Latest revision as of 11:26, 2 June 2017

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.
  • There is some confusion about the official baseline numbers, with inconsistencies between
    • the Jun 29 2016 Study of Beam Synchronization at JLEIC arxiv note (h=3422-3437)
    • Jiquan's fall 2016 collaboration talk (h=3584)
    • Shaoheng's Ion ring RF parameters as linked in the Ion Collider Ring Requirements and Parameters area of the JLEIC Baseline Parameters wiki. (h=6832?)
• 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

AOB

Materials

• JLEIC Fall 2016 Collaboration Meeting (Oct 5-7 2016, InDiCo)
• JLEIC Spring 2017 Collaboration Meeting (Apr 3-5 2017, website)
• JLEIC svn repository
• Last meeting (Apr 21 2017)

Attendance

• 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