1. Upgrade on Compensation of Detector Solenoid effects
G.H. Wei, V.S. Morozov, Fanglei Lin
Y. Nosochkov (SLAC), M-H. Wang
JLEIC R&D Meeting, JLAB
F. Lin

2. Outline Detector solenoid effects on accelerator design
Compensation scenarios in DAFNE, SuperB, RHIC and LHC
A compensation scenario for the JLEIC
(This is also a background for ion forward detection–LDRD1706)
Summary e-
pi-
proton
pi+
Ion
neutron-black
photons-blue

3. Detector solenoid effects
Ion
JLEIC Detector solenoid
Length
4 m
(1.6 m-IP-2.4 m)
Strength
< 3 T
Crossing Angle
50 mrad e
1.6 m
2.4 m

4. Detector Solenoid Effect
Coherent orbit distortion
Transverse betatron coupling
Dynamic effect
Coupling resonances
Rotates beam planes at the IP
Breaks Horizontal and vertical dispersion free
Perturbation on lattice tune & W function of the first order chromaticity compensation
Spin effect
Breaks figure 8 symmetry
Crab crossing
Complicates the design if crab cavities are installed in a coupled region

5. Orbit distortions
Detector Solenoid 1 T: Closed orbit V: ~170 mm, H: ~30 mm
Detector Solenoid > 2 T: No closed orbit

6. Coupling of X and Y betatron motion
Coupling beta ~ 5 % of nominal beta (Ion Ring, 60 GeV)
Detector solenoid OFF
Detector solenoid ON

7. Perturbation on lattice tune & W function
Chromaticity changes with detector solenoid on
Detector solenoid OFF
Detector solenoid ON IP IP

8. LHC – Vertical Dispersion & IBS Growth Rates
Frank Zimmermann, IBS in MAD-X, MAD-X Day,
LHC – Vertical Dispersion & IBS Growth Rates
Dy is generated by the crossing angles (285 mrad) at IP1 and 2, as well as by the detector fields at ALICE and LHC-B; the vertical dispersion is about 0.2 m
Dy [m]
Dx [m]
x dispersion
y dispersion
s [m]
s [m]
IBS growth times
no crossing angles & detector fields
with crossing angles
+ detector fields
tl [h]
57.5
58.6
tx [h]
103.3
104.2
ty [h]
-2.9x106
436.1

9. Compensation in DAFNE 1. Solenoid + tilt Quads + Anti-Solenoid
Pros: coupling is localized, no crab cavity problem, spin effect is compensated
Con: more complicated final focus design
DAFNF
Energy
0.5 GeV
Length
4 m
Strength
0.6 T
Crossing Angle
25 mrad

10. Compensation in SUPERB
2. Solenoid + tilt Quads + Bucking solenoid + Anti-Solenoid
Pros: coupling is localized, no crab cavity problem
Con: Difficult for variety of solenoid fields and energies
KEK-SUPERB
Energy
e+ 6.69
e- 4.18
Strength
1.5 T
Length
1.6 m
Crossing Angle
66 mrad

11. Compensation in RHIC
3. Coupling correction with the IR skew quads and the global skew quad families.
Pros: Good globally
Compared with JLEIC, detector has low strength, spin effect to break figure 8 symmetry
RHIC
Energy(proton)
250 GeV
Length
4.2 m
Strength T
Crossing Angle
mrad

12. Compensation in LHC
4. Energy is too high compared with detector solenoid strength, coupling effect of can be ignored
Old LHC
HL-LHC
Energy
7 TeV
14 TeV
Length
5.3 m
Strength
2 T
4 T
Crossing Angle
285 rad
590 rad

13. JLEIC Considerations & a Solution
Compensation constraints for both electron and ion rings
Optics fixed and uncoupled at IP due to variety of solenoid fields and energies
Coupling compensated locally and independently on each side of IP
Optics fixed at the entrance into and exit from IR
No coupling elements in the dispersive regions
Cancel spin effect to keep figure 8 symmetry 13

14. An integration scenario
A scenario:
Two dipole correctors on each side of the IP are used to make closed orbit correction.
Anti-solenoid & skew quads to make decoupling.
4 skew quads with 0.1 meter are enough for each side
: Skew Quadrupole 14

15. An integration scenario
Slices Model of Detector Solenoid
: Vertical Kick
: Edge effect ME

16. the magnet strength Correctors: 0.2 m ipuscorr1->vkick -0.9 T
: Skew Quadrupole
Correctors: 0.2 m
ipuscorr1->vkick -0.9 T
ipuscorr2->vkick 1.5 T if the length is 0.5 m, strength is 0.6 T
ipdscorr1->vkick 1.6 T if the length is 0.4 m, strength is 0.8 T
ipdscorr2->vkick -0.7 T 16

17. Correction of coherent orbit distortion
Closed Orbit
Two dipole correctors on each side of the IP are used to make closed orbit correction.
Here not only the orbit offset but also the orbit slope is corrected at the IP.

18. the magnet strength Strength of those IR triplets reduce.
: Skew Quadrupole
origin
new T
qffus01->k1
-0.058%
-5.62
qffus02->k1
-0.040%
5.96
qffus03->k1
-0.028%
-3.47
qffds01->k1
-0.081%
-7.91
qffds02->k1
-0.126%
7.95
qffds03->k1
-0.240%
-5.99
Strength of those IR triplets reduce. 18

19. Discussion on the magnet strength
: Skew Quadrupole
Skew quads: 0.1 m
qffus01s->k1s =     ; qffus02s->k1s =     ; qffus22s->k1s =     ; qffus03s->k1s =     ;
qffds01s->k1s =     ; qffds02s->k1s =       ; qffds22s->k1s =     ; qffds03s->k1s =     ;
Strengths of those skew quads are <10% of IR triplets. 19

20. Decoupling
The skew quadrupoles and final focus quadrupoles together generate an effect equivalent to an adjustable rotation angle to do the decoupling task.
After decoupling, the coupling betas (beta12 and beta21) can be controlled locally in the interaction region and compensated at the IP.
Before decoupling
After decoupling

21. Re-matching (Global)
y = 7.5
y = 5.5
x = 12.5
x = 8.5
Re-matching of Global Model. The vertical dispersion of < 0.2 m can be ignored.
Phase advances between FFQ and chromatic sextupoles are rematched

22. JLEIC – Vertical Dispersion & IBS Growth Rates
with crossing angle & detector field
No crossing angle & detector field
with crossing angle & detector field
tl [h]
5.824
5.809
tx [h]
0.444
ty [h]
22.538
21.958

23. Chromaticity Correction (W function)
Left: w/o detector; Middle: uncorrected; Right: corrected

24. Dynamic Aperture Red line: only bare lattice
Black line: with detector solenoid
Dynamic aperture has a shrinking to 50 , but large enough considering the required dynamic aperture of 10 

25. Summary
After surveying detector solenoid compensation scenarios in DAFNE, SuperB, RHIC, and LHC etc, a correction system for the JLEIC detector solenoid effects is designed.
With Correction, the dynamic aperture with integration of detector solenoid has a shrinking to 50  of beam size, which is also vary large considering the required dynamic aperture of 10 . Further study should be done with multipoles in IR magnets

26. Thank you
F. Lin

27. Re-matching (Local)
Re-matching of Transport Line Model for twiss parameters, dispersions.
Keep optics change locally except vertical dispersion

28. LHC – Vertical Dispersion & IBS Growth Rates
Frank Zimmermann, IBS in MAD-X, MAD-X Day,
LHC – Vertical Dispersion & IBS Growth Rates
Dy is generated by the crossing angles (285 mrad) at IP1 and 2, as well as by the detector fields at ALICE and LHC-B; the vertical dispersion is about 0.2 m
Dy [m]
Dx [m]
x dispersion
y dispersion
s [m]
s [m]
IBS growth times
no crossing angles & detector fields
with crossing angles
+ detector fields
tl [h]
57.5
58.6
tx [h]
103.3
104.2
ty [h]
-2.9x106
436.1

29. JLEIC – Vertical Dispersion & IBS Growth Rates
with crossing angle & detector field
with crossing angle & detector field
& Vertical dispersion as LHC level
No crossing angle & detector field
with crossing angle & detector field
crossing angles
+ detector field +
Dy (LHC level)
tl [h]
5.824
5.809
5.687
tx [h]
0.444
0.446
ty [h]
22.538
21.958
7.630

30. JLEIC – Vertical Dispersion & IBS Growth Rates
Up to 1 TeV
JLEIC
No crossing angle & detector field
with crossing angle & detector field
crossing angles + detector field + Dy ~ 1 m
tl [h]
tx [h]
4.810
4.834
4.878
ty [h]
-6.83E+04
-1.01E+05
64.013
IBS growth rates LHC
no crossing angles & detector fields
with crossing angles
+ detector fields
tl [h]
57.5
58.6
tx [h]
103.3
104.2
ty [h]
-2.9x106
436.1

31. Break of H & V dispersion-free
Left: detector solenoid off
Right: detector solenoid on

32. Perturbation on lattice tune & W function
Left: uncorrected; Right: corrected

33. JLEIC Considerations & a Solution
A solution: Solenoid + Quads(normal+skew) + Anti-Solenoid
Quads(normal+skew): a normal quad with an additional winding or a skew quad next to the normal quad
Dynamical rotation angle  of a normal quad (strength: kn) & a skew component (strength: ks) 33