CASA Collider Design Review Retreat
Other Electron-Ion Colliders:
eRHIC, ENC & LHeC
Yuhong Zhang
February 24, 2010
eRHIC: Ring-Ring
5 – 10 GeV e-ring
5 -10GeV full
energy injector
RHIC
e-cooling
(RHIC II)
 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
Polarized Electron
200 MeV
Source
Polarized Electron
200 MeV SC Linac, Tesla type cavities
Source
Copper Linac, SLAC type cavities
10 GeV
6.7 GeV
8 GeV
2 GeV
4 GeV
5 GeV
3.3 GeV
1.7 GeV
2 GeV
200 MeV
200 MeV
10 GeV
8.3 GeV
Positron Source 3.3 GeV
6 GeV
Positron Source 4 GeV
0
0
10
50
100
150
200
250
10
50
100
150
200
275 m
• Injection of polarized electrons from source
• Ring optimized for maximum current
Figure 8 booster synchrotron,
• Top-off
FFAG or simple booster
Extraction
5 - 10 GeV
Injection
0.5 GeV
Positron Source
0
10
50
100
Polarized Electron
Source, 20 MeV
150 m
eRHIC Ring-ring: Parameters
High energy setup
Low energy setup
p
e
p
e
250
10
50
5
165
55
165
55
ns
71
71
71
71
Particles / bunch
1011
1.00
2.34
1.49
0.77
Beam current
mA
208
483
315
353
p mm·mrad
15
Emittance ex
nm
9.5
53.0
15.6
130
Emittance ey
nm
9.5
9.5
15.6
32.5
bx*
m
1.08
0.19
1.86
0.22
by*
m
0.27
0.27
0.46
0.22
Beam-beam parameter xx
0.015
0.029
0.015
0.035
Beam-beam parameter xy
0.0075
0.08
0.0075
0.07
Energy, GeV
GeV
Number of bunches
Bunch spacing
95% normalized emittance
5
Bunch length sz
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
pb-1
96
17
Luminosity Integral /week
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
(Red) electron
beam magnets
(Blue) ion ring
magnets
Detector
(Yellow) ion ring magnets
•
•
•
•
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
Warm and cold
0.5
Linac-ring
5m
Detector
integrated dipole
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
J.Dainton et al, JINST 1 P10001 (2006)
operation of pp and ep
LHeC: Linac-Ring