Rob Edgecock, Roger Barlow, David Bruton, Basil Gonsalves, Carol Johnstone & Jordan Taylor Industrial partners: GE & Tesla Compact High Current FFAG for Radioisotope Production Reminder about FFAGs Status of radioisotope FFAG - results from beam dynamics - first look at machine components Potential performance Next Steps Conclusions

FFAGs 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 FFAGs Re-invented in Japan in late 1990s  For muon acceleration  Has resulted in the construction of >6 scaling machines

Non-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

First (and only) non-scaling FFAG 20MeV electron proof of principle accelerator EMMA

Carbon Therapy FFAG PAMELA – non-linear non-scaling FFAG

Our 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 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  Studied using COSY Infinity & Opal  Injection energy:75 keV  Extraction:10 MeV – 102cm 14 MeV – 120cm 28 MeV – 170cm

Performance from tracking Time of flight Protons to 28 MeV: isochronous to 0.3%

Performance from tracking Tunes Protons to 28 MeV 250 keV – just over one turn

Performance from tracking Acceptances 14 MeV 10 MeV 20 MeV 28 MeV 1 MeV

Performance from tracking Energy/MeV x/π.m.mrad y/π.m.mrad Acceptances Protons to 28 MeV – huge! In Opal, with space charge, 20mA to 28 MeV

Performance from tracking ManufacturerCyclotronEnergy/MeVMaximum Current/mA ACSTR3030~1 ACSTR2424~0.3 ACSTR1919~0.3 IBACyclone IBACyclone IBACyclone SiemensEclipse HP GEPETrace16.5~0.1 From IAEA Tech Report

Flexibility Alphas:  28 MeV protons = 28.2 MeV α  Acceleration to 28.2 MeV works with same field map  TOF ~twice - use 1 st and 2 nd 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?

Injection  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

Injection Spiral inflector Left dee Right dee Problems: -Complicated 3D fields -Tends to be lossy

Injection  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 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.

Cavities  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 cavity 400 kV/gap

Target 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 Options Internal: 200keV energy loss ≈ 10μm 100 Mo Yield/turn = 0.1mCi/μAh at 14 MeV External target yield = 4.74mCi/μAh → 48 turns Internal target issues: cooling outgasing processing

Target 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 Production Yields of various imaging isotopes – all identified of importance by IAEA - using Talys for 1 hr at 2mA IsotopeProductionBeam Energy BeamTypical patient doses/hr 99m Tc - SPECT 100 Mo(p,2n) 99m Tc14 MeVp I - SPECT 124 Te(p,2n) 123 I28 MeVp In – SPECT 109 Ag(α,2n) 111 In28 MeVα F - PET 18 O(p,n) 18 F10 MeVp C - PET 14 N(p,α) 11 C10 MeVp Ga - PET 68 Zn(p,n) 68 Ga14 MeVp80000

Therapeutic Radioisotopes All reactor produced None in the UK Supply can be a problem Some isotopes need α: 211 At, 67 Cu, 47 Sc, 161 Tb Recent review said: UK situation: It is recommended that a national strategy for the use of radiotherapeutics for cancer treatment should be developed to address the supply of radiotherapeutics, projected costs of drugs and resources, the clinical introduction of new radioactive drugs, national equality of access to treatments and resource planning.

Therapeutic Radioisotopes All reactor produced None in the UK Supply can be a problem Some isotopes need α: 211 At, 67 Cu, 47 Sc, 161 Tb Recent review said: UK situation: It is recommended that a national strategy for the use of radiotherapeutics for cancer treatment should be developed to address the supply of radiotherapeutics, projected costs of drugs and resources, the clinical introduction of new radioactive drugs, national equality of access to treatments and resource planning.

Radioisotope Production

IsotopeProductionBeam Energy BeamYield/mCi 177 LunatHf(p,x) 177 Lu28 MeVp Sm 150 Nd(α,n) 153 Sm28 MeVα8 211 At 209 Bi(α,2n) 211 At28 MeVα Cu 64 Ni(α,p) 67 Cu28 MeVα19 47 Sc 44 Ca(α,p) 47 Sc28 MeVα Ac 226 Ra(p,2n) 225 Ac19 MeVp607

Next steps Continue to search for funding! Continue modelling: - optimise lattice - study internal targets - study extraction and beam delivery - look at central region and beam capture Engineering: - magnet design - RF design - injection and extraction - target design → Business case Aim: - build it to make and sell radioisotopes - commercialise the FFAG - proof of principle of higher energy machines

Next steps

Conclusions New type of FFAG/SFC looks very promising for: - radioisotope production - proton therapy & pCT - ion therapy For radioisotopes, very large acceptance: - beam current up to 20mA - possibility of internal target Main next step: engineering, especially magnets Business case would open up opportunities for construction