Vasiliy Morozov for the JLab EIC Study Group
Review 09/2010 Page 1

MEIC Layout
3 Figure-8 rings stacked vertically
Big booster
3-5 GeV/c
 up to 20 GeV/c protons
Prebooster
0.2 GeV/c

3-5 GeV/c protons
Review 09/2010 Page 2

Big Booster
• Acceleration of protons from 3-5 GeV/c to up to 20 GeV/c for injection into ion collider ring
• Big booster implementation options
• Separate warm ring in collider rings’ tunnel (current baseline)
• Using the electron ring
• Separate cold ring in the prebooster’s tunnel
• Big booster design considerations
• Avoid transition energy crossing
• Space charge
 higher injection energy for larger ring
• Matching RF systems
 debunch low-frequency beam and then rebunch it at higher frequency?
Review 09/2010 Page 3

Ion Collider Ring Layout
• Geometrical matching of electron and ion rings
• Spin rotators in the electron ring
• Siberian snakes in the proton ring arcs
Ion Ring
Siberian snake Siberian snake
Electron Ring
Spin rotators Spin rotators
Review 09/2010 Page 4

Modular Design Concept
• Design separately and incorporate/match into the ring
• Vertical chicanes for stacking the ion ring arcs on top of the electron ring
• Injection section
• Electron cooling section
• Siberian snakes
• Interaction region with horizontal crossing
• Section for local chromaticity compensation
Review 09/2010 Page 5

Basic Ring Parameters
Proton beam momentum
Circumference
Arc’s net bend
Straights’ crossing angle
Arc length
Arc average radius
Straight section length
Lattice basic cell
Arc / straight FODO cell length
Nominal phase advance per cell
 x
/
 y
Number of arc / straight FODO cells
Dispersion suppression
GeV/c m deg deg m m m m deg
60
1041.11
240
60
300.5
71.74
220.06
FODO
9 / 6.16
90 / 90
54 / 68
Adjusting quad strengths
Review 09/2010 Page 6

Magnet Parameters
Proton beam momentum
Number of dipoles
Dipole length
Bending radius
Bending angle
Bending field
Number of quads
Quad length
Quad strength in arc / straight FODO cells
GeV/c m m deg
T m
T/m
60
108
3
38.7
4.4
5.2
288
0.5
130 / 195
Review 09/2010 Page 7

Arc FODO Cell
• 
/2 betatron phase advance in both planes
• Magnet parameters for 60 GeV/c protons:
• Dipoles:
• length = 3 m
• bending radius = 38.7 m
• bending angle = 4.4

• bending field = 5.2 T
• Quads:
• length = 0.5 m
• strength = 130 T/m
Review 09/2010 Page 8

Dispersion Suppressor
• Quads in 3 FODO cells varied to suppress dispersion while keeping

-functions from growing
• Maximum quad strength at 60 GeV/c = 148 T/m
Review 09/2010 Page 9

Short Straight for Siberian Snake
• Symmetric quad arrangement
• Initial
 values from the dispersion suppressor
• Quads varied to obtain
 x,y
= 0 in the middle at limited
• Maximum quad strength at 60 GeV/c = 130 T/m
 max
Review 09/2010 Page 10

Arc End with Dispersion Suppression
• Indicated quads varied to suppress dispersion with limitations on
 max and D max
• Maximum quad strength at 60 GeV/c = 212 T/m
Varied quads Regular FODO
To straight section
Review 09/2010 Page 11

Complete Arc
• Length = 300.5 m, net bend = 240

, average radius = 72 m
Review 09/2010 Page 12

Straight FODO Cell
• 
/2 betatron phase advance in both planes
• Drift length chosen to close the ring’s geometry
• Quad strength at 60 GeV/c = 195 T/m
Review 09/2010 Page 13

Arc to Straight Matching Section
• Four quads in two FODO cells adjusted to match
 ’s and  ’s from arcs to straight’s standard FODO cell
• Maximum quad strength at 60 GeV/c = 222 T/m
Review 09/2010 Page 14

Complete Figure-8 Ring
• Total length = 1041 m
Review 09/2010 Page 15

Figure-8 Ring Layout
100 m
Review 09/2010 Page 16

Summary of Optics Parameters
Proton beam momentum
Circumference
Arc’s net bend
Straights’ crossing angle
Arc length
Straight section length
Maximum horizontal / vertical
 functions
Maximum horizontal dispersion D x
Horizontal / vertical betatron tunes
 x,y
Horizontal / vertical chromaticities
 x,y
Momentum compaction factor

Transition energy
 tr
Horizontal / vertical normalized emittance
 x,y
At 20 GeV/c injection:
Horizontal / vertical normalized emittance
 x,y
Maximum horizontal / vertical rms beam size

15*
 horizontal / vertical beam stay clear x,y
Review 09/2010
GeV/c m deg deg m m m m
µm rad
60
1041.11
240
60
300.5
220.06
20.8 / 20.8
2.01
33.(03) / 33. (16)
-43.31 / -43.01
4.7

10 -3
14.58
0.35 / 0.07
µm rad mm mm
4 / 4
2 / 2
30 / 30
Page 17