EMMA: the first NSFFAG

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EMMA the first NS-FFAG

• Roger Barlow

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What is an FFAG?

• Like a synchrotron
• Strong Focussing (Alternating Gradient)
• Dipole field increases with particle energy
• But through path variation not time variation
• ??B/?t not dB/dt
• Orbit changes with energy
• RF changes slightly

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For and against

• Advantages
• Magnets do not cycle
• Cheaper, simpler
• High Repetition rate
• kHz rather than Hz
• High duty cycle
• Not quite DC, but
• Rapid acceleration
• Limited by RF not magnet
• Large acceptance
• Useful for protons, vital for muons

Disadvantages Limited dynamic range Magnets
complicated Limited experience Abandoned in
1950s?
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FFAG renaissance

• Improved Magnet and RF technology
• Materials, modelling
• Proton FFAG built and working in KEK, Japan
• Plans for proton, electron, muon FFAGs

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The NS-FFAG

• Scaling constant orbit shape
• Gives constant betatron tune
• Abandon scaling principle lose control of tune.
  Fall into resonance?

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Argument

• If the tune changes rapidly, resonances dont
  have time to destroy the beam.
• Rapid acceleration Big turn-to-turn variation
• Plausible but needs verifying
• Advantages (if it works)
• Very small (zero) RF change needed
• Simpler magnets (B?R not ln B ?R)
• Smaller beam pipe

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EMMA

• Proof of principle machine
• 10 to 20 MeV electrons
• 42 cells
• 16m circumference
• RF every other cell
• 1.3GHz, TESLA frequency
• magnets 5cm x 2.5cm

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EMMA at Daresbury
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More EMMA details

• Slides following taken from talk by Rob Edgecock

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CF Magnets
Flux lines at maximum dipole and quadrupole
currents. Dipole coil (blue), Quadrupole (red).
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RF System
1.3GHz ELBE-like RF Cavities 20cm slot length Few
10-4 variation in frequency to allow acceleration
mode changes Low frequency system for further
resonance crossing studies Initial design and
cost estimate done
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Non-Scaling Electron Model
EMMA
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Bid to UK Basic Technology Programme

• BASROCBritish Accelerator Science, Radiation and
  Oncology Consortium
• Request funding for
• EMMA construction (3.8M 1.8M)
• Design of proton R and D machine (PAMELA) (0.8M)
• Applications from Archaeology to Zoology (0.4M)

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The Consortium

• CCLRCCockcroft EMMA Construction
• Manchester/Cockcroft Coordination
• Liverpool/Cockcroft Magnets
• Oxford/John Adams PAMELA design
• Oxford/Gray Cancer Institute Birmingham
  Imperial Glasgow PAMELA and Hadron therapy
  applications
• SurreyLeeds general applications

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Decision

• This is still unofficial

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Plan

• Project start 1 April 2007, last 3.5 years
• Build and study EMMA
• Design and seek funding for PAMELA
• Build up portfolio of FFAG applications
• Hadron therapy
• Cell irradiation studies
• Solar wind simulator
• Accelerator Driven Thorium Reactors
• Proton drivers for muon/neutron sources
• Muon accelerator for neutrino factory
• Enlarge project through linked activities