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

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

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

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

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

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

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

LHC – Vertical Dispersion & IBS Growth Rates Frank Zimmermann, IBS in MAD-X, MAD-X Day, 23.09.2005 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

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

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

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 0.25-0.5 T Crossing Angle 0.7-1.7 mrad

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

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

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

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

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

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.

the magnet strength Strength of those IR triplets reduce. : Skew Quadrupole origin new T qffus01->k1 -0.42127 -0.421026 -0.058% -5.62 qffus02->k1 0.446686 0.446506 -0.040% 5.96 qffus03->k1 -0.34706 -0.346961 -0.028% -3.47 qffds01->k1 -0.26374 -0.263526 -0.081% -7.91 qffds02->k1 0.152085 0.151894 -0.126% 7.95 qffds03->k1 -0.10586 -0.105606 -0.240% -5.99 Strength of those IR triplets reduce. 18

Discussion on the magnet strength : Skew Quadrupole Skew quads: 0.1 m qffus01s->k1s =     0.03902141928 ; qffus02s->k1s =    -0.01476904268 ; qffus22s->k1s =    -0.02026700407 ; qffus03s->k1s =     0.01908813591 ; qffds01s->k1s =    -0.04199200154 ; qffds02s->k1s =      0.0220116615 ; qffds22s->k1s =     0.01262536581 ; qffds03s->k1s =    -0.00742312655 ; Strengths of those skew quads are <10% of IR triplets. 19

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

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

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

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

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 

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

Thank you F. Lin

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

LHC – Vertical Dispersion & IBS Growth Rates Frank Zimmermann, IBS in MAD-X, MAD-X Day, 23.09.2005 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

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

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] 264.237 264.226 318.843 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

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

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

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