1. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi PAMELA an approach to particle therapy using NS-FFAG Takeichiro Yokoi (JAI, Oxford University, UK) On behalf of PAMELA collaboration

2. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Contents Overview of CONFORM & PAMELA PAMELA design ◆ Lattice ◆ Magnet ◆ RF ◆ Extraction R&D status + extra

3. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Particle physics -factory, muon source, proton driver -factory -factory FFAG Medical Particle therapy, BNCT, X-ray source Particle therapy FFAG Energy ADSR, Nucl. Transmutation ADSR FFAG CONFORM ( 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) EMMA PAMELA (PAMELA) Introduction... FFAG(Fixed Field Alternating Gradient) Accelerator has an ability of rapid particle acceleration with large beam acceptance.  wide varieties of applications

4. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi CONFORM: Project Overview 3.5 years project(Apr. 2007~) with total funds £ 6.9m from STFC (UK government) 3 parts of the project are funded 1. 1. EMMA : Construction of electron NS-FFAG as a scale down model of muon accelerator for neutrino factory 2. 2. PAMELA : Design of proton and HI accelerator for particle therapy using NS-FFAG 3. 3. (other Applications) : ex ADSR (THoreA) 3 parts of the project are funded 1. 1. EMMA : Construction of electron NS-FFAG as a scale down model of muon accelerator for neutrino factory 2. 2. PAMELA : Design of proton and HI accelerator for particle therapy using NS-FFAG 3. 3. (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 International CERN FNAL (US) LPNS (FR) TRIUMF (CA) 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)

5. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi PAMELA: overview PAMELA (Particle Accelerator for MEdicaL Application) 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) Particlep,C Ext Energy:p (MeV)60~240 Ext Energy:C(MeV/u)110~450 Dose rate (Gy/min)>2 Repetition rate(KHz)0.5~1 Bunch charge:p(pC)1.6~16 Bunch charge;C(fC)300~3000 Voxel size (mm) 4  4  4~10  10  10 Spot scanning Switching time:p  c(s) <1 # of ring2 (*2nd ring :for C)

6. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Scaling FFAG realizes stable betatron tune by non-linear field B/B 0 =(r/r 0 ) k f(  ) Radial sector Spiral sector What is Scaling FFAG ? 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 by acceleration scheme (in principle, no limitation) ~1.2m KEK 150MeV FFAG It requires large excursion combined function magnet p/p 0 =(r/r 0 ) k+1 It can accelerate large emittance beam with high repetition rate (ex KEK PoP FFAG:1ms acceleration, 5000  mm·mrad) KEK 150MeV FFAG 100Hz extraction

7. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi By breaking or ignoring the scaling law: B/B 0 =(r/r 0 ) k f(  ), they aim to obtain various effects matching to their requirements ex. EMMA, Neutrino factory : small ToF variation,simple magnet system,large acceptance What is Non-Scaling FFAG ? A: “ Whatever else” Kinetic Energy(MeV) TOF/turn(ns) |df/f|~0.1% In PAMELA, NS-FFAG is employed to realize… (1) Small tune drift (  <1) (1) Small tune drift (  <1) (2) Small orbit excursion (2) Small orbit excursion (3) Simple lattice configuration (3) Simple lattice configuration (4) Operational flexibility (4) Operational flexibility

8. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi PAMELA: ring overview Proton ring Cyclotron (proton) ECR+RFQ (HI) 12.5m Carbon ring Ring #1 (p, c)Ring #2 (c) Energy30~250MeV (p) 8~68MeV/u (c) 68~400MeV/u # of Cell12 Diameter12.5m18.4 K-value3841 Orbit excursion18cm21 Rev. freq1.94~4.62MHz(p) 0.98~2.69MHz(c) 1.92~3.91MHz MagnetTriplet(FDF), SC length57cm113cm aperture25cm33cm Long Drift1.3m1.2m Packing factor0.480.65 Inj./Ext1turn inj/ext 2 LD (each) 1turn inj/ext 2 LD (each RFMax 8 LD Stable betatron tune ∆ <1 Long straight section (~1.3m) Small beam excursion(<20cm) Strong field (max 3T)  SC magnet Simple magnet configuration

9. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Lattice principle =simplification based on scaling FFAG(triplet FDF) 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) F FF F D D

10. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Cell layout Unknowns ….. Alignment scheme Alignment scheme Positioning error …. Positioning error …. Local field interference Local field interference By courtesy of N.Bliss, S.Pattalwar

11. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Magnet Superposition of helical field can form multipole field Challenges: Large aperture, short length, strong field Dipole Quadrupole Octapole Sectapole ~23cm 55cm Applicable to superconducting magnet Each multipole can be varied independently  Operational flexibility Present lattice parameters are within engineering limit By courtesy of H.Witte

12. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Magnet (2) Dipole Field quality of all the field components are well controlled (∆B i /B i (i =0~4) <1  10 -3 ) Now, 3D field is being included into tracking code

13. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Lattice: operation knobs In PAMELA, each multipole field up to decapole can be tuned individually.  Flexible tenability of operating point. Fields of scaling FFAGs built or designed ever are designed to form scaling field  Hard to change operating point after construction KEK 150MeV FFAG “Separated function FFAG” In fixed field accelerator (FFAG, cyclotron)….. Easiness of control  Hardness of commissioning and tuning Easiness of control  Hardness of commissioning and tuning In fixed field accelerator (FFAG, cyclotron)….. Easiness of control  Hardness of commissioning and tuning Easiness of control  Hardness of commissioning and tuning

14. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Lattice: operation knobs (2) Baseline tune (k=38) ∆ H <0.1 ∆ V <0.05 (1)Horizontal tune  k-value (2)Vertical tune  F/D ratio (3)Curve of tune drift  Octapole (4)Gradient of tune drift  Decapole (1)Horizontal tune  k-value (2)Vertical tune  F/D ratio (3)Curve of tune drift  Octapole (4)Gradient of tune drift  Decapole F F D

15. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Lattice : dynamic apertureHorizontal Vertical By courtesy of S.Sheehy

16. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Clinical requirement In dose field formation of particle therapy, uniformity and tolerance are two important factors Uniformity ”deviation of local dose from average dose” Tolerance ”deviation of average dose from prescribed dose” Uniformity : <2% Tolerance : <5% (existing facilities already achieved <2%) Medical requirement Uniformity : <2% Tolerance : <5% (existing facilities already achieved <2%)  Stability  Tuneability

17. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Dose control time Integrated current Synchrotron & cyclotron Gate width controls dose (extraction) “Analog IM” time Integrated current FFAG Step size controls dose (injection) “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 In PAMELA, option (2) is adopted, due to uncertainty on the precision of intensity modulation of ion source To achieve uniformity in spot scanning, beam intensity needs to be modulated depth-wise  IMPT (Intensity Modulated Particle Therapy)

18. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Beam extraction Hardware R&D of kicker is under planning (budget request) 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) Challenges: Energy variable extraction in fixed field accelerator 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 @kicker CO @septum 230MeV (B kicker :0.6kgauss) ∆x>2cm FDF Kicker#1 Septum

19. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi RF system Requirement : 1kHz repetition rate  100kV/turn Available space : 6 drift space  1.2m (L drift ~1.7m) Requirement : 1kHz repetition  100kV/turn Available space : 8 drift space  1.2m (L drift ~1.7m) Target energy gain: 15kV/turn/cavity Challenge : high duty cycle, high rate FM, high field gradient 1.1m 2 ferrite core layers P=V 2 /(4  fQL) Power dissipation is the most serious problem in high repetition operation Higher Q is favorable ~100kWPower/cavity 1kHzRepetition rate 23cmAperture 1.1mLength 19.4~46.2MHzFrequency(h=10) 15keV/turn Energy gain One solution : Ferrite loaded cavity * tuning bias current is required Relatively high Q (~100) h=10  power consumption is~100kW/cavity By C.Beard, I.Gardner, P.McIntosh, T.Yokoi

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

21. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi R&D plan By end of 2009, Overall ring design is to be finished Budget request for hardware R&D Budget request for hardware R&D 1.Magnet : fabrication process, field distribution, field quality etc 2.Kicker : wide-aperture kicker, life time etc 3.RF system :ferrite property, dynamic loss effect etc. Proposal for full size machine (+facility) construction

22. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi + Some Extra (Upgrade tips …) (Upgrade tips …)

23. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi 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) + = 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

24. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Slow Extraction in NS-FFAG Resonance point H v   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 Energy variable slow extraction in fixed field accelerator !! In PAMELA (high-K scaling FFAG), ~2% of F/D ratio can change the vertical tune more than 0.5 ∆ v =0.5 ∆D/F :0.017

25. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Direction of resonance crossing changes the beam motion in phase space Half int. resonance crossing Upward crossing BD deca 1.3 Downward crossing Octa 0.9, deca 0.2 Trimming of multipole field can control tune drift

26. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi E flattop :186MeV E flattop :182MeV E flattop :178MeV 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 ESS E flattop :174MeV t E “ With Flattop ”

27. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Multi-bunch acceleration time Energy 1ms Option 1 time Energy 1ms Option 2 Option 1: P  N rep 2 Option 2: P  N rep Multi-bunch acceleration is preferable from the viewpoint of efficiency and upgradeability Low Q cavity (ex MA) can mix wide range of frequencies There are two accelerating options in fixed field accelerator

28. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Multi-bunch acceleration (2) 2-bunch acceleration using POP-FFAG (PAC 01 proceedings p.588) ∆f  4 f sy 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)

29. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi 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

30. 22 Oct 2009@ NSS-MIC 09, HT09 PAMELA, T.Yokoi Special thanks to PAMELA Collaboration, and thank you for your attention