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Jun 2 2017 JLEIC Ion Integration Meeting

Collider Ring Harmonic Numbers (All)

  • Andrew Hutton and his student Andrew Dotson have need of canonical ion collider ring harmonic numbers.
  • Jiquan is working on a tech note based on a spreadsheet that has ion collider h=3584-3592 (with stretch goal to 3594).
    • h=3584 baseline is consistent with the fall collaboration meeting slides (slide 5), with h=28 split 27 times.
  • Path forward:
    • Identify Jiquan as owner
    • Establish consensus ion ring circumference (latest appears to be ~2300m from Yuhong/Vasiliy/Fanglei)
    • Establish consensus RF parameters consistent with 2n bunch splitting.
      • With 2300m, Jiquan has suggested 3648 (C=2295m) or 3712 (C=2336m) to keep 26 divisibility.
    • Update appropriate documentation, particularly JLEIC Baseline Parameters wiki.
    • Disseminate expectation that JLEIC Baseline Parameters wiki should be current canonical parameter information.

ANL Interactions (Amy, Todd)

  • Polarized ion source discussion (Amy)
    • Followup from discussions at spring collaboration meeting
    • Amy/Zack: First telecon scheduled Wed Jun 14 15:00
  • ANL visit (Todd, Tue Jul 11)
    • Coordinating visit, meeting plan with Brahim/Zack
    • Brahim: summer student extending linac to high energy
    • Linac lattice baseline/parameter area to be shared via Dropbox, reflected in JLEIC Baseline Parameters wiki
    • Linac/Booster optimal Pb charge state (67+?) (see previous meeting)

Booster Space Charge (Ed)

  • Done:
    • Using default working point (7.517,5.493) and bare chromaticities (-13.9,-11.5)
    • Installed sextupole families, chromaticities tuned to +1,+1
    • No particle loss seen at injection, cooling; some particle loss of o(percent) seen at extraction
    • Bunch length presently short (meters) per Todd's Booster parameter spreadsheet
  • To Do:
    • Evaluate alternative working point to mitigate extraction losses
    • Develop h=1 RF extraction parameters (30 kV?), start simulating at extraction




  • TBD

Old Items

Booster h=1 Capture

  • Done:
    • 30 kV seems like the appropriate voltage for capturing initial coasting beam
    • 100 ms linear RF voltage ramp is workable (see presentation); faster may be feasible
    • esme simulation is relatively straightforward: RMS sigmaE/E goes from 3.1e-3 Gaussian (coasting) to 5.4e-3 parabolic (bunched)
    • Have tools in place to quickly make esme "movies"
  • To Do:
    • Develop consensus injection energy spread (Todd/Ed/Brahim)
    • Determine how fast <math>d^2B/dt^2</math> can be (Todd/Peter)
      • Emails ongoing: Peter raises interesting questions about snapback and dynamic superconducting magnet effects
    • Turn on injection longitudinal space charge for realistic intensities
      • Compare to Synergia (Ed/Todd)

Booster Ramping

  • Done:
    • Tools in place and under development for generating ramp parameters
    • f(RF) = 700 to 1030 kHz as input to RF design
    • h=1 through Booster to extraction appears appropriate
  • To Do:
    • Add esme ramp generation to RampDesigner tool
    • Start simulating early acceleration ramp with esme (space charge off, then on)
    • Pursue cooling evaluation at 2 GeV (bunched or coasting beam? Todd/He/Ed/...)
    • Evaluate addition of realistic impedances (Todd/Rui)

Linac/Booster Pb Charge State

  • ANL has mostly been simulating/optimizing the low energy linac (c.f. HB'16 talk/paper by Ostroumov)
    • This affects charge state and stripping optimization, but does not affect latest optimizations to handle RFQ heavy ion losses
    • Heavy ion source expected to have 1-2 pi mm-mrad normalized emittance; which is it?
  • Brahim has noted that 67+ may not be the optimal charge state for the baseline high energy linac
  • Brahim and Todd are continuing to discuss
    • Tradeoff of space charge vs stripping efficiency/pulse intensity
    • Todd's initial feeling is that this is a relatively flat optimization