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The High-Emittance Muon The High-Emittance Muon ColliderCollider

David Neuffer

June 2009Low Emittance Muon Collider Workshop Preview

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OutlineOutline

Introduction Motivation

Scenario Outline and Features Parameters Proton Driver Front End Accelerator Collider

Upgrade Path(s) to Low-Emittance Muon Collider

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Motivation- E. EichtenMotivation- E. Eichten

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Other physics Other physics

Higgs at high energy σ ≈ 0.6pb

0.01 fb-1 is 1030 for 107s need more to sweep

nearby energy First

SuperDimensional DarkMatterEnergy HyperSymmetric Particle?? σ > pb !!

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2A

2 TeV

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HEMC Parameters HEMC Parameters

Parameter Symbol Value

Proton Beam Power Pp 2.4 MW

Bunch frequency Fp 60 Hz

Protons per bunch Np 3×1013

Proton beam energy Ep 8 GeV

Number of muon bunches nB 12

+/-/ bunch N 1011

Transverse emittance t,N 0.003m

Collision * * 0.05m

Collision max * 10000m

Beam size at collision x,y 0.013cm

Beam size (arcs) x,y 0.55cm

Beam size IR quad max 5.4cm

Collision Beam Energy E+,E_ 1 TeV (2TeV total)

Storage turns Nt 1000

Luminosity L0 4×1030

Proton Linac 8 GeV

Accumulator,Buncher

Hg target

Linac

RLAs

Collider Ring

Drift, Bunch, Cool

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Proton DriverProton Driver

Proton Driver is variant of Project X Other variations possible 8 GeV at Fermilab

8 GeV SRF linac , 15 Hz 1.2×1014/cycle

Accumulate, Bunch to form 4 bunches 3×1013/bunch

• εN6π =120π mm-mrad, BF = 0.005

• δν = 0.4 extract at 60Hz

Proton Linac 8 GeV

Accumulator,Buncher

Drift, Bunch, Cool

Hg target

Linac

RLAs

Collider Ring

Detector

p tot

2F N

3r N

2 B

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Solenoid lens captureSolenoid lens capture

Target is immersed in high field solenoid Particles are trapped in Larmor orbits

B= 20T -> ~2T Particles with p < 0.3 BsolRsol/2=0.225GeV/c are

trapped π→μ Focuses both + and – particles Drift, Bunch and phase-energy rotation

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High-frequency Buncher and High-frequency Buncher and φφ-E -E RotatorRotator

Drift (π→μ) “Adiabatically” bunch beam first (weak 320 to 240 MHz rf)

Φ-E rotate bunches – align bunches to ~equal energies 240to 202 MHz, 15MV/m

Cool beam 201.25MHz

10 m ~50 m

FE

Targ et

Solenoid Drift Buncher Rotator Cooler

~30m 36m ~80 m

p

π→μ

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Adiabatic Buncher; Adiabatic Buncher; φφ-E rotation-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 : 0.901.5m

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Bunch train for ColliderBunch 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 < 0.03, AL <0.2 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

εt,rms, normalized ≈ 0.003m (accepted μ’s)

εL,rms, normalized≈ 0.034m (accepted μ’s)

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Simulations (NSimulations (NBB=10)=10)

-30m 30m

500 MeV/c

0

Drift andBunch

s = 89ms = 1m

Rotate

s = 125m s = 219m

Cool

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HEMC collider bunchesHEMC collider bunches

Scenario is unoptimized ~60% of μ’s in best 12

bunches ~75% in best 16

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Acceleration-RLA’s ? Acceleration-RLA’s ?

1.2 GeV/pass7.2 GeV

1.8 GeV244 MeV

300 m

160 m

5 GeV/pass

528 m32.5GeV

7 pass Ef

E0

= 30Dogbone RLA II example

Linac

140 GeV/pass

32.5 GeV

1000 GeV

Dogbone geometry is long. (140 GeV @20MV/m is 7km.)Racetrack is more compact.

A. Bogacz – Dogbone RLAs

Beam is probably too big for 1300MHz.800 MHz - OK

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Collider RingCollider Ring

12 bunches of μ+ and μ-

1011 μ/bunch

β* = 3 to 10 cm σ= 0.01 to 0.016cm

βmax = 10000m σ=5.5cm (1TeV) IR quads are large aperture (20cm

radius)

εL =0.012 eV-s δE ~0.12 GeV if σz = 3cm δE/E = 10-4

Collider is not beam-beam limited Δν=0.000036

,4 beam beamN rms

N r

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Upgrade pathUpgrade path

More cooling εt,N→ 0.0005, β*→1cm

L→1032

Bunch recombination 12→1 L →1033

More cooling low emittance εt,N→ 0.00003, β*→0.3cm

L→1034

More Protons 2.4→5MW or more L→1035

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ConclusionsConclusions

An Initial Muon Collider (0.5 to 4 TeV) with low luminosity could be constructed, particularly if motivated by a clear physics goal. Uses trains of μ+ and μ- bunches for acceleration and storage (~ 20m trains) L= ~4×1030 cm-2s-1

needs little cooling does need front end (captures both μ+ and μ-)

Could be upgraded to high-luminosity more cooling smaller β* bunch recombination

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First First μμ Collider may not be perfect Collider may not be perfect ……