1. JLEIC High-Energy Ion IR Design: Options and Performance
Vasiliy Morozov
JLEIC Accelerator R&D Meeting
January 10, 2019

2. 100 GeV/c Ion IR Optics Pole-tip fields are limited to 6 T
FFB
Far-forward detection
Geometric match and dispersion suppression
ions
𝜎 𝑥/𝑦 =21.7/4.3 𝜇m
𝜎 𝑥 ′ / 𝑦 ′ =0.22 mrad
𝛽 𝑥/𝑦 =10/2 cm IP
Secondary
focus
iBDS2
iBDS3
iBDS1
Δ 𝑥 𝑓𝑟 = 𝐷 𝑥 Δ(𝐵𝜌)/(𝐵𝜌)
𝜎 𝑥 ′ / 𝑦 ′ =16/50 𝜇rad
𝜎 𝑥/𝑦 =292/19 𝜇m
𝛽 𝑥/𝑦 =69/37 cm
𝐷 𝑥 =−0.95 m
January 10, 2019
JLEIC Accelerator R&D Meeting

3. Modifying IR Design for 200 GeV/c
Constraints
Maximum pole-tip fields at 200 GeV/c of 6 T  4.6 T
Minimum impact on the forward hadron tagging performance compared to the 100 GeV/c design
Minimum impact on the luminosity performance compared to the 100 GeV/c design
Minimum impact on the beam dynamics compared to the 100 GeV/c design
Options explored
Reduced FF Quad Apertures
Doubled Detector Space and Halved Crossing Angle
Doubled Quad Lengths
1.5x Quad Lengths and 2/3 Crossing Angle 
January 10, 2019
JLEIC Accelerator R&D Meeting

4. Doubled Quad Lengths: pCDR Appendix Version (IR v1)
Keep maximum 𝛽-functions at ~2500 m  same maximum beam size
Quad apertures  6 T / 𝜕 𝐵 𝑦 𝜕𝑥 at 200 GeV/c = 85 / 152 / 196 mm (radius)
𝜃≡ Quad aperture / distance from IP to quad’s far end = 9.1 / 10.0 / 10.5 mrad
𝛽 𝑥,𝑦 ∗ = 18 / 2.15 cm  𝐿 𝐿 0 =0.72, 𝐷 𝑥 at roman pot = 0.97 m
January 10, 2019
JLEIC Accelerator R&D Meeting

5. Performance Optimization at Lower Energies (IR v1)
Cut first FFQ in half and use the halves as the first and second FFQs at lower energies
Can run in this mode up to 65 GeV/c proton momentum
𝛽 𝑥,𝑦 ∗ = 7.5 / 2 cm  luminosity improvement by a factor of 𝐿 𝐿 0 = 1.15 (up to 𝑝 𝑝 = 65 GeV/c)
January 10, 2019
JLEIC Accelerator R&D Meeting

6. 200 GeV/c IR Design with 4.6 T Pole-Tip Fields (IR v2)
𝛽 𝑥,𝑦 ∗ 𝑜𝑙𝑑 = cm  𝛽 𝑥,𝑦 ∗ 𝑛𝑒𝑤 = 𝟔 𝟏.𝟐 cm 𝛽 𝑥,𝑦 𝑚𝑎𝑥 𝑜𝑙𝑑 =2.5 km  𝛽 𝑥,𝑦 𝑚𝑎𝑥 𝑛𝑒𝑤 = 𝛽 𝑥,𝑦 ∗ 𝑜𝑙𝑑 𝛽 𝑥,𝑦 𝑚𝑎𝑥 𝑜𝑙𝑑 𝛽 𝑥,𝑦 ∗ 𝑛𝑒𝑤 =𝟒.𝟐 km
Constraints
𝛽 𝑥,𝑦 𝑚𝑎𝑥 ≤4200 m  𝛽 𝑥,𝑦 ∗ =19/1.6 cm  𝐿 𝐿 0 =0.48
Secondary focus in both planes
Quadrupole aperture: 𝜃≥10 mrad
Quadrupole length ratios: 1:2:1
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒 ≤4.6 T
Serious problem: forward detection region extends beyond figure-8 crossing point
Figure-8 crossing point
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a/b
2.11
4.6
−33.5
13.7
11.7
iQDS2
8.44
17.1
26.9
12.7
iQDS3
4.22
−16.3
28.2
10.7
January 10, 2019
JLEIC Accelerator R&D Meeting

7. 200 GeV/c Downstream IR Design with 4.6 T Pole-Tip Fields (IR v3)
Quadrupole doublet instead of a triplet
Constraints
𝛽 𝑥,𝑦 𝑚𝑎𝑥 ≤4200 m  𝛽 𝑥,𝑦 ∗ =19.6/1.6 cm  𝐿 𝐿 0 =0.48
Secondary focus in both planes
Quadrupole aperture: 𝜃≥10 mrad
Equal quadrupole lengths
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a/b
2.23
4.6
−37.5
12.3
10.3
iQDS2
4.45
26.4
17.5
10.0
January 10, 2019
JLEIC Accelerator R&D Meeting

8. 200 GeV/c Upstream IR Design with 4.6 T Pole-Tip Fields (IR v3)
Doublet instead of a triplet
Constraints
𝛽 𝑥,𝑦 ∗ =19.6/1.6 cm
Quadrupole aperture: 4 cm radius
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
iQUS1
2.86
4.6
−115 4
iQUS2
2.04
115
January 10, 2019
JLEIC Accelerator R&D Meeting

9. Complete 200 GeV/c IR Design (IR v3)
January 10, 2019
JLEIC Accelerator R&D Meeting

10. Optimization for Operation at up to 100 GeV (IR v4)
𝛽 𝑥 𝑚𝑎𝑥 is limited by the DA, 𝛽 𝑦 𝑚𝑎𝑥 is limited by HG effect
Constraints
𝛽 𝑥,𝑦 𝑚𝑎𝑥 ≤4200 m  𝛽 𝑥,𝑦 ∗ =8.0/1.3 cm  𝑳 𝑳 𝟎 =𝟎.𝟖𝟑 up to 100 GeV
Secondary focus in both planes
Quadrupole aperture: 𝜃≥10 mrad
Varied lengths of the first two quads
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T at 100 GeV/c
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T at 200 GeV/c
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a
2.21
4.6
−49.7
9.3
10.1
iQDS1b
2.27
38.4
12.0
10.0
January 10, 2019
JLEIC Accelerator R&D Meeting

11. Optimization for Operation at up to 100 GeV (IR v5)
Adjusting quad length/aperture does not help to increase 𝐿, reached thin-lens limit, must adjust 𝛽 ∗
Approximation used to obtain 𝛽 𝑥 𝑚𝑎𝑥 = 𝛽 𝑦 𝑚𝑎𝑥 of 4.2 km is not very accurate because triplet is not a thin lens.
Constraints
𝑳 𝑳 𝟎 =𝟏.𝟎 up to 100 GeV  𝜷 𝒙 𝒎𝒂𝒙 = 𝜷 𝒚 𝒎𝒂𝒙 ≤𝟓𝟎𝟖𝟓 m  𝛽 𝑥,𝑦 ∗ =6.6/1.1 cm (ratio is fixed for a doublet)
Secondary focus in both planes
𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T at 100 GeV/c
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T at 200 GeV/c
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a
2.21
4.6
−49.7
9.3
10.1
iQDS1b
2.27
38.4
12.0
10.0
January 10, 2019
JLEIC Accelerator R&D Meeting

12. 200 GeV/c IR Design with 4.6 T Pole-Tip Fields (IR v6)
Constraints
𝜷 𝒙,𝒚 𝒎𝒂𝒙 ≤𝟒.𝟐 km  𝛽 𝑥,𝑦 ∗ =15.2/1.5 cm  𝑳 𝑳 𝟎 =𝟎.𝟓𝟕
Secondary focus in both planes
Quadrupole aperture: 𝜽≥𝟖 mrad
Equal quadrupole lengths
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a/b
1.74
4.6
−51.4
9.0
8.2
iQDS2
3.49
37.1
12.4
8.0
January 10, 2019
JLEIC Accelerator R&D Meeting

13. 200 GeV/c IR Design with 4.6 T Pole-Tip Fields (IR v7)
Constraints
𝜷 𝒙,𝒚 𝒎𝒂𝒙 ≤𝟓 km  𝛽 𝑥,𝑦 ∗ =12.8/1.2 cm  𝑳 𝑳 𝟎 =𝟎.𝟔𝟕
Secondary focus in both planes
Quadrupole aperture: 𝜽≥𝟖 mrad
Equal quadrupole lengths
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a/b
1.74
4.6
−51.4
9.0
8.2
iQDS2
3.49
37.1
12.4
8.0
January 10, 2019
JLEIC Accelerator R&D Meeting

14. 200 GeV/c IR Design with 4.6 T Pole-Tip Fields (IR v8)
To take advantage of the smaller 𝑦 emittance must flip polarities of the quads in the doublet, otherwise run into HG problem.
Crab voltage 𝑉 𝑐𝑟𝑎𝑏 ∝ 1 𝛽 𝑥 𝑐𝑟𝑎𝑏 𝛽 𝑥 ∗
Constraints
𝜷 𝒙 𝒎𝒂𝒙 ≤𝟓 km, 𝜷 𝒚 𝒎𝒂𝒙 ≤𝟏𝟎 km,  𝛽 𝑥,𝑦 ∗ =1.3/8.2 cm  𝑳 𝑳 𝟎 =𝟎.𝟖𝟏
Secondary focus in both planes
Quadrupole aperture: 𝜽≥𝟏𝟎 mrad
Equal quadrupole lengths
Quadrupole length adjustment: 𝐵 𝑝𝑜𝑙𝑒−𝑡𝑖𝑝 ≤4.6 T
𝐵 𝑑𝑖𝑝𝑜𝑙𝑒2 ≤4.6 T, 𝐵 𝑑𝑖𝑝𝑜𝑙𝑒3 ≤6 T
Quad
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
iQDS1a/b
2.21
4.6
37.8
12.2
10.2
iQDS2
4.43
−26.5
17.4
10.0
January 10, 2019
JLEIC Accelerator R&D Meeting

15. JLEIC Accelerator R&D Meeting
Summary
Version
# of quads
L (m)
𝑩 𝒑−𝒕 (T)
𝝏 𝑩 𝒚 /𝝏𝒙 (T/m)
𝑹 (cm)
𝜽 (mrad)
𝜷 𝒙,𝒚 𝒎𝒂𝒙 (m)
𝑳/ 𝑳 𝟎 1 3
2.4/4.8/2.4 6
− /−30.7
8.5/13.8/16.9
9.1
2,500
1.15 / 0.72 (65/200 GeV) 2
4.22/8.44/4.22
4.6
− /−16.3
13.7/26.9/28.2
10.7
4,200
0.48 (200 GeV)
4.45/4.45
−37.5/26.4
12.3/17.5
10.0 4
(2.21,2.27)/4.45
−49.7/38.4
9.3/12.0
0.83 (100 GeV) 5
5,100
1.0/0.58 (100/200 GeV)
3.49/3.49
−51.4/37.1
9.0/12.4
8.0
0.57 (200 GeV) 7
5,000
0.67 (200 GeV) 8
4.43/4.43
37.8/−26.5
12.2/17.4
5,000/10,000
0.81 (200 GeV)
January 10, 2019
JLEIC Accelerator R&D Meeting