1. MEIC R&D Meeting, JLab, August 20, 2014
Possibility of Recuperating PEP-II HER Magnets for MEIC Electron Ring (III)
Fanglei Lin, Andrew Hutton, Vasiliy S. Morozov, Fulvia Pilat, Yuhong Zhang
MEIC R&D Meeting, JLab, August 20, 2014
F. Lin

2. MEIC e-ring Geometry & Lattice Function
Arc TME-like cell (46 per arc) e-
Each straight m
Each arc m
Whole ring m
Arc to straight (dispersion suppressor, 2 per arc)
Matching from arc to straight
Straight FODO cell (34 per straight)
Matching from straight to arc

3. PEP-II HER vs. MEIC Arc Cell
Parameters
Unit
PEP-II HER
MEIC TME-like cell (1.5/0.5 pha. adv.)
Energy
GeV 9 12 5
Dipole mag. (phys.) Length m
5.4
5.4 (5.68)
Bending angle
deg
1.875
2.8125
Bending radius
165.0
110.0
Magnetic field T
0.1819
0.3639
0.1516
Quad physical length
0.7185
0.76/0.66/0.66
Field gradient
T/m
5.48
27/28/27
11/12/11
Cell length
15.2
18.36
Number of cell
16*6 96
Number of dipoles
192
Arc length
1459.2
Straight length
Circumference
Nor. emittance um
845
82 (+ 547)
6 (+ 40)
SR power density
total power
kW/m 10
3.1 (11.31)
2.2 (7.87) MW
2.9 (5.49)
2.0 (3.82)
Sagitta R cm
2.2
3.3
* 40 and 547 um are the contribution of emittance from spin rotator and IR at 5 and 12 GeV, respectively.
* Width of useful field 12cm

5. Back Up

6. MEIC’s e-Ring Current Equilibrium Emittance
Normalized Equilibrium Horizontal Emittance εxN (μm)
Energy (GeV) 3 5 6 7 8 9 10 11 12
Arc FODO (120 phase advance)
6.8
31.7
54.7
86.9
129.8
184.8
253.5
337.4
438.2
Arc (FODO + spin rotators)
11.8
54.5
94.2
149.6
223.2
317.8
435.9
580.4
753.4
Whole ring (Arc + IR)
15.4
71.3
123.2
195.7
292.1
415.8
570.4
759.2
985.7
Beam energy
Gev 3 5 6 7 8 9 10 11 12
Beam current A
2.0
1.1
0.65
0.4
0.26
0.18
0.13
Total SR power MW
0.49
3.82
5.28
5.38
5.43
5.35
5.37
5.49
Linear SR power density
kW/m
1.02
7.87
10.88
11.08
11.10
11.01
11.06
11.31
Energy loss per turn
MeV
0.17
1.27
2.64
4.89
13.37
29.84
Energy spread
10-3
0.34
0.56
0.68
0.79
1.01
1.24
Longitudinal damping time ms
83.6
18.1
10.4
6.6
3.1
1.7

7. Some Practical Considerations
Orbit curvature changes inside the dipoles  limit maximum sagitta R
PEP-II FODO cell
MEIC TME-like cell
optimal curvature   7