Fast circular accelerators for future muon and proton beams

1. Fast circular accelerators for future muon and proton beams J. Pasternak, Imperial College / RAL STFC J. Pasternak

2. Fast circular accelerators for future muon and proton beams Outline of the talk • Introduction. • Present day high intensity proton accelerators. • FFAG accelerators and their history. • FFAG projects around the world.. • Neutrino Factory and muon acceleration. • Summary. J. Pasternak

3. Introduction - HEP road map LHC, ILC, CLIC, Muon Collider, laser acceleration… • Cosmic rays • Radio and visible • telescopes • CMB • … • Kaon physics • B physics • Muon physics • Neutrino beams • Neutrino Factory • Muon Collider • Neutron sources • ADS for energy • production • … J. Pasternak

4. Present day high intensity drivers ISIS 70 MeV H– linac 0.2 MW + 800 MeV H+ synchrotron J-PARC 180 MeV H– linac 0.2 MW1 + 3 GeV + 50 GeV synchrotrons LANSCE 800 MeV H+ /H– linac 0.8 MW + accumulator ring PSI 590 MeV cyclotron 1.2 MW + 72 MeV injector cyclotron SNS 1 GeV H– linac 0.6 MW2 + accumulator ring 1: For limited time during commissioning; ultimate design 1 MW with 400 MeV linac. 2: Still commissioning; 1 MW design operation. J. Pasternak

5. ISIS Facility at RAL 70 MeV H– linac 800 MeV proton synchrotron TS-1 J. Pasternak

6. ISIS Injection MICE pion line J. Pasternak

7. ISIS MW Upgrade The reference solution is based on 3.2 GeV 50 Hz RCS (Rapid Cycling Synchrotron) with bucket-to-bucket transfer from the present 800 MeV ISIS ring. The design can be further upgraded with the help of direct charge exchange injection from 800 MeV H- linac J. Pasternak

8. Introduction FFAG – Fixed Field Alternating Gradient accelerator is a ring with a strong focusing lattice, very large momentum acceptance and small dispersion First proposed by Okhawa and Symon et al. In 1953 POP-world first proton FFAG (Mori et al.- 2000) Electron model from 50ties (MURA) J. Pasternak

9. Advantages of FFAG accelerators: • Constant fields allow for very high repetition rate (100 Hz – kHz) • Constant tunes (or linear fields) give large acceptances • Strong focusing reduces dispersion (orbit excursion), which limits • the magnet size High Intensity • FFAG applications: • High power proton drivers (4-10 MW) for neutrino factory, muon collider, • neutron sources, ADS… • Acceleration of unstable particle beams (muons, radioactive ions) • Medical applications J. Pasternak

10. FFAG with respect to other circular machines Machine Cyclotron Synchrotron FFAG Magnetic field constant changing constant RF frequency constantchanging changing (not always) Orbit changing constant changing Tune changing constant constant (not always) J. Pasternak

11. Scaling versus Non-Scaling FFAG FFAG type Scaling Non-scaling Magnetic field linear Orbits scale non-scale Dispersion small very small J. Pasternak

12. FFAG type Scaling Non-scaling Tune constant changing (not always) Acceleration RF with swing RF with swing stationary bucket quasi-isochronous harmonic number jump – HNJ HNJ y x J. Pasternak

13. History of FFAG 1953- Okhawa i Symon et al. MURA two beam accelerator MURA spiral ring J. Pasternak

14. History (2) • 2000 First proton FFAG with RF acceleration, group of prof. Y. Mori at KEK – • POP (Proof Of Principle) machine • 150 MeV ring • 2008 Beam extracted from the KURRI chain J. Pasternak

15. Current Projects and R&D • KURRI FFAG chain for ADS studies • PRISM – phase rotation for muons • ERIT – neutron source for BNCT • EMMA – first non-scaling ring • RACCAM – R&D for hadrontherapy • PAMELA – R&D for hadrontherapy • (subject of another HEP seminar soon) • IDS – R&D towards the Neutrino Factory J. Pasternak

16. Projects (1) KURRI ADS chain J. Pasternak

17. PROJECTS (3) (Phase Rotated Intense Slow Muon source) J. Pasternak

18. PROJECTS (2) EMMA (Electron Model for Many Applications) • EMMA – first non-scaling FFAG: • Model for muon accelerator at the Neutrino • Factory • Demonstration of novel acceleration • principle (10 –20 MeV) • Experiments for fast resonance crossing • Under construction in DL (UK). J. Pasternak

19. Motivations for a Medical FFAG Hadrontherapy shows up to be more effective for cancer treatment comparing to the conventional radiotherapy! • Advantages of FFAG for medical applications: • - High dose delivery 5 Gy/min/l (high rep rate – 100 Hz) • - Variable energy operation without enegy degraders • - Compact size and low cost • - Simple and efficient extraction • - Stable and easy operation • Multiple extraction ports • Bunch to Pixel treatment. J. Pasternak

20. Medical FFAG - RACCAM Project Variable energy from injector by changing the stripper position –(H- AIMA cyclotron) + Variable magnetic field in FFAG magnets = Variable extraction energy from FFAG for treatment J. Pasternak

21. RACCAM Project (2) • Number of cells 10 • Field index 5. • Spiral angle 53.7° • Rmax 3.46 m • Rmin 2.8 m • (Qx, Qy) (2.77, 1.64) • Bmax 1.7 T • pf 0.34 • Injection energy 6-15 MeV • Extraction energy 75-180 MeV • h 1 • RF frequency 1.9 – 7.5 MHz • Bunch intensity 3109 protons • Normal conducting magnets • Magnet prototype successfully constructed • at SigmaPhi! J. Pasternak

22. Current R&D for Neutrino Factory American NuFact project Japan NuFact project Muon acceleration for Neutrino Factory and Muon Collider may be realized in FFAG accelerators operating with constant RF frequency J. Pasternak

23. NuFact – Lab for leptonic CP violation search J. Pasternak

24. Reference IDS Neutrino Factory Design nsFFAG J. Pasternak

25. IDS designs by J. Scott Berg J. Pasternak

26. Scott’s FODO, 1 out of 62 cells lqf lqd thd/2 (angle) Ldrift = 2 m D,+ dxf dxd F,- thf/2 (angle) b0f, b1f lqf = +2.1965 m thf = -3.1046e-02 rad dxf = -1.9979e-03 m b0f = -8.3898e-01 T b1f = +1.2202e+01 T/m n = 62 lqd = +1.2550e+00 m thd = +1.3238e-01rad dxd = +4.3393e-02 m b0d = +6.1269e+00 T b1d = -1.5752e+01 T/m b0d, b1d J. Pasternak

27. Beam dynamics in IDS nsFFAG Qx, Qy T, ns E, MeV E, MeV x’, rad Orbit in D magnet, m E, MeV x, m J. Pasternak

28. Problems of IDS nsFFAG • Very compact lattice with short straight sections - very difficult injection/extraction. • Due to natural chromaticity time of flight depends on amplitude – • longitudinal blow-up and acceptance limitation. • Beam loading. Corrected chromaticity, study by S. Machida Natural chromaticity J. Pasternak

29. Horizontal extraction m m Parameters: 10 kickers – 1.4 m, 0.125 T and septum – 1.4 m, 4 T. J. Pasternak

30. Vertical extraction m m Parameters: 6 kickers – 1.4 m, 0.07 T and septum – 1.4 m, 4 T. J. Pasternak

31. Summary and future plans for IDS nsFFAG • Reference design for the muon acceleration in • the Neutrino Factory exists. • Beam dynamics has been successfully • checked using independent codes. • Extraction looks not impossible, but very challanging! • Work continues on injectio/extraction, towards lattices with • insertions and chromaticity correction • Further beam dynamics studies are needed. • We need a study of hardware components, magnets, • RF, kickers, septum, etc. J. Pasternak

32. Summary: • We are observing a rebirth of FFAGs after 50 years of silence. • Machines constructed until now work very well! • Several projects are under implementation. • FFAGs will have a bright future in physics (high intensity drivers, • muon accelerators, etc.) • FFAG might become a next generation medical accelerator of choice J. Pasternak