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PAMELA an approach to particle therapy using NS-FFAG

PAMELA an approach to particle therapy using NS-FFAG. Takeichiro Yokoi (JAI, Oxford University, UK) On behalf of PAMELA collaboration. Contents. Overview of CONFORM & PAMELA PAMELA design Lattice Magnet RF Extraction R&D status + extra. EMMA. Particle therapy. Particle physics.

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PAMELA an approach to particle therapy using NS-FFAG

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  1. PAMELA an approach to particle therapy using NS-FFAG Takeichiro Yokoi (JAI, Oxford University, UK) On behalf of PAMELA collaboration PAMELA , T.Yokoi

  2. Contents • Overview of CONFORM & PAMELA • PAMELA design • Lattice • Magnet • RF • Extraction • R&D status • + extra PAMELA , T.Yokoi

  3. EMMA Particle therapy Particle physics Medical -factory, muon source, proton driver PAMELA FFAG Particle therapy, BNCT, X-ray source ADSR FFAG Energy (PAMELA) FFAG ADSR, Nucl. Transmutation -factory CONFORM (Construction of a Non-scaling FFAG for Oncology, Research and Medicine)aims to develop the Non-scaling FFAG as a versatile accelerator. (Project HP: www.conform.ac.uk) Introduction ... • FFAG(Fixed Field Alternating Gradient) Accelerator has an ability of rapid particle acceleration with large beam acceptance.  wide varieties of applications PAMELA , T.Yokoi

  4. 3 parts of the project are funded • EMMA : Construction of electron NS-FFAG as a scale down model of muon accelerator for neutrino factory • PAMELA : Design of proton and HI accelerator for particle therapy using NS-FFAG • (other Applications) : ex ADSR (THoreA) Project manager : K.Peach (JAI, Oxford university) UK based : Birmingham University Brunel Utility Cockcroft Institute Daresbury Laboratory Gray Cancer Institute Imperial College London John Adams Institute Manchester University Oxford University Rutherford Appleton Laboratory Project manager : K.Peach (JAI, Oxford university) UK based : Birmingham University Brunel Utility Cockcroft Institute Daresbury Laboratory Gray Cancer Institute Imperial College London John Adams Institute Manchester University Oxford University Rutherford Appleton Laboratory International CERN FNAL (US) LPNS (FR) TRIUMF (CA) International CERN FNAL (US) LPNS (FR) TRIUMF (CA) CONFORM: Project Overview • 3 parts of the project are funded • EMMA : Construction of electron NS-FFAG as a scale down model of muon accelerator for neutrino factory • PAMELA : Design of proton and HI accelerator for particle therapy using NS-FFAG • (other Applications) : ex ADSR (THoreA) • 3.5 years project(Apr. 2007~) with total funds £6.9m from STFC (UK government) PAMELA , T.Yokoi

  5. PAMELA: overview • PAMELA (Particle Accelerator for MEdicaLApplication) aims to design a particle therapy facility using NS-FFAG  Prototype of versatile FFAG(ex ADSR) • It aims to provide spot scanning with proton and carbon beam. • 2 cascaded ring (for proton, only 1st ring is used, for carbon, 1st ring works as a booster) • High repetition rate is a big challenge • on going R&D Items • 1. Injector • 2. Proton ring, Carbon ring • 3. Transport • 4. (Gantry) PAMELA , T.Yokoi

  6. Acceleration rate of ordinary synchrotron is limited by the ramping speed of magnet (magnet PS :V=L·dI/dt, eddy loss: rot E+dB/dt=0) Acceleration rate of ordinary synchrotron is limited by the ramping speed of magnet (magnet PS :V=L·dI/dt, eddy loss: rot E+dB/dt=0) Acceleration rate of fixed field accelerator is limited byacceleration scheme (in principle, no limitation) Acceleration rate of fixed field accelerator is limited byacceleration scheme (in principle, no limitation) • Scaling FFAG realizes stable betatron tune by • non-linear field B/B0=(r/r0)k f() • It requires large excursion combined function magnet p/p0=(r/r0)k+1 • It can accelerate large emittance beam with high repetition rate (ex KEK PoP FFAG:1ms acceleration, 5000 mm·mrad) ~1.2m Radial sector KEK 150MeV FFAG KEK 150MeV FFAG 100Hz extraction Spiral sector What is Scaling FFAG ? PAMELA , T.Yokoi

  7. By breaking or ignoring the scaling law: B/B0=(r/r0)k f(),they aim to obtain various effects matching to their requirements ex. EMMA, Neutrino factory : small ToF variation,simple magnet system,large acceptance |df/f|~0.1% TOF/turn(ns) Kinetic Energy(MeV) What is Non-Scaling FFAG ? A: “ Whatever else” In PAMELA, NS-FFAG is employed to realize… (1) Small tune drift (<1) (2) Small orbit excursion (3) Simple lattice configuration (4) Operational flexibility PAMELA , T.Yokoi

  8. Proton ring Carbon ring 12.5m Cyclotron (proton) ECR+RFQ (HI) • Stable betatron tune ∆<1 • Long straight section (~1.3m) • Small beam excursion(<20cm) • Strong field (max 3T)  SC magnet • Simple magnet configuration PAMELA: ring overview PAMELA , T.Yokoi

  9. Step 1. Truncated multipole field Tune drift width depends on included order of multipole field (in PAMELA, up to decapole) Step 2. Sector magnet  rectangular magnet Step 3. Magnet is linearly aligned (* scaling FFAG is co-centric) D F F D F F Lattice principle =simplification based on scaling FFAG(triplet FDF) PAMELA , T.Yokoi

  10. Cell layout • Unknowns ….. • Alignment scheme • Positioning error …. • Local field interference By courtesy of N.Bliss, S.Pattalwar PAMELA , T.Yokoi

  11. 55cm Superposition of helical field can form multipole field ~23cm Quadrupole Dipole Sectapole Octapole Magnet Challenges: Large aperture, short length, strong field • Applicable to superconducting magnet • Each multipole can be varied independently  Operational flexibility • Present lattice parameters are within engineering limit By courtesy of H.Witte PAMELA , T.Yokoi

  12. Dipole Magnet (2) Field quality of all the field components are well controlled (∆Bi/Bi (i =0~4)<110-3) Now, 3D field is being included into tracking code PAMELA , T.Yokoi

  13. In fixed field accelerator (FFAG, cyclotron)….. Easiness of control  Hardness of commissioning and tuning In fixed field accelerator (FFAG, cyclotron)….. Easiness of control  Hardness of commissioning and tuning Fields of scaling FFAGs built or designed ever are designed to form scaling field Hard to change operating point after construction KEK 150MeV FFAG In PAMELA, each multipole field up to decapole can be tuned individually.  Flexible tenability of operating point. Lattice: operation knobs “Separated function FFAG” PAMELA , T.Yokoi

  14. ∆H<0.1 ∆V<0.05 Horizontal tune  k-value Vertical tune  F/D ratio Curve of tune drift  Octapole Gradient of tune drift  Decapole Horizontal tune  k-value Vertical tune  F/D ratio Curve of tune drift  Octapole Gradient of tune drift  Decapole F D F Lattice: operation knobs (2) Baseline tune (k=38) PAMELA , T.Yokoi

  15. Lattice : dynamic aperture Vertical Horizontal By courtesy of S.Sheehy PAMELA , T.Yokoi

  16. In dose field formation of particle therapy, uniformity and tolerance are two important factors In dose field formation of particle therapy, uniformity and tolerance are two important factors Stability Tuneability Medical requirement Uniformity : <2% Tolerance : <5% (existing facilities already achieved <2%) Uniformity : <2% Tolerance : <5% (existing facilities already achieved <2%) Clinical requirement Uniformity ”deviation of local dose from average dose” Tolerance ”deviation of average dose from prescribed dose” PAMELA , T.Yokoi

  17. Synchrotron & cyclotron FFAG Gate width controls dose (extraction) Step size controls dose (injection) Integrated current Integrated current time time “Analog IM” “Digital IM” With pulsed beam of FFAG, to realize intensity modulation ….. (1) Dynamic modulation of injector beam intensity complicated system, but low repetition rate (2) multi-beam painting with small bunch intensity simple system, but high repetition rate Dose control To achieve uniformity in spot scanning, beam intensity needs to be modulated depth-wise IMPT (Intensity Modulated Particle Therapy) In PAMELA, option (2) is adopted, due to uncertainty on the precision of intensity modulation of ion source PAMELA , T.Yokoi

  18. ∆x>2cm @kicker Vertical extraction was adopted in PAMELA Advantages: (1) weaker field,(max 0.6kgauss1m) (2) good matching with FFAG transport, (3) extraction kicker can be used as injection kicker Septum Kicker#1 CO FDF FDF @septum 230MeV (Bkicker:0.6kgauss) Problems: (1) Uncertainty of inductance (aperture g:19cm,w:3cm,l:100cm) (2) Uncertainty of fringing field (*vertical dynamics is sensitive to fringing field  3D field tracking is crucially important) (3) Upgradeability to carbon ring Kicker aperture(cm) 3(V) 20(H) Kicker length(cm) 100 Inductance(H) 0.2 (anly) 0.4 (FEA) Kicker field(kgauss) 0.6 Kicker HV(kV) 25(anly) 50(sim) Beam extraction Challenges: Energy variable extraction in fixed field accelerator Hardware R&D of kicker is under planning (budget request) PAMELA , T.Yokoi

  19. Energy gain 15keV/turn Power dissipation is the most serious problem in high repetition operation Frequency(h=10) 19.4~46.2MHz 2 ferrite core layers Length 1.1m P=V2/(4fQL) Aperture 23cm Repetition rate 1kHz Higher Q is favorable Power/cavity ~100kW One solution : Ferrite loaded cavity * tuning bias current is required 1.1m • Relatively high Q (~100) • h=10  power consumption is~100kW/cavity By C.Beard, I.Gardner, P.McIntosh, T.Yokoi RF system Requirement : 1kHz repetition rate 100kV/turn Available space : 6 drift space  1.2m (Ldrift~1.7m) Target energy gain: 15kV/turn/cavity Requirement : 1kHz repetition  100kV/turn Available space : 8 drift space  1.2m (Ldrift~1.7m) Challenge : high duty cycle, high rate FM, high field gradient PAMELA , T.Yokoi

  20. PAMELA Development has just started Step 1: Ferrite property measurement Permeability of a ferrite (Ferroxcube 4D2) Q-value Power density dependence (high loss effect) Step 2: Prototyping (budget request is needed) Power dissipation FM rate dependence (dynamic loss effect) Phase error problem RF system (2) rf system operated with high power, high frequency modulation rate needs to consider ….. (1) Dynamic loss effect (2) High loss effect (3) Phase error

  21. Budget request for hardware R&D Proposal for full size machine (+facility) construction R&D plan By end of 2009, Overall ring design is to be finished Magnet : fabrication process, field distribution, field quality etc Kicker : wide-aperture kicker, life time etc RF system :ferrite property, dynamic loss effect etc. PAMELA , T.Yokoi

  22. + Some Extra (Upgrade tips …) PAMELA , T.Yokoi

  23. Active chopper might help for precise and flexible dose control (for h=1 cavity) Existing programmable delay generator can provide delay with a step size of <1ns Direct intensity modulation of large dynamics range might be possible (1voxel/1shot) + = In pulsed beam accelerator (FFAG), injector and RF scheme should be investigated from the standpoint of dose tuneability and stabilization In pulsed beam accelerator (FFAG), injector and RF scheme should be designed from the standpoint of dose tuneability and stabilization Direct Intensity modulation Dose tolerance requires precise, flexible and easy tuneabiliy of beam intensity in actual treatment  Tuneability of ion source output might be a problem (Nonlinearity of plasma formation process) PAMELA , T.Yokoi

  24. ∆D/F :0.017 H Resonance point ∆v=0.5 v In PAMELA (high-K scaling FFAG), ~2% of F/D ratio can change the vertical tune more than 0.5 • In a lattice with vertical tune drift, by changing the F/D ratio, resonance energy can be varied  Half integer resonance can be used for beam extraction Slow Extraction in NS-FFAG Energy variable slow extraction in fixed field accelerator !! PAMELA , T.Yokoi

  25. Upward crossing Downward crossing BD deca 1.3 Octa 0.9, deca 0.2 Direction of resonance crossing changes the beam motion in phase space Half int. resonance crossing Trimming of multipole field can control tune drift PAMELA , T.Yokoi

  26. Eflattop:182MeV Eflattop:174MeV Eflattop:186MeV Eflattop:178MeV ESS “With Flattop” E t Downward slow extraction • By adjusting flattop energy, low energy tail can be minimized alternative option of extraction scheme especially for carbon ring • Extraction rate control is difficult PAMELA , T.Yokoi

  27. Option 2 Energy Energy Option 1 time time 1ms 1ms Option 1: P Nrep2 Option 2: P Nrep Multi-bunch acceleration There are two accelerating options in fixed field accelerator Low Q cavity (ex MA) can mix wide range of frequencies Multi-bunch acceleration is preferable from the viewpoint of efficiency and upgradeability PAMELA , T.Yokoi

  28. ∆f  4 fsy 2-bunch acceleration using POP-FFAG (PAC 01 proceedings p.588) Multi-bunch acceleration (2) Multi-bunch acceleration has already been demonstrated In the lattice considered, typical synchrotron tune <0.01  more than 20 bunches can be accelerated simultaneously (6D Tracking study is required) PAMELA , T.Yokoi

  29. Summary • PAMELA intends to design particle therapy facility to deliver proton and carbon using NS-FFAG. • 1kH is the target repetition rate and big challenge • Fixed field and flexible tuneability of operating point can provide wide variety of operation mode  promising candidate for versatile proton accelerator • Dose control is one of key issues of particle therapy using pulsed beam accelerator • Intensive study is going on (dynamics, rf, magnet, clinical requirement etc.)  By the end of this year , an doable overall scenario is planned to be proposed .  Hardware R&D proposals will be followed PAMELA , T.Yokoi

  30. Special thanks to PAMELA Collaboration, and thank you for your attention PAMELA , T.Yokoi

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