EMMA: the first NS-FFAG Roger Barlow

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

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 1950’s?

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

The NS-FFAG ‘Scaling’: constant orbit shape Gives constant betatron tune Abandon scaling principle – lose control of tune. Fall into resonance?

Argument If the tune changes rapidly, resonances don’t 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

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

EMMA at Daresbury EMMA

More EMMA details Slides following taken from talk by Rob Edgecock

CF Magnets EMMA Flux lines at maximum dipole and quadrupole currents. Dipole coil (blue), Quadrupole (red).

RF System EMMA 1.3GHz ELBE-like RF Cavities 20cm slot length Few variation in frequency to allow acceleration mode changes Low frequency system for further resonance crossing studies Initial design and cost estimate done

Non-Scaling Electron Model EMMA EMMA

Bid to UK “Basic Technology” Programme BASROC=British 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)

The Consortium CCLRC+Cockcroft – 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 Surrey+Leeds – general applications

Decision This is still unofficial

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