CASA Collider Design Review Retreat Other Electron-Ion Colliders: eRHIC, ENC & LHeC Yuhong Zhang February 24, 2010

eRHIC: Ring-Ring Based on existing technology 5 – 10 GeV e-ring e-cooling (RHIC II) 5 -10GeV full energy injector 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

eRHIC Ring-ring: Full Energy Injection Options Recirculating SC linac Recirculating NC linac Injection of polarized electrons from source Ring optimized for maximum current Top-off Figure 8 booster synchrotron, FFAG or simple booster

eRHIC Ring-ring: Parameters High energy setup Low energy setup p e Energy, GeV GeV 250 10 50 5 Number of bunches 165 55 Bunch spacing ns 71 Particles / bunch 1011 1.00 2.34 1.49 0.77 Beam current mA 208 483 315 353 95% normalized emittance p mm·mrad 15 Emittance ex nm 9.5 53.0 15.6 130 Emittance ey 32.5 bx* m 1.08 0.19 1.86 0.22 by* 0.27 0.46 Beam-beam parameter xx 0.015 0.029 0.035 Beam-beam parameter xy 0.0075 0.08 0.07 Bunch length sz 0.20 0.012 0.016 Polarization % 70 80 Peak Luminosity 1033 , cm-2s-1 0.47 0.082 Average Luminosity 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 (Blue) ion ring magnets (Red) electron beam magnets (Yellow) ion ring magnets Detector 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

eRHIC Ring-ring: IR design Scheme Distance to nearest magnet from IP Beam separation Magnets used Hor/Ver beam size ratio Ring-ring, l*=1m 1m Combined field quadrupoles Warm and cold 0.5 Ring-ring, l*=3m 3m Detector integrated dipole Linac-ring 5m Warm 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 simultaneous operation of pp and ep J.Dainton et al, JINST 1 P10001 (2006)

LHeC: Linac-Ring