Proton acceleration using FFAGs J. Pasternak, Imperial College, London / RAL

1. Proton acceleration using FFAGs J. Pasternak, Imperial College, London / RAL J. Pasternak, IC London/RAL

2. Introduction • Lattice studies for PAMELA • Tune stabilization • Towards high intensity FFAG proton driver. J. Pasternak, IC London/RAL

3. Proton acceleration is very important: • Medical applications • neutrino factory • super beam • beta beam • neutron production • radioactive beam facility • muon collider • antiproton production • ADSR systems • etc. J. Pasternak, IC London/RAL

4. RACCAM Project • N 10 • k 5.15 • Spiral angle 53.5° • 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 Change of energy takes 0.1 s! J. Pasternak, IC London/RAL

5. Lattice studies for PAMELA Nonlinear Nonscaling FFAGs (NNSFFAG -?) were proposed by G. Rees. They use nonlinear fields for various reasons, but off-momentum orbits do not scale. • Motivations for medical Nonlinear Nonscaling design: • Reduction of orbit excursion with respect to scaling designs – in order • to achieve energy variability by kicker system and reduce the magnet cost • Acceleration with (quasi)constant tunes in order to allow for low RF gradient. • Acceleration based on MA cavities with modest gradient. Nonliner fields are used to control tune variation. J. Pasternak, IC London/RAL

6. Basic assumptions for PAMELA • Space needed for extraction sepum (1 T) defines • length of long straight • Doublet to limit number of magnets and allow for long • straight • Both magnets – rectangular of equal length • Short ss fixed to 0.1 m • Magnet packing factor fixed at 0.4 • Lattice of non-scaling type (negative deflection in F) • Chromatic correction to limit tune excursion below 0.5 per ring • by introducing multipoles – NONLINEAR NON-SCALING FFAG • Phase advance per cell > 90° for H and <90° for V • Free parameters: cell length, number of cells, negative deflection Orbit excursion ~ External magnet radius (??) J. Pasternak, IC London/RAL

7. Preliminary proton (carbon) lattice parameters • N 24 • Lcell 1.9 m • Lmagnet 0.38 m • Lstraigh 1.04 m • Orbit excursion 0.22 m • R 7.25 m • (Qx, Qy)/cell (0.26, 0.12) • Bmax 1.8 T (normal conducting) • pf 0.4 • Injection energy 17 MeV (4.2 MeV/n) • Extraction energy 250 MeV (68.3 MeV/n) J. Pasternak, IC London/RAL

8. Tune stabilization - example F magnet – negative bending Parameters: Number of cells 12 Lattice type DFD triplet (QH, QV) (3.8, 1.3) R 4.8 m Drift Length 1 m Extraction septum field 0.8 T Protons 15-200 MeV D magnet – positive bending J. Pasternak, IC London/RAL

9. Linear optics (2) Betatron functions at 84.25 MeV Dispersion J. Pasternak, IC London/RAL

10. Chromaticity correction T Magnetic field m J. Pasternak, IC London/RAL

11. Chromaticity correction T Magnetic field m J. Pasternak, IC London/RAL

12. Chromaticity correction (3) Orbits with correction Orbits without correction J. Pasternak, IC London/RAL

13. Beam Dynamics px Horizontal unnormalized DA at 84.25 Mev 780 m x, m py Vertical unnormalized DA at 84.25 Mev 1900 m y, m J. Pasternak, IC London/RAL

14. Motivations for FFAG proton driver for Neutrino Factory • Very high repetition rate – 100 Hz or more • Constant magnetic field • Simple operation • Cost effective • Magnet and RF technology known • FFAG can boost linac energy (by factor 3-4 in momentum) • Main parameters of neutrino factory proton driver: • 4 MW • 50 Hz • 5 – 10 GeV • 3-5 bunches at 2 ns (rms) J. Pasternak, IC London/RAL

15. NF Proton Driver (2) FFAG – 10 GeV RCS 50 Hz 50 Hz, 3 GeV 200 MeV • Current scenario – G. Rees: • limited to 50 Hz • 2 rings • low injection energy • complicated lattice cell • (5 magnets) H- Linac J. Pasternak, IC London/RAL

16. NF Proton Driver (3) Alternative 1) RCS or FFAG, 10 GeV, 50 Hz 300 MeV H- Linac Neutrino factory target, 4 MW, 50 Hz 2.5 GeV, 5 MW FFAG, 100 Hz Neutron production target, 2.5 MW, 50 Hz • Still 2 rings • 100 – 200 Hz for booster • FFAG operation possible J. Pasternak, IC London/RAL

17. NF Proton Driver (4) Alternative 2) Neutrino factory target, 4 MW, 50 Hz, 5GeV 800 MeV H- Linac Neutron production target, 2.5 MW, 50 Hz,2.5 GeV 5 GeV, 5 MW FFAG, 100 Hz • Now 1 FFAG ring! • 100 – 200 Hz for booster • FFAG operation possible • Operation as an accumulator ring possible J. Pasternak, IC London/RAL

18. Scaling or Non-scaling ? • High intensity operation requires • chromaticity close to zero -> scaling! • But …non-scaling designs allow for smaller • orbit excursion and simpler magnets. • Nonlinear non-scaling, tune stabilized lattices may be a solution. J. Pasternak, IC London/RAL

19. Preliminary design parameters (alternative 1) • N of cells 64 • Lattice type dublet • R 34.6 m • (Qx, Qy)/cell (0.269, 0.19) • Bmax 1.7 T • Magnet packing factor 0.4 • E 0.3 - 2.5 GeV • h 5 • RF swing 4.5– 6.5 MHz • Drift length 1.9 m • T 37.6 J. Pasternak, IC London/RAL

20. Summary and future plans • FFAGs are perfect machines for many applications! • We need to compare a scaling designs with the non-scaling tune stabilized ones. • Tune stabilization has to be studied in detail. • Space charge simulations have to be performed. • Possibility to introduce insertions has to be studied. J. Pasternak, IC London/RAL