Perspective on the Accelerator Physics Side of EICC LBNL

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Perspective on the Accelerator Physics Side of
EICC _at_ LBNL

• January 16, 2009

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• ????,?????
• ??????,?????
• ??????,?????
• ????
• If you know the enemy and know yourself, you need
  not fear the result of a hundred battles.
• If you know yourself but not the enemy, for every
  victory gained you will also suffer a defeat.
• If you know neither the enemy nor yourself, you
  will succumb in every battle.
• SunTzu

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Outline

• ELIC/mEIC
• eRHIC/MEeIC
• Others (LeHC and ENC_at_FAIR)
• Comparisons and assessments
• Remarks

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eRHIC Ring-Ring

• Conceptual design completed
• Only on2 IP
• No major RD except electron cooling (also in
  RHIC II)
• Cost 700M

• Design suffers low luminosity (lt1033)
• 165 bunches in RHIC ring? low collision frequency
• Very long ion bunch? large ß, weak final
  focusing
• Must redo AGS and RF of RHIC to improve ? too
  high cost

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eRHIC ERL-Ring

• Lianc-ring has too much technical challenges,
  some virtually impossible
• Polarization electron current too high (420mA
  vs. 0.1mA state-of-art)
• Multi-pass (5x2) high energy ERL
• linac-ring beam-beam

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MEeIC Half Way of eRHIC

• Reduce electron energy from 10 GeV to 2 or 4 GeV
• Save cost on large ERL and ring for electron
• Same design, same technologies and same problems

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MEeIC Luminosity

• MEeIC luminosity 0.09 to 0.9 (1033 1/s/cm2)
• How to get this luminosity?
• ERL for electron beam
• High polarized electron current, 50 mA vs. 0.1 mA
  state-of-art
• Large electron beam-beam tune-shift (disruption)
• Multiple-pass ERL (3x2 passes)
• Coherent electron cooling for short ion bunch and
  small emittance
• Proton energy is 250 GeV/u (vs. 11 GeV/u for
  MEIC)
• Ion bunch length reduces from 20 cm to 5 cm
• Transverse RMS emittance reduces from 9.4 nm to
  0.94 nm
• Proton bunch 21011 protons (a factor of 80
  large than MEIC bunch)
• Averaged charge density is 3.4, 8.5 up to 34
  times than MEIC
• Technology development cycle
• Polarized source
• Coherent electron cooling
• Electron cooling FEL, great idea but much more
  complex
• Conventional Electron cooling (1967 Bodlker idea
  ? 1976 Derbenev theory ? 1980? Low energy
  experiement ? 2004 FNAL 8 GeV p- demo)

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LHeC and ENC_at_FAIR
20140 GeV e 17 TeV p
3 GeV e 15 GeV p
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ELIC/MEIC vs. eRHIC/MEeIC
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Personal Reflection

• eRHIC/MEeIC
• Not a working design
• No satisfactory backup plan
• Good RD progress
• ELIC/MEIC
• Good design and schemes
• Not enough RD progress

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Suggestions

• ELIC
• As is with continue optimization
• MEIC
• Next design iteration follows science case
  evolution
• RD (till next EICC, May 28)
• Design independent
• Individual topics
• IP
• Polarization (electron/proton)
• Cooling (coherent/conventional)

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Lets hear what Slava is going to say?
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Slavas View of Staging

• Stage 1 Two warm rings in a 300 m tunnel, crab
  crossing, traveling ion focus.
• Stage 2 SC ion ring in same tunnel
• Stage 3 Full size (1.5 to 2.5 km) figure-8
  tunnel with warm electron ring
• Stage 4 SC ion ring (high energy EIC)

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Accelerator Physics RD Issues

• Why we need Figure-8 rings (tunnels)?
• Acceleration of polarized ions in boosters (small
  SC ring and e-collider ring) and ion collider
  Ring
• (AGS still struggling the intrinsic spin
  resonances)
• Longitudinal ion spin (especially deuteron)
• A modest warm solenoid or SC snake in crossing
  straight is needed to stabilize spin
• Two SC snakes in arcs (for p and 3He) are needed,
  if to have longitudinal spin at 4 IP. These three
  snakes are ease!
• Medium energy electron cooling (Fermilab/BINP)
• Traveling ion focusing
• Crab crossing
• Repetition rate synchrotron
• Synchrotron for electron cooling ring (variable
  electron orbit)
• Other RD which can lead high luminosity
• Repetition rate (0.5 to 1.5 GHz)
• Detector space (4 m to 2 m)
• Aperture size