A Muon Scientists Guide to FFAGs

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A Muon Scientists Guide to FFAGs
Rob Edgecock On behalf of BASROC/CONFORM
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Outline

• What is an FFAG?
• Scaling vs non-scaling
• Some current projects
• Next steps for NS-FFAGs
• EMMA
• PAMELA
• Conclusions

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What is an FFAG?
Fixed Field Alternating Gradient accelerator

• Fixed magnetic fields and AG focussing
  important!
• Two types scaling and non-scaling
• Start with scaling.

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What is an FFAG?
Fixed magnetic field members of the cyclotron
family
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What is an FFAG?
Horizontal tune

To 1st order
where the average field index
and

• Another reason for large k

See Symon et al, Phys. Rev. 103 (1956) 1837 for
derivation
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What is an FFAG?
Vertical tune

To 1st order
where the magnetic flutter

• Large ? - no field flip
• More compact

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Scaling FFAGs

• Radial sector FFAG

Chandrasekhar
Bohr
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Scaling FFAGs

• Spiral sector FFAG

Spiral sector machine Operated at MURA in 1957
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Interest in FFAGs

• Fixed Field - fast cycling , limited
  (sometimes) only by RF - simpler, inexpensive
  power supplies - no eddy-current effects,
  cyclical coil stress - high acceptance -
  high intensity pulsed and continuous - low
  beam loss and activation - easy
  maintenance - easy operation
• Strong focussing - magnetic ring -
  beam extraction at any energy - higher
  energies/ions possible

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Scaling FFAGs

• Created great interest in late 1990s in Japan

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Current Projects

• ADSR _at_ Kyoto funded being commissioned

• BNCT _at_ Kyoto funded under construction
• PRISM _at_ Osaka funded under construction
• LAPTOP _at_ Mitsubishi 6 MeV prototype being built

• Spiral FFAG for therapy _at_ Grenoble design study

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But
Magnets are large, complex expensive! Accelerato
rs larger than ideal
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Non-Scaling FFAGs

• Non-scaling FFAGs - throw out scaling
  requirement ? much more flexibility

• Much smaller, simpler and cheaper magnets
• More compact machines

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Non-Scaling FFAGs

• Invented in 1999
• Accelerator facility for Particle Physics -
  for muon acceleration
• More recently, potential for other applications
  noted
• High intensity proton ion beams
• fundamental physics
• proton beams for cancer therapy
• carbon
• ADSR
• etc

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But.

• NS-FFAGs have potential, but
• They also have unique optical features
• small orbit excursion large momentum
  compaction
• rapid tune changes ? multiple resonance
  crossings
• asynchronous acceleration
• All work so far is theoretical!
• no such machine ever built
• may not work, assumptions wrong, h/w impossible,
  etc
• Must build one proof-of-principle NS-FFAG -
  EMMA
• Must also do more complete study for hadron
  therapy
• And eventually build a prototype - PAMELA

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Resonances

• Resonances generally considered bad news

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Resonances
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4
4
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But.

• NS-FFAGs have potential, but
• They also have unique optical features
• small orbit excursion large momentum
  compaction
• rapid tune changes ? multiple resonance
  crossings
• asynchronous acceleration
• All work so far is theoretical!
• no such machine ever built
• may not work, assumptions wrong, h/w impossible,
  etc
• Must build one proof-of-principle NS-FFAG -
  EMMA
• Must also do more complete study for hadron
  therapy
• And eventually build a prototype - PAMELA

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Asynchronous Acceleration
For relativistic particles short acceleration
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But.

• NS-FFAGs have potential, but
• They also have unique optical features
• small orbit excursion large momentum
  compaction
• rapid tune changes ? multiple resonance
  crossings
• asynchronous acceleration
• All work so far is theoretical!
• no such machine ever built
• may not work, assumptions wrong, h/w impossible,
  etc
• Must build one proof-of-principle NS-FFAG -
  EMMA
• Must also do more complete study for hadron
  therapy
• And eventually build a prototype - PAMELA

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EMMA

• Electron Model of Many Applications
• 10-20MeV electron NS-FFAG
• Purest type for proof-of-principle
• Will be built at DL use ALICE (ERLP) as
  injector
• Design is complete
• Prototypes ordered/built
• Specs
• 42 cells, doublet lattice
• 16.5m circumference
• RF every other cell, 1.3GHz
• lots of diagnostics
• lots of flexibility

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EMMA
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EMMA
ALICE currently being commissioned
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EMMA
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EMMA Hardware

• Magnet prototypes built and tested

• 84 production magnets ordered
• Staged delivery until August
• Prototype RF cavity almost complete

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EMMA Hardware

• Magnet prototypes built and tested

• 84 production magnets ordered
• Staged delivery until August
• Prototype RF cavity almost complete
• 20 production cavities to be ordered soon
• PSUs for magnets and RF designed
• Kicker magnets and septa going for tender soon
• Diagnostics and engineering well advanced

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What will EMMA tell us..
..that is relevant for proton acceleration to
make muons?

• Dont actually know that they will work -
  studied with variety of codes - 3 home built
  codes are best - but dont know if they are
  correct!
• Unique features - huge/tiny momentum
  compaction - resonances - asynchronous
  acceleration

• Machine construction - compactness most
  difficult aspect of EMMA - magnets -
  extraction at any energy - asymmetries

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PAMELA

• Hope proton therapy facility built somewhere
• Design of a full carbon facility made with
  NS-FFAGs
• Design of prototype based on this PAMELA
• What PAMELA will be is not yet decided
• But - some part of carbon facility -
  useful energy carbon ions for study -
  expandable to full facility
• Several options..

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PAMELA
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PAMELA

• Single ring option. - F0D0 lattice (more
  space, no ve bend) - normally conducting magnets

0.25m version being developed
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PAMELA - Issues

• Non-relativistic particles large velocity
  change
• revolution frequency increase
• must change RF frequency
• low Q cavities, but with large gain (1MV/turn)?
• acceleration slower than relativistic FFAGs
• RF system is a major issue needing study
• Resonances may be a problem (EMMA, tracking)

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PAMELA - Issues

• Non-relativistic particles large velocity
  change
• revolution frequency increase
• must change RF frequency
• low Q cavities, but with large gain (1MV/turn)?
• acceleration slower than relativistic FFAGs
• RF system is a major issue needing study
• Resonances may be a problem (EMMA, tracking)

• flatten them

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PAMELA - Issues

• Non-relativistic particles large velocity
  change
• revolution frequency increase
• must change RF frequency
• low Q cavities, but with large gain (1MV/turn)?
• acceleration slower than relativistic FFAGs
• RF system is a major issue needing study
• Resonances may be a problem (EMMA, tracking)

• flatten them

• jump them
• minimise them
• Injection and extraction need work easier for
  muons
• Intensity requirements?

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Conclusions

• FFAGs look very promising for
• hadron therapy
• proton drivers ADS, neutrons, muons,
• muon, electron, etc, acceleration
• But..
• still needs to be proved!
• must build proof-of-principle NS-FFAG
• must design full energy hadron therapy complex
• must build (useful) prototype
• Will be done by BASROC/CONFORM