Source Group

Bethan DormanPaul Morris

Laura CarrollAnthony GreenMiriam Dowle

Christopher BeachSazlin Abdul Ghani

Nicholas Torr

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.

Proton Driver

Hydrogen

GasPlasma Solenoids

H-ion beam

Proton Driver

Hydrogen

GasPlasma Solenoids

Radio Frequency Quadrupole

Chopper

Proton Driver

Hydrogen

GasPlasma Solenoids

Radio Frequency Quadrupole

ChopperThin foil

Acceleration

Proton Acceleration

Linac

Super Conducting Linac

Synchrotron

Super Conducting Synchroton

Proton FFAG

Proton Driver

Hydrogen

GasPlasma Solenoids

Radio Frequency Quadrupole

ChopperThin foil

Acceleration Target

10 GeV Protons

Bunch length ~ 1 ns

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

Target, Capture & Decay

• Why not solid materials like Au (Gold), Tantalum or Thallium?

Radiation Damage Thermal shock Cooling problem Eddy current effects

Target, Capture & Decay

Figure 1: Left: Liquid Mercury target Right: Solid Carbon target

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.

Drift Section• Allows pions to decay to muons.

• Decay length L0 needed, relativity a factor.

L0 = βc x γτ where γ = E/m

•Probability of decay given by,P = 1 – exp(-LD / L0)

• Pions with E = 5GeV, ~84% decay in a tunnel of length 500m.

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.

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.

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.

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

Scaling or Non-ScalingScaling 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.

The acceleration in FFAG’s occur in RF cavities between the bending magnets.

F F D

Extraction Trajectory

Injection Trajectory

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.

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 Ring High Energy Ring

Energy range (GeV) 5 to 10 10 to 20

Ring Radius (m) 64 80

RF Characteristics 10 MV/m, 201MHz 10 MV/m, 201MHz

Total RF Volatge 480 MV 578 MV

Orbits to Emax 9.6 16.5

Acceleration Time (μs)

13 28

Particle Decay Loss 9% 10%

Muon Storage Rings

Where the muons decay to neutrinos

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Accelerated to relativistic speeds Increases muon lifetime

Muon Storage RingsGeometries

Two main types:

1.) Triangle 2.) Racetrack

Muon Storage RingsTriangular- Can produce

and simultaneouslyalong axis of the decay straights (totwo different detector sites)

- More efficient than racetrack configuration

Muon Storage RingsRacetrack

- Produces highly collimated neutrino beams

- More flexible geometry due to flexibility in number of allowed muon bunches.

Muon Storage Rings

Triangle Racetrack

Efficiencies

Summary

Thank you

http://neutrinosourcegroup.wikispaces.com

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Beam Dump Beam

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