The LargeEmittance Muon Collider

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The Large-Emittance Muon Collider

• David Neuffer
• June 2009
• LEMC Workshop

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Outline

• Introduction
• Motivation
• Scenario Outline and Features
• Parameters
• Proton Driver
• Front End
• Accelerator
• Collider
• Upgrade Path(s)
• to Medium-Emittance Muon Collider

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Motivation- E. Eichten
4
Other physics

• Higgs at high energy
• s 0.6pb
• 0.01 fb-1 is 1030 for 107s
• need more to sweep nearby energy
• First SuperDimensional DarkMatterEnergy
  HyperSymmetric Particle??
• s gt pb !!

5

• Start with 4-GeV ?-Factory scenario
• Add accelerator and storage ring
• Get Collisions

2A
2 TeV
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LEMC Parameters
Proton Linac 8 GeV
Accumulator, Buncher
Hg target
Drift, Bunch, Cool 200m
Linac
RLAs
Detector
Collider Ring
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Proton Driver
Proton Linac 8 GeV

• Proton Driver is variant of Project X
• Other variations possible
• 8 GeV at Fermilab
• 8 GeV SRF linac , 15 Hz
• 1.21014/cycle
• Accumulate, Bunch to form 4 bunches
• 31013/bunch
• eN6p 120p mm-mrad, BF 0.005
• d? 0.4
• extract at 60Hz

Accumulator, Buncher
Hg target
Drift, Bunch, Cool
Linac
RLAs
Detector
Collider Ring
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Solenoid lens capture

• Target is immersed in high field solenoid
• Particles are trapped in Larmor orbits
• B 20T -gt 2T
• Particles with p? lt 0.3 BsolRsol/20.225GeV/c are
  trapped
• p?µ
• Focuses both and particles
• Drift, Bunch and phase-energy rotation

p?m
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High-frequency Buncher and f-E Rotator

• Drift (p?µ)
• Adiabatically bunch beam first (weak 320 to 240
  MHz rf)
• F-E rotate bunches align bunches to equal
  energies
• 240to 202 MHz, 15MV/m
• Cool beam 201.25MHz

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Adiabatic Buncher f-E rotation

• Set rf phase to be zero for reference energies
• Spacing is N ?rf
• ??rf increases
• gradually increase rf gradient
• Match to ?rf 1.5m at end
• After bunching rephase rf so that higher energy
  bunches accelerate, low energy bunches
• Finish when bunch energies are aligned in E
• Transfer to cooling
• Captures both µ and µ-
• born from same proton bunch

Example ?rf 0.90?1.5m
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Bunch train for Collider

• Drift, buncher, rotator to get short bunch
  train (nB 10)
• 217m ? 125m
• 57m drift, 31m buncher, 36m rotator
• Rf voltages up to 15MV/m (2/3)
• Obtains 0.1 µ/p8 in ref. acceptance
• At lt 0.03, AL lt0.2
• Choose best 12 bunches
• 0.008 µ/p8 per bunch
• 0.005 µ/p8 in acceptance
• 3 1013 protons
• 1.5 1011 µ/bunch in acceptance
• et,rms, normalized 0.003m (accepted µs)
• eL,rms, normalized 0.034m (accepted µs)

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Simulations (NB10)
s 1m
s 89m
Drift and Bunch
Rotate
500 MeV/c
s 219m
s 125m
Cool
0
30m
-30m
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LEMC collider bunches

• Scenario is unoptimized
• 60 of µs in best 12 bunches
• 75 in best 16

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Acceleration-RLAs ?
A. Bogacz Dogbone RLAs
Bunch Combiner ring (30 GeV?) would increase
luminosity (12 -gt 1 even with 30 decay L 6)
Beam may be too big for 1300MHz SRF. 800 MHz - OK
Dogbone RLA III example
10 pass
32.5 GeV
1000 GeV
Linac 100 GeV/pass
Dogbone geometry is long. (100 GeV _at_25MV/m is
4km.) Racetrack is more compact.
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Collider Ring

• 12 bunches of µ and µ-
• 1011 µ/bunch
• ß 3 to 10 cm
• s 0.01 to 0.016cm
• ßmax 10000m
• s5.5cm (1TeV)
• IR quads are large aperture (15cm radius)
• eL 0.012 eV-s
• dE 0.12 GeV if sz 3cm
• dE/E 10-4
• Collider is not beam-beam limited
• ??0.000036

R500m Bave 6.7T
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Upgrade path

• More cooling
• et,N? 0.0005, ß?1cm
• L?1032
• Bunch recombination
• 12?1
• L ?1033
• More cooling
• low emittance
• et,N? 0.00003, ß?0.3cm
• L?1034
• More Protons
• 2.4?5MW or more
• L?1035

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LEMC Parameters -Upgrade

• Reduce transverse emittance to 0.001m
• Could then use 1300MHz ?
• IR quads less than r 10cm
• Combine 12 bunches to 1

Proton Linac 8 GeV
Accumulator, Buncher
Hg target
Drift, Bunch, Cool
Linac
RLAs
Bunch Combiner
Collider Ring
d?BB 0.0014
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Conclusions

• An Initial Muon Collider (0.5 to 4 TeV) with low
  luminosity could be constructed, particularly if
  motivated by a clear physics goal.
  Lgt41030cm-2s-1
• L -gt 1032 cm-2s-1
• needs little cooling
• does need front end (captures both µ and µ-)
• Could be upgraded to high-luminosity
• more cooling
• smaller ß
• more protons
• Accelerator is most expensive item
• 10 pass RLA - 100 GeV

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Start with 1032
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????? Collider Parameters