1. Source Group Bethan Dorman Paul Morris Laura Carroll Anthony Green Miriam Dowle Christopher Beach Sazlin Abdul Ghani Nicholas Torr

2. Why? A Neutrino Factory yields the highest flux neutrino beams achievable, and the beam parameters are well controlled and understood A Neutrino Factory is the only way to produce equal ratios of electron and muon type neutrinos Thus, the Neutrino Factory and its remote detector will enable precision measurements of all the unknown parameters.

4. Proton Driver Hydrogen Gas Plasma Solenoids

5. H-ion beam

6. Proton Driver Hydrogen Gas PlasmaSolenoids R adio F requency Q uadrupole Chopper

8. Proton Driver Hydrogen Gas PlasmaSolenoids R adio F requency Q uadrupole ChopperThin foil Acceleration

9. Proton Acceleration  Linac  Super Conducting Linac  Synchrotron  Super Conducting Synchroton  Proton FFAG

10. Proton Driver Hydrogen Gas PlasmaSolenoids R adio F requency Q uadrupole ChopperThin foil Acceleration Target 10 GeV Protons Bunch length ~ 1 ns

11. Target, Capture & Decay Target material – Liquid-Hg. Why?  High atomic number, Z = 80. Target limitations:  Bunch length ~ 1 ns  Bunch Intensity ~ to be determined  Pulse Duration ~ < 40 μs  Repetition Rate ~ 50 Hz

12. Target, Capture & Decay Why not solid materials like Au (Gold), Tantalum or Thallium?  Radiation Damage  Thermal shock  Cooling problem  Eddy current effects

13. Target, Capture & Decay Figure 1: Left: Liquid Mercury target Right: Solid Carbon target

14. Target, Capture & Decay The Hg-jet target inside a 20-T solenoid magnet to capture the decayed pions and muons. The pion-muon production in the target followed by a transport channel of a magnetic solenoid.

15. Drift Section Allows pions to decay to muons. Decay length L 0 needed, relativity a factor. L 0 = βc x γτ where γ = E/m Probability of decay given by, P = 1 – exp(-L D / L 0 ) Pions with E = 5GeV, ~84% decay in a tunnel of length 500m.

16. Phase Rotation Needed to match initial muon “longitudinal phase space” into RF buckets for further cooling/acceleration. To determine how well matched the phase space of a particle an acceptance is defined. Each section of the accelerator complex will have a different acceptance measured in πm-rad. 1-D longitudinal acceptance is given by, A || = βγ(ΔE/E)cΔt where ΔE/E is the energy spread of the beam and Δt is the time spread between individual particles arriving. Matching is achieved by decelerating particles that arrive with high energy and accelerating those with low energy. This bunches the particles together.

17. Ionization cooling Reduces transverse emittance and match transverse acceptance in later accelerators. Uses liquid hydrogen absorbers to reduce the energy of the particles in 3-dimensions and then re-accelerates them in a linear path along the required axis. Reduces energy spread (emittance). Reduces time spread. Ensures healthy flux. Matches RF frequencies for later acceleration. Improves performance by a factor of 10 and cost by 20%. Many ways to accomplish this. Decisions based on effectiveness, cost and necessity.

18. The ‘Neuffer’ System Many different methods but ‘Neuffer’ uses existing technology – more cost effective. Allow particles to drift – means there is then a correlation between position and momentum. Bunch the beam using RF cavities – which use a standing wave whose frequency is set such that it gives particles an accelerating push as they pass through. Phase Rotate to align the energies. Inject into a cooler system – probably use a wedge absorber. This focuses the beam (reduces its emittance) so that it is accepted into the accelerator system. Accepts both positive and negative muons – will need a sign divider to filter out the sign that is not wanted for a particular experiment.

19. FFAG’s for Muon Acceleration Fixed Field Alternating Gradient accelerators: Muon decays occur too quickly for cycling magnets. Require less RF then Linacs and RLA. FFAG lattice can accept beam over large energy range (5-20 GeV). And a large momentum acceptance. High repetition rate. Small magnet apertures. Field increases with particle energy but through path variation not time variation. Orbit changes with energy, RF changes slightly. Injection low energy Extraction high energy

20. Scaling or Non-Scaling Scaling FFAG’s have a constant orbit shape, Which gives constant betaron tune. If Non-Scaling then can lose control of tune so get resonance. However with rapid acceleration betaron doesn’t have time to build up resonances that destroy the beam. Advantages to Non-Scaling FFAG’s: Smaller orbit excursion thus small/cheaper magnets. Higher RF system can be used ~200MHz Linear variation of magnetic field with radius which leads to a large dynamic aperture and transverse acceptance.

21. The acceleration in FFAG’s occur in RF cavities between the bending magnets. RF Cavities The accelerating field varies sinusoidally with time. For a particle to be accelerated, they must arrive at the cavity at the right time. RF Voltage Time Example: For a muon (negative charge) to be accelerated it should arrive in the RF cavity at positive and exit at negative voltage.

22. Typical Values Depending on the desired energy one or two FFAG’s can be used. The values for the two ring case are shown below: Low Energy RingHigh Energy Ring Energy range (GeV)5 to 1010 to 20 Ring Radius (m)6480 RF Characteristics10 MV/m, 201MHz Total RF Volatge480 MV578 MV Orbits to E max 9.616.5 Acceleration Time (μs) 1328 Particle Decay Loss9%10%

23. Muon Storage Rings Where the muons decay to neutrinos. Accelerated to relativistic speedsIncreases muon lifetime

24. Muon Storage Rings Geometries Two main types: 1.) Triangle 2.) Racetrack

25. Muon Storage Rings Triangular - Can produceandsimultaneously along axis of the decay straights (to two different detector sites) - More efficient than racetrack configuration

26. Muon Storage Rings Racetrack - Produces highly collimated neutrino beams - More flexible geometry due to flexibility in number of allowed muon bunches.

27. Muon Storage Rings Triangle Racetrack Efficiencies

28. Summary

29. Thank you http://neutrinosourcegroup.wikispaces.com

31. Slow Chopper Beam DumpBeam Fast Chopper