Normal Conducting RF Cavity Normal Conducting RF Cavity R&D for Neutrino Factory or R&D for Neutrino Factory or Muon Collider Muon Collider Thomas Jefferson National Laboratory Facility Thomas Jefferson National Laboratory Facility (Sept. 11, 2006) Derun Li and Steve Virostek Virostek Derun Li and Steve Center for Beam Physics Center for Beam Physics Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory Derun Li – NCRF R&D for NF and MC Page 1
Acknowledgements Acknowledgements Work was done in collaboration with Work was done in collaboration with Fermi National Accelerator Laboratory Fermi National Accelerator Laboratory Argonne National Laboratory Argonne National Laboratory Thomas Jefferson National Laboratory Facility Thomas Jefferson National Laboratory Facility Illinois Institute of Technology Illinois Institute of Technology University of Mississippi University of Mississippi Oxford University, UK Oxford University, UK Derun Li – NCRF R&D for NF and MC Page 2
Outline Outline • • Introduction Introduction – – Muon Ionization Cooling Muon Ionization Cooling – – International Muon Ionization Cooling Experiment (MICE) International Muon Ionization Cooling Experiment (MICE) • • Experimental study program Experimental study program – – 805 MHz cavity design 805 MHz cavity design – – Fabrication Fabrication – – Coupler design Coupler design – – Achievable accelerating gradient under a few Tesla magnetic fields Achievable accelerating gradient under a few Tesla magnetic fiel ds – – Button tests with different materials and coatings Button tests with different materials and coatings • • Thin beryllium windows for RF cavity Thin beryllium windows for RF cavity – – Pre- -stressed flat windows, grids stressed flat windows, grids Pre – – Curved Be windows Curved Be windows • • 201 MHz Cavity Program 201 MHz Cavity Program – – Cavity design Cavity design – – Fabrication techniques Fabrication techniques • • Spinning Spinning • • Extruding Extruding • • E E- -beam welding beam welding • • Cleaning and electro- -polishing (EP) polishing (EP) Cleaning and electro – – Loop coupler and conditioning Loop coupler and conditioning – – Preliminary test results of the cavity Preliminary test results of the cavity • • Some of the US MICE responsibilities Some of the US MICE responsibilities • • Summary Summary Derun Li – NCRF R&D for NF and MC Page 3
Introduction Introduction • • R&D program under auspices of the U.S. Neutrino Factory and R&D program under auspices of the U.S. Neutrino Factory and Muon Collider Collaboration (NFMCC) Muon Collider Collaboration (NFMCC) • • Three leading national laboratories (BNL, FNAL, LBNL) + JLab JLab and and Three leading national laboratories (BNL, FNAL, LBNL) + other university research groups other university research groups – Production, acceleration and storage of intense muon beams Production, acceleration and storage of intense muon beams – (hardware and software) (hardware and software) Technology and engineering solutions • Technology and engineering solutions • • Accelerator physics of intense muon beams Accelerator physics of intense muon beams • • • Support from DOE, NSF, Illinois State and U.S.- -Japan Japan Support from DOE, NSF, Illinois State and U.S. • • R&D progress enhanced significantly by corresponding programs R&D progress enhanced significantly by corresponding programs in Europe and Japan in Europe and Japan • • Long term goals Long term goals – – Continue evaluating physics opportunities afforded by intense muon intense muon Continue evaluating physics opportunities afforded by beams from from Neutrino Factory Neutrino Factory through through a Muon Collider a Muon Collider beams • • Near term goals Near term goals – – Muon cooling R&D (software and hardware) Muon cooling R&D (software and hardware) – – International International M Muon uon I Ionization onization C Cooling ooling E Experiment ( xperiment (MICE MICE) ) – Cost effective Neutrino Factory Design – Cost effective Neutrino Factory Design Derun Li – NCRF R&D for NF and MC Page 4
Neutrino Factory Ingredients Neutrino Factory Ingredients Neutrino Factory comprises Neutrino Factory comprises • • Proton Driver Proton Driver – – primary beam on production primary beam on production target target • • Target, Capture, and Decay , and Decay Target, Capture π ; decay into Create π – – ; decay into µ µ Create • • Bunching and Phase Rotation Bunching and Phase Rotation Conditioning: reduce Δ Δ E of bunch – – E of bunch Conditioning: reduce • • Cooling Cooling – – Reduce transverse emittance Reduce transverse emittance – – MICE MICE • • Acceleration Acceleration – – 130 MeV MeV ~ ~ 20 20– –50 50 GeV GeV 130 • • Storage Ring Storage Ring 0 50 100 m – – Store for ~ 500 turns; long Store for ~ 500 turns; long straight straight Challenging, but no show stoppers! Challenging, but no show stoppers! Derun Li – NCRF R&D for NF and MC Page 5
Cooling R&D Programs Cooling R&D Programs Cooling • Cooling • – Components R&D: Components R&D: NC RF cavities NC RF cavities, absorbers and solenoids , absorbers and solenoids – – Normal conducting RF cavity studies: Normal conducting RF cavity studies: – • Experimental studies at 805 MHz using a pillbox cavity Experimental studies at 805 MHz using a pillbox cavity • Be windows R&D • • Be windows R&D – Thermal and mechanical stabilities at high accelerating gradient Thermal and mechanical stabilities at high accelerating gradients s – – Scattering and limits Scattering and limits – • Tests are being conducting now at MTA (MUCOOL Test Area), Tests are being conducting now at MTA (MUCOOL Test Area), • FNAL FNAL • 201 MHz cavity design, fabrication • 201 MHz cavity design, fabrication and tests and tests – Absorbers (ICAR, Japan – Absorbers (ICAR, Japan- -US funding) US funding) • Absorbers, windows and safety issues • Absorbers, windows and safety issues • Design and FEA simulations of absorber windows • Design and FEA simulations of absorber windows • Absorber tests at MTA, FNAL • Absorber tests at MTA, FNAL – SC solenoids (magnets) – SC solenoids (magnets) – – International MICE International MICE experiment experiment Derun Li – NCRF R&D for NF and MC Page 6
Muon Ionization Cooling Muon Ionization Cooling LH Absorbers dE dE dE dx dx dx RF Cavities Magnets – High gradient RF cavities to compensate for lost longitudinal en High gradient RF cavities to compensate for lost longitudinal energy ergy – Strong magnetic field to confine muon beams – Strong magnetic field to confine muon beams – Energy loss in LH – Energy loss in LH 2 absorbers 2 absorbers Goal: Goal: – Development of NC 201 – Development of NC 201- -MHz cavity operating at MHz cavity operating at ~ 16 MV/m in a few in a few- -Tesla Tesla solenoidal solenoidal B B field field ~ 16 MV/m (~ 30 MV/m at 805- (~ 30 MV/m at 805 -MHz) MHz) Derun Li – NCRF R&D for NF and MC Page 7
Demand for High Gradient RF Demand for High Gradient RF Technical challenges Technical challenges • • μ s at rest) Muon beam is unstable, and has short decay time (~ 2 μ Muon beam is unstable, and has short decay time (~ 2 s at rest) • • Muon beam is created with LARGE LARGE 6 6- -D phase space D phase space Muon beam is created with – – Muon beam manipulation must be done Muon beam manipulation must be done quickly quickly including including cooling cooling → Highest possible gradient normal conducting RF cavity • • Requirements of RF cavity for muon beams Requirements of RF cavity for muon beams – – High cavity shunt impedance, high gradient and high field High cavity shunt impedance, high gradient and high field • Gradient at 201 MHz: ~ 16.5 MV/m { • Gradient at 201 MHz: ~ 16.5 MV/m {Kilpatrick criterion: 15 MV/m Kilpatrick criterion: 15 MV/m} } • Gradient at 805 MHz: ~ 30 MV/m { • Gradient at 805 MHz: ~ 30 MV/m {Kilpatrick criterion: 26 MV/m Kilpatrick criterion: 26 MV/m} } – RF cavity with closed iris – RF cavity with closed iris (iris terminated by Be window) (iris terminated by Be window) • Higher shunt impedance • Higher shunt impedance • Independent phase control, higher transit factor • Independent phase control, higher transit factor • Lower peak surface field • Lower peak surface field Derun Li – NCRF R&D for NF and MC Page 8
Experimental Studies at 805 MHz Experimental Studies at 805 MHz LBNL 805- -MHz pillbox cavity design, MHz pillbox cavity design, LBNL 805 fabrication and tests fabrication and tests Derun Li – NCRF R&D for NF and MC Page 9
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