1. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Proton acceleration using FFAGs J. Pasternak, Imperial College, London / RAL

2. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 1.Introduction 2.Lattice studies for PAMELA 3.Tune stabilization 4.Towards high intensity FFAG proton driver.

3. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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.

4. FFAG’08 04.09.2008J. Pasternak, IC London/RAL RACCAM Project N 10 k 5.15 Spiral angle 53.5° R max 3.46 m R min 2.8 m (Qx, Qy) (2.77, 1.64) B max 1.7 T p f 0.34 Injection energy 6-15 MeV Extraction energy 75-180 MeV h 1 RF frequency 1.9 – 7.5 MHz Bunch intensity 3  10 9 protons Change of energy takes 0.1 s!

5. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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. Lattice studies for PAMELA

6. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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 (??)

7. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Preliminary proton (carbon) lattice parameters N 24 L cell 1.9 m L magnet 0.38 m L straigh 1.04 m Orbit excursion 0.22 m R 7.25 m (Qx, Qy)/cell (0.26, 0.12) B max 1.8 T (normal conducting) p f 0.4 Injection energy 17 MeV (4.2 MeV/n) Extraction energy 250 MeV (68.3 MeV/n)

8. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Tune stabilization - example Parameters: Number of cells 12 Lattice type DFD triplet (Q H, Q V ) (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 F magnet – negative bending

9. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Linear optics (2) Betatron functions at 84.25 MeV Dispersion

10. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Chromaticity correction Magnetic field m T

11. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Chromaticity correction Magnetic field m T

12. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Chromaticity correction (3) Orbits without correction Orbits with correction

13. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Beam Dynamics x, m py y, m px Vertical unnormalized DA at 84.25 Mev 1900  m Horizontal unnormalized DA at 84.25 Mev 780  m

14. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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)

15. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Current scenario – G. Rees: limited to 50 Hz 2 rings low injection energy complicated lattice cell (5 magnets) RCS 50 Hz 50 Hz, 3 GeV 200 MeV H - Linac NF Proton Driver (2) FFAG – 10 GeV

16. FFAG’08 04.09.2008J. Pasternak, IC London/RAL NF Proton Driver (3) Alternative 1) 300 MeV H - Linac 2.5 GeV, 5 MW FFAG, 100 Hz Neutrino factory target, 4 MW, 50 Hz Neutron production target, 2.5 MW, 50 Hz RCS or FFAG, 10 GeV, 50 Hz Still 2 rings 100 – 200 Hz for booster FFAG operation possible

17. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 800 MeV H - Linac Neutrino factory target, 4 MW, 50 Hz, 5GeV 5 GeV, 5 MW FFAG, 100 Hz NF Proton Driver (4) Neutron production target, 2.5 MW, 50 Hz,2.5 GeV Now 1 FFAG ring! 100 – 200 Hz for booster FFAG operation possible Operation as an accumulator ring possible Alternative 2)

18. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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.

19. FFAG’08 04.09.2008J. Pasternak, IC London/RAL Preliminary design parameters (alternative 1) N of cells 64 Lattice type dublet R 34.6 m (Qx, Qy)/cell (0.269, 0.19) B max 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

20. FFAG’08 04.09.2008J. Pasternak, IC London/RAL 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.