1. JLEIC Reaching 140 GeV CM Energy: Concept and Luminosity Estimate
Yuhong Zhang
April 18, 2019

2. Road to 140 GeV CM Energy Two roads to 400 GeV protons
Standard approach
Increase maximum proton energy to 400 GeV in the collider ion ring
No change of the electron energy/complex
Two roads to 400 GeV protons
Present footprint: T / 200 GeV  12 T / 400 GeV
Large footprint (deep tunnel): about 1.5 times large  8 T / 400 GeV
Same design concepts
“Many-small-bunch” approach for high luminosity
Multi-staged electron cooling (particularly DC cooling)
Figure-8 rings for high polarizations
Full-acceptance/Forward-tagging oriented IR design
Other gradients: crab crossing
Rules of Parameters
In principle, follows the pre-CDR design range/limits
There are other alternate ways, but not considered here
This study: shows the performance range based on reasonable estimate, not rigorously defendable

3. A Few Key Parameters Electron beam parameters: No Change
Proton/Ion beam parameters
Still up to 0.75 A, and up to 476 MHz rep rate
DC cooling always available
ERL cooling during collision up to ~150 GeV
0.5/0.5 mm mrad by 8 GeV/4.3 MeV DC cooling
(limited by Space Charge, could go down if DC cooling at ~10 GeV/5.5 MeV)
Lower emittance at collision (0.5/0.1 mm mrad) at lower energy (<100 GeV) by ERL cooler
Lower current ~0.75/2 A for 150 GeV proton beam with ERL cooling
Ion Injector complex and beam formation (Jiquan Guo’s presentation)
Basically the same, but higher extraction energy of HEB (~25 GeV, rap range ~16)
Proposing DC cooling at 10 GeV/5.5 MeV

4. Large aperture magnets
A Few Key Parameters
Energy (GeV)
βx* (cm)
βy* (cm)
Up to 100 8
1.3
100 to 200 21
1.6
200 to 400 40 3
Collision/IP parameter
Magnet strength vs. proton energy
Increase focusing length to preserve detector acceptance
Matching under no ERL cooling
Emittance grow during beam store if there is no high energy ERL cooling
Beam spot size matched at IP for better beam-beam mitigation
(the condition may be relaxed if the beam with a
larger spot size has much smaller beam-beam
tune-shifts compared to limit of the parameter)
Aperture in (ion) upper-stream final focusing magnets must be watched
3 cm and
4 cm
Large aperture magnets
Down stream 

5. JLEIC Luminosity Calculation of average luminosity takes into accounts
Beam formation time: 5 min (with a full size high energy booster) No full-size HEB
With high energy cooling, hrs beam store, (120 min / 125 min ~ 96%) (vs. 80%)
Without high energy cooling, 1 hrs beam store, (60 min / 65 min ~ 92%) (vs. 67%)
Operation duty factor: 75%

6. JLEIC Luminosity
With ERL cooling

7. Luminosity “Leveling” (Optimization)
Proton (300 GeV)
Electron (5 GeV)
Time
Emittance
Current
βx*/βy*
b-b
Instant Lumi
min
mm mrad A cm
1033 /cm2/s
0.5/0.5
0.58
83/16.6 5
0.9/0.5
40/3
0.015/0.0056
1.3
13.4/2.75
0.136/0.137
7.57 20
1.8/0.5
0.008/0.0043
0.015/0.0079
2.4
26.0/2.75
0.143/0.104
5.45
10.07 35
2.4/0.5
0.006/0.0037
0.015/0.0091
3.2
35.5/2.75
0.146/0.091
4.62
11.37 50
2.9/0.5
0.005/0.0034
0.014/0.0094
3.6
43.5/2.75
0.148/0.083
4.15
11.50 65
3.4/0.5
0.004/0.0032
0.012/0.0088
50.5/2.75
0.149/0.077
3.84
10.62
Average luminosity:
7.28

8. Bring Average Luminosity at 200 x 12 GeV Above 1033
Not matching beam spot sizes at IP  beam-beam parameters an order of magnitude small
Increase proton beam current to 1 A  Large cooled emittance, less space charge
Short beam store to 30 min  less DC cooling
If not including 75% operation duty factor, average luminosity is already at 1x1033
Optimized
Bunch rep rate
MHz
475/4 = 119
476/4 = 119
Proton beam current A
0.75 1
Proton emittance at start of counting
at end of counting
mm mrad
1.5 / 0.5
1.9 / 1
3.5 / 1
Proton beam spot size at IP at start of counting µm
44 / 8.8
73.7 / 8.8
58.7 / 8.8
Electron beam spot size at IP at start of counting
44 / 88
Mismatching
Up to 1.33
Proton beam-beam at IP at start of counting
0.003 / /
0.002 / 0.008
0.002 /
Electron beam-beam at IP at start of counting
0.013 / 0.013
0.014 /
0.017 / 0.025
0.01 / 0.017
Store time
min 60 30
Average luminosity (including 75% DF) , 1033
1/cm2/s
0.74
1.00

9. Large Footprint (1.5x) with Deep Tunnel
Energy
Current footprint
Large footprint (1.5x)
Emittance
Current
(GeV)
(mm mrad) A 3
17.9
>3.6
5.3 4
42.5
12.6 5 83
24.6 6
143 7
228
3.33
67.5 8
340
1.95
101 9
484
1.22
2.74 10
664
0.8
197
1.8 11
884
0.55
262
1.23 12
1147
0.39
0.87
Assuming same linear SR power (10 kW/m), thus total SR power at ~15 MW

10. JLEIC Luminosity (Large Footprint)
Calculation of average luminosity takes into accounts
Beam formation time: 5 min (with a full size high energy booster) No full-size HEB
With high energy cooling, hrs beam store, (120 min / 125 min ~ 96%) (vs. 80%)
Without high energy cooling, 1 hrs beam store, (60 min / 65 min ~ 92%) (vs. 67%)
Operation duty factor: 75%

11. JLEIC Luminosity

13. JLEIC Parameters and Luminosity Performance
04/18/2019
CM energy
GeV
21.9
44.7
63.3
89.4 98 p e E
Beam energy 40 3
100 5
200 10 12
Collision freq
MHz
476
476/4=119
Particles/bunch
1010
0.59
3.9
0.98
4.7
8.9
3.93
4.2
2.05
Beam current A
0.45
0.75
3.6
0.57
1.7
0.8
0.39
Polarization % 85
>85
>80
~80
Bunch length cm
2.5 1
3.2
Norm. emitt, x µm
0.5 18
0.65 83
1.26
1.5
664
1145
Norm. emitt, y
0.2
0.13
16.6
133
229
Horizontal β* 8 30
5.72 21
14.5
19.2 4
27.5
Vertical β*
1.3
9.8
0.93
1.6
2.2
2.3
3.3
Beam-beam, x
0.015
0.12
0.045
0.136
0.006
0.022
0.003
0.013
0.01
0.15
0.0135
0.041
0.0065
0.120
0.002
Laslett tune-shift
0.055
small
0.018
0.0039
Small
0.0051
0.0052
Hour-glass (HG)
0.85
0.73
0.84
0.66
0.67
Peak lumi., w/HG
1033/cm2s
14.6
9.84
3.8
1.31
Average lumi.*
10.5
8.2
1.9
0.74
* Average luminosity was calculated assuming a one or two hour proton beam store without or with high energy bunched beam electron cooling respectively plus 5 min beam formation time (mainly due to detector overhead), and a 75% duty factor of machine operation.

14. JLEIC Parameters and Luminosity Performance
03/29/2019
CM energy
GeV
21.9
44.7
63.3
89.4 98 p e E
Beam energy 40 3
100 5
200 10 12
Collision freq
MHz
476
476/2=238
476/4=119
Particles/bunch
1010
0.59
3.9
0.98
4.7
1.97
6.8
3.93
4.2
2.05
Beam current A
0.45
0.75
3.5
2.58
0.8
0.39
Polarization
85%
>85%
>80%
~80%
Bunch length cm
2.5 1
2.1 4
Norm. emitt, hori. μm
0.5 18
0.65 83
0.96
3.1
664
1145
Norm. emitt, vert.
0.2
3.6
0.13
16.6
0.25
1.5
133
229
Horizontal β* 8 30
5.72 21
11.2
9.1
6.6
Vertical β*
1.3
9.8
0.93
1.6
1.1
1.65
1.15
Beam-beam, hori.
0.015
0.12
0.045
0.09
0.003
0.02
0.0013
0.014
Beam-beam, vert.
0.01
0.15
0.013
0.041
0.008
0.065
0.001
0.0005
0.012
Laslett tune-shift
0.055
small
0.018
Small
0.0014
Hour-glass (HG)
0.85
0.73
0.82
0.67
Peak lumi., w/HG
1033/cm2s
3.2
14.7
15.5
1.9
0.86
Average lumi.*
2.3
10.6
9.3
0.71
* Average luminosity was calculated assuming a one or two hour proton beam store without or with high energy bunched beam electron cooling respectively plus 5 min beam formation time (mainly due to detector overhead), and a 75% duty factor of machine operation.