CASA Collider Design Review Retreat Other Electron-Ion Colliders: eRHIC, ENC & LHeC

CASA Collider Design Review Retreat

Other Electron-Ion Colliders:eRHIC, ENC & LHeC

Yuhong Zhang

February 24, 2010

eRHIC: Ring-Ring

Based on existing technology

Collisions at 12 o’clock interaction region

10 GeV, 0.5 A e-ring with 1/3 of RHIC circumference (similar to PEP II HER)

Inject at full energy 5 – 10 GeV

Polarized electrons and positrons

RHIC

5 – 10 GeV e-ring

e-cooling(RHIC II)

5 -10GeV full energy injector

eRHIC Ring-ring: Full Energy Injection Options

0 50 10010 150 200 250 275 m

2 GeV4 GeV

6 GeV4 GeV

200 MeV

200 MeV

Polarized ElectronSource

Positron Source

2 GeV

Copper Linac, SLAC type cavities10 GeV

8 GeV

1.7 GeV3.3 GeV

5 GeV6.7 GeV

200 MeV

200 MeV

Polarized ElectronSource

Positron Source 3.3 GeV

SC Linac, Tesla type cavities

8.3 GeV10 GeV

0 50 10010 150 200 250 275 m

Recirculating NC linacRecirculating SC linac

Figure 8 booster synchrotron,

FFAG or simple booster

Injection0.5 GeV

Polarized ElectronSource, 20 MeV

Positron Source

0 50 10010 150 m

Extraction5 - 10 GeV

• Injection of polarized electrons from source

• Ring optimized for maximum current

• Top-off

eRHIC Ring-ring: ParametersHigh energy setup Low energy setup

p e p e

Energy, GeV GeV 250 10 50 5

Number of bunches 165 55 165 55

Bunch spacing ns 71 71 71 71

Particles / bunch 1011 1.00 2.34 1.49 0.77

Beam current mA 208 483 315 353

95% normalized emittance mm·mrad 15 5

Emittance x nm 9.5 53.0 15.6 130

Emittance y nm 9.5 9.5 15.6 32.5

x* m 1.08 0.19 1.86 0.22

y* m 0.27 0.27 0.46 0.22

Beam-beam parameter x 0.015 0.029 0.015 0.035

Beam-beam parameter y 0.0075 0.08 0.0075 0.07

Bunch length z m 0.20 0.012 0.20 0.016

Polarization % 70 80 70 80

Peak Luminosity 1033 , cm-2s-1 0.47 0.082

Average Luminosity 1033 , cm-2s-1 0.16 0.027

Luminosity Integral /week pb-1 96 17

eRHIC Ring-ring: e-Ring Design• Two 180° arc sections• 84 FODO cells with 10.86 m length

– vertical betatron phase advance fixed at 60°,

– horizontal betatron phase advance tuneable between 30° to 80°

• Dispersion suppressors at each end of an arc• Energy loss per turn for 10 GeV: 10.9 MeV x I (A) • Damping wiggler or super-bend for low beam energy

eRHIC Ring-ring: Dynamical Aperture• Momentum acceptance:

– At injection: at least 0.5% of injection energy

– In the ring: at lease 7 σE

• Dynamical aperture: large than 10 σ• Damped energy spread

– 1x10-3 for 10 GeV

– 0.5x10-4 for 5 GeV

• Dynamical aperture is sensitive to betatron tune working point

• Tracking 1024 turns with natural horizontal emittance and half for vertical emittance

eRHIC Ring-ring: Other Studies• Beam Instabilities

– Single & coupled bunch instabilities, HOM heating, ion related effects, electron cloud

– Provide calculation results on inpedance budget, transverse mode coupling instability, longitudinal microwave instability threshold, longitudinal coupled bunch instability, transverse coupled bunch instability, fast beam-ion instability,

• Beam-beam issue

• Beam polarization

• RF in electron ring

• Electron cooling

eRHIC Ring-ring: Interaction Region

• Yellow ion ring makes 3m vertical excursion.

• Design incorporates both normal and superconducting magnets.

• Fast beam separation. Besides the interaction point no electron-ion collisions allowed.

• Synchrotron radiation emitted by electrons does not hit surfaces of cold magnets

(Blue) ion ring magnets

(Red) electron beam magnets

(Yellow) ion ring magnets

Detector

eRHIC Ring-ring: IR design SchemeDistance to nearest

magnet from IPBeam separation Magnets used

Hor/Ver beam size ratio

Ring-ring,

l*=1m1m

Combined field quadrupoles

Warm and cold 0.5

Ring-ring, l*=3m

3mDetector

integrated dipoleWarm and cold 0.5

Linac-ring 5mDetector

integrated dipoleWarm 1

• No crossing angle at the IP• Linac-ring: larger electron beta*; relaxed aperture limits ; allows round

beam collision geometry (the luminosity gains by a factor of 2.5).• Detector integrated dipole: dipole field superimposed on detector solenoid.

eRHIC Ring-ring: Interaction Region

eRHIC: ERL-Ring

eRHIC ERL-Ring: Full Energy

eRHIC ERL-Ring: Parameters

eRHIC ERL-Ring: Recent Developments

Presentations at Stony Brook EIC Meeting, Jan. 2010

Electron Nucleon Collider at FAIR

ENC@FAIR: Parameters

ENC@FAIR: Interaction Region

LHeC: Ring-Ring

LHeC Ring-Ring: Interaction Region

foresees simultaneousoperation of pp and epJ.Dainton et al, JINST 1 P10001 (2006)

LHeC: Linac-Ring