1. Overview of IR Design V.S. Morozov 1, P. Brindza 1, A. Camsonne 1, Ya.S. Derbenev 1, R. Ent 1, D. Gaskell 1, F. Lin 1, P. Nadel-Turonski 1, M. Ungaro 1, Y. Zhang 1, Z.W. Zhao 1,2, C.E. Hyde 3, K. Park 3, M. Sullivan 4 1 JLab, 2 Duke, 3 ODU, 4 SLAC MEIC Collaboration Meeting, JLab October 5-7, 2015

2. MEIC Collaboration Meeting, JLab, October 5-7, 20152 Forward detection concept Detector integration Forward ion tagging Forward electron tagging Summary Outline

3. MEIC Collaboration Meeting, JLab, October 5-7, 20153 MEIC Layout & Detector Location Warm Electron Collider Ring (3 to 10 GeV) Ion Source Booster Linac Cold Ion Collider Ring (8 to 100 GeV) Two IP locations: One has a new detector, fully instrumented Second is a straight-through, minor additional magnets needed to turn into IP Considerations: Minimize synchrotron radiation –IP far from arc where electrons exit –Electron beam bending minimized in the straight before the IP Minimize hadronic background –IP close to arc where protons/ions exit

4. MEIC Collaboration Meeting, JLab, October 5-7, 20154 50 mrad crossing angle ̶ Improved detection, no parasitic collisions, fast beam separation Forward hadron detection in three stages ̶ Endcap ̶ Small dipole covering angles up to a few degrees ̶ Far forward, up to one degree, for particles passing through accelerator quads Low-Q 2 tagger ̶ Small-angle electron detection Full-Acceptance Detector P. Nadel-Turonski, R. Ent, C.E. Hyde

5. MEIC Collaboration Meeting, JLab, October 5-7, 20155 Detector Modeling & Machine Integration Fully-integrated detector and interaction region satisfying –Detector requirements: full acceptance and high resolution –Beam dynamics requirements: consistent with non-linear dynamics requirements –Geometric constraints: matched collider ring footprints far forward hadron detection low-Q 2 electron detection large-aperture electron quads small-diameter electron quads central detector with endcaps ion quads 50 mrad beam (crab) crossing angle n,  e p p small angle hadron detection ~60 mrad bend (from GEANT4) 2 Tm dipole Endcap Ion quadrupoles Electron quadrupoles 1 m IPFP Roman pots Thin exit windows Fixed trackers Trackers and “donut” calorimeter RICH + TORCH? dual-solenoid in common cryostat 4 m coil barrel DIRC + TOF EM calorimeter Tracking EM calorimeter e/π threshold Cherenkov

6. MEIC Collaboration Meeting, JLab, October 5-7, 20156 Electron IR Optics IR region (baseline, has been slightly optimized since) –Final focusing quads with maximum field gradient ~63 T/m –Four 3m-long dipoles (chicane) with 0.44 T @ 10 GeV for low-Q2 tagging with small momentum resolution, suppression of dispersion and Compton polarimeter IP e-e- forward e - detection region FFQs Compton polarimetry region

7. MEIC Collaboration Meeting, JLab, October 5-7, 20157 IR design features ̶ Modular design ̶ Based on triplet Final Focusing Blocks (FFB) ̶ Asymmetric design to satisfy detector requirements and reduce chromaticity ̶ Spectrometer dipoles before and after downstream FFB, second focus downstream of IP ̶ No dispersion at IP, achromatic optics downstream of IP Ion IR Optics IP ions match/ beam expansion FFB detector elements geom. match/ disp. suppression match/ beam compression

8. MEIC Collaboration Meeting, JLab, October 5-7, 20158 ultra forward hadron detection large aperture electron quads small diameter electron quads central detector with endcaps ion quads 50 mrad beam (crab) crossing angle n,  e p p small angle hadron detection 60 mrad bend e Roman pots Thin exit windows Fixed trackers Nuclear Physics view of IR Layout Integrated Interaction Region & Detector Design emphasis on polarization (figure-8) and on integrated detector/interaction region Accelerator view of IR Layout IP e-e- ions crab cavities FFQs (top view) low-Q 2 electron detection and Compton polarimeter

9. MEIC Collaboration Meeting, JLab, October 5-7, 20159 Forward Hadron Detection Large crossing angle (50 mrad) –Moves spot of poor resolution along solenoid axis into the periphery –Minimizes shadow from electron FFQs Dipole before quadrupoles –Further improves resolution in the few-degree range Low-gradient quadrupoles –Allow large apertures for detection of all ion fragments 89 T/m, 9.0 T, 1.2 m 51 T/m, 9.0 T, 2.4 m 36 T/m, 7.0 T, 1.2 m Permanent magnets 34 T/m46 T/m38 T/m2 x 15 T/m e 5 T, 4 m dipole Ion quadrupoles: gradient, peak field, length 2 T dipole Endcap detectors Electron quadrupoles TrackingCalorimetry 1 m 7 m from IP to first ion quad Crossing angle

10. MEIC Collaboration Meeting, JLab, October 5-7, 201510 Far-Forward Hadron Detection Good acceptance for ion fragments –Large downstream magnet apertures/ small downstream magnet gradients Good acceptance for low-p T recoil baryons –Small beam size at second focus –Large dispersion Good momentum and angular resolution –Large dispersion –No contribution from D to angular spread at IP –Long instrumented magnet-free drift space Sufficient separation between the beam lines e p (n,  ) 20 Tm dipole (in) 2 Tm dipole (out) solenoid Roman pots at focal point Thin exit windows Aperture-free drift space ZDC S-shaped dipole configuration optimizes acceptance for neutrals 50 mrad crossing angle Ions x IP FP β x * = 10-20 cm β y * = 2 cm D* = D'* = 0 β FP < 1 m D FP ~ 1 m Asymmetric IR (minimizes chromaticity)

11. MEIC Collaboration Meeting, JLab, October 5-7, 201511 Far-Forward Acceptance for Charged Fragments Δp/p = -0.5 Δp/p = 0.0Δp/p = 0.5 (protons rich fragments) (exclusive / diffractive recoil protons) (tritons from N=Z nuclei) (spectator protons from deuterium) (neutron rich fragments)

12. MEIC Collaboration Meeting, JLab, October 5-7, 201512 Far-Forward Ion Acceptance Transmission of particles with initial angular and  p/p spread vs peak field –Quad apertures = B max / (fixed field gradient @ 100 GeV/c) –Uniform particle distribution of  0.7 in  p/p and  1  in horizontal angle originating at IP –Transmitted particles are indicated in blue (the box outlines acceptance of interest) 6 T max 9 T max 12 T max  electron beam

13. MEIC Collaboration Meeting, JLab, October 5-7, 201513 Far-Forward Angular Ion Acceptance –Quad apertures = 9, 9, 7 T / (  By /  x @ 100 GeV/c), dipole aperture = -30/+50  40 cm –Uniform distribution of  1  in x and y angles around proton beam at IP for a set of  p/p –The circle indicates neutrals’ cone  electron beam  p/p = -0.5  p/p = 0  p/p = 0.5 neutrons

14. MEIC Collaboration Meeting, JLab, October 5-7, 201514 Far-Forward Ion Acceptance for Neutrals Transmission of neutrals with initial x and y angular spread vs peak field –Quad apertures = B max / (fixed field gradient @ 100 GeV/c) –Uniform neutral particle distribution of  1  in x and y angles around proton beam at IP –Transmitted particles are indicated in blue (the circle outlines  0.5  cone) 6 T max 9 T max 12 T max  electron beam

15. MEIC Collaboration Meeting, JLab, October 5-7, 201515 Ion Momentum & Angular Resolution –Protons with  p/p spread are launched at different angles to nominal trajectory –Resulting deflection is observed at the second focal point –Particles with large deflections can be detected closer to the dipole  electron beam ±10  @ 60 GeV/c |  p/p| > 0.005 @  x,y = 0

16. MEIC Collaboration Meeting, JLab, October 5-7, 201516 Ion Momentum & Angular Resolution –Protons with different  p/p launched with  x spread around nominal trajectory –Resulting deflection is observed 12 m downstream of the dipole –Particles with large deflections can be detected closer to the dipole |  x | > 3 mrad @  p/p = 0  electron beam  electron beam ±10  @ 60 GeV/c

17. MEIC Collaboration Meeting, JLab, October 5-7, 201517 Far-Forward Ion Detection Summary e p n, γ 20 Tm dipole 2 Tm dipole solenoid Neutrals detected in a 25 mrad (total) cone down to zero degrees  Space for large (> 1 m diameter) Hcal + Emcal Excellent acceptance for all ion fragments Recoil baryon acceptance:  up to 99.5% of beam energy for all angles  down to at least 2-3 mrad for all momenta  full acceptance for x > 0.005 Resolution limited only by beam  longitudinal  p/p ~ 3  10 -4  angular  ~ 0.2 mrad 15 MeV/c resolution for 50GeV/u tagged deuteron beam

18. MEIC Collaboration Meeting, JLab, October 5-7, 201518 Forward e - Detection & Pol. Measurement Dipole chicane for high-resolution detection of low-Q 2 electrons Compton polarimetry has been integrated to the interaction region design – same polarization at laser as at IP due to zero net bend e-e- ions IP forward ion detection forward e - detection Compton polarimetry local crab cavities c Laser + Fabry Perot cavity e - beam from IP Low-Q 2 tagger for low-energy electrons Low-Q 2 tagger for high- energy electrons Compton electron tracking detector Compton photon calorimeter Compton- and low-Q 2 electrons are kinematically separated! Photons from IP e - beam to spin rotator Luminosity monitor A. Camsonne, D. Gaskell

19. MEIC Collaboration Meeting, JLab, October 5-7, 201519 Downstream Electron Acceptance –5 GeV/c e -, uniform spreads: -0.5/0 in  p/p and  25 mrad in horizontal/vertical angle –Apertures: Quads = 6, 6, 3 T / (  B y /  x @ 11 GeV/c), Dipoles =  20  20 cm ion beam 

20. MEIC Collaboration Meeting, JLab, October 5-7, 201520 Downstream Angular Electron Acceptance –Uniform e - distribution horizontally & vertically within  25 mrad around 5 GeV/c beam –Apertures: Quads = 6, 6, 3 T / (  B y /  x @ 11 GeV/c), Dipoles =  20  20 cm  p/p = -0.5  p/p = -0.25  p/p = -0.1  p/p = 0 ion beam  ion beam 

21. MEIC Collaboration Meeting, JLab, October 5-7, 201521 Electron Momentum & Angular Resolution –Electrons with  p/p spread launched at different angles to nominal 5 GeV/c trajectory |  p/p| > 0.01 @  x,y = 0 ion beam 

22. MEIC Collaboration Meeting, JLab, October 5-7, 201522 Electron Momentum & Angular Resolution –e - with different  p/p launched with  x spread around nominal 5 GeV/c trajectory |  x | > 0.4-4 mrad @  p/p = 0 ion beam 

23. IR Quad: permanent magnet and superconducting Requirements:39 T/m 3 cm bore radius @ inner surface of quad 7 cm max radius of quad structure to clear i-beam tube P. McIntyre et al., Texas A&M University

24. MEIC Collaboration Meeting, JLab, October 5-7, 201524 Conceptual design of the interaction region completed –Interaction region integrated into collider rings –Forward detection requirements fully satisfied Ongoing and future work –Solenoid integration and compensation –Crab cavity integration –Detector modeling –Polarimetry development –Design optimization –Engineering design of interaction region magnets –Systematic investigation of non-linear dynamics –Development of beam diagnostics and orbit correction scheme Summary & Outlook