1.  First discussion on the IR magnets for the detector solenoid compensation
G.H. Wei, V.S. Morozov, Fanglei Lin
Y. Nosochkov (SLAC), M-H. Wang
JLEIC R&D Meeting, JLAB, March 16, 2017
F. Lin

2. Outline Detector solenoid effects on accelerator design
A compensation scenario for the detector solenoid effects
(This is also a background for ion forward detection)
Discussion on the layout and parameters of IR magnets in the scenario
Summary e-
pi-
proton
pi+
Ion
neutron-black
photons-blue

3. Detector solenoid effects
JLEIC Detector solenoid
Length
4 m
(1.6 m-IP-2.4 m)
Strength
< 3 T
Crossing Angle
50 mrad
Ion e
1.6 m
2.4 m
Effects
e ring
ion ring
Coherent orbit distortion N Y
Coupling resonances
Rotates beam planes at the IP
Breaks H & V dispersion free
Perturbation on lattice tune & W function
Breaks figure-8 spin symmetry

4. Coherent orbit distortion
Detector solenoid 1 T: closed orbit V: ~170 mm, H: ~30 mm
Detector solenoid > 2 T: no closed orbit

5. Coupling of X and Y betatron motion
Coupling betas (beta12 & beta 21) are not 0 at IP & other place.
Beta 11 & beta 22, are usual beta x and beta y without coupling.
Left: detector solenoid off Right: detector solenoid on

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

7. Perturbation on lattice tune & W function
W function with detector solenoid: Left: off; Right: on
For the particles with momentum spread IP IP

8. 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 8

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

10. 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.

11. 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

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

13. 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

14. Vertical dispersion effect to IBS growth rates
with crossing angle & detector field
without crossing angle & detector field
with crossing angle & detector field (ignorable)
tl [h]
5.824
5.809
tx [h]
0.444
ty [h]
22.538
21.958

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

16. 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 

17. Discussion on the layout
: Skew Quadrupole
0.3 m
0.3 m
0.5 m
0.4 m
0.2 m
1 m
Skew quads: 0.1 m; corrector: 0.2 m
Skew quads are just beside the FFQ without space.
The space for magnet layout seems tight, we need realistic advises from magnet group and mechanic group 17

18. Discussion on the layout
: Skew Quadrupole
0.5 m
0.5 m
1.9 m
0.9 m
0.9 m
0.5 m
downCorrector02downSkewQuad01: 0.2 m
The space downstream of IR in ion collider ring is also used for ion forward detection, we need discussion with nuclear physics group 18

19. Discussion on the magnet strength
: 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 19

20. Discussion on the magnet strength
Correctors: 0.2 m
Strengths of horizontal correctors are 2 order lower, so we do not need to worry about that.
Two Anti-solenoids:
Upstream one : 3 T, 1.6 m
Downstream one : 3 T, 2.4 m 20

21. Discussion on the magnet strength
: Skew Quadrupole
origin
new
qffus01->k1
2.8%
qffus02->k1
-0.8%
qffus03->k1
-4.8%
qffds01->k1
-1.5%
qffds02->k1
1.9%
qffds03->k1
10.3%
Strength changes of those IR triplets are acceptable.
The 3rd downstream FFQ has a strength of 10.3 % increase. 21

22. 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. 22

23. Summary
Based on a sliced solenoid model, a correction system for the JLEIC detector solenoid 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 .
The space for magnet layout seems tight, we need realistic advises from magnet group and mechanic group, and also discussion with nuclear physics group

24. Thank you
F. Lin

25. Simulation setup & method

26. 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

27. 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

28. 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

29. Vertical and horizontal orbit oscillations
DX max. : mm
DY max. : mm
MADX
ealign
1.6 m + IP m
4.0 m
Slice
Model
1 Slice
40 Slices
100 Slices
200 Slices

30. Detector Solenoid Issues
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

31. Vertical and horizontal orbit oscillations
DX : mm
DY : mm
MADX
ealign
1.6 m + IP m (1)
1.6 m + IP m (2)
4.0 m
Slices
Model
1 Slice
40 Slices
100 Slices
200 Slices
400 Slices
1.6 m + IP m (1):
select,flag=error,class=SOLDETDS;
ealign, DX:=-0.08, DTHETA:=-0.05;
select,flag=error,pattern="SOLDETUS";
ealign, DTHETA:=-0.05;
1.6 m + IP m (2):
select,flag=error,pattern="SOLDETUS";
ealign, DTHETA:=-0.05;
select,flag=error,class=SOLDETDS;
ealign, DX:=-0.08, DTHETA:=-0.05;

32. 2