Salvachua
  • Daniel Wollmann
  • Danila Nikiforov
  • Dario Pellegrini
  • Elias Metral
  • Fanouria Antoniou
  • Georges Trad
  • Gerard Alain Tranquille
  • Gianluigi Arduini
  • Giovanni Iadarola
  • Giulio Stancari
  • Guido Sterbini
  • Hannes Bartosik
  • Hermann Schmickler
  • Jiri Kral
  • Kyriacos Skoufaris
  • Manuel Gonzalez Berges
  • Markus Zerlauth
  • Miriam Fitterer
  • Mirko Pojer
  • Nikos Karastathis
  • Oliver Bruning
  • Rhodri Jones
  • Riccardo De Maria
  • Roderik Bruce
  • Rogelio Tomas Garcia
  • Stefania Papadopoulou
  • Stefano Redaelli
  • Stephane Fartoukh
  • Tom Levens
  • Xavier Buffat
  • Yannis Papaphilippou
Support
    • 1
      Welcome and motivations
    • Hardware and beam instrumentation sensitivity and requirements on minimum beam parameters
      Convener: Hermann Schmickler (CERN)
    • 11:00
      Coffee
    • Machine optics and set up considerations: Machine optics and plans
      Convener: Adriana Rossi (CERN)
      • 6
        Potential of wire compensation for (HL-)LHC & Optimal optics and hardware conditions
        Speaker: Stephane Fartoukh (CERN)
        SF_wireworkshop.pdf
        SF_wireworkshop.pptx
      • 7
        Collimator settings with ATS optics & commissioning with wire
        • Minimum half gap of the collimator inner jaw during the tests (is it related to the wire current?
        • Machine protection issues
        • Feedback on “weak” beam parameters
        Speaker: Roderik Bruce (CERN)
        2017.03.20-BBLR_coll_hierarchy.pdf
        2017.03.20-BBLR_coll_hierarchy.pptx
      • 8
        Integration of Wire measurements in the MD planning
        • Estimate of how long it will take to get to commissioned a beam with 2 trains for 2 following scenarios: using ATS ’standard’ optics as for physics, and with P1 unsqueezed
        • Suggest which measurements should be done during commissioning
        • Flat optics MDs and readiness.
        Speaker: Rogelio Tomas Garcia (CERN)
        SLIDES.pdf
    • 13:10
      Lunch
    • Beam-Beam measurements and simulations
      Convener: Yannis Papaphilippou (CERN)
    • 16:20
      coffee
    • Beam-Beam measurements and simulations
      • 13
        Impact of crossing angle reduction - simulations and observations

        — Observables from simulations and experience during 2016
        — Other factors affecting beam lifetime
        — Review of measurements results with 2 trains (lifetime, emittance blow-up)
        — Measurements proposal with weak beam + 1 train strong with supporting simulations

        Speaker: Dario Pellegrini (CERN)
        wire2017_Pellegrini.pdf
        wire2017_Pellegrini.pptx
    • Wishlist and final discussion on MD (everyone)
      • Collimators set up and considerations on TCT4/TCL4 protection
      • What else can cause beam losses and tune shift, which could mask the wire effect or pollute our measurements?
      • What can we measure for the same working point?
      • Should we push to have unsqueezed beam in IP1?
      • What can we measure outside the MD time?
      • . . . .
    • 20:00
      Banquet dinner
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