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Overview of IR Design

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

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Overview of IR Design

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  1. Overview of IR Design V.S. Morozov1, P. Brindza1, A. Camsonne1, Ya.S. Derbenev1, R. Ent1, D. Gaskell1, F. Lin1, P. Nadel-Turonski1, M. Ungaro1, Y. Zhang1, Z.W. Zhao1,2, C.E. Hyde3, K. Park3, M. Sullivan4 1JLab, 2Duke, 3ODU, 4SLAC MEIC Collaboration Meeting, JLab October 5-7, 2015

  2. Forward detection concept Detector integration Forward ion tagging Forward electron tagging Summary Outline

  3. MEIC Layout & Detector Location 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 Warm Electron Collider Ring (3 to 10 GeV) Booster Linac Ion Source 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. 50 mrad crossing angle Improved detection, no parasitic collisions, fast beam separation Forward hadron detection in three stages Endcap Small dipole covering anglesup to a few degrees Far forward, up to one degree,for particles passing through accelerator quads Low-Q2 tagger Small-angle electron detection Full-Acceptance Detector P. Nadel-Turonski, R. Ent, C.E. Hyde

  5. 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 small angle hadron detection IP FP (from GEANT4) far forward hadron detection n, g low-Q2 electron detection ion quads large-aperture electron quads ~60 mrad bend p small-diameter electron quads e 50 mrad beam (crab) crossing angle p Fixed trackers Thin exit windows Roman pots central detector with endcaps dual-solenoid in common cryostat 4 m coil 1 m Ion quadrupoles RICH + TORCH? 1 m Endcap barrel DIRC + TOF 2 Tm dipole Electron quadrupoles e/π threshold Cherenkov EM calorimeter Tracking EM calorimeter Trackers and “donut” calorimeter EM calorimeter Detector Modeling & Machine Integration

  6. 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 forward e- detection region Compton polarimetry region FFQs FFQs e- IP

  7. 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 detector elements match/ beam compression IP match/ beam expansion geom. match/ disp. suppression FFB FFB ions

  8. Integrated Interaction Region & Detector (top view) Accelerator view of IR Layout crab cavities ions FFQs FFQs e- IP crab cavities • Design emphasis on polarization (figure-8) and on integrated detector/interaction region Nuclear Physics view of IR Layout (top view) ultra forward hadron detection small angle hadron detection central detector with endcaps n, low-Q2 electron detection and Compton polarimeter large aperture electron quads 60 mrad bend ion quads p small diameter electron quads e e p Roman pots Fixed trackers Thin exit windows 50 mrad beam (crab) crossing angle

  9. 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 7 m from IP to first ion quad Ion quadrupoles: gradient, peak field, length 36 T/m, 7.0 T, 1.2 m 51 T/m, 9.0 T, 2.4 m 89 T/m, 9.0 T, 1.2 m 1 m 1 m Endcap detectors 2 T dipole Permanent magnets e Electron quadrupoles 2 x 15 T/m 34 T/m 46 T/m 38 T/m Tracking Calorimetry 5 T, 4 m dipole Crossing angle

  10. Far-Forward Hadron Detection Good acceptance for ion fragments Large downstream magnet apertures/ small downstream magnet gradients Good acceptance for low-pT 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 (n, ) ZDC Aperture-free drift space 20 Tm dipole (in) 2 Tm dipole (out) p solenoid e S-shaped dipole configuration optimizes acceptance for neutrals Thin exit windows Roman pots at focal point 50 mrad crossing angle Asymmetric IR (minimizes chromaticity) x Ions βFP < 1 m βx* = 10-20 cm DFP ~ 1 m βy* = 2 cm D* = D'* = 0 FP IP

  11. Far-Forward Acceptance for Charged Fragments (protons rich fragments) (neutron rich fragments) Δp/p = -0.5 Δp/p = 0.0 Δp/p = 0.5 (spectator protons from deuterium) (exclusive / diffractive recoil protons) (tritons from N=Z nuclei)

  12. 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) 9 T max 6 T max 12 T max  electron beam

  13. 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  electron beam p/p = 0.5 p/p = -0.5 neutrons p/p = 0

  14. 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) 9 T max 6 T max 12 T max  electron beam

  15. 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 |p/p| > 0.005 @ x,y = 0  electron beam ±10 @ 60 GeV/c

  16. 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 ±10 @ 60 GeV/c  electron beam  electron beam

  17. Far-Forward Ion Detection Summary • 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 n, γ 20 Tm dipole p 2 Tm dipole solenoid e • 15 MeV/c resolution for 50GeV/u tagged deuteron beam

  18. Forward e- Detection & Pol. Measurement Dipole chicane for high-resolution detection of low-Q2 electrons local crab cavities local crab cavities forward e- detection forward ion detection Compton polarimetry Compton photon calorimeter Low-Q2 tagger for low-energy electrons c localcrab cavities Low-Q2 tagger for high-energy electrons Laser + Fabry Perot cavity • Compton polarimetry has been integrated to the interaction region design • same polarization at laser as at IP due to zero net bend IP Compton electron tracking detector e- Luminosity monitor e- beam to spin rotator e- beam from IP ions Compton- and low-Q2 electrons are kinematically separated! Photons from IP A. Camsonne, D. Gaskell

  19. Downstream Electron Acceptance • 5 GeV/c e-, uniform spreads: -0.5/0in p/pand25 mradin horizontal/vertical angle • Apertures: Quads = 6, 6, 3 T / (By /x @ 11 GeV/c), Dipoles = 2020 cm ion beam 

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

  21. 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. 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. 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

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