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Status of the MEIC Machine Design

Status of the MEIC Machine Design. Andrew Hutton Associate Director, Accelerators For the JLab EIC Study Group. Outline. Introduction and the big picture Machine design status Critical R&D and path forward Summary. Electron Ion Colliders.

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Status of the MEIC Machine Design

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  1. Status of the MEIC Machine Design Andrew Hutton Associate Director, Accelerators For the JLab EIC Study Group

  2. Outline • Introduction and the big picture • Machine design status • Critical R&D and path forward • Summary

  3. Electron Ion Colliders Design Goals for Colliders Under Consideration World-wide Present focus of interest (in the US) are the (M)EIC and Staged MeRHIC versions, with s up to ~3000 and 5000, resp.

  4. ELIC: JLab’s Future • Over the last decade, JLab has been developing an electron-ion collider (ELIC) based on the CEBAF recirculating SRF linac • The future nuclear science program drives ELIC design, focusing on: • High luminosity per detector (up to 1035 cm-2s-1) in multiple detectors • High polarization (>80%) for both electrons & light ions • We have made significant progress on design optimization • The primary focus is a Medium-energy Electron Ion Collider ( ) as the best compromise between science, technology and project cost • Energy range is up to 60 GeV ions and 11 GeV electrons • Well-defined upgrade capability to higher energies is maintained (ELIC) • High luminosity & high polarization continue to be the design drivers

  5. EICAC (November 2010) Report From report by Allen Caldwell to CU Collaboration Meeting

  6. Comments from EICAC Report • “The highest priority on the facility side is to develop the JLAB design to a stage similar to where the BNL design is at present” • This is our highest priority and we are making progress • “The JLab . . . concept is at a less mature state . . . It is difficult to assess the credibility of predicted performance, due to many unresolved but very challenging accelerator aspects” • We have been addressing the accelerator aspects and integrating more closely with the detector design • “On the other hand, luminosity performance is predicted to be very high” • More space for the detector means lower luminosity • But more physics!

  7. Comments from EICAC Report • “design should be able to be credibly costed, and should identify a comprehensive table of performances including center of mass energies and luminosities that can be achieved” • We are aiming for performance estimates by Q2FY11 and a cost estimate by Q1FY12 • “the highest R&D priority for JLAB should be the design, even if that activity is not strictly considered R&D, and resources need to be made available to do the work” • Resources have been made available • Thanks to DOE-NP for additional funding • This talk presents the present state of the design

  8. EIC Realization Imagined

  9. Outline • Introduction and the big picture • Machine design status • Critical R&D and path forward • Summary

  10. Highlights of recent Design Activities • Continuing design optimization • Optimizing main machine parameters to match the science program • Now aim for high luminosity AND full detector acceptance • Simplified design and reduced R&D requirements • Focused on detailed design of major components • Completed baseline design of the two collider rings • Completed first design of the ion linac and Figure-8 pre-booster • Completed beam polarization scheme with universal electron spin rotators • Updated IR optics design • Selected bunch collision frequency of 750 MHz • Made considerable progress on beam synchronization • Continuing work on critical R&D • Beam-beam simulations • Nonlinear beam dynamics and instabilities • Chromatic corrections

  11. Short-Term Strategy • MEIC accelerator team is developing an integrated MEIC design • MEIC accelerator team will create a complete design with sufficient technical detail to evaluate performance • Design basis will be reviewed every ~ 6 months and specifications updated to reflect developments in: • Nuclear science program • Accelerator R&D • The current design is conservative, restricting the design parameters to close to the present state of the art • Maximum peak field of ion superconducting dipole is 6 T • Maximum synchrotron radiation power density is 20 kW/m • Maximum beta at final focus quad is 2.5 km (field gradient <200 T/m)

  12. Short-Term Strategy • Present design (assuming 6T magnets) has the following features: • Center-of-mass energy up to 51 GeV: • 3 - 11 GeV electron, 20 – 60 GeV protons, 15-30 GeV/u ions • Upgrade option to high energy • 3 interaction regions, 2 available for medium energy collisions • Luminosity up to ~1034 cm-2s-1 per collision point • Full acceptance for at least one medium-energy detector • Large acceptance with a higher luminosity for other detector • High polarization for both electron and light ion beams

  13. MEIC : Medium Energy EIC medium-energy IPs polarimetry low-energy IP • Three compact rings: • 3 to 11 GeV electron • Up to 12 GeV/c proton (warm) • Up to 60 GeV/c proton (cold)

  14. Detailed Layout warm ring cold ring

  15. ELIC: High Energy & Staging Serves as a large booster to the full energy collider ring

  16. Ring-Ring Design Features Very high luminosity Polarized electrons and polarized light ions (longitudinal and transverse at IP) Up to 3 interaction regions (detectors) for high science productivity Figure-8 ion and lepton storage rings Ensures spin preservation and ease of spin manipulation Avoids energy-dependent spin sensitivity for all species Only practical way to accommodate polarized deuterons 12 GeV CEBAF meets electron injector requirements for MEIC Simultaneous operation of collider & CEBAF fixed target program possible Experiments with polarized positrons would be possible

  17. Luminosity Approach High luminosity at B factories comes from: Very small β* (~6 mm) to reach very small spot sizes at collision points Very short bunch length (σz~ β*) to avoid hour-glass effect Very small bunch charge which makes very short bunch possible High bunch repetition rate restores high average current and luminosity Synchrotron radiation damping  KEK-B and PEPII already over21034cm-2 s-1 These concepts are the basis for the MEIC design

  18. High Acceptance Detector 7 meters detectors solenoid ion FFQs ion dipole w/ detectors ions IP 0 mrad electrons electron FFQs 50 mrad 2+3 m 2 m 2 m Central detector Detect particles with angles below 0.5obeyond ion FFQs and in arcs. Detect particles with angles down to 0.5obefore ion FFQs. Need 1-2 Tm dipole. TOF Solenoid yoke + Muon Detector RICH or DIRC/LTCC Tracking RICH EM Calorimeter HTCC 4-5m Muon Detector Hadron Calorimeter EM Calorimeter Very-forward detector Large dipole bend @ 20 meter from IP (to correct the 50 mr ion horizontal crossing angle) allows for very-small angle detection (<0.3o) Solenoid yoke + Hadronic Calorimeter 2m 3m 2m Pawel Nadel-Turonski & Rolf Ent

  19. MEIC Design Parameters For a Large-Acceptance Detector

  20. The second option is using 1 km medium-energy ion ring for higher proton beam current at 30 GeV protons for lowering the space charge tune-shift ELIC Luminosity: 2.5 km Ring, 8 Tesla Full acceptance High luminosity

  21. Figure-8 Ion Rings • Figure-8 is optimum for polarized ion beams • Simple solution to preserve full ion polarization by avoiding spin resonances during acceleration • Energy independence of spin tune • g-2 is small for deuterons; a figure-8 ring is the only practical way to accelerate deuterons and to arrange for longitudinal spin polarization at interaction point • Transverse polarization for deuterons looks feasible

  22. Figure-8 Collider Rings Ion Ring IP IP Siberian snake Siberian snake Potential IP Electron Ring IP IP RF RF Spin rotators Spin rotators Potential IP

  23. MEIC Design Details • Our present design is mature, having addressed -- in various degrees of detail -- the following important aspects of MEIC: • Beam synchronization • Ion polarization (RHIC-type Siberian snakes) • Electron polarization • Universal spin rotator • Electron beam time structure & RF system • Forming the high-intensity ion beam: SRF linac, pre-booster • Synchrotron rad. background • Beam-beam simulations • Beam stability • Detector design • IR design and optics • Electron and ion ring optics

  24. Outline • Introduction and the big picture • Machine design status • Critical R&D and path forward • Summary

  25. MEIC Critical Accelerator R&D • We have identified the following critical R&D issues for MEIC: • Interaction region design and limits with chromatic compensation • Electron cooling • Crab crossing and crab cavity • Forming high-intensity low-energy ion beam • Beam-beam effect • Depolarization (including beam-beam) and spin tracking • Traveling focusing for very low energy ion beam

  26. Electron Cooling: ERL Circulator Cooler Electron circulator ring • Design goal • Up to 33 MeV electron energy • Up to 3 A CW unpolarized beam • (~nC bunch charge @ 499 MHz) • Up to 100 MW beam power! • Solution: ERL Circulator Cooler • ERL provides high average current CW beam with minimum RF power • Circulator ring for reducing average current from source and in ERL(# of circulating turns reduces ERL current by same factor) Technologies • High intensity electron source/injector • Energy Recovery Linac (ERL) • Fast kicker Derbenev & Zhang, COOL 2009

  27. Ongoing Accelerator R&D We are concentrating R&D efforts on the most critical tasks: Focal Point 1: Forming high-intensity short-bunch ion beams & cooling Sub tasks: Complete design of the RF linac and pre-booster Ion bunch dynamics and space charge effects (simulations)Led by Peter Ostroumov (ANL) Focal Point 2: Electron cooling of medium-energy ion beam Sub tasks: Electron cooling dynamics (simulations) Complete design of the ERL-based circulator cooler Dynamics of cooling electron bunch in ERL circulator ring Focal Point 3: Beam-beam interaction Sub tasks: Include crab crossing and/or space charge Include multiple bunches and interaction points

  28. Collaborations Established • IR/detector design M. Sullivan (SLAC) • MEIC ion complex front end P. Ostroumov (ANL) (From source up to injection into collider ring) • Ion source V. Dudnikov, R. Johnson (Muons, Inc) V. Danilov (ORNL) • SRF Linac P. Ostroumov (ANL), B. Erdelyi (NIU) • Chromatic compensation A. Netepenko (Fermilab) • Beam-beam simulation J. Qiang (LBNL) • Electron cooling simulation D. Bruhwiler (Tech X) • Polarization A. Kondratenko (Novosibirsk) • Electron spin tracking D. Barber (DESY)

  29. EIC Study Group A. Accardi, A. Afanasev, A. Bogacz, J. Benesch, P. Brindza, A. Bruell, L. Cardman, Y. Chao, S. Chattopadhyay, J.P. Chen, E. Chudakov, P. Degtiarenko, J. Delayen, Ya. Derbenev, R. Ent, P. Evtushenko, A. Freyberger, D. Gaskell, J. Grames, V. Guzey, L. Harwood, T. Horn, A. Hutton, C. Hyde, N. Kalantarians, R. Kazimi, F. Klein, G. A. Krafft, R. Li, F. Marhauser, L. Merminga, V. Morozov, J. Musson, P. Nadel-Turonski, F. Pilat, M. Poelker, A. Prokudin, R. Rimmer, H. Sayed, M. Spata, A. Thomas, M. Tiefenback, B. Terzić, H. Wang, C. Weiss, B. Wojtsekhowski, B. Yunn, Y. Zhang - Jefferson Laboratory staff and users W. Fischer, C. Montag - Brookhaven National Laboratory D. Barber - DESY V. Danilov - Oak Ridge National Laboratory V. Dudnikov - Brookhaven Technology Group P. Ostroumov - Argonne National Laboratory B. Erdelyi - Northern Illinois University and Argonne National Laboratory V. Derenchuk - Indiana University Cyclotron Facility A. Belov - Institute of Nuclear Research, Moscow, Russia R. Johnson - Muons Inc. A. Kondratenko - Novosibirsk

  30. Outline • Introduction and the big picture • Machine design status • Critical R&D and path forward • Summary

  31. Summary • MEIC is optimized to collide a wide variety of polarized light ions and unpolarized heavy ions with polarized electrons (or positrons) • MEIC covers an energy range matched to the science program proposed by the JLab nuclear physics community (~150 - 2600 GeV2) with luminosity up to 1.4x1034 cm-2s-1 • An upgrade path to higher energies (250x10 GeV2) is being maintained, which should provide luminosity of close to 1035 cm-2s-1 • The design is based on a Figure-8 ring for optimum polarization, and an ion beam with high repetition rate, small emittance and short bunch length • Electron cooling is absolutely essential for cooling & bunching the ion beam • We have identified the critical accelerator R&D topics for MEIC, and are presently working on them • Our present MEIC design is mature and flexible, able to accommodate revisions in design specifications and advances in accelerator R&D • We are aiming for performance estimates by Q2FY11 • and a cost estimate by Q1FY12

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