Rob Edgecock, Roger Barlow, David Bruton, Basil Gonsalves, Carol Johnstone & Jordan Taylor Industrial partners: GE & Tesla Compact High Current FFAG for Compact High Current FFAG for Radioisotope Production Radioisotope Production • Reminder about FFAGs • Status of radioisotope FFAG - results from beam dynamics - first look at machine components • Potential performance • Next Steps • Conclusions
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Rob Edgecock, Roger Barlow, David Bruton, Basil Gonsalves, Carol Johnstone & Jordan Taylor Industrial partners: GE & Tesla Compact High Current FFAG for.
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Rob Edgecock, Roger Barlow, David Bruton, Basil Gonsalves, Carol Johnstone & Jordan
Taylor
Industrial partners: GE & Tesla
Compact High Current FFAG for Compact High Current FFAG for Radioisotope ProductionRadioisotope Production
• Reminder about FFAGs
• Status of radioisotope FFAG- results from beam dynamics- first look at machine components
• Potential performance
• Next Steps
• Conclusions
FFAGsFFAGs
Fixed Field Alternating Gradient accelerators:
Very similar to cyclotrons
Two types (sort of): scaling and non-scaling
Scaling invented in late 1950s
20 to 400 keV machine
Operated at MURA in 1956
Sector focussed
cyclotron but much larger
flutter and field gradient
Scaling for constant
betatron tunes
Bohr
Chandrasekhar
Scaling FFAGsScaling FFAGs
Re-invented in Japan in late 1990s
For muon acceleration
Has resulted in the construction of >6 scaling machines
Non-scaling FFAGsNon-scaling FFAGs
Invented in US in late 1990s
For muon acceleration
First type: linear non-scaling FFAG
o Large beam acceptance
o Parabolic time of flight
/p
Path length
/p
Travel time
27
14
8
First (and only) non-scaling FFAGFirst (and only) non-scaling FFAG
20MeV electron proof of principle accelerator
EMMA
Carbon Therapy FFAGCarbon Therapy FFAG
PAMELA – non-linear non-scaling FFAG
Our FFAGOur FFAG
More cyclotron-like
Wedge-shaped magnets
o Gradient focussing
o Edge focussing
o Weak focussing
Allows simultaneous tune and tof control
o Flat(ish) tunes
o Isochronous enough for fixed RF frequency
o CW operation
Three designs done:
o ~ 28 MeV for radioisotope production
o 330 MeV for proton therapy and proton CT
o 430MeV/n for therapy with ions up to neon
Radioisotope machineRadioisotope machine
Four identical wedge-shaped magnets
No reverse bend, fields to sextupole
Assumed 2 RF cavities – 200 keV/turn
Plenty of space for:- injection- extraction- instrumentation- pumps
Performance from trackingPerformance from tracking
Manufacturer Cyclotron Energy/MeV Maximum Current/mA
ACS TR30 30 ~1
ACS TR24 24 ~0.3
ACS TR19 19 ~0.3
IBA Cyclone 30 30 1.2
IBA Cyclone 70 70 0.75
IBA Cyclone 19 19 0.15
Siemens Eclipse HP 11 0.12
GE PETrace 16.5 ~0.1
From IAEA Tech Report 465 2008
FlexibilityFlexibility
Alphas:
28 MeV protons = 28.2 MeV α Acceleration to 28.2 MeV works with same field map TOF ~twice
- use 1st and 2nd RF harmonics?- but with small frequency change- needs to be studied
Variable energy:
10 MeV orbit moved to 28 MeV radius by simple field scaling
TOF a little worse Fixed by a very small tweak But RF frequency quite different?
InjectionInjection
Use external ion sources: - high beam current - more flexibility - easier to replace
But beam capture more difficult Usually, axial injection Various methods used to steer vertical beam into horizontal plane
InjectionInjection
Spiral inflector
Left dee
Right dee
Problems:-Complicated 3D fields-Tends to be lossy
InjectionInjection
Alternative: horizontal injection Allows higher energy Use septum, electrostatic deflector, etc to steer beam onto EO Separation between first two orbits >7cm, plenty of space Beam dynamics under investigation
Magnet ConceptsMagnet Concepts
Sector gradient magnets Scaling FFAGs and AVF cyclotrons (higher energy cyclotrons have gradient
magnets)
Several designs under study Vary gap size as a function of energy to create increasing gradient Coils - TRIUMF and PSI cyclotrons have coils to tune gradients Hybrid designs exploiting permanent magnet yoke material with
electromagnets
High energy gradient magnet (left) and hybrid permanent magnet design (right) which can be scaled to achieve the correct radial gradient. Coils can be added to slots in poles in both designs.
CavitiesCavities
Initial thoughts only Use cyclotron Dee cavity designs:
- 2 cavities- double gap(?)
- 50 kV/gap- tunable for α’s
Main issue: gap at low energy- higher energy injection?- variable voltage with energy
Central region needs optimisation Need expert input!
PSI injector double gap cavity400 kV/gap
Target OptionsTarget Options
Two possibilities
• Internal:- pass the beam through thin target many times- restore lost energy every turn- relies on large acceptance- similar to ERIT, but heavier target
• External:- multiple targets
Target OptionsTarget Options
Internal:200keV energy loss ≈ 10μm 100Mo
Yield/turn = 0.1mCi/μAh at 14 MeV
External target yield = 4.74mCi/μAh
→ 48 turns
Internal target issues:cooling
outgasingprocessing
Target OptionsTarget Options
External – two options:
• Charge exchange extraction, as used in cyclotrons:- lossy- not possible for α’s- foil heating and lifetime can be a problem
• Electrostatic deflector and septum
Radioisotope ProductionRadioisotope Production
Yields of various imaging isotopes – all identified of importance by IAEA - using Talys for 1 hr at 2mA
Isotope Production Beam Energy
Beam Typical patient
doses/hr99mTc - SPECT 100Mo(p,2n)99mTc 14 MeV p 2300123I - SPECT 124Te(p,2n)123I 28 MeV p 18000111In – SPECT 109Ag(α,2n)111In 28 MeV α 10018F - PET 18O(p,n)18F 10 MeV p 1300011C - PET 14N(p,α)11C 10 MeV p 1600068Ga - PET 68Zn(p,n)68Ga 14 MeV p 80000