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Muon Cooling

Muon Cooling. Robert D. Ryne Lawrence Berkeley National Laboratory. Snowmass 2013: Lepton Collider Workshop 10-11 April, 2013 MIT. The future of accelerator-based, energy-frontier HEP in the USA: It’s not that complicated. Someday….

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Muon Cooling

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  1. Muon Cooling Robert D. Ryne Lawrence Berkeley National Laboratory Snowmass 2013: Lepton Collider Workshop 10-11 April, 2013 MIT

  2. The future of accelerator-based, energy-frontier HEP in the USA: It’s not that complicated Someday… Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) We will accept that it is extremely unlikely the US gov't will build a new accelerator facility in the USA for energy-frontier HEP We will decide to explore as far into the energy frontier as possible on our biggest existing site in the USA We will use the highest accelerating gradients possible We will collide leptons for maximum energy reach The facility will be circular to enable multiple passes We will use the strongest magnets we can build for maximum energy reach within the facility footprint We will accelerate heavy particles to limit synchrotron radiation

  3. Someday... We will collide muons if it is feasible Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  4. A staged vision encompassing the Intensity Frontier and the Energy Frontier, but we haven't proven it is feasible yet MAP Feasibility Assessment Advanced Systems R&D Indicates a date whenan informed decisionshould be possible Muon Ionization Cooling Experiment (MICE) Proj X Ph I Proj X Ph II Proj X Ph III & IV IDS-NF RDR Proposed Muon Storage Ring Facility (nSTORM) Evolution to Full Spec n Factory Collider Conceptual  Technical Design Collider Construction Physics Program Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  5. Muon cooling is a critical issue for demonstrating feasibility Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) Muon beams are "born" with very large emittance A high energy collider requires cooling the 6D emittance by a factor of ~1 million The muon Cooling subsystem is a critical section of an energy-frontier muon collider

  6. Ionization Cooling Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  7. Ionization Cooling Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) Energy loss in absorbers RF cavities compensate for lost longitudinal energy Cooing w/ 201-805 MHz cavities in multi-Tesla fields

  8. MICE experiment Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) MICE aims to initially measure transverse ionization cooling on a particle-by-particle basis

  9. Technology challenges for beamline components of a cooling channel Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) Operating vacuum rf cavities in high B field Operating gas-filled rf cavities in high B field Developing and operating dielectric-loaded, gas filled rf cavities in high B field (for HCC) Developing very high magnetic field solenoids (for final cooling in an energy frontier collider)

  10. MuCool: R&D program at Fermilab to develop ionization cooling components Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) Mission: • Design, prototype and test components for ionization cooling • Absorbers (LH2, solid LiH) • RF cavities • Magnets • Diagnostics • Carry out associated simulation and theoretical studies • Support system tests (MICE, future cooling expts) • Current focus: RF cavity performance in strong external magnetic fields

  11. MTA Program Overview Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Goal: Demonstrate a working solution to RF cavity operation in high external magnetic field for muon cooling • Major MAP deliverable • and near-term technical risk for MICE • Major impact on cooling channel design and future system tests • A multipronged approach has been followed aIdentify most promising paths for detailed study

  12. RF in high B-field: Potential Solutions Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Better materials: more robust against breakdown/damage (melting point, energy loss, skin depth, thermal diffusion length, etc.) • Surface treatment: suppress field emission(SRF techniques, coatings, atomic layer deposition) • Shielding: iron, bucking coils (IDS-NF option)

  13. RF in high B-field: Potential Solutions • High-pressure gas: suppress breakdown by moderating electrons Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  14. Magnetic Field Dependence“All-season” Cavity (MuonsInc, LANL) Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Modular pillbox with replaceable endplates • Designed for both vacuum and high pressure • Operated in magnet • 25 MV/m at B=0 and 3 T • Follow-on testing underway. Might be seeing first signs of B-field induced degradation

  15. Future Vacuum Pillbox Cavity R&D805-MHz Modular Cavity (SLAC/LBNL) Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • New R&D vehicle for detailed systematic studies • Modular design for easy assembly, parts replacement • Removable endplates (Cu, Be, other materials, treated surfaces) • Coupling iris moved to center ring and field reduced (more realistic design) • RF design validated by detailed simulation • Ports for instrumentation • In fabrication @ SLAC • Expected delivery to MTA: Fall `13

  16. 805-MHz HPRF Cavity Beam Test 1470psi H2aw/beamaadd 1% dry air Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Wide range of parameters • 1010-3x1011ppp, 5-50 MV/m • 300-1520 psi H2, B=0 and 3T • Electronegative Dopant Studies: SF6 and dry air versus concentration • Ion Mobility Studies: He+air, N2+air, D2 • Publication in preparation • Quantitative theory validated by measurement of energy in H2/D2+dopant • Electronegative dopants turn mobile ionization electrons into heavy ions, reducing RF losses by large factor • Results extrapolate well to Neutrino Factory operation and a range of Muon Collider beam parameters • Plasma loading < beam loading • Bunch intensity limits being evaluated

  17. HTS High-Field Solenoid Development • Plan built on significant results from PBL/BNL YBCO solenoid last year: • Bo>15 T (record), Bpeak >16 T with full insert (25 mm, 14 pancakes) • Record for magnet fabricated solely with HTS SC • Bo> 6 T, Bpeak > 9 T in half midsert(100 mm, 12 pancakes) • Full midsert worked well (see below) and is ready for test at 4K The route to a ≥ 30T Solenoid Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  18. Outlook Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Experimental program • HPRF beam tests successfully concluded • Looks promising for Neutrino Factory and Muon Collider application • Dielectric loading to be tested soon [Fall] • Vacuum cavity R&D bearing fruit • 25 MV/m @ 3T demonstrated in Cu pillbox (all-season cavity), follow-on testing underway. Might be seeing first signs of B-field induced degradation. Will be opened for detailed exam late spring. • Alternative window geometry to be explored [Spring] • New modular cavity in fabrication for detailed systematic studies (Cu/Be walls, gradient vs B) [Fall] • Beam tests will be included in experimental program • 201-MHz single-cavity module (MICE) tests [Summer] • Tests with Coupling Coil Magnet will follow when magnet prototype ready • Infrastructure upgrades (beamline, RF, magnets) • R&D program now pointing the way to RF solutions for ionization cooling channels!

  19. Beyond overcoming component technology challenges, a full 6D cooling system is still highly complex and challenging Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Forming a bunch train in the Front End via buncher and phase rotator • Charge separation • 6D cooling • Guggenheim, Helical Cooling Channel (HCC), FOFO Snake, Rectilinear RFOFO • Bunch merging • Bunch recombination • Final cooling to reduce eperp at expense of elong

  20. Helical Cooling Channel (HCC) R&D Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) HCC: Dielectric-Loaded RF cavities filled with high pressure hydrogen

  21. Guggenheim R&D Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Elements of the Guggenheim: • vacuum RF cavities • Flip, non-flip, and half-flip lattices being studied • challenging geometry constraints • High JE required in final stages • Demonstration magnets on 3 yr timescale for RF tests

  22. Guggenheim lattice Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  23. 15-stage post-merge Guggenheim tracking results Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  24. HPC as an Enabling Capability for MAP FY13 onward Pre-FY13 Main MAP codes G4Beamline & ICOOL typically run w/ 10K-100K particles using PC’s and clusters Run times of many hours “Noisy” simulations due to small # of particles Not suitable for design optimization Simplified physics models G4Beamline & ICOOL parallelized Ported to 150,000 core supercomputer “Hopper” at NERSC Simulations now performed with millions of particles Run times reduced by orders of magnitude Big impact to MAP D&S effort Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013)

  25. Impact of HPC to MAP D&S Previously, serial jobs were slow and low resolution Now we can do “small” (~million particle) parallel jobs in minutes Can do large jobs when needed Neutrino Factory Front End test problem, Longitudinal emittancevs z. Green: serial ICOOL. Red: Parallel ICOOL. Identical except for stochastics. Differences vanish for large # of particles. Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • Execution time/job reduced from hours to minutes • Muon cooling design w/ parallel G4Beamline code • Up to 35,000x performance improvement! • Target and front end optimization w/ parallel ICOOL • Studies of space charge in 6D cooling w/ Warp • Parallel design optimization effort underway

  26. Cooling: Summary and Conclusion Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • We are making steady progress on: • Technology R&D • vacuum RF, high pressure RF, high field HTS magnets • D&S for Cooling system for a collider • Guggenheim, HCC, FOFO-snake, rectilinear RFOFO • 325 MHz a strong possibility (instead of 201) • Schedule: • Metrics for Cooling baseline selection by end of FY13 • Initial baseline selection by ~end of FY14 • Paradigm shifts from exploring options to emphasis on strengthening baseline in FY15-18, feedback to tech-dev, input to 6D demo planning • reduction in exploring alternatives (only mgmt-approved, high-leverage alternatives) • Much D&S work remains to be done • more realistic modeling (matching, fringe fields,...), collective effects, start-to-end cooling simulations

  27. It's good to have big dreams, but let's not ignore technological feasibility and political realities Not in the USA Does a muon collider belong here? Politics Politics + Feasibility (somedayjust politics?) Not feasible?A long way off for sure Does a muon collider belong here? Not feasible? feasibility Muons: the "only game in town" or "no game in town" Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • ILC, TLEP, Super-Tristan, CLIC • Muon collider? • A big, new, green-field USaccelerator facility • HEP accelerator facility with its own accelerator-driven sub-critical system • uses some power for science, sells the rest and is a money-maker • LPA-based Multi-TeV collider • Muon collider?

  28. The pursuit of muon acceleration, and doing it at a US facility, is not just about building the next HEP accelerator Robert D Ryne, Snowmass 2013 Lepton Collider Workshop (MIT, April 10-11, 2013) • It's about laying a foundation for a new type of particle accelerator technology that will affect HEP research for many decades to come • It's about a US facility that is a magnet for inspiring and training future generations • not the only energy-frontier facility, but one of a few worldwide • It's about developing new technologies whose impact beyond HEP is yet to be known • but is likely to be significant if history is a guide

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